Articles containing the keyword 'EC'

The paper elaborates upon various theories to explain economic development and restructuring in the forested regions of advanced countries. The concepts of communities based on the forest sector and the concept of restructuring are discussed before presenting the diversity of relevant theories. Different theoretical approaches in geography and regional and socio-economic sciences are analysed, and the paper concludes that each theory gives only a partial explanation of restructuring under certain conditions. This paper recommends that an explanatory framework should take into account – in addition to general explanatory factors – sectoral, local-specific and policy-related factors and the role of human agency in attempts to explain restructuring and development.

• Tykkyläinen, E-mail: mt@mm.unknown
• Hyttinen, E-mail: ph@mm.unknown
• Mononen, E-mail: am@mm.unknown

The study proposes a technique which enables the computation of user-defined indices for species diversity. These indices are derived from characteristics, called diversity indicators, of inventory plots, stand compartments, and the whole forest holding. The study discusses the modifications required to be made to typical forest planning systems due to this kind of biodiversity computation. A case study illustrating the use of the indices and a modified forest planning system is provided. In the case study, forest-level species diversity index was computed from the volume of dead wood, volume of broadleaved trees, area of old forest, and between-stand variety.

At the stand level, the area of old forest was replaced by stand age, and variety was described by within-stand variety. All but one of the indicators were further partitioned into two to four sub-indicators. For example, the volume of broadleaved trees was divided into volumes of birch, aspen, willow, and other tree species. The partial contribution of an indicator to the diversity index was obtained from a sub-priority function, determined separately for each indicator. The diversity index was obtained when the partial contributions were multiplied by the weights of the corresponding indicators and then were summed. The production frontiers computed for the harvested volume and diversity indices were concave, especially for the forest-level diversity index, indicating that diversity can be maintained at satisfactory level with medium harvest levels.

• Pukkala, E-mail: tp@mm.unknown
• Kangas, E-mail: jk@mm.unknown
• Kniivilä, E-mail: mk@mm.unknown
• Tiainen, E-mail: at@mm.unknown

The effects of precommercial thinning on the quantity and external quality of young Scots pine (Pinus sylvestris L.) stands were examined over two 10-year periods in an experiment comprising five stands growing on sub-dry sites in Finnish Lapland, northern Finland. The thinning treatments applied resulted in stand densities of 625, 1111, 1600, 2500 and 4444 stems ha^-1 and a no-treatment, unthinned plot with a randomised block lay-out of two or three replications in each stand. The dominant height of the stands varied between 4 and 8 m at the time of thinning.

The trees reacted only slightly to the increase in growing space during the first ten years following precommercial thinning. During the second 10-year period, increased growing space was reflected more clearly in diameter and volume increment. These reactions were more evident in stands thinned at an early stage. The increment of the thinnest 100–200 trees ha^-1 in each treatment was poor. The results showed that when the main principle in precommercial thinning is to achieve even spacing, the remaining smallest trees fail to react positively to the increase in growing space. In other words, the target of precommercial thinning should be to concentrate the increment on the tallest trees, even though they are located in groups. The external quality of the trees in stands where precommercial thinning was carried out at a later stage was high, and the diameter of the thickest branch along the butt log remained under 20 mm. Branch diameter was greater in stands thinned at an early stage. The effect of precommercial thinning on branch diameter when comparing the extreme treatments averaged 5 mm. When the aim of stand management is to combine high quality and good yield in naturally regenerated Scots pine stands in northern Finland, precommercial thinning should not be carried out before the dominant height of 7–8 m. The intensity of precommercial thinning depends on the yield targets of the first commercial thinning. A spacing of 2,500 stems ha^-1 satisfies the requirements of both high quality and adequate yield.

• Ruha, E-mail: tr@mm.unknown
• Varmola, E-mail: mv@mm.unknown

In the last decades, architectural analysis has been used to understand and to model plant development. These studies have led us to reconsider the problem of measuring plants while taking into account their topological structure at several scales of detail. A computational platform, called AMAPmod, was created to work on such plant representations. This paper outlines the general methodology used in AMAPmod to represent plant topological structures and to explore these special types of databases. Plant structures are first encoded in order to build corresponding formal representations. Then, a dedicated language, AML, enables the user to extract various types of information from the plant databases and provides appropriate analysing tools.

• Godin, E-mail: cg@mm.unknown
• Caraglio, E-mail: yc@mm.unknown
• Costes, E-mail: ec@mm.unknown

A new approach for modelling plant growth using the software AMAPpara is presented. This software takes into consideration knowledge about plant architecture which has been accumulated at the Plant Modelling Unit of CIRAD for several years, and introduces physiological concepts in order to simulate the dynamic functioning of trees. The plant is considered as a serial connection of vegetative organs which conduct water from the roots to the leaves. Another simple description of the plant as a network of parallel pipes is also presented which allows an analytical formulation of growth to be written. This recurring formula is used for very simple architectures and is useful to understand the role of each organ in water transport and assimilate production. Growth simulations are presented which show the influence of modifications in architecture on plant development.

• de Reffye, E-mail: pd@mm.unknown
• Barthélémy, E-mail: db@mm.unknown
• Blaise, E-mail: fb@mm.unknown
• Fourcaud, E-mail: tf@mm.unknown
• Houllier, E-mail: fh@mm.unknown

The rule-based formal language of "stochastic sensitive growth grammars" was designed to describe algorithmically the changing morphology of forest trees during their lifetime under the impact of endogenous and exogenous factors, and to generate 3-D simulations of tree structures in a systematic manner. The description in the form of grammars allows the precise specification of structural models with functional components. These grammars (extended L-systems) can be interpreted by the software GROGRA (Growth grammar interpreter) yielding time series of attributed 3-D structures representing plants. With some recent extensions of the growth-grammar language (sensitive functions, local variables) it is possible to model environmental control of shoot growth and some simple allocation strategies, and to obtain typical competition effects in tree stands qualitatively in the model.

• Kurth, E-mail: wk@mm.unknown
• Sloboda, E-mail: bs@mm.unknown

The model HYDRA, which simulates water flow in the branched tree architecture, is characterized. Empirical studies of the last decades give strong evidence for a close structure-function linkage in the case of tree water flow. Like stomatal regulation, spatial patterns of leaf specific conductivity can be regarded as a strategy counteracting conductivity losses, which may arise under drought. Branching-oriented water flow simulation may help to understand how damaging and compensating mechanisms interact within the hydraulic network of trees. Furthermore, a coupling of hydraulic to morphological modelling is a prerequisite if water flow shall be linked to other processes. Basic assumptions of the tree water flow model HYDRA are mass conservation, Darcy's law and the spatial homogeneity of capacitance and axial conductivity. Soil water potential is given as a one-sided border condition. Water flow is driven by transpiration. For unbranched regions these principles are condensed to a nonlinear diffusion equation, which serves as a continuous reference for the discrete method tailored to the specific features of the hydraulic network. The mathematical derivation and model tests indicate that the realization of the basic assumptions is reproducible and sufficiently exact. Moreover, structure and function are coupled in a flexible and computationally efficient manner. Thus, HYDRA may serve as a tool for the comparative study of different tree architectures in terms of hydraulic function.

• Früh, E-mail: tf@mm.unknown

A method for the measurement of the three-dimensional (3D) architecture of trees was applied to describe two 20-year-old walnut trees, one of them is a timber tree while the other is a fruit tree. The method works at the shoot level and simultaneously describes the plant topology, the plant geometry and the shoot morphology. The method uses a 3D digitiser (3SPACE® FASTRAK®, Polhemus Inc.) associated with software DiplAmi designed for digitiser control and data acquisition management. Plant images may be reconstructed from the data set by using the ray tracing software POV-Ray. Visual comparison between photographs of the walnut trees and images synthesised from digitising was satisfactory. Distribution of basal shoot diameter, as well as leaf area and fruit distributions for both the timber and the fruit tree were non-uniformly distributed in the crown volume. Gradients were likely to be related to the light distribution within the tree. This is in agreement with previous experimental results on several tree species, and also with the predictions of tree architecture models based on light-vegetation interactions.

• Sinoquet, E-mail: hs@mm.unknown
• Godin, E-mail: cg@mm.unknown
• Rivet, E-mail: pr@mm.unknown

The existence and direction of causal relationships between the time series for the Finnish roundwood market for the period 1960–1994 is tested. Using simple bivariate analysis, we found evidence that for both logs and pulpwood, the lagged prices are helpful in forecasting quantity for the next year, but not vice versa. Saw log stumpage prices have significantly Granger-caused pulpwood prices over the business cycles, but the effect has diminished towards the present time. For quantities traded, the direction of causality was rather from pulpwood to saw logs. The consistency of bivariate test results was checked by the Granger-causality tests within trivariate VAR-models for both markets, and the results were found to be fairly similar to bivariate tests. The price fluctuations in the international markets for forest products have been found to be carried to domestic wood markets dominantly via the pulpwood part of the market.

• Toppinen, E-mail: at@mm.unknown

Many kinds of planning systems have been labelled decision support systems (DSS), but few meet the most important features of real DSSs in planning and control of wood procurement. It has been concluded that many reasons exist to develop DSSs for wood procurement. The purchasing of timber seems to be one of the most promising areas for DSS, because there is no formal structure for these operations and decisions deal with human behaviour. Relations between DSSs and different features of the new approaches in wood procurement are also discussed, and hypotheses for future studies suggested.

• Harstela, E-mail: ph@mm.unknown

Linear programming (LP) is an important method for allocation of wood inventory stock. It is, for instance, used alone in tactical planning systems, which currently are in wide use at the higher hierarchical level in the functionally decentralized planning of the Finnish forest industry. Unfortunately, LP as a solution method has not been capable of handling spatial data that seem to characterize planning systems in geographical decentralization. In the present study, GIS was used to assimilate data from different wood procurement functions, to calculate transportation distances and cost figures, and to write the data in ASCII files, which were then used as input for the LP model. Using the experiments and methods of GIS on a planning system developed according to participatory planning, the results of this study suggest that the participatory method was faster than the conventional LP method, when solved using actual data. The participatory method was also capable of providing the same global optimum for a wood allocation problem. The implications of these results for improving operational and tactical planning of wood procurement in Finland are discussed.

• Palander, E-mail: tp@mm.unknown

Three most promising protection methods of pine pulp wood stacks against the attacks of Tomicus piniperda L. were compared. The methods were the covering of stacks by fibreglass-strengthened paper or twofold achrylene netting, removing the upper parts of stacks, and enhanced planning of the placement of the timber store using ARC/INFO GIS-software. T. piniperda was observed to strongly prefer the upper parts of the stacks: 90 % of the beetles occurred within 0.5 meters of the top of the stacks. Covering of the stacks decreased the attack density of T. piniperda, and the protection effect of covering was 80 %. Due to long transport distances and fragmentation of forest landscape the relocation of timber store was found to be an unsuitable method in the practical level. Also, taking into account the costs of the method, removing of the upper parts of stacks was considered to be the optimal solution.

• Jääskelä, E-mail: mj@mm.unknown
• Heliövaara, E-mail: kh@mm.unknown
• Peltonen, E-mail: mp@mm.unknown
• Saarenmaa, E-mail: hs@mm.unknown

Distribution and occurrence of bark beetles and other forest insects in relation to environmental variation were analysed by multivariate methods. Eight different forest edges were studied using 10 x 10 m sample plots that formed 200 m linear transects perpendicular to the forest edge. Forest edge affected the distribution of insect species only in the edges between mature, non-managed spruce stands and clear cuts or young seedling stands, but not in the pine stands. The occurrence of the selected forest insects mainly depended on variables associated with the amount and quality of suitable woody material. The most significant environmental variables were forest site type, crown canopy coverage, tree species, number of stumps, number of dead spruce trunks and amount of logging waste at site. Quantitative classification of species and sample plots showed that some specialized species (Xylechinus pilosus, Cryphalus saltuarius, Polygraphus poligraphus and P. subopacus) adapted to mature spruce forests, tended to withdraw from the forest edge to interior stand sites. By contrast many generalized species (Pityogenes chalcographus, P. quadridens, Pissodes spp., Hylurgops palliatus, Tomicus piniperda, Dryocoetes spp. and Trypodendron lineatum) benefitted from cuttings and spread over stand borders into mature forest.

• Peltonen, E-mail: mp@mm.unknown
• Heliövaara, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown

The carbon reservoir of ecosystems was estimated based on field measurements for forests and peatlands on an area in Finland covering 263,000 km² and extending about 900 km across the boreal zone from south to north. More than two thirds of the reservoir was in peat, and less than ten per cent in trees. Forest ecosystems growing on mineral soils covering 144,000 km² contained 10–11 kg C m^-2 on an average, including both vegetation (3.4 kg C m^-2) and soil (uppermost 75 cm; 7.2 kg C m^-2). Mire ecosystems covering 65,000 km² contained an average of 72 kg C m^-2 as peat. For the landscape consisting of peatlands, closed and open forests, and inland water, excluding arable and built-up land, a reservoir of 24.6 kg C m^-2 was observed. This includes the peat, forest soil and tree biomass. This is an underestimate of the true total reservoir, because there are additional unknown reservoirs in deep soil, lake sediments, woody debris, and ground vegetation. Geographic distributions of the reservoirs were described, analysed and discussed. The highest reservoir, 35–40 kg C m^-2, was observed in sub-regions in central western and north western Finland. Many estimates given for the boreal carbon reservoirs have been higher than those of ours. Either the Finnish environment contains less carbon per unit area than the rest of the boreal zone, or the global boreal reservoir has earlier been overestimated. In order to reduce uncertainties of the global estimates, statistically representative measurements are needed especially on Russian and Canadian peatlands.

• Kauppi, E-mail: pk@mm.unknown
• Hänninen, E-mail: ph@mm.unknown
• Henttonen, E-mail: hh@mm.unknown
• Ihalainen, E-mail: ai@mm.unknown
• Lappalainen, E-mail: el@mm.unknown
• Posch, E-mail: mp@mm.unknown
• Starr, E-mail: ms@mm.unknown
• Tamminen, E-mail: pt@mm.unknown

The prefire fungal flora (polypores and corticoid fungi) of 284 dead trees, mainly fallen trunks of Norway spruce (Picea abies (L.) H. Karst.), was studied in 1991 in an old, spruce-dominated mesic forest in Southern Finland. Species diversity of the prefire fungal flora was very high, including a high proportion of locally rare species and four threatened polypore species in Finland.

In 1992 part of the study area (7.3 ha) was clear-cut and a 1.7 ha forest stand in the centre of study area was left standing with a tree volume of 150 m³/ha, and later on (June 1st) in the same year the whole area was burned. Burning was very efficient and all trees in the forest stand were dead one year after the fire. Also, the ground layer burned almost completely.

In 1993 the fungal flora of the 284 sample trees was studied again. Most of the trees had burned strongly and the fungal species diversity and the evenness in community structure had decreased considerably as compared with the prefire community. Species turnover was also great, especially in corticoid fungi. Greatest losses in the species numbers occurred in moderately and strongly decayed trees, in coniferous trees and in very strongly burned trees. Fungal flora of non-decayed and slightly decayed trees, deciduous trees and slightly burned trees seemed to have survived the fire quite well, and in these groups the species numbers had increased slightly as compared with the prefire community.

Fungal species suffering from fire (anthracophobe species) were mainly growing in moderately and strongly decayed trees before the fire, whereas species favoured by fire (anthracophile species) were growing in less decayed trees. No fruitbodies of threatened polypores or other "old-forest species" of polypores were found again after fire. Some very common and effective wood-rotting fungi (e.g. Fomitopsis pinicola, Fomes fomentarius, Antrodia serialis) survived the fire quite well (anthracoxene species). Species favoured by fire were mainly ruderal species which can utilize new, competition-free resources created by fire, and species that have their optima in dry and open places also outside forest-fire areas. Some rarities, e.g. Phanerochaete raduloides and Physisporinus rivulosus, were favoured by fire.

• Penttilä, E-mail: rp@mm.unknown
• Kotiranta, E-mail: hk@mm.unknown

Addressing the potential impact of climate change on boreal forest ecosystems will require a range of new conservation techniques. During the early 1990s, the scope of WWF's (the World Wide Fund for Nature) forest policy work has broadened from a focus on tropical moist forests to a more general consideration of all the world's forests. Climate change is only one of a series of threats currently facing boreal forests.

Planning conservation strategies that take account of global warming is not easy when there are many computer models of climate change, sometimes predicting very different ecological effects. Climate change could result in some particularly extreme problems for the boreal forest biome. A summary of the problems and opportunities in boreal forests is presented. WWF has also been drawing up strategies for conservation on a global, regional and national level. The organization has concluded that conservation strategies aimed at combatting climate change need not be in direct conflict with other conservation planning requirements. However, proposals have emerged for ways to address the impacts of climate change that would have detrimental impacts on existing conservation plans.

• Dudley, E-mail: nd@mm.unknown
• Jeanrenaud, E-mail: jj@mm.unknown
• Markham, E-mail: am@mm.unknown

Four governmental efforts are underway to reach consensus on indicators of sustainable forestry. Through the Helsinki process, European countries have developed and reached a pan-European, binding consensus, The Montreal process includes non-European Temperate and boreal forest countries, the International Tropical Timber Organization (lTTO) have developed guidelines for the sustainable management of natural tropical forests, and the countries around the Amazon basis have developed a joint initiative for creating guidelines of sustainable forest management of the Amazonian tropical rain forests. It is estimated that as many as 15–20 distinct processes are under way in the private sector by non-profit organizations and for-profit companies, some domestic and other international in scope. Perhaps the most wide-ranging definition work of non-governmental organizations is the undertake by the Forest Stewardship Council, FSC. The paper discusses the Helsinki and Montreal processes and the tasks for research.

• Parviainen, E-mail: jp@mm.unknown

Nearly every forest land in Finland has been burnt down by a wildfire at least once during the past 400–500 years. Slash and burn cultivation (1700–1920) was practised on 50–75 percent of Finland's forests, while prescribed burning (1920–1990) has been applied to 2–3 percent of the country's forests. Because of land-use changes and efficient fire prevention and control systems, the occurrence of wildfires in Finland has decreased considerably during the past few decades. Owing to the biodiversity and ecologically favourable influence of fire, the current tendency is to revive the use of controlled fire in forestry in Finland. Prescribed burning is used in forest regeneration and endeavours are being made to revert old conservation forests to the starting point of succession through forest fires.

• Parviainen, E-mail: jp@mm.unknown

Distribution, biodiversity and reforestation dynamics of the platyphyllous forests in the Northwest European Russia were investigated. Data assembled from 21 landscape regions (250–350 km² each) show special features of small-leaved lime (Tilia cordata Mill., Norway maple (Acer platanoides L.), mountain elm (Ulmus glabra Mill.) and English oak (Qurecus robur L.) reforestation during the last two decades. New tendencies were found for the taiga areas with natural Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) vegetation. Natural platyphyllous reforestation in cut spruce areas poses as supposed a special question for forest management policy in the relationship to global climate changes. Feasible unsustainability of the common types of succession (Norway spruce - European birch (Betula pendula Roth); Norway spruce - European aspen (Populus tremula L.)) is discussed. Biodiversity of herbs, shrubs and tree species of platyphyllous forests is high and complex and is situated in 4–15 old-growth relics in each landscape region. Low-level genotype heterogeneity of nemoral flora species of such isolated populations is presumed. Special biodiversity conservation regulations are proposed.

• Chtchoukine, E-mail: ac@mm.unknown

Postfire recovery of species diversity (including a number of species, entropy of species relative coverage (Shannon index of species diversity) was studied in lichen and green moss site types of Scots pine (Pinus sylvestris L.) forests in the central part of the Kola Peninsula. The results obtained indicate the difference in the dynamics of characteristics of biodiversity of forest components during postfire recovery. The stabilization of separate components of forest community varies in time from 5–15 to 120–140 years after the fire. Characteristics of the dwarf shrub and herb stratum recovered and stabilized 5–15 years after fire, while the complete stabilization of characteristics of moss-lichen cover is observed in community with fire ages of 90–140 years. Species richness of tree stratum recovered 120–140 years after fire. Time of complete stabilization of species richness of the community was estimated 120–140 years after fire. The size of the area over which characteristics of the biodiversity were estimated effected the mean values and, in most cases, the character of variation of studied characteristics. Over an area of 1 x 1 m dynamics of characteristics of species diversity coincide in forests of the studied types. Regardless of forest type within the area of 100 m² species richness recovered 30 years after the fire (i.e. 3–5 times earlier than the establishment of the complete stabilization of the forest structure). That means that floristic composition of the forest remained unchanged from 30 to 210 years after the fire.

• Gorshkov, E-mail: vg@mm.unknown
• Bakkal, E-mail: ib@mm.unknown

There is no doubt that tree survival, growth, and reproduction in North America's boreal forests would be directly influenced by the projected changes in climate if they occur. The indirect effects of climate change may be of even greater importance, however, because of their potential for altering the intensity, frequency, and perhaps even the very nature of the disturbance regimes which drive boreal forest dynamics. Insect defoliator populations are one of the dominating disturbance factors in North America's boreal forests and during outbreaks trees are often killed over vast forest areas. If the predicted shifts in climate occur, the damage patterns caused by insects may be considerably changed, particularly those of insects whose temporal and spatial distributions are singularly dependent on climatic factors. The ensuing uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns also lead to uncertainties in fire regimes. In addition, because the rates of processes key to biogeochemical and nutrient recycling are influenced by insect damage, potential changes in damage patterns can indirectly affect ecosystem resilience and the sustainability of the multiple uses of the forest resource.

In this paper, a mechanistic perspective is developed based on available information describing how defoliating forest insects might respond to climate warming. Because of its prevalence and long history of study, the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is used for illustrative purposes in developing this perspective. The scenarios that follow outline the potential importance of threshold behaviour, historical conditions, phenological relationships, infrequent but extreme weather, complex feedbacks, and natural selection. The urgency of such considerations is emphasized by reference to research suggesting that climate warming may already be influencing some insect lifecycles.

• Fleming, E-mail: rf@mm.unknown

The productivity of Scots pine (Pinus sylvestris L.) under changing climatic conditions in the southern part of Finland was studied by scenario analysis with a gap-type forest ecosystem model. Standard simulations with the model predicted an increased rate of growth and hence increased productivity as a result of climatic warming. The gap-type model was refined by introducing an overwintering sub-model describing the annual growth cycle, frost hardiness, and frost damage of the trees. Simulations with the refined gap-type model produced results conflicting with those of the standard simulation, i.e., drastically decreased productivity caused by mortality and growth-reducing damage due to premature dehardening in the changing climate. The overwintering sub-model was tested with frost hardiness data from Scots pine saplings growing at their natural site 1) under natural conditions and 2) under elevated temperature condition, both in open-top chambers. The model predicted the frost hardiness dynamics quite accurately for the natural conditions while underestimating the frost hardiness of the saplings for the elevated temperature conditions. These findings show that 1) the overwintering sub-model requires further development, and 2) the possible reduction of productivity caused by frost damage in a changing climate is less drastic than predicted in the scenario analysis. The results as a whole demonstrated the need to consider the overwintering of trees in scenario analysis carried out with ecosystem model for boreal conditions. More generally, the results revealed a problem that exists in scenario analysis with ecological models: the accuracy of a model in predicting the ecosystem functioning under present climatic condition does not guarantee the realism of the model, nor for this reason the accuracy for predicting the ecosystem functioning under changing climatic conditions. This finding calls for the continuous rigorous experimental testing of ecological models used for assessing the ecological implications of climatic change.

• Hänninen, E-mail: hh@mm.unknown
• Kellomäki, E-mail: sk@mm.unknown
• Leinonen, E-mail: il@mm.unknown
• Repo, E-mail: tr@mm.unknown

Investigations carried out in the Kola peninsula (northern taiga) and in the South-western part of Western Siberia (southern taiga and forest-steppe) revealed identical course of the postfire restoration process of forest litter thickness in Scots pine (Pinus sylvestris L.) forests. Despite the differences in mean annual temperature (2°C) and other climatic characteristics the recovery time for thickness of forest litter in both regions amounts to 90–100 years after fire in pine forests of lichen site type and 120–140 years – in green moss type; the thickness of forest litter therewith corresponds 3–4 cm and 7–8 cm respectively. That mean that within the natural borders of pine forests, communities of a specific type possess uniform characteristics of restoration. On the basis of empirical data, it appears that the predicted increase of mean annual temperature of earth surface by (2°C) will not bring changes into the character of postfire recovery of forest litter thickness. It was shown that during the period of the recovery, which spans about 90 years after fire in pine forests of lichen and green moss-lichen site types and 140 years in ones of green moss site types, the rate of increasing of carbon store in the forest litter averaged 0.6 t ha^-1 year^-1, 0.1 t ha^-1 year^-1 and 0.2 t ha^-1 year^-1, respectively.

• Gorshkov, E-mail: vg@mm.unknown
• Bakkal, E-mail: ib@mm.unknown
• Stavrova, E-mail: ns@mm.unknown

The European Pine Sawfly (Neodiprion sertifer Geoffroy) is one of the most serious defoliators of Scots pine (Pinus sylvestris L.) in northern Europe. We studied the pattern in the regional occurrence of the outbreaks of N. sertifer in Finland in years 1961-90, and made predictions about the outbreak pattern to the year 2050 after predicted winter warming. We tested whether minimum winter temperatures and forest type and soil properties could explain the observed outbreak pattern. We analysed outbreak patterns at two different spatial levels: forest board- and municipal-level.

The proportion of coniferous forests on damage-susceptible soils (dry and infertile sites) explained a significant part of the variation in outbreak frequency at small spatial scale (municipalities) but not at large spatial scale (forest boards). At the forest board level, the incidence of minimum temperatures below -36 °C (= the critical value for egg mortality) explains 33% of the variation in the outbreak pattern, and at the municipal level the incidence of cold winters was also the most significant explaining variable in northern Finland. Egg mortality due to cold winters seems to be the most parsimonious factor explaining why there have been so few N. sertifer outbreaks in northern and north-eastern Finland. We predict that climate change (increased winter temperatures) may increase the frequency of outbreaks in eastern and northern Finland in the future.

• Virtanen, E-mail: tv@mm.unknown
• Neuvonen, E-mail: sn@mm.unknown
• Niemelä, E-mail: pn@mm.unknown
• Nikula, E-mail: an@mm.unknown
• Varama, E-mail: mv@mm.unknown

BOREAS is a four-year, regional-scale experiment to study the forested continental interior of Canada. It aims at improving our understanding of the interaction between the earths' climate system and the boreal forests at short and intermediate time scales, in order to clarify their role in global change.

During the winter, spring and summer of 1994, five field campaigns were conducted. About 85 investigation teams including nearly 300 scientists participated, including forest ecologists and ecophysiologists, atmospheric physicists, boundary-layer meteorologists, hydrologists, biochemists, atmospheric chemists and remote sensing specialists.

The findings so far have been significant in terms of their implication for global change. The boreal ecosystem, occupying roughly 17 percent of the vegetated land surface and thus an important driver of global weather and climate, absorbs much more solar energy than is assumed by operational numerical weather prediction models. Albedo measurement show that this forest absorbs nearly 91% of the sun's incident energy. Additionally, while it is known that much of the boreal ecosystems consists of forested wetlands, lakes, bogs and fens, the measurements show that the atmosphere above was extremely dry; humidity and deep boundary layer convection (3,000 m) mimicked conditions found only over deserts. Physiological measurements of the trees show that this atmospheric desiccation was a result of the forests' strong biological control limiting surface evaporation. This tight control was linked to the low soil temperature and subsequently reduced rates of photosynthesis. BOREAS measurement also focused on net ecosystem carbon exchange. Data acquired during the late spring and summer, showed the boreal forests to be a net carbon sink. However, no measurements were taken in the early spring following thaw, and in the late fall, where the balance between photosynthesis and respiration is poorly understood. During 1996 additional data will be acquired to resolve the annual carbon budget and how it might depend on interannual climate differences.

• Hall, E-mail: fh@mm.unknown
• Sellers, E-mail: ps@mm.unknown
• Williams, E-mail: dw@mm.unknown

The eddy covariance technique is a novel micrometeorological method that enables the determination of the atmosphere-biosphere exchange rate of gases such as ozone and carbon dioxide on an ecosystem scale. This paper describes the technique and presents results from the first direct measurements of turbulent fluxes of O₃, CO₂ and H₂O above a forest in Finland. The measurements were performed during 15 July-5 August 1994 above a Scots pine (Pinus sylvestris L.) stand near the Mekrijärvi research station in Eastern Finland.

The expected diurnal cycles were observed in the atmospheric fluxes of O₃, CO₂ and H₂O. The data analysis includes interpretation of the O₃ flux in terms of the dry deposition velocity and evaluation the dependency of the net CO₂ flux on radiation. The eddy covariance method and the established measurement system has proved suitable for providing high-resolution data for studying ozone deposition to a forest as well as the net carbon balance and related physiological processes of an ecosystem.

• Aurela, E-mail: ma@mm.unknown
• Laurila, E-mail: tl@mm.unknown
• Tuovinen, E-mail: jt@mm.unknown

Investigation on the relationship between the size of the Megastigmus suspectus Borr. (Hymenoptera, Torymidae) and the size of Abies alba Mill. seeds from which those insects emerged was conducted. The examined insects (n = 46) originated from southern Poland, and were obtained from cones collected in 1993. M. suspectus thorax length was used as an index of adult insect size, because that was correlated with 8 other body measurements. In addition, the diameter of the emergence hole of this insect was measured. All data were log-transformed and analysed using regression analysis. There was no linear correlation between adult size and seed size, using either length of thorax or any of the other 8 body traits tested.

• Skrzypczynska, E-mail: ms@mm.unknown

In the winter of 1977/78, a White-backed Woodpecker (Dendrocopos leucotos Bechstein) was observed in the archipelago of southwestern Finland 200 km from its breeding areas. It foraged on insects living in mall dead alder and birches. The potential prey species were identified by rearing the insects from the trunks used by the White-backed Woodpecker. Altogether 628 adult insects emerged. In addition to the big larvae the potential food also included larvae of Sciaridae and Cecidomyidae (Diptera) living in dense clumps.

• Nuorteva, E-mail: mn@mm.unknown
• Saari, E-mail: ls@mm.unknown

The effect of species mixture was studied in a mixed stand of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) by simulating around 100 different treatment schedules during the rotation in a naturally regenerated even-aged stand located on a site of medium fertility in North Karelia, Finland. Both thinning from below and thinning from above were applied. Optimum rotations were determined by maximising the net present value calculated to infinity and different treatment schedules were compared with the net present value over one rotation as per rotation applied. In the optimum treatment programme, the proportion of pines was decreased by half of the basal area in the first thinning stage and by the end of the rotation to about one third. In thinning from above, the proportion of pines can be maintained at a slightly higher level. It is economically profitable to maintain the growing stock capital at approximately the level recommended by Forest Centre Tapio, a semi-governmental forestry authority. With non-optimum species composition, the loss in net present value over one rotation can be about 10 % in thinning from below and about 20 % in thinning from above.

• Vettenranta, E-mail: jv@mm.unknown

Spatial variation in the density of soil organic carbon (kg/m²) and the thickness of soil horizons (F/H, E) were investigated in a 6 m x 8 m area in Scots pine (Pinus sylvestris L.) stand in Southern Finland for designing an effective sampling for the C density and studying the effect of trees on the variation. The horizon thickness of the podzolized soil were measured on a total of 126 soil cores (50 cm deep) and the C density of the organic F/H and 0–10 cm, 10–20 cm and 20–40 cm mineral soil layers was analysed.

The C density varied 3–5 fold within the layers and the coefficients of variation ranged from 22 % to 40%. Considering the gain in confidence per sample, 8–10 samples were suggested for estimating the mean C density in the F/H and 0–40 cm layers, although about 30 samples are needed for 10% confidence in the mean. The C densities and horizon thicknesses were spatially dependent within the distances of 1–8 m, the spatial dependence accounting for 43–86% of the total variance. The F/H layer was thicker and contained more C within 1–3 m radius from trees. In the 10–20 cm and 20–40 cm layers (B horizon) the C density also increased towards the trees, but more pronouncedly in the immediate vicinity of the stems. Because the spatial patterning of the E horizon thickness was similar, the increase was attributed to stemflow and precipitation of organic compounds in the podzol B horizon.

• Liski, E-mail: jl@mm.unknown

The aim of the study was to compare the behaviour of three selected provenances of Eucalyptus microtheca F. Muell. that were likely to respond differently to drought. For this purpose, we studied the effects of vapour pressure deficit and soil water content on leaf water potential in an irrigated plantation in Bura, eastern Kenya.

An international provenance trial of Eucalyptus microtheca, established as a part of Finnida-supported Bura Forestry Research Project in eastern Kenya in 1984 was used as a plant material in the study. The eastern provenance showed generally the lowest leaf water potential on a daily basis. Statistically significant differences in the daily leaf water potential fluctuations were detected. The eastern provenance exhibited the greatest and the northern one the smallest values. The minimum daily leaf water potential of the provenances responded well to changes in gravimetric soil water content, the western provenance being the most sensitive one. The relationship of the observed results and annual rainfall distribution in the geographic regions of the studied provenances is discussed.

• Tuomela, E-mail: kt@mm.unknown
• Kanninen, E-mail: mk@mm.unknown

One-hectare plot in a Scots pine (Pinus sylvestris L.) forest was systemically sampled for surface soil characteristics: humus layer thickness, soil carbon and nitrogen content, pH, electrical conductivity and respiration were determined from 106 samples. The effects of large trees on the plot were mapped and their joint influences at the locations of soil sampling were described as the influence potential, derived from the ecological field theory, and were calculated based on the locations and dimensions of trees.

The range of variation of soil characteristics was from three to sevenfold; no spatial autocorrelation was detected. The calculated influence potential of trees, as determined by their size and spatial distribution, was related to the spatial variation of top soil properties. Top soil properties were also related to thickness of the humus layer but they were poorly correlated with underlying mineral soil characteristics. Humus layer thickness, with the calculated influence potential of trees, may provide a means to predict top soil characteristics in specific microenvironments in the forest floor.

• Hokkanen, E-mail: th@mm.unknown
• Järvinen, E-mail: ej@mm.unknown
• Kuuluvainen, E-mail: tk@mm.unknown

A multi-factor experimental approach and proportional odds model were used to study interactions between five environmental factors significant to Norway spruce (Picea abies (L.) H. Karst.) seed germination: prechilling (at +4.5°C), suboptimal temperatures (+12 and +16°C), osmotically induced water stress (0.3 Mpa and 0 Mpa), prolonged white light, and short-period of far-red light. Temperature and osmotic stress interacted with one another in the germination of seeds; the effect off osmotic stress being stronger at +16°C than at +12°C. In natural conditions, this interaction may prevent germination early in the summer when soil dries and temperature increases. Prolonged white light prevented germination at low temperature and low osmotic potential. Inhibitory effect was less at higher temperatures and higher osmotic potential, as well as after prechilling. Short-period far-red light did not prevent germination of unchilled seeds in darkness. Prechilling tended to make seeds sensitive to short pulses of far-red light, an effect which depended on temperature: at +12°C the effect on germination was promotive, but at +16°C, inhibitory and partly reversible by white light. It seems that Norway spruce seeds may have adapted to germinate in canopy shade light rich in far-red. The seeds may also have evolved mechanisms to inhibit germination in prolonged light.

• Leinonen, E-mail: kl@mm.unknown
• Rita, E-mail: hr@mm.unknown

Seedlings of Picea abies (L.) H. Karst. full-sib families of contrasting origins were cultivated in a phytotron under different photoperiodic, light-intensity and temperature treatments during their first growth period. The effects of the treatments on juvenile growth traits – whether enhanced or delayed maturation was induces – were observed during the two subsequent growth periods. The following hypotheses were tested: (A) Enhanced maturation can be induced in the first growth period from sowing with (i) a long period of continuous light during active growth (24 weeks vs. 8 weeks); (ii) a shorter night during bud maturation (12 h vs. 16 h); high temperature (25°C vs. 20°C) during (iii) active growth, growth cessation and bud maturation; and during (iv) the latter part of growth cessation and bud maturation only. (B) Delayed maturation can be induced after (i) low light intensity during growth cessation and bud maturation (114 μmol m^-2 s^-1 vs. 340 μmol m^-2 s^-1); low temperature (15°C vs. 20°C) during (ii) active growth, growth cessation and bud maturation; and during (iii) the latter part of growth cessation and bud maturation only.

The most dramatic effect was observed after 24 weeks of continuous light during active growth. All traits showed a significantly more mature performance in the second growth period compared with the control. The effect for all but one trait was carried over to the third growth period. This is in accordance with the hypothesis that the activity of apical shoot meristems controls the maturation process. For the other treatments there was only weak or no support for the hypothesis of induction of enhanced or delayed maturation. Strong family effects were observed for all traits. Differential responses of the various latitudinal families were observed, suggesting that family effects must be considered to predict and interpret correctly how plants will respond to environmental effects.

• Kang, E-mail: hk@mm.unknown
• Ekberg, E-mail: ie@mm.unknown
• Eriksson, E-mail: ge@mm.unknown
• Ununger, E-mail: ju@mm.unknown

Snow damage to forests in Southern Finland in November 1991 was examined in relation to meteorological conditions. The combined effect of different factors proved to be necessary for severe damage. First, the snow load, in terms of precipitation, should exceed a certain limit. The limit can be set for weak or moderate damage at about 40 mm and for very severe damage at about 60 mm. Second, temperature at the time of precipitation should be above 0°C, which enables the slightly wet snow to attach to twigs during the subsequent period with temperature below 0°C. On the other hand, temperatures exceeding 0.6°C prohibit damage by permitting the snow load to fall from the branches. Wind speed exceeding 9 ms^-1, as observed 15 m above ground, were strong enough to dislodge the snow which is not attached, and thus reduce the damage. There are few statistics either of snow damage or of the relation between the snow damage and precipitation. However, there is causal connection between snow damage and heavy snowfalls. Therefore, the regions with a high frequency of heavy snowfalls, as indicated by orographical features and occurrence of thick snow cover, were investigated.

• Solantie, E-mail: rs@mm.unknown

For biomass forestry in the inland parts of Southern and Central Finland, the obvious choice of willow species is Salix myrsinifolia. However, selection of clones of indigenous species has not yet been completed and more research and selection is needed. In the Piipsanneva old peatland trial, indigenous species of willow, mostly clones of S. myrsinifolia and S. phylicifolia, were compared in terms of biomass production, coppicing, height growth and diameter distributions. In this trial, the mean annual biomass production was not particularly high; more important results were attained in the ranking of clones. The trial strengthens the hypothesis that, over the long-term, the biomass production of S. myrsinifolia is higher than that of S. phylicifolia. It was supposed that behind the highest yield there was a clone with uniform quality, one whose diameter distribution would be narrow and positively skewed. Comparisons of parameters of Weibull functions showed that the distributions of the best clones were wide, indicating that those clones use the whole growth space better than those with narrow distribution.

• Honkanen, E-mail: ah@mm.unknown

A Gremmeniella abietina (Lagerb.) race of type A was found to produce pycnidia in cankers of previous year’s shoots (1991) on branches of Scots pine (Pinus sylvestris L.) bearing green needles and living buds in the current-year shoots (1992) with no apparent symptoms of infection by G. abietina. The restricted colonization of green shoots by G. abietina, with only restricted canker development, may indicate that older, slow-growing natural Scots pines of the northern boreal forests resists the fungus well. However, the ability of the fungus to survive and even sporulate in such cankers indicates one way of surviving over consecutive years otherwise unfavourable for it.

• Jalkanen, E-mail: rj@mm.unknown
• Kaitera, E-mail: jk@mm.unknown

Abundant snowfalls and thick snow cover influence forest ecology mainly in two ways. Snow loading increases the number of damaged stems, which increases the amount of decay in stems, in its turn important for many animals. Second, the ground remains unfrozen under the snow cover, which is of crucial importance for many perennial species of ground vegetation. These winter phenomena also have influenced the early Finnish culture as man in his everyday life in the wilderness was in close contact with nature. In this paper, ecological interactions between snow conditions, forest flora, fauna and early culture are discussed mainly with reference to the province of Uusimaa in Southern Finland.

• Solantie, E-mail: rs@mm.unknown

The paper discusses how the general trend towards increasing growth and productivity in the European societies is expressed also in forestry. It is reflected, for instance, in the increasing production and productivity of forest industries. Technological progress and call for economic growth require great flexibility from all resources. These pressures for effectiveness and production also concern Finnish forestry and forest management. Industrialization, urbanization and development of forestry have increased the pressure to use forests in recreation, preserving human environment and nature conservation in addition to production of timber. Through the development the definition of sustainability has become wider.

• Vehkamäki, E-mail: sv@mm.unknown

The paper deals with the application of forest dynamics. Reference is made to two studies, which have been carried out at a national level. The simulations of forest decline as well as the production of exceedingly thick timber of spruce and fir provide various examples of the major problems of forest simulation and of some possible solutions. It is pointed out that the statistical analysis of empirical data is most important for modelling and it might bring about even more valuable results than the ultimate simulation itself.

• Sekot, E-mail: ws@mm.unknown

Moose (Alces alces L.) browsing was studied in young Scots pine (Pinus sylvestris L.) stands mixed with deciduous trees in high-density winter ranges. The proportional use of twig biomass decreased as the availability increased. The total as well as proportional biomass consumption were higher on the moist than on the dry type of forest. The per tree consumption of pine was higher on the moist type, where the availability of pine was lower. Deciduous trees were more consumed on the moist type, where their availability was relatively high. The consumption of pine saplings increased as the availability of birch increased. Pine stem breakages were most numerous when birch occurred as overgrowth above pine and at high birch densities. The availability of other deciduous tree species did not correlate with browsing intensity of Scots pine. Moose browsing had seriously inhibited the development of Scots pines in 6% of the stands, over 60% of available biomass having been removed. Rowan and aspen were commonly over-browsed and their height growth was inhibited, which occurred rarely by birch. There was no difference in the proportion of young stands in forest areas with high and low moose density. A high proportion of peatland forests was found to indicate relatively good feeding habitats in the high-density areas.

The PDF includes an abstract in Finnish.

• Heikkilä, E-mail: rh@mm.unknown
• Härkönen, E-mail: sh@mm.unknown

The paper, presented at the seminar ”Forestry in Europe: Implications of European Integration for National Forestry”, discusses the effects of first Forestry Action Programme in the European Community, UNCED 1992, the European Community’s new Forestry Strategy and the second Forestry Action Programme directives of conservation of habitats on forestry within the EC.

• Koch, E-mail: nk@mm.unknown

The paper, presented at the seminar ”Forestry in Europe: Implications of European Integration for National Forestry”, discusses the meaning of the European Community for the forestry sector, putting a special emphasis on recycling. Subsidies and the so-called ”Forestry Action Program” are among the topics that have raised controversial discussions within the EC. In addition, wood fibre recycling and the EC draft directive on packaging waste includes ambiguous targets for recycling.

• Wermann, E-mail: ew@mm.unknown

Ten trails, one kilometre each, were evaluated by 15 persons for scenic beauty, recreational value and variety. All trails passed through commercially managed forests dominated by conifers. The trails were first evaluated by viewing computer simulations based on a series of graphical illustrations of forest landscapes, then from a slide show, and finally in the field. In the computer simulation and slide show, landscape pictures along the trail at an interval of 35–40 m were presented for 3–4 seconds. The ranks between slide show and field were slightly more similar than those between simulation and field. The mean correlation of 12 persons between the field ranking and assessment of either computer simulations or slide shows or graphics than scenic beauty or recreational value. Spearman’s rank correlations computed from median scores of a group of 12 peers were clearly better than the average of individual persons varying from 0.6 to 0.9.

The PDF includes an abstract in Finnish

• Nousiainen, E-mail: in@mm.unknown
• Pukkala, E-mail: tp@mm.unknown

An alternative approach to formulating a forestry goal programming problem is presented. First, single objective optima levels are solved. The Analytical Hierarchy Process is applied in the estimation of a priori weights of deviations from the goal target levels. The ratios of the weights can be interpreted as relative importance of the goals, respectively. The sum of the weighted deviations from all single optima levels associated with the management goals is minimized. Instead of absolute deviations, relative ones are used. A case study problem of forest management planning with several objectives, measured in different units, is analysed.

The PDF includes an abstract in Finnish.

• Kangas, E-mail: jk@mm.unknown
• Pukkala, E-mail: tp@mm.unknown

The article is a literature review focusing on the reaction of soil respiration, litter decomposition and microflora of forest soils to various pollutants like acidic deposition, heavy metals and unusual high amounts of basic cations. There is a great deal of evidence indicating that environmental pollution affects soil microbial activity and community structure. Much of the data originates from experimental designs where high levels of pollutants were applied to the soil under field or laboratory conditions. Furthermore, many were short-term experiments designed to look for large effects. These experiments have an indicative value, but it has to be kept in mind that environmental pollution is a combination of many pollutants, mostly at low concentrations, acting over long periods of time. There is therefore consequently a demand for research performed in natural forest environments polluted with anthropogenic compounds. 

• Fritze, E-mail: hf@mm.unknown

A model for the succession of the forest ecosystem is described. The growth and development of trees and ground cover are controlled by temperature and light conditions and the availability of nitrogen and water. In addition, the effects of the annual cycle of trees including the risk of frost damage, wild fire, and wind damages are contained in the model as factors which control the survival and productivity of trees. The model also makes it possible to evaluated the risk of insect attack assuming that this risk is inversely related to the growth efficiency of trees.

The PDF includes an abstract in Finnish.

• Kellomäki, E-mail: sk@mm.unknown
• Hänninen, E-mail: hh@mm.unknown
• Kolström, E-mail: tk@mm.unknown
• Lauhanen, E-mail: rl@mm.unknown
• Mattila, E-mail: um@mm.unknown
• Pajari, E-mail: bp@mm.unknown
• Väisänen, E-mail: hv@mm.unknown

During the past 30 years, genetics research has accumulated much information on black spruce (Picea mariana). The adoption of less intensive and faster plustree selection, establishment of seedling seed orchards and family selection significantly increased the rate of progress in improvement of the species. In New Brunswick this approach made it possible to obtain substantial quantities of seeds 10 years after the initiation of the program, and now all the seeds used in reforestation are derived from seed orchards.

Fourteen years after beginning the black spruce breeding program, second generation breeding is underway. The possibility of implementing alternative breeding strategies using ”breeding – cloning” procedures are explored for the advanced generation. Until somatic embryogenesis techniques become fully operational, ”backward selection” schemes and crossing in breeding halls followed by vegetative multiplication using serial rooted cuttings can be adopted. Larger genetic gains than those from conventional breeding are expected not only from the utilization of both additive and non-additive variances, but also from the elimination of inefficiencies of large conventional seed orchards.

• Morgenstern, E-mail: em@mm.unknown
• Park, E-mail: yp@mm.unknown

Forest tree breeding involves manipulation of genetic composition of populations and individuals, and biotechnology focuses on selected individuals. The new techniques cannot replace the conventional breeding techniques but both need effective cooperation of each other. Thus, the distinction between conventional breeding and biotechnology is artificial. The biotechnology methods are new and fast developing and the future with field and progeny testing will show which techniques will be permanently adopted into tree breeding. For instance, the earlier hope of the use of somaclonal variation as a new source of variability and a powerful tool for the breeder seem today quite the opposite. Somaclonal variation constituting a major problem in present-day micropropagation is due to the unpredictable variation. Based on knowledge of today, especially micropropagation via somatic embryos, transgenic trees and the identification of major genes seem to be good candidates to be permanently adopted into tree breeding.

• Häggman, E-mail: hh@mm.unknown

The paper introduces different ways plant physiology research can avail the process of tree improvement. The breeding of tree cultivars that efficiently produce a particular wood product or amenity will be an important aspect of forest management. What physiologist can provide to breeders and genetic engineers is the opportunity to move their work from empirical level towards a more theoretical level, and help to make breeding more predictable and more precise in its objectives. The areas of research discussed in the paper are biotechnology, flowering, selection criteria, adaptability and application of ideotypes.

• Dickmann, E-mail: dd@mm.unknown

Four different methods of truncation selection were studied in a population consisting of a large number of unrelated full sib families of equal size: phenotype selection, family selection, within-family selection and combined index selection (optimal weighting of individual and family performance to get the best prediction of breeding value). Methods were developed for calculating diversity (”relative effective family number”) for the different selection methods. Numerical calculations were made for genetic gain and diversity. Model assumptions are additive gene control and normal distribution. Phenotypic was good at high heritabilities and between family at low heritabilities. Loss of diversity was strongly dependent on selection method and selection strength. Compared at the same diversity, genetic gain was lower for combined index compared to phenotypic. There is a need for methods combining the goals gain and diversity.

The PDF includes an abstract in Finnish.

• Wei, E-mail: rw@mm.unknown
• Lindgren, E-mail: dl@mm.unknown

The mating system was analysed in the upper and lower crown of two groups of European larch (Larix decidua Mill.) clones divided according to the percentage of full seeds in the upper and lower crown parts. The overall multilocus estimate of outcrossing rate (t) was calculated to be 0.929. The differences of outcrossing rates between crown levels and clonal groups respectively were not statistically significant. The t estimates were greater for the upper crown level and for clones with higher percentage of full seeds in the upper crown level. However, among all observations there was no correlation between outcrossing rates and percentages of full seeds for particular crown levels and groups of clones. Observed similarity of outcrossing among grafts of the same clones may indicate genetic control of self-fertilization rate in individual European larch. 

The PDF includes an abstract in Finnish.

• Burczyk, E-mail: jb@mm.unknown
• Kosiński, E-mail: gk@mm.unknown
• Lewandowski, E-mail: al@mm.unknown

Shoot losses due to maturation feeding by pine shoot beetles (Tomicus piniperda (L.) and T. minor (Hart.), Col., Scolytidae) and subsequent growth losses were studied in Scots pine (Pinus sylvestris L.) stands growing at different distances from a timber yard, where pine timber was stored during the years 1982–84. In autumn 1985, pine trees were felled at 20, 40, 80, 500 and 1,500 m distance from the timber yard, five trees in each distance class. Trees were analysed for beetle attack, needle biomass and growth. In autumn 1988, increment cores were taken from 20 trees in each distance class.

In 1985, different damage estimates showed that beetle damage was more than 10-fold in the crowns of pine trees growing close to the timber yard as compared to less damaged trees in greater distance. Crude needle biomass estimates indicated that the trees attacked most had lost more than half of the total foliage. Following three years of attack, basal area growth decreased for 2–3 years and recovered during the subsequent 3 years, the total period of loss thus being 5–6 years. The loss in volume growth during 1983–85 was ca. 70, 40, 20 and 10% at 20, 40, 80 and 500 m distance from the beetle source, respectively, compared to the stand at 1,500. Growth losses did not occur until the number of beetle-attacks, ”pegs”, exceeded ca. 200 per tree. The highest observed growth losses occurred in trees with more than 1,000 pegs per tree.

The PDF includes an abstract in Finnish

• Långström, E-mail: bl@mm.unknown
• Hellqvist, E-mail: ch@mm.unknown

The profitability of forestry in the context of recent economic developments in Finland suggest a more systematic analysis of the profit and the cost structure of small-scale forestry than is normally made today. The domestic and international pressure on farming emphasizes the development of rural areas by means of other business than agriculture, in practice this may mean forestry. Financing in terms of the new law concerning agriculture requires projects to be profitable. Thus, the profitability of different lines of production, including forestry, needs to be reported more carefully than is the practice today.

A network of forestry bookkeeping farms covering the whole Austria has existed for 20 years. The organization and the operation of the forestry bookkeeping and the cost accounting system is based on the scientific cooperation and exchange of information between the organizations in charge. The practical experience and recommendations based thereon might be useful for Finland, when implementing a country-wide network of forestry bookkeeping and cost accounting.

The PDF includes an abstract in English.

• Penttinen, E-mail: mp@mm.unknown

The light reflected from the crowns of Scots pine (Pinus sylvestris L.) clones was measured spectroradiometrically during and after growing season. Standard deviations of the spectra of pine clones showing differences in moose browsing intensity were compared. A new algorithm was developed for predicting the browsing intensity of moose (Alces alces).

The PDF includes an abstract in Finnish.

• Silvennoinen, E-mail: rs@mm.unknown
• Hämäläinen, E-mail: rh@mm.unknown
• Nygrén, E-mail: kn@mm.unknown
• Weissenberg, E-mail: kw@mm.unknown

Effect of dolomite lime and wood ash (0, 0.5, 1, 2, 4, 8 and 16 kg m^-3) on the chemical composition of low humified Sphagnum peat was studied. Germination of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and silver birch (Betula pendula Roth) and the subsequent growth of these seedlings were investigated in a greenhouse experiment. Nutrient concentrations in shoots and roots of pine seedlings were also analysed. The pH of peat increased asymptotically from 3.8 to about 7.0 with increasing lime regimen and to about 8.0 with increasing ash regimen. Wood ash linearly increased electrical conductivity and P, K, and Ca concentrations of peat. Rate of germination, within 7 days, of pine and spruce was best at low pH (<5) while birch seeds had a slightly higher pH optimum (4–6). Germination capacity, within 21 days, was not affected by pH or application regimen of either lime or ash. Pine and spruce seedlings grew best with lime and ash doses of 0.5–2.0 kg m^-3, the pH of peat being 4–5. Lime and ash treatments did not affect the growth of birch seedlings, but wood ash increased nutrient concentration of pine seedlings.

The PDF includes an abstract in Finnish.

• Rikala, E-mail: rr@mm.unknown
• Jozefek, E-mail: hj@mm.unknown

Four dispersal stages of the nematode Bursaphelenchus mucronatus (Nematoda: Aphelenchoididae) were surveyed in Finland during the summers 1989 and 1990 examining field collected conifer beetle (Coleopterea) adults of the following species: Monochamus sutor, M. galloprovincialis, Acanthocinus aedilis, Rhagium inquisitor, Asemum striatum, Spondylis buprestoides and Hylobius abietis. All but the last one (Curculionidae) belong to genus Cerambycidae. The two Monochamus species were the only ones carrying B. mucronatus fourth dispersal stages, total number of nematode larvae per beetle being higher in M. galloprovincialis. The frequency of infestation was 24% in M. galloprovincialis and 14% in M. sutor but the difference eas not statistically significant.

The PDF includes an abstract in Finnish.

• Tomminen, E-mail: jt@mm.unknown

The influence of different fertilization treatments and ditch spacings on the height growth of young Scots pine (Pinus sylvestris L.) seedling stands growing under various climatic regimes were determined. Comparisons were made between naturally regenerated and planted seedling stands. The effective temperature sum had a stronger effect on the height growth of planted seedlings, and in Northern Finland the planted seedlings seemed to be influenced to a greater degree by the adverse climatic conditions. The heavier the dose of fertilizer that had been applied, the greater the difference in growth caused by macroclimate. A considerably larger proportion of natural seedlings were located on hummocks compared with that of planted seedlings, irrespective of the region. On plots with wider ditch spacings, seedlings growing on hummocks were superior in height growth to those on flat surfaces.

The PDF includes an abstract in Finnish.

• Miyazava, E-mail: tm@mm.unknown
• Laine, E-mail: jl@mm.unknown

The paper presents a simple model of long-term forest management planning in tree plantations. The model is particularly suitable for developing countries where the research resources are limited. The management plan is prepared in two steps. First, one or several treatment schedules are simulated for each calculation unit (age class, compartment, etc.) over the selected planning period. Second, an optimal combination treatment schedules according to the selected objectives and constraints is searched by mathematical programming. The simulation of growth is based on the prediction of the diameter distribution at the desired time point. All stand characteristics are derived from this distribution. The models needed in the yield simulation can be estimated from temporary sample plots. A case study management plan for 13,000 ha of Pinus kesiya (Royle ex Gordon) plantations in Zambia is presented to demonstrate the system.

The PDF includes an abstract in Finnish.

• Pukkala, E-mail: tp@mm.unknown
• Mubita, E-mail: om@mm.unknown
• Saramäki, E-mail: js@mm.unknown

In soil profiles from a series of uplands of different site types bulk density, density of solids and porosity of soil were clearly related to soil organic matter content and its distribution in the soil profile. Soil organic matter contents were also strongly correlated to effective cation exchange capacity (CEC) and soil acidity. Site fertility was primarily related to the fine fraction (ø<0.06 mm) content in the C horizon and related properties (i.e. CEC). In the humus layer, the content of exchangeable bases and base saturation most strongly related to site fertility.

The PDF includes an abstract in English.

• Westman, E-mail: cw@mm.unknown

Based on a survey of world literature it is concluded that 1) the better -researched epidemic forest pathosystems are caused by anthropogenic factors, 2) the systems most likely have a polygenic background, and 3) resistance breeding should maintain polygenic resistance with restrictive incorporation of oligogenic resistance. Corresponding objectives are valid in breeding programs of presently balanced pathosystems, which may turn epidemic if man causes changes in the gene pool and alters critical environmental conditions.

The PDF includes an abstract in English.

• Weissenberg, E-mail: kw@mm.unknown

Seed mass within any plant species is one of the least plastic components of plant structure. The aim of this study was to analyse the variation in the seed mass of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in relation to three environmental factors: soil fertility, mean temperature and precipitation during seed filling period. Data published earlier on seed mass of these species on different sites and different years was used in the study.

The seed mass of both species was independent of soil fertility (forest type) but did vary between different years. It is hypothesized that if the seed-ripening summer is warmer than average, Scots pine seed mass tends to be smaller. In this study, seed mass varied independently of the amount of precipitation during the ripening summer. However, generalization of the results requires further study.

The PDF includes an abstract in English.

• Nygren, E-mail: mn@mm.unknown

While the most common type of mycorrhizae is endomycorrhizae, ectomycorrhizae dominate in the case of coniferous trees. Pine, in particular, has a strong association with mycorrhizae. Mycorrhizae enable trees to take up water and nutrients much more efficiently than the roots themselves. The fungus, in return, obtain carbohydrates and is able to grow and fruit. Mycorrhizal fungi are probably numbered in their thousands but so far few are known. Knowledge about their physiology, in particular, is lacking and studies dealing with their isolation and inoculation, which may be commercially valuable, remain unpublished. A new challenge for mycorrhiza research is the effects of air pollution. Forest suffering from extensive air pollution have few mycorrhizal fungi., infection is weak and the number of root deformations is high. As good mycorrhizae are important to tree health, there is a particular need to intensify mycorrhiza research.

The PDF includes an abstract in English.

• Laiho, E-mail: ol@mm.unknown

Based on literature this paper describes the natural afforestation of Finland that took place after the last ice age and the changes which have taken place during the last 10,000 years. The origin and development of the vegetation and trees are related to the changes in the edaphic and climatic factors. The first tree species to arrive in Finland were the primary colonizing species, birch and Scots pine. The appearance of Norway spruce dates back to about 5000 B.P. There have been great changes in the species composition of Finnish forests during the last several thousands of years but some 2,000–3,000 years ago the various species reached their present balance. The epoch of naural forests, which had lasted some 9,500 years, came to a conclusion, however, when man started to have a marked effect on the forest’s development 300–400 years ago.

The PDF includes an abstract in English.

• Alho, E-mail: pa@mm.unknown

This paper is a review on the development of sustainable forest management and what has been meant with the term in different times. The article summarises the birth of sustainable use of forests in the world and in Finland, and discusses sustainability in forest management, for instance from the point of view of one forest holding, large clearcuttings performed in Lapland, biological sustainability, business economics and overall planning.

• Kilkki, E-mail: pk@mm.unknown

This review discusses whether forests are affected by biotic damages due to present or future environmental disturbances, and do environmental threats, such as air pollution and climatic change, weaken the condition of forest in a way that makes them vulnerable to damages by fungi and insect. The defence mechanisms of trees and factors affecting the development of an outbreak are described. Finally, the ways that air pollution and climatic change may affect biotic damages are discussed. 

• Annila, E-mail: ea@mm.unknown

The development of shoot number and shoot properties was examined in successive shoot cohorts of young widely-spaced Scots pine trees (Pinus sylvestris L.) growing in a progeny trial. This was accomplished by reconstructing the branching process of the trees over a period of five years, from tree age 4 to 8. During this time the number of shoots in successive shoot cohorts increased rapidly, while at the same time the mean shoot length decreased. The decrease in shoot lengths from older to younger shoots was accompanied by a decline in the bifuraction frequency of the shoots. In general, rapid changes occurred in the branching characteristics during the yearly development of the trees. The variation in the branching characteristics was reflected in the development of the architecture and biomass production of the trees.

The PDF includes an abstract in Finnish.

• Kuuluvainen, E-mail: tk@mm.unknown

The study uses the methodology of ecological field theory to model the effect of Scots pine (Pinus sylvestris L.) seed trees on the density of tree seedlings and other plants in the field layer. The seed trees had a clear effect on the expected value of the amount and distribution of the ground vegetation. The vicinity of seed trees had an adverse effect on the growth of grasses, herbs and seedlings, while mosses were most abundant near the trees. Models based on the ecological field approach were derived to describe the effect of seed trees on the ground vegetation.

The PDF includes an abstract in Finnish.

• Kuuluvainen, E-mail: tk@mm.unknown
• Pukkala, E-mail: tp@mm.unknown

Seven hundred one-year-old Betula pendula Roth seedlings were given different concentrations of potassium fertilizer. Over the study period seedlings were subjected to artificial growing and dormant phases. Frost resistance of the seedlings was assessed by artificial freezing tests and electrical impedance measurements on stem cuttings. In general, high concentrations of potassium fertilizer reflected a low tolerance to frost. Pre-freezing impedance readings decreased with increasing potassium fertilizer dosages. Results from pre-freezing impedance measurements were found to be in broad agreement with the hypothesis that high impedance readings indicate a frost hardy tissue whereas low readings imply the opposite.

The PDF includes an abstract in Finnish.

• Jozefek, E-mail: hj@mm.unknown

The two introductory books written by emeritus professor William Duerr provide an opportunity to scope the research progress in the forest economic discipline during almost a quarter century. This paper gives a presentation of the books (Fundamentals of Forest economics, 1960, and Forestry Economics as Problem Solving, 1984), and the development of forest economics during the period.

The PDF includes a summary in English.

• Ollonqvist, E-mail: po@mm.unknown

The economic analysis is based on computer simulations which covered a seedling rotation and three successive coppice rotations. Calculations were carried out for the four site productivity classes in Eucalyptus globulus plantations. The rotation length that maximized the land expectation value is 12–20 years for seedling rotation and 8–16 years for coppice rotations with discounting rates 2–8%. The mean wood production is over 40 m³/ha/a in the best site class and about 10 m³/ha/a in the poorest class with rotation lengths ranging from 10 to over 20 years. Thinnings increase the wood production and land expectation value by a few percentage points. In areas suitable to Eucalyptus globulus growth, the land expectation value is considerably higher in forestry than in agriculture, except in very poor areas or with very high rate of interest.

The PDF includes an abstract in Finnish.

• Pohjonen, E-mail: vp@mm.unknown
• Pukkala, E-mail: tp@mm.unknown

Succession of insect attacks on young Scots pine (Pinus sylvestris L.) was studied in heavily, moderately and slightly polluted pine stands within a three-kilometre distance from a prominent emission source in Western Finland. The total number of pest species was highest in the moderately polluted stand, but unlike other herbivores, aphids were also abundant in the heavily polluted stands. A few positive but no negative interactions were detected between herbivores, which suggests that insect species may benefit from a previous occurrence of other species in the same tree.

The PDF includes an abstract in Finnish.

• Heliövaara, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown

The purpose was to analyse the importance of forestry and forest industry in the Finnish economic development since the 1950’s, and to find out how the sector has contributed to the growth of the national economy through other sectors. Data were derived from the input-output tables of 1959, 1970 and 1980. Information provided by Hirschmanian linkages was expanded by taking into account e.g. induced, consumption, final demand and absorption linkages. The linkages of forestry and forest industry had multiplied during the study period. Both final demand linkages and intermediate product linkages were significant. The sector’s contribution to the development of metal and machinery and equipment industries as well as that of energy/water supply was significant. Integration with most other sectors has increased. Indirect production coefficients of forestry and forest industry were larger than on average in manufacturing. Because of labour productivity growth, production and employment coefficients were different.

The PDF includes an abstract in Finnish.

• Haltia, E-mail: oh@mm.unknown
• Simula, E-mail: ms@mm.unknown

The effect of different environmental conditions (four outdoor localities and one greenhouse locality in Northern Sweden) on cold hardening of 29 one-year-old full-sib families from plus-trees of Scots pine (Pinus sylvestris L.) were studied by artificial freeze testing. Plants exposed to low night temperatures during August achieved faster cold hardening than plants raised in milder localities. The family ranking for rate of winter hardening was consistent among outdoor localities if freeze testing was performed at times when plants from different localities had attained similar levels of cold hardiness. However, significant family x locality interactions were obtained when plants from the outdoor localities were freeze tested on the same occasion. Freeze damage was positively correlated with plant height but not correlated with dry matter content in the autumn. Freezing damage of greenhouse raised plus-tree families was uncorrelated with damage of plants raised outdoors. Possible implications for hardiness breeding are suggested.

The PDF includes an abstract in Finnish.

• Nilsson, E-mail: jn@mm.unknown

Electrical impedance characteristics of plant cells are dependent on such physiological factors as physiological condition, developmental stage, cell structure, nutrient status, water balance and temperature acclimation. In the measurements also such technical and physical factors as type of electrodes, frequency, geometry of the object, inter-electrode distance and temperature have an effect. These factors are discussed especially with respect to the impedance method in frost resistance studies of plants.

The PDF includes an abstract in Finnish.

• Repo, E-mail: tr@mm.unknown

The architecture of Scots pine (Pinus sylvestris L.) was studied in an eight-year-old progeny test. The measurements included characteristics of crown structure, spatial distribution of shoots and yield components. The spatial distribution of shoots showed striking between-tree differences, and two extreme distribution patterns were detected. One represented a non-layered structure with a vertically relative even shoot distribution, and the other a layered structure with a vertically highly uneven shoot distribution.

Close correlations existed between several components of tree architecture and it is suggested that changes in the phenotypic architecture in Scots pine follow an epigenetic pattern, which enables the prediction of adaptational changes in structural components. The structural characteristics related to high above-ground biomass were a long crown, high total shoot length, high number of branches per whorl and big shoots of low needle density occupying a big share of the crown volume.

The PDF includes a summary in Finnish.

• Kuuluvainen, E-mail: tk@mm.unknown
• Kanninen, E-mail: mk@mm.unknown
• Salmi, E-mail: js@mm.unknown

The study presents methods that incorporate the amenity of a forest area into the management planning. The management plan is based on treatment schedules simulated for each compartment over the 20-year planning period. The best combination of treatment schedules is selected by multi-objective optimization. The amenity is divided into two parts: (1) within-stand amenity and (2) the amenity of landscape when viewed afar (distant scene). The within-stand amenity is expressed in terms of adjective sum which is estimated from stand characteristics. The adjective sum of the whole area in a selected year can be taken as an objective or constraining variable of optimization. The assessment of the distant scene is based on computer illustrations which show the predicted temporal change of landscape according to a particular management plan.

The PDF includes a summary in Finnish.

• Pukkala, E-mail: tp@mm.unknown

Possibilities of developing suitable willow (Salix spp.) clones for short-rotation forestry on mined peatlands in the north-western area of Finland were studied in a field experiment in which 300 willow clones were tested during 1985–87. Most of the tested clones started to grow from cuttings on limed and fertilized peat soil. Salix viminalis L. clones of southern origin had a higher leafless above ground biomass production than the well adapted control clone and the local Finnish willows, but their winter hardiness was not satisfactory. The growth habit of some southern willows was also better than that of the control clone. It was also possible to select clones with good sprouting capacity. There were few Salix myrsinifolia Calisb. clones of Finnish origin, which had better cold tolerance than all other willows tested and higher biomass production than that of the control clone. The most critical factor to be selected for this is the optimal combination of winter hardiness and biomass production. This is attempted by selecting clones on the basis of this experiment for a breeding program.

The PDF includes a summary in Finnish.

• Lumme, E-mail: il@mm.unknown
• Törmälä, E-mail: tt@mm.unknown

The fungal symbiont of ectendomycorrhizae is an ascomycete Wilcoxina (Tricharina) mikolae Yang & Korf. It forms ectendomycorrhizae with Pinus and Larix and ectomycorrhizae with Abies, Picea, Pseudotsuga and Tsuga. It is common in forest nurseries around the world. After transplanting the seedlings into natural forest soil, indegenous fungi rapidly replace Wilcoxina. Inoculation of nursery soil with Wilcoxina is recommended if soil has been sterilized or for other reasons mycorrhizal fungi are absent.

The PDF includes a summary in Finnish.

• Mikola, E-mail: pm@mm.unknown

The paper presents aspects of town and forest architecture. A feature of the Finnish building tradition is that the forest is allowed to grow next to buildings. After the Second World War a new type of town was created in Finland, ”the forest town”. The most prominent feature of the history of Finnish architecture, from national romanticism to functionalism and up to the present day, is the modification of international ideals to a certain ”forest culture” style.

The paper is based on a lecture given in the seminar ‘The forest as a Finnish cultural entity’, held in Helsinki in 1986. The PDF includes a summary in English.

• Pallasmaa, E-mail: jp@mm.unknown

The occurrence of Caleopsis bifida on clear-cut and burned forest soil and its disappearance in 4–6 years after disturbance is attributed to its germination ecology. Initially the seeds are dormant 96–100% and remain dormant in nylon gaze bags in different types of forest humus layers at least 10 years. Dormancy is released in laboratory (1) by treatment of 100 ppm aqueous solution of GA₃, (2) by heating the dormant seeds to 40–55°C for 1–5 h, and (3) by 1% KNO₃ solution. It is concluded that conditions in clear-cut and burned areas favour germination of seeds in regard to temperature and content of nitrates in contrast to humus of closed vegetation where the seeds remain dormant.

The PDF includes an abstract in Finnish.

• Hintikka, E-mail: vh@mm.unknown

In laboratory studies the heartwood content seems to be the only natural property of a wood of different tree species influencing the decay resistance. Moistening and drying by diffusion happen quite slowly. Scots pine (Pinus sylvestris L.) sapwood takes moisture by capillary action quicker than pine heartwood and Norway spruce (Picea abies (L.) H. Karst.) wood. Swelling and shrinkage are also greatest in pine sapwood. Impregnation of pine sapwood can give it better hydrophobic and dimensional stability than that of pine heartwood.

The PDF includes an abstract in English.

• Kärenlampi, E-mail: pk@mm.unknown

The usefulness of forest sector models in forest policy analysis is discussed, mainly based on experiences from Norway. Forest sector modelling is contrasted to two alternative approaches: (i) Intuitive, verbal analysis, and (ii) econometric models. It is concluded that forest sector models, properly developed in contact with the policy makers, should be of considerable value in forest policy analysis.

• Solberg, E-mail: bs@mm.unknown

Comprehensive state laws regulating the practice of forest management on private lands are in effect in seven of the United States. Established to protect a wide range of non-timber forest resources and to ensure reforestation after harvest, these laws may impose significant administrative costs on states and significant compliance costs on landowners and timber operators. Total state administration costs for 1984 are estimated at $10.1 and total private sector compliance costs are estimated at $120.5 million, for a total regulation cost of $130.6 million.

The resource protection effectiveness of state forest practice regulation is difficult to quantify. However, agreement is strong that regulation has led to significant improvements in forest resource conditions and has helped to increase reforestation.

• Henly, E-mail: rh@mm.unknown
• Ellefson, E-mail: pe@mm.unknown

A nation that wishes to enhance its social and economic well-being through more intensive utilization of its forest resources must develop a rather comprehensive policy statement to ensure that the expanded exploitation does not lead to the destruction of these resources. The policy must specify the goals to be achieved, provide general direction on how these goals can be achieved, and develop a system of checks-and-balances to ensure achievement of the long-term objectives. The policy must consider resource protection, the economic needs at the various levels of government, the social impacts of utilization on ways of life in all areas of the nation, and the infrastructure needed in the short and long terms.

• Lewis, E-mail: gl@mm.unknown

Standard methods of welfare economics are used in a market simulating framework to evaluate policy measures designed to increase future timber supplies. Forest management cost-share programs are examined using this methodology. The differential regional impact of cost-share payments is considered, as is the distribution of these benefits between stumpage producers (owners of forest land) and stumpage consumers (producers of forest products). Previous estimates of the welfare gains that would result from a higher level of forest management cost-share payments in the southern United States are revised to account for the loss of public revenue resulting from lower future prices. A methodology for comparing alternative policy instruments is discussed, and a preliminary, qualitative comparison is made between the use of cost-share payments and alternative policy measures.

• Brooks, E-mail: db@mm.unknown

To conduct an efficient forest policy, both a normative and a positive theory are necessary. In addition, however, the explicit intertemporal considerations in natural resource economics demand that it is made crystal clear which means are permanent and which are non-permanent. The permanent case is far from easy to solve.

That the theoretical problems have practical relevance is shown by Swedish experience. A practical course of action is to weight possible positive effects from a permanent subsidy against possible deleterious outcomes. It is also desirable to avoid jerkiness in forest policy, which is likely to create uncertainty about the permanence of permanent means.

Law may sometimes be more efficient in creating ”credibility” than economic incentives. Regeneration has been mandatory in Sweden since 1903, and nobody refrains from cutting because he believes that regeneration duty will be abolished in some near future.

• Löfgren, E-mail: kl@mm.unknown

Development of timber sale accounting system for the U.S. Department of Agriculture, Forest Service ordered by the U.S. Congress, has entailed numerous evaluations and research projects. Critics of the current process claims administrative costs are not recovered by the prices paid for Federal timber. However, management of multiple resources for multiple uses makes traditional accounting difficult; i.e., keeping track of cash flows. A further complication involves allocating costs to the various resources (joint cost allocation), for which no nonarbitrary method currently exists. A concurrent issue involves the building of roads for timber harvest into areas released from wilderness consideration. Environmentalists see the road building program of the Federal land management agencies as an additional reason Federal management costs are not recovered from timber-generated revenues. The heart of the issue is which lands are economically suited for timber management, and what nonmarket benefits and costs accrue from the timber management.

• Risbrudt, E-mail: cr@mm.unknown

The purpose of this paper is to present an approach to evaluate the profitableness of a forest policy program and to discover from among the feasible programs the one that best complies with the desired performance of the economy. At first the procedures of forest policy-making in a country like Finland is considered. After that a method to evaluate forest policy programs is derived.

• Vehkamäki, E-mail: sv@mm.unknown

This paper considers the problems of world’s forestry and emphasizes the policy nature of the most threatening issues. A policy science approach is needed in order to be able to provide effective tools to solve the problems. Incremental forest policies followed are evaluated to be too tardy to respond to the many forestry issues of today. Managing the global forestry issues presupposes the design of new and more effective and efficient public policy programs. More profound policy analysis is therefore needed to improve the intellectual basis for planning and decision making. The advancement of the research on the effectiveness presupposes further development of the theories of timber supply and forestry investments as well as the improvement of national forestry statistics. The whole forest policy process should be a subject to intensified systematic research.

• Tikkanen, E-mail: it@mm.unknown

The issue of Silva Fennica comprises 22 papers on forest policy and program analysis, and evaluation presented at the XVIII IUFRO World Congress in 1986 arranged in Ljubljana. The papers discuss the future and role of policy and program analysis, the effectiveness of policy programs on timber supply and private forestry investments as well as the application of forest sector models to policy analysis.

The PDF includes the preface and list of authors in English and an abstract in Finnish.

• Tikkanen, E-mail: –

Paratization of Petrova resinella L. in the gall stage was studied in the surrounding of Harjavalta, south-western Finland, in relation to industrial air pollution. Of the studied 283 galls, 28% produced a moth, 52% of the larvae/pupae were paratisized, and 20% were empty or contained a dead larva. The proportion of paratisized galls did not depend on the distance from emission sources of industrial air pollutants.

The PDF includes an abstract in Finnish.

• Heliövaara, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown

The structure of 20 Scots pine (Pinus sylvestris L.) trees was analysed as a water transport system. There is a tight linear regression between the cross-sectional area of the stem at the height of its lowest living branch and the cross-sectional area of its coarse roots, between the cross-sectional area of the stem at the height of its lowest living branch and the total cross-sectional area of its branches, and between the cross-sectional area of the base of a branch and the total cross-sectional area of subsidiary branches of that branch. The capacity of successive organs, measured as cross-sectional areas, to transport water was thus found to be regular within a tree.

The PDF includes an abstract in Finnish.

• Hari, E-mail: ph@mm.unknown
• Heikinheimo, E-mail: ph@mm.unknown
• Kaipiainen, E-mail: lk@mm.unknown
• Korpilahti, E-mail: eeva.korpilahti@luke.fi
• Mäkelä, E-mail: am@mm.unknown
• Samela, E-mail: js@mm.unknown

This paper is a theoretical study of what is considered to constitute the proper perception of time in forest economics and management. A stumpage appraisal model that recognizes the influence of time is developed within the framework of a national aggregate economy. To demonstrate how a socially optimal land for timber production may be determined in a given nation, a stock-supply model is derived. The stumpage appraisal rule of development determines the market stumpage price that maintains a state of balance between timber production and other land use activities.

The PDF includes an abstract in Finnish.

• Omwami, E-mail: ro@mm.unknown

The relationship between industrial air pollutants and the occurrence of galls of Petrova resinella (Lepidoptera, Torticiadae) was studied around the industrialized town of Harjavalta in Western Finland. There were 44 sampling sites set out at logarithmic distances along five transects (NW, W, SW, SE) froma a distive source of emissions. Each site consisted of three circular sample plots (30 m²) in young Scots pine (Pinus sylvestris L.) stands. The number of galls, including cankers from several years earlier, was highest in the vicinity of the factory complex on each transect. The highest number of two-year-old galls containing living larvae was usually recorded at the ends of the transects several kilometres from the factories. However, the significance of the differences both between zones and transects was rather low. Correlations between the deposition of heavy metals (Cd, Cu, Ni, Pb, Zn), used as an indication of the general level of air pollution, and the total number of galls, were positive and generally highly significant. It is concluded that P. resinella has benefitted from air pollution although perhaps to less extent than some sap-sucking species.

The PDF includes an abstract in Finnish.

• Heliövaara, E-mail: kh@mm.unknown

The natural resistance of Finnish-grown Pinus sylvestris L. heartwood to Macrotermitinae termites was tested in Zambia in graveyard conditions. The heartwood exhibited some natural resistance but durability was, however, far from practical immunity. There was significant tree-to-tree variation in the resistance of heartwood of P. Sylvestris.

The PDF includes a summary in Finnish.

• Löyttyniemi, E-mail: kl@mm.unknown
• Uusvaara, E-mail: ou@mm.unknown

Different sampling methods (the percentage cover scale, the graphical method, two-point quadrat methods, the five-, nine- and twelve-class cover scales, and the biomass harvesting) were used in estimating abundance of ground vegetation in clear-cut areas and on an abandoned field in Southern and Central Finland. The results are examined with the help of DCA ordinations. In addition, the species numbers and diversity indices obtained by different sampling methods are compared.

There were no large differences in DCA configurations between the sampling methods. According to all the sampling methods, a complex soil fertility-moisture gradient (a forest site type) was interpreted as the main ordination gradient in the vegetation data for clear-cut areas. However, different sampling methods did not give similar estimates of species numbers and diversity indices.

The PDF includes a summary in Finnish.

• Jukola-Sulonen, E-mail: ej@mm.unknown
• Salemaa, E-mail: ms@mm.unknown

The abundance of main invertebrate groups was studied in clear-fellings, forests and in edges between them in Northern Finland in June-August 1983. Five trapping transects were used. Each transect had 48 pitfall traps and 16 window traps on the ground and 4-6 window traps in bushes or trees.

Invertebrate groups Homoptera, Diptera, Formicidae, Coleoptera and Gastropoda were more abundant in forest than in clear-cuts according to the pitfall data. In window traps the catches of all the main groups were larger in the forest side. Six out of the eight most important groups preferred the edge in pitfall data. Formicidae, other Hymenoptera, Arachnida and Gastropoda were more numerous in the edges than in the interior habitats in both sides of the edge. In window trap material no consistent edge preference was found in clear-fellings, but in the forest side it was evident. Coleoptera and Arachnida preferred the edge on both sides of it.

The variations in the catches of the invertebrate groups were studied by regression analyses. Independent variables used were the distance to the edge, the coverage of mosses, litter, mineral soil, grasses and sedges, herbs and the density of saplings. The percentage of variance explained in multiple regression analyses were highest for the group of other Hymenoptera and Arachnida and lowest for Coleoptera and Homoptera. As regards the explanation power of the independent variables the distance to the edge and the density of saplings clearly exceeded the others.

The results support the assumption that the breeding bird densities at forest edges, which is often high, may depend on high prey density there.

The PDF includes a summary in Finnish.

• Helle, E-mail: ph@mm.unknown
• Muona, E-mail: jm@mm.unknown

The paper discusses the evaluation of timber production policies with different income (timber drain) schedules. Special attention is given to the temporal smoothness of the income flow. A utility model is formulated in which the objective is to maximize a fixed consumption pattern, and money can be saved and borrowed at different interest rates. We thus have smoothness requirements only for consumption, the capital market then determines the smoothness of the optimal income flow. Present discounted value and maximization of even income flow criteria are special cases of the utility model. Consumption can be maximized by linear programming. A sample problem is presented.

The PDF includes a summary in Finnish.

• Lappi, E-mail: jl@mm.unknown
• Siitonen, E-mail: ms@mm.unknown

Especially in forest vegetation studies, the light climate below the canopy is of great interest. In extensive forest inventories, direct measurement of the light conditions is too time-consuming. Often only the standard tree stand parameters are available. The present study was undertaken with the aim to develop methods for estimation of the light climate on the basis of readily measurable tree stand characteristics. The study material includes 40 sample plots representing different kinds of more or less mature forest stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.).

In each forest stand, a set of hemipherical photographs was taken and standard tree stand measurements were performed. A regression approach was applied in order to elaborate linear models for predicting the canopy coverage. The total basal area of the stand explained 63% of variance in the canopy coverage computed from hemipherical photographs. A coefficient representing the relative proportion of Norway spruce in the stand increased the explanatory power into 75%. When either the stand density (stems/unit area) or dominant age of the stand was included into the model, increment of the explanatory power into 80% was achieved. By incorporating both of the preceding predictors, an explanatory power of 85% was reached.

The PDF includes a summary in Finnish.

• Kuusipalo, E-mail: jk@mm.unknown

1983 was the so-called ”Year o the Forest” in Finland. To mark the occasion, the Society of Forestry in Finland (now the Finnish Society of Forest Science) arranged a series of Studia Forestalia lectures which covered, in general form, a wide range of subjects. 12 of the 14 lectures given in this series are included in this edition.

The PDF includes a summary in English.

• Leikola, E-mail: –
• Koponen, E-mail: –

This article reviews experiments and practical experience of forest management by the selection system in Finland. In an experiment of 25-year duration the annual growth of uneven-aged Norway spruce (Picea abies (L.) H. Karst.) stands was only about 50% of the average annual yield of even-aged stands in normal rotation on the same site.

In Finland the selection system is applicable under exceptional conditions only, viz. In intensively managed park stands and, on the other hand, on very marginal sites, e.g. on peat bogs and mountains near the tree-line. Even normal silviculture, however, may include cuttings which somewhat resemble selection system, e.g. removal of standards or restoration of mismanaged forests.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

The aim of the present study was to survey the occurrence of Otiorrhynchus nodosus Müller weevils and their significance for the natural regeneration of Scots pine (Pinus sylvestris L.). The study was carried out during summer 1982 at Inari in northern Lapland.

There were two sample plots, one situated in a Scots pine seed-tree area and the other, the control sample plot, in an area with a coverage of mountain birch (Betula pubescens subsp. tortuosa, now subsp. czerepanovii). A total of 177 Otiorhynchus weevils were caught. Movement of the weevils reached its climax in July. There were 86% more individuals in the seed-tree area than in the mountain birch area. No damage to the pine germlings or seedlings was not observed, although the situation could be different during the peaks of the veewil populations.

The PDF includes a summary in English.

• Suoheimo, E-mail: js@mm.unknown

A total of 146 Norway spruce-dominated clear-cutting areas and 140 of the sample plots included in the 7th National Forest Inventory in Finland were examined during 1974–78. The micro-organisms causing decay in Norway spruce (Picea abies (L.) H. Karst.) sample trees were identified. The most common causal agent of butt-rot was Heterbasidion annosum (Fr.) Bref. Other fungi causing decay in the spruce trees were Armillaria mellea (Vahl.) Quél, Stereum sanguinolentum (Alb. & Schw. ex Fr.), Resinicum bicolor (Alb. & Schw. ex Fr.) Parm. and Climacocystis borealis (Fr.) Kotl. & Pouz. Species of Ascocoryne were very often present in the decay. The decay caused by H. annosum was considerably more extensive than cases of decay where the fungus was not present.

The PDF includes a summary in Finnish.

• Hallaksela, E-mail: ah@mm.unknown

In the 1980 and 1981, windthrown and felled Scots pine (Pinus sylvestris L.) were examined at 8 localities in Sweden. The number and length of egg galleries as well as the number of exit holes of Tomicus piniperda (L.) and T. minor (Hart.) were recorded on sample sections (30 m in length) distributed at 3 m intervals on the 37 fallen pine stems, which were successfully colonized by the beetles. In addition, 78 uprooted pines were surveyed in 6 localities. Most trees were attacked by T. piniperda, but only a few by T. minor. Successful colonization often resulted in the production of several thousand beetles per tree, the maximum being approximately 1,800. The attack density of T. piniperda seldom exceeded 200 egg galleries/m³ bark area, and the brood production usually remained below 1,000 beetles/m³. Much higher figures were obtained or T. minor. In T. piniperda, the rate of reproduction (i.e. the number of exit holes /egg gallery) decreased rapidly with increasing attack density, whereas T. minor seemed to be less sensitive to intraspecific competition.

The PDF includes a summary in Finnish.

• Långström, E-mail: bl@mm.unknown

A field data set representing boreal forest-floor vegetation in Southern Finland was analysed using a simultaneous equation model. Some physical and chemical characteristics of the soil and some structural characteristics of the tree stand were treated as predictors in such a way that the tree stand factor was specified to be dependent on the soil variables. Alpha diversity, measured as the total number of species per plot, was treated as a criterion variable.

The model explains 60% of variance in the alpha diversity indicating markedly strong relationships with the site characteristics. Alpha diversity appears to increase with increases in site fertility characteristics. On the other hand, measured characteristics of the tree stand indicate no significant independent effects on the alpha diversity.

The PDF includes a summary in Finnish.

• Kuusipalo, E-mail: jk@mm.unknown

The Lauhavuori area is barren, consisting of sandstone and granite bedrock covered by coarse moraine and sand. The woodlands are dominated by Scots pine (Pinus sylvestris L.) and Calluna. The top of the hill, rising 230 metres above the sea level, is more fertile, as it was never covered by the ancient Baltic Sea. Numerous springs and spring brooks are bordered by herb-rich Norway spruce (Picea abies (L.) H. Karst.) woodlands and swamps. Although most of the peatlands are oligotrophic, several mesotrophic peatland plants occur, some southern, giving the peatlands a rather northerly character.

The study area is 8 by 12 km. According to the vegetation analysis, 310 species were identified, 208 of which were native to the area and 102 immigrants. The native species can be separated from the immigrants because the area is largely undisturbed.

The PDF includes a summary in English.

• Suominen, E-mail: js@mm.unknown
• Varkki, E-mail: av@mm.unknown

Flight periods of insects breeding on birch (Betula sp.) timber were observed by means of window flight traps baited with freshly cut birch logs in five locations in Finland from 1972 to 1976. Only few species were caught during the study. In general, these species were on the wing during midsummer, although flight periods of some of them were relatively long. Scolytus ratzeburgi Jans. caused harmful staining of wood within a month from attack, but the damage by the wood-boring pests remained negligible throughout the first storage summer.

The PDF includes a summary in Finnish.

• Löyttyniemi, E-mail: kl@mm.unknown

Vegetation data collected from a random sample of mature forest stands representing mesic upland forest sites in Southern Finland were analysed and classified using two-way indicator species analysis (TWINSPAN). The variation of some characteristics of the tree stand and soil fertility between the produced vegetation units were analysed statistically.

Both the species list and the sample list arranged by TWINSPAN reflects the overall site fertility considerably well. The results are in agreement with the main division of mesic forest sites in the Finnish forest site type classification: vegetation units which can be assigned to the Oxalis-Myrtillus site type are clearly separated from the remaining units, and the overall site fertility indicates a statistically significant difference. The within-type variation in the vegetation composition in the Oxalis-Myrtillus site type reflects the variation in site fertility, whereas the within-type variation in the Myrtillus site type is mainly caused by the tree stand factor.

The PDF includes a summary in Finnish.

• Kuusipalo, E-mail: jk@mm.unknown

The effect of nitrogen fertilization and two insecticides on the occurrence of the plant pine bark bug, Aradus cinnamomeus Panzer, was investigated in a young Scots pine (Pinus sylvestris L.) stand in Southern Finland. Three years after the treatment the bug density was lowest in the trees treated with lindane or dimethoate. However, in spite of the increasing height growth of the trees, they did not grow significantly faster than the control trees. Nitrogen fertilization increased both bug density and the height growth of the trees. Thus, the value of nitrogen fertilization against Aradus cinnamomeus remains obscure.

The PDF includes a summary in Finnish.

• Heliövaara, E-mail: kh@mm.unknown
• Annila, E-mail: ea@mm.unknown
• Terho, E-mail: et@mm.unknown

An inventory of Scots pine (Pinus sylvestris L.) graft collection in Kolari (67°15’ N, 23°45’ S) showed that severe damage by arctic hare (Lepus timidus L.), root and bank vole (Microtus oeconomus Pallas and M. agrestis L.) and moose (Alces alces L.) was done to grafts in size and in rather poor condition. Furthermore, the damage by arctic hare was dependent on the dry matter content of the needles. Another inventory in a fertilization experiment in a pine pole-stage forest showed that nitrogen fertilization increased the damage by arctic hare. On the basis of the present results, an assumption was made that the formation of repellent substances against herbivorous mammals is connected with wintering process of northern pines.

The PDF includes a summary in Finnish.

• Rousi, E-mail: mr@mm.unknown

Sawmilling and Carpentry, Forestry and Hunting, and Food Grains are the economic sectors compared in this study by means of the total input-output coefficient. The coefficient measures the value of direct and indirect demand in the economy caused by a demand worth one monetary unit on the sector in focus. Forestry sector has the weakest linkage to other sectors. The derived coefficients are 1.693 for Sawmilling and Carpentry, 1.183 for Food Grain and 1.167 for Forestry and Hunting.

The PDF includes a summary in Finnish.

• Koljonen, E-mail: kk@mm.unknown

Methods involving the use of moving averages, trend surfaces and their combination are compared in deriving local values of monthly mean temperatures and precipitation sums from the observations made by the Finnish Meteorological Office. Correlation between meteorological variables and sea index, lake index and height above sea level were used in the trend surface method and in the combined method. Combined method, with a trend surface calculated from means of a long time period, was the most reliable method to estimate long local time series.

A method to calculate unbiased estimates of effective temperature sums from monthly mean temperatures is presented.

The PDF includes a summary in English.

• Ojansuu, E-mail: ro@mm.unknown
• Henttonen, E-mail: hh@mm.unknown