article id 445, category Commentary
Northern Primeval Forests – Ecology, Conservation and Management. Silva Fennica vol. 45 no. 5 article id 445. https://doi.org/10.14214/sf.445
article id 448, category Commentary
New paradigm for saving the world’s forests? Silva Fennica vol. 45 no. 4 article id 448. https://doi.org/10.14214/sf.448
Book review: Douglas, J. and Simula, M. 2010. The Future of the World’s Forests. Ideas vs Ideologies. World Forests, volume 7. Springer. 211p.
Category: Research article
article id 90, category Research article
Protecting forest areas for biodiversity in Sweden 1991–2010: the policy implementation process and outcomes on the ground. Silva Fennica vol. 45 no. 5 article id 90. https://doi.org/10.14214/sf.90
Swedish forest and environmental policies imply that forests should be managed so that all naturally occurring species are maintained in viable populations. This requires maintenance of functional networks of representative natural forest and cultural woodland habitats. We first review the policy implementation process regarding protected areas in Sweden 1991–2010, how ecological knowledge was used to formulate interim short-term and strategic long-term biodiversity conservation goals, and the development of a hierarchical spatial planning approach. Second, we present data about the amount of formally protected and voluntarily set aside forest stands, and evaluate how much remains in terms of additional forest protection, conservation management and habitat restoration to achieve forest and environmental policy objectives in the long-term. Third, a case study in central Sweden was made to estimate the functionality of old Scots pine, Norway spruce and deciduous forest habitats, as well as cultural woodland, in different forest regions. Finally, we assess operational biodiversity conservation planning processes. We conclude that Swedish policy pronouncements capture the contemporary knowledge about biodiversity and conservation planning well. However, the existing area of protected and set-aside forests is presently too small and with too poor connectivity. To bridge this gap, spatial planning, management and restoration of habitat, as well as collaboration among forest and conservation planners need to be improved.
article id 89, category Research article
Microsite occupancy and the spatial structure of understorey regeneration in three late-successional Norway spruce forests in northern Europe. Silva Fennica vol. 45 no. 5 article id 89. https://doi.org/10.14214/sf.89
We compared microsite occupancy and three spatial structure of regeneration in three primeval late-successional Norway spruce dominated forests. One area lay in the middle boreal zone in Russia (Dvina-Pinega) where larger-scale disturbance from bark beetles and drought had occurred; the other areas lay in the northern boreal zone, one in Finland (Pallas-Ylläs) had encountered only small-scale disturbance, and one in Russia (Kazkim) had been influenced by fire. We mapped all spruce (Picea abies) and birch (Betula pendula and Betula pubescens) trees with diameter at breast height (DBH) ≥ 10 cm on 40 m 400 m plots, and those with DBH < 10 cm on 2 m or 4 m 400 m subplots. On the subplots we also recorded microsite occupancy and estimated microsite availability. At all study areas small seedlings (h < 0.3 m) of both spruce and birch were found largely on disturbance-related microsites. Birch saplings (h ≥ 1.3 m, DBH < 10 cm) disproportionately occupied deadwood-related microsites at Dvina-Pinega. In contrast, spruce saplings at all study areas, and birch saplings at Kazkim and Pallas-Ylläs, showed less, or no, preference. Our results thus confirm the importance of disturbance-related microsites for regeneration establishment, but not necessarily for long-term survival. No spatial segregation between the overstorey (DBH ≥ 10 cm) and saplings (h ≥ 1.3 m, DBH < 10 cm) or seedlings (h < 1.3 m) was found at Pallas-Ylläs or Kazkim, and only three instances of very weak segregation were found at Dvina-Pinega. This suggests that the regeneration gap concept may not be useful for describing the regeneration dynamics of primeval boreal forests.
article id 88, category Research article
Tree regeneration in artificial canopy gaps established for restoring natural structural variability in a Scots pine stand. Silva Fennica vol. 45 no. 5 article id 88. https://doi.org/10.14214/sf.88
In Finland and elsewhere in Europe, many protected forest areas include also stands that were previously managed and that lack several naturally occurring stand characteristics. In these areas, ecosystem restoration can be used to facilitate and accelerate the formation of structural and habitat features resembling those of natural forests. For example, by creating small gaps it could be possible to diversify forest structure and tree species composition and to produce dead wood while still maintaining mostly continous canopy coverage. We examined experimentally the effects of artificial gap formation on post-disturbance tree regeneration in the gaps in a young protected, but formerly commercially managed pine (Pinus sylvestris L.) dominated forest. In the experimental sites, gap size and the portion of girdled trees out of all treated trees (girdled and felled trees combined) in the gaps varied. Natural and artificial (direct seeding of silver birch Betula pendula Roth) tree regeneration and development was monitored both on disturbed (scarified soil patches) and undisturbed forest floor during three growing seasons. Results show that gaps can be valuable in diversifying stand structure but to be successful and rapid, tree regeneration needs disturbed forest floor. Pine regenerated numerously, but birch had clearly lower regeneration, especially on small-sized gaps. In conclusion, increasing tree diversity in young pine-dominated forests seems to be difficult when only small artificial gaps are used. But even small gaps can be used to create and maintain diverse cohort structure of the dominant species and thus they can contribute to restoration goals.
article id 87, category Research article
Density and height structure of seedlings in subalpine spruce forests of Central Europe: logs vs. stumps as a favourable substrate. Silva Fennica vol. 45 no. 5 article id 87. https://doi.org/10.14214/sf.87
Decaying logs and stumps provide an important seedling substrate in natural subalpine forests. However, only stumps present such a role in managed forests. The aim of this study was to assess the differences in the process of seedling colonization between logs and stumps. The study was carried out in the Czech Republic, in two old-growth subalpine spruce forests located in the Bohemian Forest and Ash Mts., dominated by Athyrium distentifolium Opiz and Vaccinium myrtillus L. undergrowth, respectively. Norway spruce (Picea abies (L.) Karst.) regeneration growing on logs, stumps and non-coarse woody debris (CWD) microsites was surveyed. Regeneration (height 0–2.0 m) densities exceeded 5000 individuals per ha on both sites. The average density of P. abies regeneration per square meter of substrate was 0.3-5.7-19.6 and 0.5-3.8-11.0 on non-CWD microsites, logs and stumps, located in A. distentifolium and V. myrtillus undergrowth, respectively. Stumps and non-CWD microsites dominated by V. myrtillus, supported a higher proportion of taller seedlings per plot compared to the small seedlings growing on logs and non-CWD dominated by A. distentifolium ground-cover. The disproportion in regeneration densities between the stumps and the original logs decreased with increasing stages of decay. The tallest regeneration growing on stumps (root-soil plates) was significantly older than that growing on the logs (stems). Based on these two latter findings, the stumps appeared to provide suitable seedling substrates several years earlier than the logs did. Therefore, we conclude that the stumps play a more important role (relative to their covered area, 21–28 m2 ha–1) in terms of suitable microsites for regeneration, than the logs do.
article id 86, category Research article
Logs and stumps in clearcuts support similar saproxylic beetle diversity: implications for bioenergy harvest. Silva Fennica vol. 45 no. 5 article id 86. https://doi.org/10.14214/sf.86
Stumps from clear cuts are increasingly used for bioenergy. Extracting this wood will reduce the habitat available for saproxylic (wood-living) organisms. As little is known about the species assemblages that will be affected, we investigated the diversity of saproxylic beetles in stumps on clear-felled sites and as a reference, we compared it with the diversity in downed logs. Stumps and logs of aspen (Populus tremula L.), birch (Betula pubescens Ehrh. and B. verrucosa Ehrh.[syn. B. pendula Roth]), spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) were examined in clear cuts of two different ages: one summer old and 4–5 years old. The beetles were sampled by sieving bark (0.25 m2) peeled from the wood. The samples were taken in pairs of one log and one stump situated close together and of the same tree species, age since death and diameter. In total 3348 saproxylic beetles belonging to 124 species were found in 176 samples. The stumps had a similar number of species to the logs both as measured per sample and as an accumulated number. Exceptions were 4–5 years old wood of birch and pine where the number was significantly higher in the stumps. The number of red-listed species was also similar between stumps and logs. Species composition was more different between the stumps and logs of conifers than of deciduous trees. We conclude that clear-felled stumps have a diverse saproxylic insect fauna. This has to be taken into account if large scale extraction of logging stumps is implemented.
article id 85, category Research article
The conservation potential of brook-side key habitats in managed boreal forests. Silva Fennica vol. 45 no. 5 article id 85. https://doi.org/10.14214/sf.85
Today, maintaining biodiversity is included in the targets of boreal forest management. A widespread approach in northern Europe is to identify and preserve woodland key habitats within managed forests. Woodland key habitats are expected to be patches that host populations of threatened and declining species, and the preservation of these patches is assumed to enable the persistence of the focal species in the landscape. In Finland, the criteria for selecting woodland key habitats are defined in the Finnish Forest Act, and the selection has been done by forest practitioners. Our objective was to determine whether the surroundings of boreal brooks and rivulets qualified as key habitats are truly different from brook-side habitats not granted the key habitat status, and whether the brook-side habitats of the two types differ from the forest matrix managed for timber production. We found that the two brook-side habitats were in most aspects rather alike but there was a difference in the composition of ground vegetation assemblages. In contrast, the control forests were distinct from the brook-sides in terms of dead wood, species richness and assemblages of polypores, species richness of epiphytic mosses, and the composition of beetle assemblages. We conclude that brook-sides in general provide an important habitat clearly diverging from the surrounding matrix but that the conservation value of the brook-sides granted the key habitat status may not be substantially larger than that of the brook-sides without the status.
article id 84, category Research article
Old-forest species: the importance of specific substrata vs. stand continuity in the case of calicioid fungi. Silva Fennica vol. 45 no. 5 article id 84. https://doi.org/10.14214/sf.84
Appropriate conservation management of old-forest species depends on the causes of their old-forest affinity, which, however, are insufficiently known. Calicioid fungi are often considered old-forest dependent because of their special requirements for microhabitat, microclimate, and stand continuity for at least two tree generations. We demonstrate that, for several methodological or interpretational problems, published studies do not provide unequivocal evidence for such mechanisms and even for old-forest dependency of calicioids in general. We then analyse a large Estonian dataset (ca. 2300 records of 32 species) representing various management types and site types to answer whether old forests have more calicioid species, and any specific species, than could be expected for the substratum availability observed. Although old growth had more species and records than mature managed stands or cutover sites, those substratum types that occurred at roughly similar abundances also hosted comparable numbers of species in different management types. The characteristic substrata adding extra species to old growth were snags and root-plates of treefall mounds; wood surfaces in general comprised more than half of all calicioid records. Although substratum abundance did not fully explain the species-richness contrast between old growth and mature stands, additional evidence suggested that the unexplained variance is rather due to small-scale habitat characteristics than stand-scale continuity or microclimate. Finally, we review the evidence for old-forest affinity of calicioid species and distinguish a set of threatened species. We conclude that the availability of specific substrata is the main limiting factor for calicioid fungi in forests, and its quantitative and stochastic nature explains the large random and region-specific variation in the published lists of ‘old-forest species’.
article id 83, category Research article
Relationships between wood-inhabiting fungal species richness and habitat variables in old-growth forest stands in the Pallas-Yllästunturi National Park, northern boreal Finland. Silva Fennica vol. 45 no. 5 article id 83. https://doi.org/10.14214/sf.83
Indicators for biodiversity are needed for efficient prioritization of forests selected for conservation. We analyzed the relationships between 86 wood-inhabiting fungal (polypore) species richness and 35 habitat variables in 81 northern boreal old-growth forest stands in Finland. Species richness and the number of red-listed species were analyzed separately using generalized linear models. Most species were infrequent in the studied landscape and no species was encountered in all stands. The species richness increased with 1) the volume of coarse woody debris (CWD), 2) the mean DBH of CWD and 3) the basal area of living trees. The number of red-listed species increased along the same gradients, but the effect of basal area was not significant. Polypore species richness was significantly lower on western slopes than on flat topography. On average, species richness was higher on northern and eastern slopes than on western and southern slopes. The results suggest that a combination of habitat variables used as indicators may be useful in selecting forest stands to be set aside for polypore species conservation.
article id 82, category Research article
Dynamic old-growth forests? A case study of boreal black spruce forest bryophytes. Silva Fennica vol. 45 no. 5 article id 82. https://doi.org/10.14214/sf.82
Old-growth forests have sparked significant interest over the last twenty years and definitions have evolved from structure based to process based, acknowledging the diversity of forests that could be considered old growth. However studies frequently group all forests over a certain age into a single type, negating the dynamic processes that create old growth. In this study we examine a 2350-year chronosequence in boreal black spruce forests in northwestern Quebec to determine whether continued community change can be observed in the bryophyte layer. Bryophytes dominate the understory of boreal forests and influence ecosystem functioning, particularly in paludified forests where production exceeds decomposition in the organic layer. Community composition and richness changed throughout the chronosequence with no evidence of a steady state associated with an old-growth phase. In contrast the bryophyte community continued to evolve with multiple phases being evident. These results suggest that old-growth forests on the Clay Belt of northwestern Quebec and northeastern Ontario, Canada, should be regarded as part of the continuous gradient in forest development rather than a single state. This complicates conservation of these forests as multiple phases should be considered when planning forest reserves.
article id 81, category Research article
Temporal variability of deadwood volume and quality in boreal old-growth forests. Silva Fennica vol. 45 no. 5 article id 81. https://doi.org/10.14214/sf.81
Reference deadwood volumes from natural forests for forest management and restoration are often derived from one-time measurements or from repeated measurements over short time-scales. Such an approach often assumes an equilibrium state between tree mortality and decomposition, which is questionable in many boreal forest ecosystems due to the occurrence of allogenic disturbances. Using a simulation model based on empirical estimates of tree mortality, disturbance chronologies and models of wood decay class dynamics, this study aimed at characterizing variability in the volume and quality of deadwood for the past 200 years. The variability of deadwood volumes in old-growth forests, arising from differences in disturbance regimes and differing decay rates, was exemplified in two areas of Picea abies-dominated forests in northern Europe. The results imply that with stable deadwood input and slow decay rates the deadwood volume may be in an equilibrium state. On the contrary, if moderate-severity disturbances occur such a state seems improbable. Both study areas displayed continuity in deadwood availability, although temporary paucity in the early decay classes with shortest residence times was also observed. The results stress the importance of understanding the dynamic nature of deadwood in old-growth forests, instead of the traditional view of deadwood as a static ecosystem component.
article id 80, category Research article
Spatio-temporal variation of coarse woody debris input in woodland key habitats in central Sweden. Silva Fennica vol. 45 no. 5 article id 80. https://doi.org/10.14214/sf.80
The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies of CWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWD input. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites’ varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.
article id 79, category Research article
Alternative silvicultural practices in irregular boreal forests: response of beetle assemblages. Silva Fennica vol. 45 no. 5 article id 79. https://doi.org/10.14214/sf.79
In the process of implementing sustainable management in the eastern Canadian boreal forest, we tested two selection cutting methods and compared them with two widely used practices in the boreal forest: clearcutting with protection of the advanced growth and soils and irregular shelterwood cutting leaving small merchantable stems. We used old-growth irregular stands as references in comparing the impact of these silvicultural treatments on the diversity and abundance of beetles. Three groups were targeted: saproxylic flying beetles, epigaeic saproxylic beetles and epigaeic non-saproxylic beetles. A sampling design including 320 pitfall traps and 80 multidirectional flight-interception traps was deployed in 2007. A total of 26 906 beetles was captured including 407 taxa distributed among 52 families. We found that clearcutting with protection of the advanced growth and soils and irregular shelterwood cutting leaving small merchantable stems had a greater impact on beetle communities than both selection cuttings. Canopy opening as well as the presence of snags and downed woody debris appear as important attributes for several saproxylic and non-saproxylic species. Beetle communities in selection cuttings remained more similar to those found in controls; these silvicultural treatments are new tools to implement ecosystemic and sustainable management in irregular boreal forests.
article id 78, category Research article
Reappearance of old-growth elements in lowland woodlands in northern Belgium: Do the associated species follow? Silva Fennica vol. 45 no. 5 article id 78. https://doi.org/10.14214/sf.78
The forest cover of the western European lowland plain has been very low for centuries. Remaining forests were intensively managed, and old-growth elements like veteran trees and coarse woody debris became virtually absent. Only over the last decades have these old-growth elements progressively redeveloped in parks, lanes and forests, and have now reached their highest level over the last 500–1000 years. Biodiversity associated with these old-growth elements makes up an important part of overall forest biodiversity. The ability of species to recolonise the newly available habitat is strongly determined by limitations in their dispersal and establishment. We analyse the current status and development of old-growth elements in Flanders (northern Belgium) and the process of recolonisation by means of specific cases, focussing on saproxylic fungi and saproxylic beetles. Our results show that ‘hotspots’ of secondary old growth, even isolated small patches, may have more potential for specialised biodiversity than expected, and may provide important new strongholds for recovery and recolonisation of an important share of old-growth related species.
article id 77, category Research article
Fire regime and old-growth boreal forests in central Quebec, Canada: an ecosystem management perspective. Silva Fennica vol. 45 no. 5 article id 77. https://doi.org/10.14214/sf.77
Boreal forest management in Eastern Canada has caused depletion and fragmentation of old-growth ecosystems, with growing impacts on the associated biodiversity. To mitigate impacts of management while maintaining timber supplies, ecosystem management aims to narrow the gap between natural and managed landscapes. Our study describes the fire history and associated natural old-growth forest proportions and distribution of a 5000 km2 area located in the black spruce-feather moss forest of central Quebec. We reconstructed a stand-origin map using archival data, aerial photos and dendrochronology. According to survival analysis (Cox hazard model), the mean fire cycle length was 247 years for the 1734–2009 period. Age-class distribution modelling showed that old-growth forests were present on an average of 55% of the landscape over the last 275 years. The mean fire size was 10 113 ha, while most of the burned area was attributable to fires larger than 10 000 ha, leading to old-growth agglomerations of hundreds of square kilometres. In regards to our findings, we propose ecosystem management targets and strategies to preserve forest diversity and resilience.
article id 76, category Research article
Gap-phase dynamics in the old-growth forest of Lom, Bosnia and Herzegovina. Silva Fennica vol. 45 no. 5 article id 76. https://doi.org/10.14214/sf.76
We investigated forest canopy gaps in the mixed beech (Fagus sylvatica L.), silver fir (Abies alba Miller), and Norway spruce (Picea abies (L.) Karst.) old-growth forest of Lom in the Dinaric Mountains of Bosnia and Herzegovina. Gap size, age, gap fraction, gapmaker characteristics and the structure and composition of gapfillers were documented to investigate gap dynamics. The percentages of forest area in canopy and expanded gaps were 19% and 41%, respectively. The median canopy gap size was 77 m2, and ranged from 11 to 708 m2. Although there were many single tree-fall gaps, the majority had multiple gapmakers that were often in different stages of decay, suggesting gap expansion is important at the study site. Of the gapmakers recorded, 14% were uprooted stems, 60% snapped stems, and 26% were standing dead trees. Dendroecological analysis suggests that gap formation varied in time. The density of gapfillers was not correlated to gap size, and the species composition of gapfillers varied between seedling, sapling, and tree life stages. The results suggest that gaps are mainly formed by endogenous senescence of single canopy trees. Exogenous disturbance agents, most likely related to wind and snow, act mainly as secondary agents in breaking weakened trees and in expanding previously established gaps. Although the findings are partially consistent with other studies of gap disturbance processes in similar old-growth forests in central Europe, the observed gap dynamic places the Lom core area at the end of a gradient that ranges from forests controlled by very small-scale processes to those where large, stand replacing disturbances predominate.
article id 75, category Research article
Spatial structure in four Norway spruce stands with different management history in the Alps and Carpathians. Silva Fennica vol. 45 no. 5 article id 75. https://doi.org/10.14214/sf.75
In Europe most Norway spruce (Picea abies (L.) Karst.) mountain forests have been altered by human activities, leading to a lack of reference condition concerning their original structure. Nonetheless, remnants of Norway spruce primeval forests still exist in the Carpathians. Our objective was to assess the differences in structure between managed and unmanaged stands, concerning diameter distributions, amount of standing deadwood, spatial distributions and spatial structure of trees. We established four permanent plots: one in a virgin forest in the Eastern Carpathians and three in a previously managed forest in the Alps. In each plot, species, DBH, and position of the live and dead standing trees were collected. Spatial distribution and structure of all the trees was analysed through several indices. In the Carpathians forest there are clear signs of natural density-dependent mortality processes whereas in the Alpine plots such dynamics are less evident. In these latter plots, the lower snags volume and the random trees spatial distribution can be considered the legacies of past management. Nonetheless, despite the different history of the four stands, they all seem to converge towards a similar spatial structure with the presence of groups (30–40 m) of trees of similar size.
article id 447, category Research article
Histochemical and geometric alterations of sapwood in coastal Douglas-fir following mechanical damage during commercial thinning. Silva Fennica vol. 45 no. 4 article id 447. https://doi.org/10.14214/sf.447
Histochemical and geometric alterations to sapwood in mechanically damaged Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) trees were quantified 14 years after thinning. Discoloration and decay were measured in felled damaged and undamaged trees. Compartmentalized walls were identified and measured macroscopically. Sapwood to heartwood ratio was measured incrementally along the boles. Results showed a distinct reaction zone forming at the time of injury. Compartmentalized walls 1–3 were less distinct and heavily resinous streaking was evident in extant tissues, particularly in the axial direction. Post-damaged sapwood was burl-like for 4–6 years and tracheids contained resin-filled lumina. Damaged wood volumes were modeled by multiple regression. Wound depth, wound area, and diameter inside bark (DIB) accounted for 73% of the discolored volume (p = 0.02). DIB alone accounted for just over 55% of the response. Post-damaged sapwood averaged 15 mm (SE = 2.3 mm) greater in width on the side opposite the damage along the length of the boards. Wound area explained just over 65% of this response (p = 0.003). Sapwood area was not significantly different between damaged and control trees (p = 0.56). Results indicate that wounded Douglas-fir trees may slow conversion of sapwood to heartwood on the bole side opposite the wound, possibly as a response to maintain sapwood area necessary for physiological maintenance of the existing crown. About 19% of the lower bole volume in damaged trees was affected by discoloration and secondarily by structural changes. Reduction in value of the lower log can be as high as 19% by conventional bucking practices. Alternatives are presented to reduce the value loss to between 2.5% to 3.5%.
article id 103, category Research article
Making sustainability rankings using compromise programming. An application to European paper industry. Silva Fennica vol. 45 no. 4 article id 103. https://doi.org/10.14214/sf.103
This paper characterizes the sustainability of the European paper industry. To undertake this task the sustainability of each country is defined by using fourteen indicators of a diverse nature (economic, environmental and social). These indicators are aggregated into a composite or synthetic index with the help of a compromise programming model. In order to associate different weights with each indicator, a survey among international experts has been carried out. In this way, a ranking of seventeen European countries analysed in terms of the sustainability of the European paper industry has been established, where Finland is the most sustainable paper industry in Europe except when the most balanced solution is chosen. Also, the results are robust when different preferential weights are attached. Finally, this methodology can be applied at a more disaggregated level and other indicators can be introduced.
article id 102, category Research article
Network co-operation as a source of competitiveness in medium-sized Finnish sawmills. Silva Fennica vol. 45 no. 4 article id 102. https://doi.org/10.14214/sf.102
In the Finnish sawmill industry, inter-firm collaboration has often been brought up as a means of creating a competitive edge in global markets by achieving economies of scale. According to the resource-based view (RBV), a firm can evaluate its current or potential partners by considering firm-level collaboration as a portfolio of complementary strategic resources. The specific focus of the study is on examining the types and forms of sawmill co-operation, how the co-operation emerged and which firm-specific resources are mainly related to co-operation. Based upon this, we can see how the managers of medium-sized sawmills perceive network co-operation as facilitating the achievement of a sustainable competitive advantage. The empirical data for this study were collected by interviewing 16 managers and employees in medium-sized non-integrated sawmills, a joint-venture marketing company and other co-operative partners. The findings of the study show that meaningful and beneficial co-operation partnerships exist in the Finnish sawmilling industry, but the sawmill managers do not perceive this collaboration as a strategic resource. The marketing company was the only firm in this study that relied on its co-operative networks in seeking a sustainable competitive advantage. To make more of co-operative partnerships, the principles of co-operative networking should be understood better in the sawmilling industry in order to know what to expect from co-operation. Furthermore, the managers should have the courage to engage in more extensive co-operation in order for strategic rents to materialize. Since the selection of the right partners is fundamental, further studies could be conducted on the reasons behind failed or terminated co-operative arrangements to gather further empirical knowledge in this subject area.
article id 101, category Research article
Large-scale forest owner’s information needs in operational planning of timber harvesting - some practical views in Metsähallitus, Finnish state-owned enterprise. Silva Fennica vol. 45 no. 4 article id 101. https://doi.org/10.14214/sf.101
Metsähallitus in Finland is a state enterprise that manages about 3.5 million hectares of productive commercial state-owned forest land. Metsähallitus has a forest management planning system which uses information stored in a GIS-based forest resource information system. The information on forest resources is currently collected using a standwise inventory system with ocular estimation of stand characteristics. New promising inventory methods based on laser scanning have been introduced. Before taking a new system into use, the information needs of Metsähallitus must be analysed. In this study, information needs in operational harvest planning have been analysed with a qualitative approach. A total of eight team leaders in the forestry business unit were interviewed, six of them representing the process responsible for the operational harvest planning and two representing the process responsible for the harvest and deliveries. Based on the study, two main decision making points with different information needs were confirmed. The first decision making point is related to finding the areas potential for immediate or near future harvesting. Here, geographical information on the need for the treatment as well as rough information on the harvestable volume is needed. In the second decision making point, a final decision of sites to be harvested is made with rather intensive field work. Precise delineations of the treatment are needed as well as good estimates of volumes of different timber assortments. When considering a new inventory system it is justified to consider how much of the information needs in these decision making points can be covered. Two different approaches are proposed for further analysis. The interviews revealed a need for a more structured tactical planning system. Some of the findings of this study – especially the decision making points and information needs in them – may be transferable to other large-scale forest owners.
article id 100, category Research article
Sensitivity of harvest decisions to errors in stand characteristics. Silva Fennica vol. 45 no. 4 article id 100. https://doi.org/10.14214/sf.100
In forest planning, the decision maker chooses for each stand a treatment schedule for a predefined planning period. The choice is based either on optimization calculations or on silvicultural guidelines. Schedules for individual stands are obtained using a growth simulator, where measured stand characteristics such as the basal area, mean diameter, site class and mean height are used as input variables. These characteristics include errors, however, which may lead to incorrect decisions. In this study, the aim is to study the sensitivity of harvest decisions to errors in a dataset of 157 stands. Correct schedules according to silvicultural guidelines were first determined using error-free data. Different amounts of errors were then generated to the stand-specific characteristics, and the treatment schedule was selected again using the erroneous data. The decision was defined as correct, if the type of harvest in these two schedules were similar, and if the timings deviated at maximum ±2 for thinning and ±3 years for clear-cut. The dependency of probability of correct decisions on stand characteristics and the degree of errors was then modelled. The proposed model can be used to determine the required level of measurement accuracy for each characteristics in different kinds of stands, with a given accuracy requirement for the timing of treatments. This information can further be utilized in selecting the most appropriate inventory method.
article id 99, category Research article
Local prediction of stand structure using linear prediction theory in Scots pine-dominated stands in Finland. Silva Fennica vol. 45 no. 4 article id 99. https://doi.org/10.14214/sf.99
This study produced a family of models for eight standard stand characteristics, frequency and basal area-based diameter distributions, and a height curve for stands in Finland dominated by Scots pine (Pinus sylvestris L.). The data consisted of 752 National Forest Inventory-based sample plots, measured three times between 1976 and 2001. Of the data, 75% were randomly selected for modelling and 25% left out for model evaluation. Base prediction models were constructed as functions of stand age, location and site providing strongly average expectations. These expectations were then calibrated with the known stand variables using linear prediction theory when estimating the best linear unbiased predictor (BLUP). Three stand variables, typically assessed in Finnish forest management planning fieldwork, were quite effective for calibrating the expectation for the unknown variable. In the case of optional distributions, it was essential to choose the weighting of the diameter distribution model such that the available input variables and the model applied were based on the same scale (e.g. arithmetic stand variables for frequency distribution). Additional input variables generally improved the accuracy of the validated characteristics, but the improvements in the predicted distributions were most noteworthy when the arithmetic mean and basal area-weighted median were simultaneously included in the BLUP estimation. The BLUP method provided a flexible approach for characterising relationships among stand variables, alternative size distributions and the height–diameter curve. Models are intended for practical use in the MOTTI simulator.
article id 98, category Research article
Mounding and scalping prior to reforestation of hydrologically sensitive deep-peated sites: factors behind Scots pine regeneration success. Silva Fennica vol. 45 no. 4 article id 98. https://doi.org/10.14214/sf.98
Watering up typically ensues after clearcutting forestry-drained peatland forests. Thus, the effectiveness of maintenance drainage and soil preparation procedures becomes paramount for establishing a new generation of commercial forest. Mounding is the primary method of soil preparation applied in regeneration sites lying on deep peat. As raised planting spots, mounds are resistant to waterlogging and assumed to be beneficial for organic matter (OM) decomposition via, e.g., increased soil aeration and temperature, which would also enhance seedling growth. In recent years, however, less intensive and cheaper alternatives like scalping have been sought with some reported cases of success. Our case study investigated the survival and growth of Scots pine outplants in mounds, scalps, and unprepared microsites along a moisture gradient. After three growing seasons, mounding accelerated neither seedling growth nor OM decomposition relative to the unprepared treatment. Survival in mounds was nonetheless superior overall. Scalps behaved as water collecting depressions leading to a catastrophic regeneration result. Based on our findings, water table level (WTL) overrides other growth-controlling factors in excess moisture conditions. To combat watering up coupled with greater than normal rainfall, we recommend reforestation strategies which provide elevated, prepared planting spots (i.e., mounds) or utilize unprepared, higher microforms.
article id 97, category Research article
Seedling survival and establishment in small canopy openings in drained spruce mires in Northern Finland. Silva Fennica vol. 45 no. 4 article id 97. https://doi.org/10.14214/sf.97
A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. Traditional regeneration methods with effective site preparation and planting generally result in satisfactory seedling stands also in spruce mires. However, natural regeneration methods may be more appropriate in protecting watercourses and minimizing regeneration costs. We studied the survival of advance growth and establishment of new seedlings in small canopy openings that were cut at three different diameters in two experimental drained spruce mire stands in Northern Finland (Tervola and Oulu) in 2004. The number of seedlings was repeatedly surveyed from five small circular plots (one 10 m2 and four 5 m2 plots in size) located within the opening. Advance growth which survived the cutting and new seedlings were separated in the surveys. The density of advance growth was on average 9000 ha–1 after cutting, and it decreased by 30% during the five-year monitoring period (2006–2010) due to natural mortality. The number of new seedlings increased rapidly within the three years after cutting the openings. In 2010, 11 000–26 000 new seedlings ha–1 in Tervola and 12 000–16 000 ha–1 in Oulu on average were observed. The size of the opening had no clear effect on the regeneration result. The proportion of birch of the new seedlings increased with time and opening size in Tervola. The results show that Norway spruce regenerates naturally in small canopy openings cut in mature drained spruce mire stands.
article id 96, category Research article
How well do U.S. Forest Service terrestrial ecosystem surveys correspond with measured vegetation properties? Silva Fennica vol. 45 no. 4 article id 96. https://doi.org/10.14214/sf.96
Reliable estimates of species composition that forest sites are capable of supporting – specific to ecosystem mapping units across landscapes – are useful for many purposes in forest science and management. Like forestry agencies in numerous countries, the U.S. Forest Service has invested in ecological land classification (termed terrestrial ecosystem survey [TES] in the study region of Arizona) that includes ecosystem-explicit species lists taken to be estimated potential natural vegetation (PNV). Using multivariate community analyses, PNV in the TES was compared to measured species composition on 66 sites representing among the least-disturbed vegetation (considered this study’s measured PNV) spanning 11 ecosystem types on a Pinus ponderosa P. & C. Lawson landscape in northern Arizona, USA. Agreement between the TES PNV and measured species composition was lowest for forbs and shrubs (compared to graminoids), and species composition differed significantly between the TES and this study for at least one plant lifeform in 73% of ecosystems. Reasons for differences between the TES and this study are difficult to resolve, but in some cases appear to result from identification of different species pools in the region. This study suggests that the TES is a useful starting point in understanding vegetation-environment relationships, but further work is needed to refine species lists and more thoroughly account for the influences of fire, grazing, and climate that can influence both PNV and current vegetation. Refining and updating ecosystem-specific species lists may benefit existing forest site classifications and could be planned for when new site classifications are developed, especially with changing climates.
article id 95, category Research article
Thinning effects on jack pine and black spruce photosynthesis in eastern boreal forests of Canada. Silva Fennica vol. 45 no. 4 article id 95. https://doi.org/10.14214/sf.95
A decrease in the average diameter of commercially harvested tree species in the Eastern boreal forest of Canada has led to a decrease in availability of quality wood for the forest industry. Commercial thinning has been proposed as a means to increase stem diameter growth. However, little is known about physiological responses underlying species responses to thinning. We assessed the effect of canopy opening on the photosynthetic response of mature jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) trees. Two years after thinning and for each species, light response curves and the diurnal course of photosynthesis were characterized from measurements taken in a completely randomized block experiment on current-year and one-year-old needles of 12 trees from stands subjected to different levels of canopy opening. Soil water content, air and soil temperatures, and needle N concentration were not affected by thinning for either species. However, light availability increased with basal area removed and could explain the significantly positive relationship between thinning intensity and diurnal course of photosynthesis for one-year-old needles of jack pine. Black spruce photosynthesis did not respond to increases in light. Light-saturated rate of net photosynthesis (Amax), photosynthetic efficiency (α), light compensation point (LCP), and diurnal respiration (Rd) did not vary with thinning for either of the species. Jack pine and black spruce responses to thinning should be interpreted in light of species autecology.
article id 94, category Research article
Phylogeographic pattern of Populus cathayana in the southeast of Qinghai-Tibetan Plateau of China revealed by cpSSR markers. Silva Fennica vol. 45 no. 4 article id 94. https://doi.org/10.14214/sf.94
The vegetation in the Qinghai-Tibetan Plateau is thought to be highly sensitive and more vulnerable to global climate change than that of other areas. The uplift of the plateau as well as the climatic oscillations during glacial periods had a profound impact on plant species distribution and genetic diversity there. In the present study, seven pairs of cpSSR (chloroplast Simple Sequence Repeat) primers were utilized to detect genetic varieties of Populus cathayana Rehd populations from their natural range in the southeastern areas of Qinghai-Tibetan Plateau. A total of 28 alleles and 12 different haplotypes were detected. The proportion of haplotype variation among populations (GST = 0.794, NST = 0.900) indicated high level of genetic differentiation among populations and a significant phylogeographic structure (NST > GST, P < 0.05). This appears to support the hypothesis that these populations were derived from multiple refugia areas during the Quaternary climatic oscillations. Based on the haplotype network and mismatch distribution analyses, we found no evidence of postglacial range recolonization and expansion by P. cathayana in this region. This might be mainly due to the complex topography of the southeastern part of the Qinghai-Tibetan Plateau. The lofty mountain ranges and deep valleys in this region might have prevented long-distance migrations of this species during the climatic amelioration.
article id 93, category Research article
Increasing survival and growth of Scots pine seedlings with selection based on autumn coloration. Silva Fennica vol. 45 no. 4 article id 93. https://doi.org/10.14214/sf.93
This study evaluates the possibility of using autumn coloration of young Scots pine (Pinus sylvestris L.) seedlings as an indicator of adaptation to harsh climate conditions. One-year old seedlings from natural stands with different origins and seed orchards were classified as “red/reddish” and “green” based on the needle color after artificially increased night length in nursery and then measured after 14 years in field trials. In almost all the studied groups seedlings classified as “red/reddish” had significantly higher survival rate than seedlings classified as “green”. The survival of “red/reddish” was 14.2% higher than “green” among natural stand seed material and 56.2% among seed orchard material. During the study period the survival difference between “red/reddish” and “green” seedlings tended to increase. The seedling color had limited connection with the height growth, even though the trees classified as “red/reddish” were slightly taller than those classified as “green”. However, the total productivity over all field trials, described here as a heightsum, of “red/reddish” trees was 15% higher than productivity of “green” trees from natural stand material, and 61% higher than those from seed orchard material. It seems that controlled selection based on autumn color can be utilized within seed crops of different types with the aim to increase the adaptability of seed material to different environmental conditions.
article id 450, category Research article
Application of the functional-structural tree model LIGNUM to growth simulation of short-rotation eastern cottonwood. Silva Fennica vol. 45 no. 3 article id 450. https://doi.org/10.14214/sf.450
The functional-structural tree growth model LIGNUM was developed as a general research tool that can be applied to several tree species. The growth simulation of short-rotation eastern cottonwood (Populus deltoides Bartr. ex Marsh.) inherits the basic LIGNUM modeling concepts including modular tree structure, L-system-based description of structural development, and carbon budget. New developments of LIGNUM model in this study were the incorporation of a biochemically-derived photosynthesis submodel; nested time steps for simulating physiological processes, structural development, and annual biomass production; incorporation of field-measured weather data for modeling the response of physiological processes to environmental variation; and application of a Monte-Carlo voxel space submodel for simulating the stochasticity of tree growth and improving computational efficiency. A specific parameter system was applied for modeling P. deltoides growth in the central Missouri, USA, environment. This adaptation of LIGNUM was applied on modeling growth of P. deltoides in a short-rotation agroforestry practice. The simulated height and biomass growth were close to field observations. Visualization of simulation results closely resembled the trees growing in an open site. The simulated response of tree growth to variations in photon flux input was reasonable. The LIGNUM model may be used as a complement to field studies on P. deltoides in short-rotation forestry and agroforestry.
article id 449, category Research article
Quantifying tree biomass carbon stocks, their changes and uncertainties using routine stand taxation inventory data. Silva Fennica vol. 45 no. 3 article id 449. https://doi.org/10.14214/sf.449
For carbon (C) trading or any other verifiable C reports, it would be reasonable to identify and quantify continuous changes in carbon stocks at regional scales without high investments into additional C-specific, time- and labor-intensive inventories. Our study demonstrates the potential of using routine stand taxation data from large scale forestry inventories for verifiable quantification of tree biomass C stocks, C stock change rates, and associated uncertainties. Empirical models, parameters, and equations of uncertainty propagation have been assembled and applied to data from a forest management unit in Central Germany (550 000 ha), using stand taxation inventories collected between 1993 and 2006. The study showed: 1) The use of stand taxation data resulted in a verifiable and sufficiently precise (cv = 7%) quantification of tree biomass carbon stocks and their changes at the level of growth-regions (1700 to 140 000 ha). 2) The forest of the test region accumulated carbon in tree biomass at a mean annual rate of 1.8 (–0.9 to 4.5) tC/ha/yr over the studied period. 3) The taxation inventory data can reveal spatial patterns of rates of C stock changes, specifically low rates of 0.4 tC/ha/yr in the northwest and high rates of 3.0 tC/ha/yr in the south of the study region.
article id 110, category Research article
Climate for innovation and innovation strategy as drivers for success in the wood industry: moderation effects of firm size, industry sector, and country of operation. Silva Fennica vol. 45 no. 3 article id 110. https://doi.org/10.14214/sf.110
This study examines the relationships between firm financial performance and a) the climate for innovation and b) innovation strategy in the wood products industry. The focus is on the moderator effects of firm size, country of operation, and industry sector. Using a sample of 460 responses from chief executive officers and top managers of Norwegian and US firms, we conducted a regression analysis to probe for interaction effects. The sample included primary and secondary manufacturers of various sizes. Consistent with previous studies, we found a positive impact for both a climate for innovation and an innovation strategy on firm performance. In terms of moderation, only one interaction was found to be significant, representing a moderator effect of industry size on the climate-performance relationship. Further testing showed that secondary, large manufacturers exhibited a weaker, yet still positive, relationship between climate for innovation and performance. This low level of significant interactions suggests stability of the relationship among the main factors depicted in the model, with important implications for managers and future research. These findings indicate that a positive climate for innovation and a management committed to innovation through an innovation strategy have a positive effect on the bottom line of wood products firms. This effect holds true regardless of industry, size, or country, so most firms can benefit from the implementation of these pro-innovation practices.
article id 109, category Research article
Optimal forest management with carbon benefits included. Silva Fennica vol. 45 no. 3 article id 109. https://doi.org/10.14214/sf.109
In this paper, we analyse how optimal forest management of even aged Norway spruce changes when economic values are placed on carbon fixation, release, and saved greenhouse gas emissions from using wood instead of more energy intensive materials or fossil fuels. The analyses are done for three different site qualities in Norway, assuming present climate and with a range of CO2 prices and real rates of return. Compared to current recommended management, the optimal number of plants per ha and harvest age are considerably higher when carbon benefits are included, and increase with increasing price on CO2. Furthermore, planting becomes more favourable compared to natural regeneration. At the medium site quality, assuming 2% p.a. real rate of return and 20 euros per ton CO2, optimal planting density increases from 1500 per ha to 3000 per ha. Optimal harvest age increases from 90 to 140 years. Including saved greenhouse gas emissions when wood is used instead of more energy intensive materials or fossil fuels, i.e. substitution effects, does not affect optimal planting density much, but implies harvesting up to 20 years earlier. The value of the forest area increases with increasing price on CO2, and most of the income is from carbon. By using the current recommended management in calculations of carbon benefit, our results indicate that the forest’s potential to provide this environmental good is underestimated. The study includes many uncertain factors. Highest uncertainty is related to the accuracy of the forest growth and mortality functions at high stand ages and densities, and that albedo effects and future climate changes are not considered. As such, the results should be viewed as exploratory and not normative.
article id 108, category Research article
The cost-efficiency of seedling packaging specifically designed for tree planting machines. Silva Fennica vol. 45 no. 3 article id 108. https://doi.org/10.14214/sf.108
Today’s crane-mounted planting heads plant seedlings with biologically similar or better results than operational manual planting. However, the total cost of mechanized tree planting in southern Sweden must decrease at least 25% to compete economically with manual planting. Although seedlings packed in machine-specific packaging increase the productivity of planting machines by reducing seedling reloading time, they also increase logistics and investment costs. In this study, we analyzed the total cost of outplanting seedlings with an excavator-mounted Bracke Planter and seedlings packed according to four different concepts: cultivation trays, cardboard boxes, band-mounted seedlings in cardboard boxes and linked pots in container modules. The total cost per planted seedling was calculated for each packaging system as the sum of all costs from nursery to the recovery of empty packaging. The results showed that today’s system of transporting seedlings in cultivation trays is the most cost-efficient of the four alternatives. Machine-specific seedling packaging was 16–23% costlier per planted seedling than cultivation trays when trucking distances were 100 km. Sensitivity analyses indicated that machine-specific seedling packaging increased in cost-efficiency relative to cultivation trays primarily when more planting machines were contracted, but also as planting machine fixed costs and productivity increased. Moreover, the relative cost-efficiency of band-mounted seedlings, but not seedlings in container modules, increased with increasing trucking distance. Thus, we show that investments in machine-specific seedling packaging for today’s planting machines are justified only when the fixed costs, productivity and number of contracted planting machines increase substantially.
article id 107, category Research article
Machine planting of Norway spruce by Bracke and Ecoplanter: an evaluation of soil preparation, planting method and seedling performance. Silva Fennica vol. 45 no. 3 article id 107. https://doi.org/10.14214/sf.107
We evaluated the effects of planting date and planting machine (Bracke: three machines, 69 regeneration areas in three years; Ecoplanter: six areas, two years) on the quality and field performance one and three years after planting of Norway spruce (Picea abies (L.) Karst.) seedlings in central Finland. Both machine types planted on average 1800 seedlings per hectare, and after three years approximately 1600 (Bracke) and 1200 (Ecoplanter) were still alive. This study suggests that planting with a Bracke machine can achieve better regeneration rates than those observed in privately-owned Finnish forests. We characterized the quality of mounding and planting with the Bracke machine as excellent and that of the Ecoplanter as good. The soil preparation method of the Ecoplanter produced humus-rich mounds where seedlings were susceptible to pine weevils and consequently suffered higher mortality. Different machines were used in different regional areas and each machine was operated by different driver/s which may have influenced the results. No negative effects of planting date were observed. Seedling growth decreased if they were tall in relation to their root plug volume, grown too densely in the nursery, and if stored in the field for several months prior to planting. We conclude that mechanized planting is successful when the soil preparation method produces mounds covered by purely mineral soil. Planting from May to the end of September is suitable for seedlings intended for use during this period.
article id 106, category Research article
Effect of peak runoff control method on growth of Scots pine stands on drained peatlands in central Finland. Silva Fennica vol. 45 no. 3 article id 106. https://doi.org/10.14214/sf.106
In drained peatland forests ditch networks need regular maintenance operations in order to sustain their drainage capacity. These operations however have a significant impact on the quality of the runoff water from the ditched areas. Peak runoff control (PRC) method has been proposed as a possible method to diminish the load to water courses through retention of the runoff temporarily in the ditch network during maximum runoff events using dams with a plastic control pipe. However, blocking water into the ditched area for periods of varying length during the growing season may have a negative impact on the growth of the tree stands. In this study past stand growth was investigated in Central Finland in altogether 10 sample Scots pine thinning stands in which the PRC method has been applied 5 growing seasons earlier. In each stand, a pair of sample plots was established: one plot next to the dam within the influence of periodic flooding and the other one outside the effect of periodic flooding. For determining stand growth, field measurements were made in August 2009. Stand growth near the dam was on average 0.54 m3 ha-1 a-1 lower than farther away from the dam but the analysis of covariance showed that the dam effect was not significant. The results of this study suggest that the PCR method does not decrease Scots pine stand growth during the first five year growth period after ditch cleaning.
article id 105, category Research article
Nutrient loading of Norway spruce seedlings hastens bud burst and enhances root growth after outplanting. Silva Fennica vol. 45 no. 3 article id 105. https://doi.org/10.14214/sf.105
We studied the effects of late season nutrient loading (NLOAD) on the timing of bud burst, growth and changes in nitrogen (N) concentrations in the first growing season after seedlings were outplanted. Two-year-old Norway spruce (Picea abies (L.) Karst.) seedlings with three foliar nitrogen concentration levels (NLOAD levels 11.3, 22.5 and 27.5 g N kg-1 for L, M- and H-seedlings, respectively) were examined in the following three experiments: root growth capacity test (RGC), rooting experiment in the field and soil fertility experiment (‘rich’ or ‘poor’ soil) in the field. Bud burst in RGC was monitored daily and foliar N concentration (field experiments), height and root growth (rooting experiment) at monthly intervals. With respect to the RGC test, no differences in root growth were observed among the three NLOAD levels, but buds of H-seedlings burst 2–6 days earlier than others. In the rooting experiment, nutrient loading increased height and root growth but did not affect the timing of height growth. In the soil fertility experiment, foliar N of H- and M-seedlings decreased rapidly, but the decline was slower in rich soil. Current-year needles had more N in seedlings growing in rich soil and the N concentration declined until height growth ceased whereafter it increased until autumn. Improved growth from nutrient loading seems to last only for the first season after planting and the greatest benefits are enjoyed by seedlings planted in poor soils.
article id 104, category Research article
The effect of latitude, season and needle-age on the mycota of Scots pine (Pinus sylvestris) in Finland. Silva Fennica vol. 45 no. 3 article id 104. https://doi.org/10.14214/sf.104
The seasonal and latitudinal influences on the diversity and abundance of mycota of Pinus sylvestris needles were investigated. A sample of 1620 needles resulted in a total of 3868 fungal isolates, which were assigned to 68 operational taxonomic units (OTUs). The majority of these OTUs (65%) belong to Ascomycota and only 0.03% was grouped as Basidiomycota. The dominant and most frequently isolated OTU was Hormonema dematioides. Other well-known species with a saprotrophic nutritional mode such as Lophodermium spp. were also observed. The abundance of fungi increased from fall to spring. Frequencies varied significantly in Northern and Southern Finland suggesting that factors associated with latitudinal differences have an impact on the abundance of fungi.
article id 117, category Research article
Saw log recovery and stem quality of birch from thinnings in southern Finland. Silva Fennica vol. 45 no. 2 article id 117. https://doi.org/10.14214/sf.117
The objective of this study was to examine the timber quality of silver birch (Betula pendula Roth) and European white birch (Betula pubescens Ehrh.) trees in the first and second thinnings in southern parts of Finland, from the viewpoint of sawing of small-diameter, short logs, in particular. The average stem volume of birch was 0.140 m3 in the first thinning stands and 0.206 m3 in the second thinning stands. In planted stands, the trees were larger in the first thinnings but slightly smaller in the second thinnings, compared with naturally regenerated pure birch stands or mixed stands of Norway spruce and birch species. Almost 60% of the harvested and 35% of the remaining stems that could provide saw logs were graded as pulpwood for timber quality due to the occurrence of stem defects. The most common stem defects were multiple crooks and middle crooks. Only minor between-stratum differences were detected in the numbers of defects. Depending on the bucking option, the total percentage of saw and plywood logs from the total birch recovery in the thinning of the sample stands varied between 11.7 and 18.2. The recovery of saw logs was clearly higher in the second thinnings, 12–19%, than in the first thinnings, 8–14%. Of the stand types, saw log recovery was the highest in planted birch stands, 12–19%, but lower in naturally regenerated pure birch stands and mixed stands of Norway spruce and birch. The highest share of saw logs was in the second thinning of planted stands, 17–25%. This study shows that the harvesting recoveries of end-use based timber assortments can be estimated in different kinds of thinning birch stands. Based on tree and log dimensions and stem squality, silver birch firstly from plantations and secondly from mixed stands should be the most interesting source of raw material for the saw milling, furniture and interior product sectors.
article id 116, category Research article
Multiple criteria decision analysis with consideration to place-specific values in participatory forest planning. Silva Fennica vol. 45 no. 2 article id 116. https://doi.org/10.14214/sf.116
The combination of multiple criteria decision analysis (MCDA) and participatory planning is an approach that has been applied in complex planning situations where multiple criteria of very different natures are considered, and several stakeholders or social groups are involved. The spatial character of forest planning problems adds further to the complexity, because a large number of forest stands are to be assigned different treatments at different points in time. In addition, experience from participatory forest planning indicates that stakeholders may think about the forest in terms of place-specific values rather than in forest-wide terms. The objective of this study was to present an approach for including place-specific values in MCDA-based participatory forest planning and illustrate the approach by a case study where the objective was to choose a multipurpose forest plan for an area of urban forest in northern Sweden. Stakeholder values were identified in interviews, and maps were used to capture place-specific spatial values. The nonspatial and nonplace-specific spatial values were formulated as criteria and used to build an objective hierarchy describing the decision situation. The place-specific spatial values were included in the creation of a map showing zones of different silvicultural management classes, which was used as the basis for creation of forest plan alternatives in the subsequent process. The approach seemed to work well for capturing place-specific values, and the study indicates that formalized methods for including and evaluating place-specific values in participatory forest planning processes should be developed and tested further.
article id 115, category Research article
Variations of yield and utilisation of bilberries (Vaccinium myrtillus L.) and cowberries (V. vitis-idaea L.) in Finland. Silva Fennica vol. 45 no. 2 article id 115. https://doi.org/10.14214/sf.115
So far, only rough estimates for the utilisation rates of wild berries in Finland have been available. One reason for this is that there has been a lack of empirical-knowledge-based studies concerning total yields of wild berries and their yield variations. This study had three aims: 1) total bilberry and cowberry yields of an average crop year were calibrated for different (abundant and poor) crop years using the inventory data on wild berries collected by the Finnish Forest Research Institute (1997–2008); 2) national utilisation rates of bilberries and cowberries were calculated for three different berry years 1997–1999; and 3) regional utilisation rates of these berry species were calculated for the year 1997. According to calculations, annual bilberry yields in Finland vary from 92 to 312 million kg. For cowberry, the range of variation in total berry yields is from 129 to 386 million kg. It was also found that approximately the same proportion of the total yield of bilberries (i.e. 5–6%) was collected between 1997 and 1999. Utilisation rates of cowberries were also quite constant varying from approximately 8% to nearly 10%. In 1997, bilberries and cowberries were utilised most intensively in the eastern parts of the country and in the Oulu-Kainuu region. The results of this present study describe the situation before the phenomenon of foreign pickers. It can be presumed that commercial wild berry picking by migrant collectors has so far affected both national and regional utilisation rates of wild berries.
article id 114, category Research article
Impacts of moose (Alces alces) browsing on paper birch (Betula papyrifera) morphology and potential timber quality. Silva Fennica vol. 45 no. 2 article id 114. https://doi.org/10.14214/sf.114
Although moose browsing effects on the growth and morphology of birch are well studied, effects of moose browsing on potential timber quality of birch have received little attention. Here, an assessment was made of the impacts of moose (Alces alces L.) damage to Paper Birch (Betula papyrifera Marsh.) trees from a 20-year old clear cut area in a sub-boreal spruce forest within the Aleza Lake Research Forest, near Prince George, British Columbia, Canada. Specifically, differences in overall tree architecture and in the internal characteristics of trees that had been severely damaged and suppressed by moose winter browsing were compared to birch trees that had not been damaged by moose in this way and were considered free-to-grow. The average stem diameter, number of annular growth rings, and height of stem breaks made by moose on suppressed birches at the point of breakage was 17.9 ± 6.6 mm, 4.6 ± 1.2, and 141.8 ± 32.0 cm, respectively. Stem diameters and the heights above-the-ground of stem breaks made by moose during sequential breakage events were not significantly different (all p ≥ 0.05) from one another. Decay was significantly (all p ≤ 0.001) more extensive in trees where branches had been broken off by moose than in trees with no breaks or where breaks were from unknown agents. Suppressed birches were significantly (p = 0.048) more exposed (farther from their nearest tree neighbor) when compared to birches that were free-to-grow. The distance from birch trees to species-specific neighbors (of any species) did not differ (all p ≥ 0.05) between suppressed and free-to-grow birches. Suppressed birches damaged from intense browsing and stem breakage were significantly (≤ 0.001) farther away from other birches showing signs of slight to moderate browsing than free-to-grow birches were from similar conspecifics. Because moose appear to impact the potential wood quality of birch, forest managers should consider the impacts that browsing and stem breakage can have on birch timber where these trees co-occur with and are eaten by moose.
article id 113, category Research article
Biomass structure and allometry of Abies nephrolepis (Maxim) in Northeast China. Silva Fennica vol. 45 no. 2 article id 113. https://doi.org/10.14214/sf.113
Above- and below-ground tree biomass structure and allometric relationships of Abies nephrolepis (Maxim) were assessed in an old secondary forest dominated by A. nephrolepis, Pinus koraiensis, Quercus mongolica, Tilia amurensis, Fraxinus mandshurica and Acer mono in northeast China. Based on the breast-height diameter (D), a total of 21 sample trees were divided into three tree size classes: the small trees (1 cm ≤ D < 10 cm), the medium trees (10 cm ≤ D < 20 cm) and the big trees (D ≥ 20 cm). The greatest amount of live branch biomass was located in the middle and bottom layers of the crown, while the largest foliage biomass was found in the middle layer in each tree size category. The relative contribution of canopy biomass components (live branches and foliage) decreased with increasing tree size, while that of coarse root biomass remained almost constant. The relationship between above- and belowground biomass was linear. D and tree height (H) decreased with increasing competition intensity. The small trees had lower average crown ratio and higher average height-to-diameter ratio than those of the medium and big trees. The big trees had higher average stem to foliage mass ratio than those of the small and medium trees. Crown ratio, height-to-diameter ratio and stem to foliage mass ratio were not correlated with competition intensity in the same tree size class. Root to shoot mass ratio was almost constant among tree sizes. Allometric equations based on D gave higher correlations compared to those with other stem diameters: at tree base, at 30-cm height and at crown base.
article id 112, category Research article
Nutrient concentration of down woody debris in mixedwood forests in central Maine, USA. Silva Fennica vol. 45 no. 2 article id 112. https://doi.org/10.14214/sf.112
Both nutrient concentrations and pre- and post-harvest pool sizes were determined across down woody debris decay classes of several hardwood and softwood species in a long-term, natural disturbance based, silvicultural experiment in central Maine. Concentrations of N, P, Ca, Mg, Cu, Fe, and Zn generally increased 2- to 5-fold with increasing decay class. Concentrations of Mn, Al and B did not differ among decay classes, while K decreased by 20–44% from decay class 1 to class 4. C:N-ratios declined with increasing decay class, while N:P-ratios increased from decay class 1 to 2 and then plateaued with further decay. Within decay classes, softwoods generally had lower nutrient concentrations and higher C:N-ratios than hardwoods; N:P-ratios did not differ between hardwoods and softwoods. Although gap harvesting increased the size of the overall down woody debris nutrient pools, mostly through a large pulse of decay class 1 material, harvesting generally reduced the nutrients held in advanced decay classes. Pre-harvest down woody debris pools for N, P, K and Ca were 11.0, 0.6, 2.1 and 21.1 kg ha–1, respectively, while postharvest were 20.0, 1.3, 6.2 and 46.2 kg ha–1, respectively. While the gap-based silvicultural systems sampled in this study doubled the size of the pre-harvest, downed woody debris nutrient pools, the post-harvest pools were estimated to be only 3.2–9.1% of aboveground nutrients.
article id 41, category Research article
Morphological mechanism of growth response in treeline species Minjiang fir to elevated CO2 and temperature. Silva Fennica vol. 45 no. 2 article id 41. https://doi.org/10.14214/sf.41
To test whether and how morphological traits are linked with growth responses of plants to temperature and CO2 is important for understanding the mechanism underlying how plant growth will respond to global warming. In this study, using closed-top chambers to mimic future elevated CO2 and temperature, the growth response, morphological traits of Minjiang fir (Abies faxoniana Rehd.et Wils.) and the relationship of the two were investigated after two years of exposure to the single and combined elevation of CO2 and temperature. The results showed that biomass of Minjiang fir was 21%, 31%, and 35% greater than the control in elevated CO2, elevated temperature and the combination of elevated CO2 and temperature treatments, respectively. Elevated CO2 and temperature significantly affected the morphology of Minjiang fir, and a few morphological traits were highly correlated with growth responses. Larger branch angles at the upper layer, crown volume, and relative crown length contributed to positive growth responses to elevated CO2, while decreased specific leaf area (SLA) constricted any further growth response. Leaf morphological traits were more closely correlated with the response ratio than crown did in the elevated temperature, while in the combination of elevated CO2 and temperature, crown was more correlated with the response ratio than the leaf morphological traits. Thus, our results indicate that morphological traits may contribute differently to growth responses under different experimental conditions.
article id 40, category Research article
Factors influencing endophytic communities in poplar plantations. Silva Fennica vol. 45 no. 2 article id 40. https://doi.org/10.14214/sf.40
The fungal species associated with leaves and twigs from stands of Populus x euramericana in northern Spain were studied with the aim of evaluating the effects of several factors on endophytic communities in these plantations. Endophyte assemblages were analysed in 12 poplar plantations (clone I-214), chosen according to a factorial scheme with two factors: age and site quality. Crown condition, dendrometric variables and foliar nutrients were recorded in each sampled tree to evaluate their effects on endophytic communities. Fungal species richness and relative isolation frequency (RIF) were higher in young stands than in adult stands. Moreover, the age-related differences depended on site quality, with the lowest richness levels observed in adult stands located in poor sites. At stand level, endophyte assemblages varied among stands according to site quality and, to a lesser extent, stand age. On the other hand, crown discoloration, total height and foliar concentrations of iron and zinc may be key indicators of endophytic communities in poplar plantations, at tree level.
article id 35, category Research article
Democratic legitimacy of the forest sector and nature conservation decision-making in Finnish print media discussion. Silva Fennica vol. 45 no. 1 article id 35. https://doi.org/10.14214/sf.35
The study explores perceived democratic legitimacy of forest-related decision-making processes in the Finnish print media discourse. The data consists of the readers’ letters in four journals (n = 530), and the comments given during the preparation of the Finnish National Forest Program (n = 140). The objective is to identify the patterns of democratic legitimacy and respective performance evaluations of actual decision-making processes. The patterns can be classified as support for: (A) democracy and other forms of government, (B) different forms of participation, and (C) principles of democracy. The principles can be further classified into 1) core regime, 2) input, 3) throughput, and 4) output principles. Democratic legitimacy was found to be an important source of legitimacy in the public discussion since democratic patterns were found in more than half of the texts. The most common core legitimacy principles included freedom of speech, good national and international standing, forerunnership, and legality at national and international level. The central principles related to input legitimacy included popular sovereignty, a voice for the people, popular participation, openness, presenting alternatives, and urgency. The consensus and majority rules were found to be the most prominent throughput principles. Democratic output legitimacy included accountability, responsibility, cooperation, commitment, responsiveness, the possibility to appeal, credibility, comprehensiveness, and understandability. The findings suggest that among the writers of readers’ letters there is less contestation regarding the principles of democratic legitimacy but there are significant disagreements concerning the performance of decision-making processes. The negative performance evaluations were two times more frequent than the positive evaluations.
article id 34, category Research article
Examining the effect of environmental certification, wood source, and price on architects’ preferences of hardwood flooring. Silva Fennica vol. 45 no. 1 article id 34. https://doi.org/10.14214/sf.34
This article examines the importance architects place on three factors, environmental certification, wood source, and price, when specifying hardwood flooring. Architects were presented with nine flooring scenarios, in which the three factors were present in varying levels. They were asked to rank the scenarios from the least preferred to the most preferred. Data were obtained from a mail survey of architects in Oregon and Washington, U.S.A. (n = 402). Conjoint analyses determined that architects consider price and wood source to be the most important factors when specifying hardwood flooring. Interestingly, environmental certification was considered the least important factor. The respondents were then separated into three groups for further analysis based on whether they identified themselves as more influenced by environmental factors (biocentric) or human needs (anthropocentric). This analysis showed that the biocentric group favored wood source over price and environmental certification, while the anthropocentric group favored price.
article id 33, category Research article
Determining the impact of some wood characteristics on the performance of a mobile chipper. Silva Fennica vol. 45 no. 1 article id 33. https://doi.org/10.14214/sf.33
A study was conducted to determine the effect of some wood characteristics such as species, moisture content and tree part on the performance and product quality offered by a mobile industrial chipper, of the type commonly used for roadside chipping. Two main species, two tree parts and two moisture content levels were combined in a factorial design yielding 8 treatments, each replicated 5 or 6 times. A flow meter was installed on the chipper engine, and all chips produced were weighed and sampled for moisture content and particle size distribution. The results indicated that some wood characteristics such as species and moisture content have a secondary effect on chipper productivity and fuel consumption, which are primarily controlled by piece size. In particular, fuel consumption per unit dry mass seem to be rather constant and in the range of 3.2 l per oven dry ton. Moisture content and tree part may have a significant effect on the particle size distribution of chips. Of course, these results were only verified for the species used in the test and for industrial chippers, and may change if substantially different species or machines are used.
article id 32, category Research article
Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal. Silva Fennica vol. 45 no. 1 article id 32. https://doi.org/10.14214/sf.32
Forest and fire management planning activities are carried out mostly independently of each other. This paper discusses research aiming at the development of methods and tools that can be used for enhanced integration of forest and fire management planning activities. Specifically, fire damage models were developed for Eucalyptus globulus Labill stands in Portugal. Models are based on easily measurable forest characteristics so that forest managers may predict post-fire mortality based on forest structure. For this purpose, biometric data and fire-damage descriptors from 2005/2006 National Forest Inventory plots and other sample plots within 2006, 2007 and 2008 fire areas were used. A three-step modelling strategy based on logistic regression methods was used. In the first step, a model was developed to predict whether mortality occurs after a wildfire in a eucalypt stand. In the second step the degree of damage caused by wildfires in stands where mortality occurs is quantified (i.e. percentage of mortality). In the third step this mortality is distributed among trees. Data from over 85 plots and 1648 trees were used for modeling purposes. The damage models show that relative damage increases with stand basal area. Tree level mortality models indicate that trees with high diameters, in dominant positions and located in regular stands are less prone to die when a wildfire occurs.
article id 31, category Research article
Snag characteristics and cavity-nesting birds in the unmanaged post-fire northeastern Canadian boreal forest. Silva Fennica vol. 45 no. 1 article id 31. https://doi.org/10.14214/sf.31
We studied the availability and characteristics of snags and their use by cavity-nesting birds in the northeastern part of the Canadian boreal forest. We built up two long-term (> 200 years) chronosequences following time since the last fire in the unmanaged boreal forest of northeastern Québec, one in the balsam fir-white birch domain (southern region) and one in the spruce-mosses domain (northern region). We then sampled and characterized snags and live trees in 30 stands from each of these two chronosequences. We also looked for nest cavities on all sampled snags, performed bird inventories by point counts, and calculated tree mortality rate from permanent sample plots. Results show that mortality rates follow a U-shaped pattern, with more snags of large diameter (> 20 cm DBH) in young (< 50 years) and in old (> 200 years) forests. In the latter, we also found more nest cavities than in any other age classes. Although abundance of primary cavity nesters (excavating species) did not vary among age classes, secondary cavity nesters (using cavities already available) tend to be more numerous in older forests. Our results highlight the capacity for young and old-growth forests to provide quality habitat for species that are dependent on large snags. Proper forest management should maintain a mosaic of different age forest stands, including snags, to promote biodiversity and provide important resources for resident bird species.
article id 30, category Research article
Combined occurrence of wind, snow loading and soil frost with implications for risks to forestry in Finland under the current and changing climatic conditions. Silva Fennica vol. 45 no. 1 article id 30. https://doi.org/10.14214/sf.30
This work focuses on the combined occurrence of wind, snow loading and soil frost with implications for risks to forestry in Finland under the current and changing climatic conditions. For this purpose, we employ meteorological datasets, available for the period of 1971–2009 and global climate model (GCM) simulations for the current climate 1971–2000, and periods 2046–65 and 2081–2100 applying the A1B-climate change scenario. Based on our results, the wind and snow induced risks to Finnish forests are projected to increase in the future although the change in the occurrence of strong winds is small. This is because soil frost depths that support tree anchorage from late autumn to early spring in Finland are projected to nearly disappear in the southern and central parts of the country. Heavy snow loads > 30 kg m–2 are becoming more common in southern and eastern Finland despite that the average cumulative 5-day snow loads decrease in these areas by 18 to 50%, respectively. As a result of the changes in the combined occurrence of wind, snow loading and soil frost, the risk of climatic conditions making conifers liable to uprooting are projected to increase in southern, central and eastern Finland. In the north, the risk of stem breakage is becoming more pronounced under snow loading > 20 kg m–2. Despite some uncertainties related to this work, we assume that the findings can serve as valuable support for the risk assessment of wind and snow induced damages to Finnish forests and for forestry, in general.
article id 29, category Research article
B-SAP markers derived from the bacterial KatG gene differentiate populations of Pinus sylvestris and provide new insights into their postglacial history. Silva Fennica vol. 45 no. 1 article id 29. https://doi.org/10.14214/sf.29
The aim of the studies was to evaluate the efficiency of the KatG gene based B-SAP markers as a tool to distinguish morphologically diversified and geographically distant Scots pine populations and to track the routes of migrations. The 19 populations growing in the IUFRO 1982 provenance experiment and representing the natural distribution of the species in Europe were scored using 103 B-SAP loci. Among them 26% loci were polymorphic. The level of polymorphism was associated with the location of primers on the KatG template. The diversity was low, He = 0.086, and deposited mostly among populations. Seven unique markers were found that identified populations and likely they were associated with morphology. The overall genetic identity was relatively low, I = 0.933 (D = 0.069). The block of six B-SAP markers discriminated populations into two groups in agreement with their geographic origin and thereby further described as the North and the South. The North group was uniform with genetic diversity, He = 0.026 and the overall genetic distance D = 0.022. Presumably, it migrated from refugia in the Alps via France, northern Germany and Denmark, to Scandinavia and Russia. The South group was heterogeneous with He = 0.063 and D = 0.047. This group migrated from the Carpathians via Slovakia to Germany and Poland. The Balkans and Asian refugia did not take part in recolonization of Europe. The block of six B-SAP/KatG markers can be recommended for tracking postglacial history of Scots pine.
article id 28, category Research article
Leaf number indicates salt tolerance of young seedling families of European aspen (Populus tremula L.) growing in different soils. Silva Fennica vol. 45 no. 1 article id 28. https://doi.org/10.14214/sf.28
Soil salinity limits plant productivity and quality. We evaluated the response of 12 aspen (Populus tremula) families to salt stress in two different soils irrigated for 4-weeks with 0, 80 or 160 mM saline solution. Easily measurable characteristics such as shoot height, leaf number, dry mass as well as the distribution of sodium (Na+) ions were measured in 5-month-old aspen seedlings raised in controlled greenhouse conditions on two different soils. Growth among families varied significantly, and the interaction between family and soil type was significant. From 2–5 months, leaf number correlated with that of the first month and salinity tolerance. Sodium ions varied significantly within plants and among families; seedlings that accumulated higher Na+ concentrations in root had more leaves and lower Na+ in shoot. These results suggest that leaf number indicates salt tolerance in young seedlings. Seedling performance was also affected by soil type, especially the root/shoot ratio, suggesting an interaction between salt tolerance and growth medium. This study has identified significant intra-specific variation in salt tolerance of aspen in 160 mM saline and highlighted the potential to select and develop a method for efficient pre-screening of trees to be used in the reclamation of salt-affected land.
Category: Review article
article id 446, category Review article
Forest naturalness in northern Europe: perspectives on processes, structures and species diversity. Silva Fennica vol. 45 no. 5 article id 446. https://doi.org/10.14214/sf.446
Saving the remaining natural forests in northern Europe has been one of the main goals to halt the ongoing decline of forest biodiversity. To facilitate the recognition, mapping and efficient conservation of natural forests, there is an urgent need for a general formulation, based on ecological patterns and processes, of the concept of “forest naturalness”. However, complexity, structural idiosyncracy and dynamical features of unmanaged forest ecosystems at various spatio-temporal scales pose major challenges for such a formulation. The definitions hitherto used for the concept of forest naturalness can be fruitfully grouped into three dimensions: 1) structure-based concepts of natural forest, 2) species-based concepts of natural forest and 3) process-based concepts of natural forest. We propose that explicit and simultaneous consideration of all these three dimensions of naturalness can better cope with the natural variability of forest states and also aid in developing strategies for forest conservation and management in different situations. To become operational, criteria and indicators of forest naturalness need to integrate the three dimensions by combining species (e.g. red-listed-, indicator- and umbrella species) with stand and landscape level structural features that are indicative of disturbance and succession processes.
article id 74, category Review article
The restorative imperative: challenges, objectives and approaches to restoring naturalness in forests. Silva Fennica vol. 45 no. 5 article id 74. https://doi.org/10.14214/sf.74
Many of the world’s forests are not primeval; forest restoration aims to reverse alterations caused by human use. Forest restoration (including reforestation and forest rehabilitation) is widely researched and practiced around the globe. A review of recent literature reveals some common themes concerning forest restoration motivations and methods. In some parts of the world, forest restoration aims mainly to re-establish trees required for timber or fuelwood; such work emphasizes the propagation, establishment and growth of trees, and equates with the traditional discipline of silviculture. Elsewhere, a recent focus on biocentric values adopts the goal of supporting full complements of indigenous trees and other species. Such ecosystem-based restoration approaches consider natural templates and a wide array of attributes and processes, but there remains an emphasis on trees and plant species composition. Efforts to restore natural processes such as nutrient cycling, succession, and natural disturbances seem limited, except for the use of fire, which has seen widespread adoption in some regions. The inherent challenges in restoring “naturalness” include high temporal and spatial heterogeneity in forest conditions and natural disturbances, the long history of human influence on forests in many regions of the world, and uncertainty about future climate and disturbance regimes. Although fixed templates may be inappropriate, we still have a reasonably clear idea of the incremental steps required to make forests more natural. Because most locations can support many alternative configurations of natural vegetation, the restoration of forest naturalness necessarily involves the setting of priorities and strategic directions in the context of human values and objectives, as informed by our best understanding of ecosystem structure and function now and in the future.
article id 73, category Review article
Natural forest dynamics in boreal Fennoscandia: a review and classification. Silva Fennica vol. 45 no. 5 article id 73. https://doi.org/10.14214/sf.73
The aim here was to review and summarize the findings of scientific studies concerning the types of forest dynamics which occur in natural forests (i.e. forests with negligible human impact) of boreal Fennoscandia. We conducted a systematic search for relevant studies from selected reference databases, using search terms describing the location, structure and processes, and degree of naturalness of the forest. The studies resulting from these searches were supplemented with other known works that were not indexed in the databases. This procedure yielded a total of 43 studies. The studies were grouped into four types of forest dynamics according to the information presented on the characteristics of the native disturbance-succession cycle: 1) even-aged stand dynamics driven by stand-replacing disturbances, 2) cohort dynamics driven by partial disturbances, 3) patch dynamics driven by tree mortality at intermediate scales (> 200 m2) and 4) gap dynamics driven by tree mortality at fine scales (< 200 m2). All four dynamic types were reported from both spruce and pine dominated forests, but their commonness differed. Gap dynamics was most commonly reported in spruce forests, and cohort dynamics in pine forests. The studies reviewed provide the best obtainable overall picture of scientific findings concerning the characteristics and variability of the unmanaged boreal forest dynamics in Fennoscandia. The results demonstrate that the unmanaged Fennoscandian forests are characterized by more diverse and complex dynamics than has traditionally been acknowledged.
article id 72, category Review article
Variability and dynamics of old-growth forests in the circumboreal zone: implications for conservation, restoration and management. Silva Fennica vol. 45 no. 5 article id 72. https://doi.org/10.14214/sf.72
Due to the unprecedented loss of old-growth forests to harvesting throughout circumboreal regions an understanding of similarities and differences in old-growth dynamics is needed to design effective restoration, management and conservation efforts. This paper reviews concepts, prevalence and variability of old-growth forests across landscapes, and evaluates different stand scale dynamics at the old-growth stage across the circumboreal zone. Old-growth historically dominated many boreal forest landscapes in both Eurasia and North America. Throughout much of North America, and to some extent in western Siberia, the natural prevalence and development of old-growth forests are regulated by the occurrence of stand-replacing fires. In eastern North America and Siberia, insect outbreaks may, however, be more important. Insect outbreaks as well as recurrent non-stand replacing surface fires and windthrows, when occurring at the old-growth stage, often form stands characterized by several tree age-class cohorts. This multi age-class forest development type is common in Europe and eastern Siberia but its prevalence and importance in boreal North-America is not well documented. Similarities in successional dynamics across the circumboreal region are found in the development of mono-dominant even-aged stands, the replacement of shade intolerant tree species by shade tolerant species, as well as in all-aged stands driven by small-scale gap dynamics. The message to land managers is that the focus should not only be on setting aside remaining old-growth forests or in restoring static old-growth attributes, but also in emulating natural disturbances and successional dynamics at landscape and regional scales to maintain natural variability in old-growth attributes through time.
article id 38, category Review article
Estimating tree biomass of sub-Saharan African forests: a review of available allometric equations. Silva Fennica vol. 45 no. 3B article id 38. https://doi.org/10.14214/sf.38
In response to the growing interest in estimating carbon stocks in forests, available allometric equations have been compiled for sub-Saharan Africa. Tree, sprout and stand volume and biomass equations were reviewed. The 850 equations and 125 related references were incorporated into an open-access database on the Carboafrica website (http://www.carboafrica.net). The collected information provides a basic tool for the estimation of biomass and carbon stocks and other purposes, such as bioenergy and fodder supply assessment. A Tier-method approach was developed to illustrate the possible use of the equations. Current available biomass expansion factors that are used to convert a volume to the total aboveground biomass appear to be limited; incomplete species-specific allometric equations are preferred to generalised equations. The analysis of the database highlighted important gaps in available tools to assess forest carbon stocks and changes in these stocks. A quality control assessment revealed that 22% of the equations were misreported and recommendations were proposed to guide further research. Further statistical analyses, such as the Bayesian approach, would help to produce more accurate biomass estimates.
article id 36, category Review article
Major decline in fires in coniferous forests – reconstructing the phenomenon and seeking for the cause. Silva Fennica vol. 45 no. 1 article id 36. https://doi.org/10.14214/sf.36
Steep decline in forest fires about a century ago occurred in coniferous forests over large areas in North America and Fennoscandia. This poorly understood phenomenon has been explained by different factors in different regions. The objective of this study is to evaluate the validity of the four most commonly suggested causes of the decrease in forest fires: fire fighting, over-grazing, climate change and human influence. I compiled the available dendrochronological data and estimated the annually burned proportions of Pinus-dominated forests in four subcontinental regions during the past 500 years. These data were compared to the development of fire suppression, grazing pressure, climate and human livelihoods. The annually burned proportions declined over 90% in all studied regions. In three out of the four regions fires decreased decades before fire suppression began. Available drought data are annually well correlated with fires but could not explain the decrease of the level in annually burned areas. A rapid increase in the number of livestock occurred at the same time with the decrease in fires in the Western US but not in Fennoscandia. Hence, fire suppression in Central Fennoscandia and over-grazing in the Western US may have locally contributed to the reduction of burned areas. More general explanation is offered by human influence hypothesis: the majority of the past forest fires were probably caused by humans and the decrease in the annually burned areas was because of a decrease in human caused fires. This is in accordance with the old written records and forest fire statistics. The decrease in annually burned areas, both in Fennoscandia and the United States coincides with an economic and cultural transition from traditional livelihoods that are associated with high fire use to modern agriculture and forestry.
Category: Research note
article id 92, category Research note
A comparison of avian diversity in spruce monocultures and spruce-birch polycultures in southern Sweden. Silva Fennica vol. 45 no. 5 article id 92. https://doi.org/10.14214/sf.92
The replacement of some spruce monocultures with stands composed of planted Norway spruce (Picea abies) and naturally regenerated birch (Betula spp.) has a range of potential benefits, but the implications for biodiversity are generally unknown. Here we conduct a paired replicated study in southern Sweden of the avian biodiversity found within Norway spruce monocultures, and within Norway spruce stands possessing approximately 20% birch. Our research leads us to three findings. First, avian diversity was significantly higher in the spruce–birch polycultures. Second, spruce–birch polycultures exclusively attracted broadleaf-associated bird species and retained the majority of conifer-associated bird species found in the spruce monocultures. Third, avian biodiversity within the spruce–birch polycultures did not incorporate threatened taxa. We suggest that in addition to the apparent benefits for stand level diversity, widespread use of spruce–birch polycultures could provide a means of softening the matrix for broadleaved-associated species, while concurrently providing an increased broadleaf base from which future conservation actions could be implemented. Our results are relevant to multi-use forestry, and recent policy initiatives by forest certification agencies which aim to increase broadleaf-associated biodiversity within conifer-dominated production forest landscapes.
article id 91, category Research note
A non-destructive field method for measuring wood density of decaying logs. Silva Fennica vol. 45 no. 5 article id 91. https://doi.org/10.14214/sf.91
Decaying dead wood density measurements are a useful indicator for multiple purposes, such as for estimating the amount of carbon in dead wood and making predictions of potential diversity of dead wood inhabiting fungi and insects. Currently, qualitative decay phases are used as wood density estimates in many applications, since measuring the density is laborious. A quantitative measure of density would, however, be preferred over the qualitative one. Penetrometers, which are commonly used for measuring the density of standing trees, might also be applicable to dead wood density measurements. We tested the device for making quick, quantitative measurements of decaying logs. The penetrometer measures the depth into which a pre-loaded spring forces a pin in the wood. We tested pins of 5 and 10 mm diameter together with an original 2.5 mm pin and compared the results with gravimetric density measurements of the sample logs. Our results suggest that the standard pin works for less decayed wood, but for more decomposed wood, the thicker 5 mm pin gave more reliable estimates when the penetration measures were converted to densities with a linear regression function (R2 = 0.62, F = 82.9, p = 0.000). The range of wood densities successfully measured with the 5 mm pin was from 180 to 510 kg m–3. With the 10 mm pin, the measuring resolution of denser wood was compromised, while the improvement at the other end of density scale was not large. As a conclusion, the penetrometer seems to be a promising tool for quick density testing of decaying logs in field, but it needs to be modified to use a thicker measuring pin than the standard 2.5 mm pin.
article id 118, category Research note
Mycorrhization, establishment and growth of outplanted Picea abies seedlings produced under different cultivation systems. Silva Fennica vol. 45 no. 2 article id 118. https://doi.org/10.14214/sf.118
In forest nurseries seedlings are commonly produced using different cultivation systems which may have a profound effect on the extent of root colonisation by ectomycorrhizal (ECM) fungi and, consequently, on subsequent performance of the outplanted seedlings under field conditions. In this study, we compare effects of bare-root and containerised cultivation systems on mycorrhization, establishment and growth of nursery-produced Picea abies. One hectare experimental plantation was established on poor fertility sandy site. In total, 1250 seedlings of each treatment were planted in rows as ten individual replicates. The results of this study showed that production of P. abies seedlings using containerised system can yield abundant ECM colonisation of seedling roots and significantly improve seedling survival in the field. Some reduction in height increment may occur during the first years as a possible cost for support of ECMs. Study demonstrated that selection of proper cultivation system might result in similar or higher mycorrhization and survival rates of outplanted seedlings than achieved by expensive and laborious artificial mycorrhization.
article id 37, category Research note
Host tree and insect genetic diversity on the borderline of natural distribution: a case study of Picea abies and Pityogenes chalcographus (Coleoptera, Scolytinae) in Greece. Silva Fennica vol. 45 no. 1 article id 37. https://doi.org/10.14214/sf.37
Picea abies (L.) Karst. and Pityogenes chalcographus constitute a commonly observed host tree–insect association in Eurasia, with the natural distribution of the bark beetle overlapping that of Norway spruce. The southernmost borderline of their distributions occurs in the Elatia forest (Mt. Rodopi, Greece), where these interacting organisms may experience severe conditions due to the effects of climate change. In order to assess the dynamics of this host tree–insect association, the genetic diversity of both organisms was studied. In contrast to previous studies, the assessment of molecular diversity was based on the same mitochondrial gene (Cytochrome Oxidase One) sequence for both host and pest. This analysis revealed a remarkably higher genetic diversity of P. chalcographus compared to that of P. abies, something that renders the insect capable not only of adapting to novel environmental conditions, but even of shifting to other host species. On the contrary, P. abies presented a narrow genetic base, a potential drawback at the southern-most region of the species natural distribution. Synthesizing the preliminary outcome for both organisms, it appears that P. chalcographus exhibits an evolutionary advantage over P. abies, something that should be considered when planning conservation strategies for the relict forest of Elatia.
Category: Discussion article
article id 119, category Discussion article
Cross-section mass: an improved basis for woody debris necromass inventory. Silva Fennica vol. 45 no. 2 article id 119. https://doi.org/10.14214/sf.119