article id 443, category Commentary
Category: Research article
article id 924, category Research article
On non-circularity of tree stem cross-sections: effect of diameter selection on cross-section area estimation, Bitterlich sampling and stem volume estimation in Scots pine. Silva Fennica vol. 46 no. 5B article id 924. https://doi.org/10.14214/sf.924
In the common methods of forest mensuration, including stem volume models and Bitterlich sampling, stem cross-sections are assumed to be circular. In nature this assumption is never exactly fulfilled. Errors due to non-circularity have been presumed to be small and unimportant but studied little: theoretical and empirical studies exist on cross-section area estimation, but errors in stem volume estimation have not been investigated at all, and errors in Bitterlich sampling are theoretically known only for stand basal area estimation. In the theoretical part of this study, we developed methods for quantifying the systematic and sampling errors that 22 common ways of selecting diameter within non-circular cross-sections induce (i) in area estimates by the circle area formula, (ii) in stand total estimates by Bitterlich sampling, and (iii) in stem volume estimates by a volume equation, by a cubic-spline-interpolated stem curve, and by a generalised volume estimator. In the empirical part, based on the digital images of 709 discs taken at 6–10 heights in 81 Scots pine stems from different parts of Finland, we investigated the variation in cross-section shape, and demonstrated the magnitude of the errors presented in the theoretical part. We found that non-circularity causes systematic overestimation of area and volume, and inflicts potentially systematic error on stand total estimates by Bitterlich sampling. In our data these effects were small, but the finding is not generalisable due the skewed size distribution and poor geographical representativeness of the data. We recommend using diameter derived from girth for both tree and stand level estimation, as it involves no sampling error and produces clearly the most stable systematic errors.
article id 922, category Research article
Forest planning in a Swedish company – a knowledge management analysis of forest information. Silva Fennica vol. 46 no. 5 article id 922. https://doi.org/10.14214/sf.922
Forest data and forest information are central to forest management planning. The knowledge a large forest-owning company possesses about its forests could potentially be a strategic capability. In this study, the forest-planning process of a large forest company is analyzed in terms of knowledge management (KM). The study was conducted as a case study of Sveaskog – the largest forest-owning company in Sweden. The study focuses on the long-term harvest strategy through medium-term planning until the stands are transferred to the tract bank and ready for operational planning. Interviews with key persons within the organization were conducted to assess how forest knowledge is used in this process. The results are presented for the four knowledge management processes: creation, storage-retrieving, transferring and applying. They show that the planning system relies to a great extent on codified knowledge realized by a push strategy.
article id 921, category Research article
Tracheid wall thickness and lumen diameter in different axial and radial locations in cultivated Larix sibirica trunks. Silva Fennica vol. 46 no. 5 article id 921. https://doi.org/10.14214/sf.921
In Larix trunks the properties of wood differ clearly radially, but the axial differences are smaller as well as being less studied. Wood anatomy is in particular poorly studied, even though all other wood properties derive from cell and tissue structure. The aim of this study was to chart variation in tracheid size (double wall thickness (2CWT), diameter of lumen (RD)) within fast grown cultivated Siberian larch (Larix sibirica Ledeb.) trunks. The differences in 2CWT and RD were clear between earlywood (EW) and latewood (LW), 2CWT increasing clearly less in EW than in LW towards the bark, while RD stayed quite stable in LW but in EW increased markedly towards the bark. The difference in 2CWT between EW and LW increased towards the upper trunk. In conclusion, the radial variation in RD and 2CWT was different between the butt and other studied heights. As the difference in 2CWT between EW and LW was smaller at the butt than the upper portion of the trunk, the wood was the most homogenous at the butt.
article id 920, category Research article
Seedling establishment on small cutting areas with or without site preparation in a drained spruce mire – a case study in northern Finland. Silva Fennica vol. 46 no. 5 article id 920. https://doi.org/10.14214/sf.920
A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. We studied the effect of cutting – small canopy openings (78, 177, and 314 m2) and small clear-cuts (0.25–0.37 ha) – with or without site preparation (scalping) on the establishment of natural Norway spruce seedlings in one experimental drained spruce mire stand in northern Finland. The cuttings were made in winter 2004–2005 and site preparation with scalping in early June 2005. The experimental design was composed of four blocks with altogether four clear-cuts and 33 canopy openings. The seedling establishment was surveyed annually (2006, 2008–2010) from five circular sample plots (one 10 m2 and four 5 m2 plots in size) located within the canopy openings and from 18 circular 5 m2 sample plots systematically located in the scalped and untreated halves of the clear-cuts. Site preparation was found unnecessary, because it resulted in a clearly lower number of seedlings in the openings. A slight negative effect was also found in the clear-cuts. In the two years following the cuttings, the number of seedlings increased quickly in the canopy openings, but more gradually in the clear-cut areas. In 2010, on average 15 500 new seedlings were observed in the canopy openings and 6700 in the clear-cut areas, of which 5050 and 1200, respectively, were >0.1 m tall spruces. The proportion of birch increased in the last two years, being ca. 22% in the openings and 45% in the clear-cuts in 2010. The spatial distribution of seedlings was more uneven in the clear-cuts than in the openings, with 41% and 20% of survey plots empty, respectively.
article id 919, category Research article
Estimating the need for early cleaning in Norway spruce plantations in Finland. Silva Fennica vol. 46 no. 5 article id 919. https://doi.org/10.14214/sf.919
Effective management of Norway spruce (Picea abies (L.) Karst.) plantations requires detailed information on stand development, which is costly to measure. However, estimating the need for early stand management from site attributes that persists stabile after ones measured, may provide an inexpensive alternative. This study compared hardwood competition in spruce plantations of varying ages and tested the usability of this information in estimating the need for early cleaning. The data included 197 spruce plantations (4–7 years old) inventoried in southern Finland in 2007. The level (Low, Substantial, High) of need for early cleaning was subjectively determined by contrasting location and size of competing hardwoods to a conifer crop tree. Then the stage of the need for early cleaning was modelled according to site and stand attributes. Nearly 60% of the conifer crop trees in the plantations were subjectively judged to require early cleaning (Substantial 37.2%, High 21.2%), but only 10 per cent of the evaluated area was cleaned. Need for cleaning was intense on peatlands or damp soils, whereas it was mild on unprepared soils or cleaned sites. Traditional site characteristics used in forest management planning can be useful for recognising the peripheral cases, where need for cleaning is probably high or low. However, on a typical mineral soil plantation (uncleaned, soil prepared) the model indicates the differences in the need for early cleaning weakly. The need for early cleaning was already high in 4-year-old plantations, why stand age did not have significant effect on development of the need. Thus, the timing of an operation can not be predicted with the model. Nonetheless, early cleaning very likely opens growth space of crop trees in a 4–7-year-old spruce plantation. Therefore, from an aspect of crop growth, an uncleaned Norway spruce plantation in this age group is quite consistently worth cleaning.
article id 918, category Research article
Planted Picea mariana growth and nutrition as influenced by silviculture x nursery interactions on an ericaceous-dominated site. Silva Fennica vol. 46 no. 5 article id 918. https://doi.org/10.14214/sf.918
We aimed at evaluating the interacting effects of silvicultural and nursery practices on planted black spruce (Picea mariana (Mill.) BSP) dimensions, growth, survival and nutrition, 8 years following planting on a carefully logged boreal stand heavily invaded by Kalmia angustifolia L. and Rhododendron groenlandicum (Oeder) Kron & Judd. We also evaluated functional traits related to light and nutrient acquisition and key environmental resource availability to interpret treatment impacts on spruce seedling leaf traits and growth. An experimental black spruce plantation, consisting in a randomized block split-split-split plot design with 13 replicates was established in northeastern Quebec (Canada). Scarification (single-pass, double-pass), fertilization at the time of planting (control; macronutrients only; macro + micronutrients), stock type (container-grown; bare-root), and initial foliar N concentration (4 increasing levels) treatments were applied, and measurements were performed 5 and 8 years following planting. Double-pass scarification significantly increased soil temperature and reduced the competition cover, compared to the single-pass treatment. As a result, double-pass scarification promoted seedling growth over the single-pass treatment, and influenced the expression of other treatment effects. However, the relative gains associated with the second scarification pass have to be balanced against the supplemental investment involved by the treatment before being recommended. Our results point to variable effects of fertilization at planting to stimulate seedling initial growth. In this ecosystem, it appears that the silvicultural gains of this treatment depend on the variable of interest. Bare-root seedlings grew faster than containerized seedlings in the most intense site preparation treatment, but the differences have limited silvicultural impacts.
article id 917, category Research article
Control efficacy of stump treatment and influence of stump height on natural spore infection by Heterobasidion spp. of precommercial thinning stumps of Norway spruce and birch. Silva Fennica vol. 46 no. 5 article id 917. https://doi.org/10.14214/sf.917
An alternative precommercial thinning technique results in trees being cut higher up the stem compared to the normal method using a brush saw. The aims of this study were to investigate if primary infection of Heterobasidion spp. on precommercial thinning stumps of Norway spruce and birch is influenced by stump height and to test the control efficacy of stump treatment with Phlebiopsis gigantea on precommercial thinning stumps of Norway spruce. Small Norway spruce and birch trees were felled on five sites in southern Sweden and their stumps subjected to natural spore infection. For each species, two treatments of stump height were created: 15 and 100 cm. Half of the Norway spruce stumps were treated with P. gigantea. After two months, 896 stumps were sampled and infection by Heterobasidion spp. was quantified. The height of stumps did not significantly influence infection frequency or size of infection on either tree species. Untreated Norway spruce stumps had an infection frequency of 55% while 31% of the treated stumps were infected. The control efficacy of stump treatment in terms of reduced relative infected area was 61–65%. The area occupied by Heterobasidion spp. on birch stumps was generally small, on average 0.4 cm2 per infected stump, although 15% of the stumps were infected. The risk of primary infection in Norway spruce dominated stands should be considered when precommercial thinning is conducted but the control efficacy and economy of stump treatment warrants further investigation before practical recommendations can be made.
article id 916, category Research article
Effect of indole-3-butyric acid on root formation in Alnus glutinosa microcuttings. Silva Fennica vol. 46 no. 5 article id 916. https://doi.org/10.14214/sf.916
A study of the in vitro rooting process in mature alder (Alnus glutinosa (L.) Gaertn.) shoots is described. Microcuttings from shoots cultured in vitro were transferred to a half-strength Woody Plant Medium containing 0 or 0.1 mg l–1 indole-3-butyric acid (IBA) for 0 to 7 days. The presence of IBA in the medium increased the rooting percentage, number of roots, percentage of lateral roots, and length of the shoots. Histological studies were carried out with shoots treated with 0 or 0.1 mg l–1 IBA for 7 days. According to these criteria, treatment with IBA for 2–3 days proved to be the most successful. In both treatments, substancial reactivation of cell division was observed at the base of the shoots after 1 day. Some cambial zone and adjacent phloem cells became dense cytoplasm, having nuclei with prominent nucleoli. The first cell divisions were also observed at this time. In the treatment with IBA (0.1 mg l–1 for 7 days), meristemoids became individualized, consisting of densely staining cells, by day 3. Identifiable conical shaped root primordia with several cell layers were visible after 4–5 days. Roots with an organized tissue system emerged from the stem after 6 days in the IBA-treated shoots. Meristemoid formation was delayed until the fourth day and root emergence until the eight day in the control treatment (no IBA).
article id 913, category Research article
Markets, government policy, and China's timber supply. Silva Fennica vol. 46 no. 4 article id 913. https://doi.org/10.14214/sf.913
China's domestic demand and exports of wood products are rising rapidly compared to domestic supply. The determinants of timber supply in China were investigated with panel data from 25 provinces from 1999 to 2009. The results indicated that China’s timber supply had responded to both market forces, reflected by timber prices largely determined by world demand and supply, and to government policies expressed by production quotas and the tenure reform on collective forestland. The price elasticity of China’s timber supply was estimated at 0.31±0.12. The inelastic response of production to the quota (0.20±0.02) suggested that government had a limited, though significant, control of timber supply. Other things being equal, the land tenure reform increased timber supply by 18±8 percent, where and when it had been implemented.
article id 912, category Research article
Commercialisation and international market potential of Finnish silvicultural machines. Silva Fennica vol. 46 no. 4 article id 912. https://doi.org/10.14214/sf.912
Recently, the need to mechanise silvicultural operations has increased in the Nordic countries. While several new machine concepts have been developed, the manufacture of silvicultural devices remains at the market introduction stage. Information is required in support of existing and forthcoming Finnish small-scale producers of silvicultural devices, who wish to commercialise and further market their innovations in domestic and export markets. The aim of this study was to identify the opportunities, challenges and market potential of business activities that develop in connection with device or machine production. Small-scale Finnish manufacturers of silvicultural devices, Finnish large-scale harvester manufacturers and international silvicultural experts participated in the study. The results show that participant groups have varying opinions of cooperation methods and export activities, as well as of the export markets with the best potential. According to international silvicultural experts, mechanised planting and pre-commercial thinning have the greatest potential worldwide. However, demand for mechanised pre-commercial thinning and planting has been mainly confined to the Nordic countries. For a foreign firm marketing a new silvicultural machine concept, the most important customers and cooperation partners are locally operating forest firms, machine contractors and research organisations. The results of the study provide a useful overview of the current state of silvicultural device manufacturing in Finland.
article id 911, category Research article
Picking of wild edible mushrooms in Finland in 1997–1999 and 2011. Silva Fennica vol. 46 no. 4 article id 911. https://doi.org/10.14214/sf.911
This study reports on national survey results concerning mushroom picking in Finland during four separate years: 1997–1999 and 2011. The material was collected by mailed questionnaire surveys amongst Finnish households. The sample size varied from 1858 (in 1998) to 6849 households (in 1997) and the response rates varied from 51% (in 2011) to 70% (in 1999). The results indicate that both the rate of participation in mushroom picking and estimates of the quantities collected varied greatly depending on whether the survey was conducted in a favourable or unfavourable year. In 1998, when the mushroom crop was abundant, a total of 47% of all households were engaged in picking and the total harvest was 16.1 million kg. In 1999, when the crop was poor, the estimates were the lowest (23% and 3.3 million kg, respectively) and in a year with a relatively abundant crop (2011), the estimates were 42% and 15.0 million kg, respectively. Mushrooms were collected mainly for home use, which accounted for 85–90% of the total harvest depending on the year. Only a small proportion of all households (0.3–1.3%) were engaged annually in commercial mushroom picking. In 1997–1999, milk caps formed the major part of the total amount picked (i.e. 37–53% depending on the year), whilst in 2011 their share was approximately one fifth of the total harvest. The results also indicate that the proportion of ceps in commercial picking has increased since the 1990s
article id 910, category Research article
Predicting moisture content in a pine logwood pile for energy purposes. Silva Fennica vol. 46 no. 4 article id 910. https://doi.org/10.14214/sf.910
Determining the moisture content of naturally dried fuel stock without frequent measuring is a problem still unsolved. Modelling moisture content based on automatically captured meteorological data could provide a solution. An accurate model would allow the drying period and the point of chipping to be optimised. For the experimental study, a metal frame supported by load sensors and loaded with 17 tons of logwood was set up next to a meteorological station. A multiple linear regression model was used to link meteorological and load data to provide a formula for determining the moisture content. The pile dried for a period of 14 months (average temperature of 7.3 °C, a humidity of 81%, and 777 mm of rainfall). The overall moisture content dropped from 50.1% to 32.2%. The regression model, which based on daily means and sums of meteorological parameters, provided a mean deviance from the observed curve of –0.51%±0.71% within the period of investigation. Relative humidity was found to be most important parameter in drying. Increased moisture content resulting from rainfall greater than 30 mm per day reverted back to pre-rainfall values within two to three days, if no other rainfall events followed. Covering the pile would have a positive effect on the drying performance. In terms of economic benefit it could be shown that natural drying is beneficial. Overall this study shows that meteorological data used in site specific drying models can adequately predict the moisture content of naturally dried logwood.
article id 909, category Research article
Strengthening top-level guidance in geographically hierarchical large scale forest planning: experiences from the Finnish state forests. Silva Fennica vol. 46 no. 4 article id 909. https://doi.org/10.14214/sf.909
Different planning approaches conclude to different results. The top-down approach allocates resources efficiently from the top-level perspective, while the bottom-up approach provides optimal results for the lower levels. Integrated approach that combines the elements of these two basic approaches provides compromise solutions for decision makers. The aim of this study was to examine potential efficiency improvements in hierarchically structured large scale forest management through increased top-level guidance. The resulting effects on the acceptability of the plans on the lower level were also studied. Large scale planning typically considers forests owned by states, companies and municipalities. In the case study of the Finnish state forests, alternative country level solutions were generated by combining regional forest plans in different ways. The results showed that the currently applied bottom-up approach, which produces regionally optimal management strategies, did not result in the most efficient use of resources on the country level. However, the new country level solutions did not produce huge improvements in the country level objective values compared to the results of the current approach. Furthermore, if country level efficiency improvements were emphasized more, together with wide approval by regional stakeholders and local residents, new kind of interaction and participation between the planning levels and also between the regions would be needed.
article id 908, category Research article
Recovery of soil bulk density, porosity and rutting from ground skidding over a 20-year period after timber harvesting in Iran. Silva Fennica vol. 46 no. 4 article id 908. https://doi.org/10.14214/sf.908
Ground-based skidding can have detrimental effects on soil properties trough soil profile disturbance and compaction that can persist for decades. We investigated the recovery of physical properties of disturbed brown soils on four abandoned downhill skid trails in a deciduous mountain forest in northern Iran. The most recent skidding operations had taken place 1–5 yrs, 6–10 yrs, 11–15 yrs, and 16–20 yrs ago, providing a 20-year chronosequence with four 5-year recovery periods. For each recovery period, mean values for soil bulk density (BD), total porosity (TP), macroporosity (MP), soil moisture content (SM), and rut depth (RD) were assessed for three levels of traffic intensity (Primary (PS), Secondary (SS) and Tertiary (TS) skid trails) and two levels of slope gradients (Gentle (G) and Steep (S)) and compared to those in undisturbed (control) areas. Over the 20-year recovery period, PS trails on gentle slopes exhibited mean values that were 35–42% (BD), 3–7% (SM), and 13–19 cm (RD) greater and 18–24% (TP) and 19–28% (MP) lower compared to undisturbed areas; on steep PS trails, values were 40–46% (BD), 2–13% (SM), and 13–21 cm (RD) greater and 23–27% (TP) and 28–35% (MP) lower, respectively. While RD and SM recovered, 20 years was not long enough for the other physical soil properties, particularly on steep slopes. To minimize soil disturbance, skidding should be confined to areas with gentle slopes and alternative harvesting methods such as cable yarding should be used where slope gradients exceed 20%.
article id 907, category Research article
Species-habitat associations in a northern temperate forest in China. Silva Fennica vol. 46 no. 4 article id 907. https://doi.org/10.14214/sf.907
This contribution identifies species-habitat associations in a temperate forest in north-eastern China, based on the assumption that habitats are spatially autocorrelated and species are spatially aggregated due to limited seed dispersal. The empirical observations were obtained in a large permanent experimental area covering 660 x 320 m. The experimental area was subdivided into four habitat types using multivariate regression tree (MRT) analysis. According to an indicator species analysis, 38 of the 47 studied species were found to be significant indicators of the MRT habitat types. The relationships between species richness and topographic variables were found to be scale-dependent, while the great majority of the species shows distinct habitat-dependence. There are 188 potential species-habitat associations, and 114 of these were significantly positive or negative based on habitat randomization. We identified 139 significant associations using a species randomization. A habitat is not a closed system it may be both, either a sink or a source. Therefore, additional to the randomization, the Poisson Cluster Model (PCM) was applied. PCM considers the spatial autocorrelation of species and habitats, and thus appears to be more realistic than the traditional randomization processes. It identified only 37 associations that were significant. In conclusion, the deviation from the random process, i.e. the high degree of species spatial mingling may be explained by persistent immigration across habitats.
article id 906, category Research article
Forest stand modelling as a tool to predict performance of the understory herb Cornus suecica. Silva Fennica vol. 46 no. 4 article id 906. https://doi.org/10.14214/sf.906
Forest simulation models have been widely used to predict future stand structure. Generally these models do not include the understory vegetation and its response on stand structure change or other environmental factors. Previous simulation studies have shown that stand structure related variables, e.g. basal area, can explain diversity of the forest floor vegetation in boreal forests. We hypothesise that such variables also can be used to explain the performance of understory species and we conceptualise how plant ecology and forest modelling can be combined to predict the performance of understory plants in Norwegian boreal forests. We predict the performance of an understory plant species (Cornus suecica) over time using simulated values of forest variables as input to models expressing the relationship between forest environment variables and plant performance variables (viz. plant height, plant dry weight, number of flowers, number of branches and number of leaves). We also present relationships between plant performance and explanatory variables commonly used in basic ecological research, variables that currently not are readily compatible with forest simulators (e.g. soil chemical variables).We found basal area of canopy trees being the most important explanatory variable explaining C. suecica performance. The performance variable dry weight was predicted by one single model whereas the other performance variables were best predicted by model averaging. Forest simulations for 150 years showed values of plant performance of C. suecica to be reduced during forest succession.
article id 905, category Research article
Population history, genetic variation and conservation status of the endangered birch species Betula nana L. in Poland. Silva Fennica vol. 46 no. 4 article id 905. https://doi.org/10.14214/sf.905
The effective conservation of species requires data on the levels and distribution of genetic diversity within and among populations. In this study, we estimated the genetic variation in three isolated populations of Betula nana in Poland. An analysis of 11 nuclear microsatellites revealed moderate mean heterozygosities (HO=0.556, HE=0.562), low mean number of alleles per locus (A=4.57) and no inbreeding in the total sample. An M-ratio test indicated that each population had experienced a severe bottleneck in the past. Tests for heterozygosity excess revealed that a significant decrease in the numbers of individuals in two populations had occurred quite recently. The large number of private alleles and very restricted number of migrants between populations (Nm=0.35) strongly suggest that genetic drift and geographic isolation are the primary factors responsible for the reduction of genetic variation in the Polish populations of B. nana. We detected two cpDNA haplotypes in the study populations, which can be explained in terms of either the genetic drift acting on the relict localities or a postglacial recolonisation from distinct refugia. Palynological data indicated that one refugium could be located in the Carpathians and their northern foreland. The primary threat to B. nana in Poland is the overgrowth of its habitats by competing species, which has likely resulted in a lack of generative reproduction in the mountain populations.
article id 440, category Research article
Detection of electric resistivity tomography and evaluation of the sapwood-heartwood demarcation in three Asia Gymnosperm species. Silva Fennica vol. 46 no. 3 article id 440. https://doi.org/10.14214/sf.440
The proportions of sapwood and heartwood of trees have significant impacts on various uses. Electric resistivity tomography (ERT) and corresponding electrical resistance (ER) value maps were examined in Japanese cedar (Cryptomeria japonica D. Don), Taiwania (Taiwania cryptomerioides Hayata), and Luanta fir (Cunninghamia konishii Hayata) trees. The position of the sapwood-heartwood demarcation was measured on incremental cores from living trees and the corresponding ER of the sapwood-heartwood boundary was acquired from the ER map. A positive significant relationship was found between the maximum ER plus minimum ER values (ERmax + ERmin) and ER of the sapwood-heartwood demarcation from the tomographic data. The position of the sapwood-heartwood demarcation was determined by corresponding ER, and the critical ER can be established by the ERmax + ERmin value of the tomographic data. The results from this study indicate that ERT technique can be used to determine the position of the sapwood-heartwood boundary and can serve as a methodology in undamaged living trees of Gymnosperm species.
article id 52, category Research article
Measuring and monitoring socio-cultural sustainability in the action of forest biodiversity cooperation networks. Silva Fennica vol. 46 no. 3 article id 52. https://doi.org/10.14214/sf.52
To safeguard overall sustainability in forest resource management, the ecological, economic, social, and cultural dimensions of sustainability should all be considered. However, the socio-cultural impacts are frequently contemplated only weakly in sustainability assessments. Hitherto, attempts to operationalize socio-cultural impacts arising from economic utilization or conservation of forest resources have been perceived as vague when compared to rigorous ecological and economic indicators. One reason is that socio-cultural impacts of forest management on individuals and communities are many and by nature context- and case-specific: they need local definition, which hampers diffusion of good solutions. This study developed a multi-criteria method for measuring and monitoring socio-cultural impacts of forest resource management; the case of cooperation network projects within Forest Biodiversity Programme for Southern Finland (METSO) provided empirical data. Based on a literature review, a set of 10 criteria and 25 indicators was compiled. Cumulative utility scores, presenting networks’ contributions to socio-cultural sustainability, were generated using performance, expert evaluation and weighting data and an additive utility model. The method enables longitudinal monitoring of socio-cultural impacts, which is beneficial because outcomes are different at different time points of projects’ life cycles and some appear with a delay. The method can be used in comparing sub-utility distributions i.e. monitoring units’ performance profiles, providing valuable information for policy-makers. The multi-criteria approach and the list of socio-cultural criteria are internationally transferable to other countries and contexts such as forest bioenergy, nature tourism, watershed management, that call for analysing socio-cultural impacts of forest resource management activity on private lands.
article id 51, category Research article
Substitution in the Finnish forest industry’s roundwood procurement. Silva Fennica vol. 46 no. 3 article id 51. https://doi.org/10.14214/sf.51
In this study, the interaction and substitution between domestic and imported roundwood in the Finnish forest industry’s wood procurement is analysed by timber assortments. The results from the translog cost function approach and quarterly data of the total wood procurement and its components during the euro regime indicate that, to a certain extent, the Finnish forest industry has had the possibility of substituting imported roundwood volumes between countries in the Baltic Sea region. Contrary to earlier studies, also in the case of Russian birch pulpwood, the most important imported timber assortment, the results suggest that Russian birch pulpwood has rather substituted for than complemented the domestic supply in Finland. The increase in roundwood export duties in Russia has had a statistically significant effect on the trade in birch pulpwood and spruce sawlogs. Moreover, the results confirm the earlier findings of a rigid demand for roundwood in Finnish roundwood markets.
article id 49, category Research article
The operational efficiency of waterway transport of forest chips on Finland’s Lake Saimaa. Silva Fennica vol. 46 no. 3 article id 49. https://doi.org/10.14214/sf.49
New and cost-efficient methods for use in supply chains for energy wood should be found, to reach the targets of the renewable energy utilisation set by the European Union. The long-distance waterway transportation of forest fuels should be thoroughly investigated, especially in areas where the transport distance is long and waterways could provide a feasible method of conveying forest fuel. In comparison to transport of forest chips by truck, barge-based waterway transport shows a competitive advantage due to the larger loads and higher bulk density of chips it allows. The cost-efficiency of waterway transportation operations related to forest chips in Finland’s Lake Saimaa region was studied using practical demonstrations and discrete-event simulation. The varying demand for fuel wood in three separate bio-power plants on the Saimaa lakeside (near the cities of Varkaus, Mikkeli, and Savonlinna) was addressed in several barge transportation scenarios. Finally, the economy of barge transportation was compared to the economy of truck transportation as a function of transportation distance and in terms of the annual performance of the transportation methods examined. The waterway supply chain of forest chips was cost-competitive to road transport by truck after 100–150 km. According to the simulation study, the most economical waterway transport options were based on fixed barge system and shift-independent harbor logistics where loading and unloading of barges were carried-out with a wheeled loader and a belt conveyor. Total supply chain costs including the best waterway logistics from road side storage to power plant ranged from 10.75 euros to 11.64 euros/MWh in distances of 100–150 km by waterways. The energy-density of forest chips in the barge load was found to be, on average, 25% higher than that in truck hauling, because of the better compaction of chips. Waterway transport is a viable option for long-distance transportation of forest chips in Eastern Finland.
article id 48, category Research article
Biomass and nutrition of naturally regenerated and coppiced birch on cutaway peatland during 37 years. Silva Fennica vol. 46 no. 3 article id 48. https://doi.org/10.14214/sf.48
Biomass production and nutrient use of birch thickets with a mixture of willow on a cut away peatland in southern Finland over a period of 37 years was studied. Dense, naturally regenerated 16-year-old birch stands were cut down, fertilized with either wood ash (P 108 and K 339 kg ha–1) or PK fertilizer (P 50 and K 95 kg ha–1) or left unfertilized. The biomass production of the coppiced stands and one uncut stand was monitored for a period of 21 years. Soil nutrient and foliar nutrient concentrations were analyzed several times during the study period. Ash fertilization supplied more nutrients than PK fertilization and increased the soil nutrient amounts more. The foliar phosphorus concentration of birch on control plots indicated a severe phosphorus deficiency which was removed by PK and ash fertilization. Fertilization did not increase nutrient concentrations of the stem (wood + bark) nor the amount of nutrients bound in the biomass. Two energy wood rotations (16+21 years) produced 124–158 Mg ha–1 of leafless, above-ground biomass altogether corresponding to 61–78 Mg ha–1 of carbon. The highest biomass yield was achieved with a rotation of 37 years in the uncut stand (211 Mg ha–1). Corresponding values for mean annual increment (MAI) were 3.4–4.3 Mg ha–1 and 5.7 Mg ha–1. This study shows that the length of the rotation for birch in energy wood production should be longer than 21 years. PK and ash fertilization increased the biomass of coppiced 21-year-old birch by 23 Mg ha–1 and 33 Mg ha–1, respectively.
article id 47, category Research article
A comparison of residual forest following fires and harvesting in boreal forests in Quebec, Canada. Silva Fennica vol. 46 no. 3 article id 47. https://doi.org/10.14214/sf.47
Residual forests are a key component of post-burned areas creating structure within burns and providing habitat and seed sources. Yet, despite their importance to biodiversity and ecosystem processes there is little information on how similar or different residuals in burned landscape are to harvested landscapes. Our goal was to examine and compare the density, size, shape, and spatial arrangement of residual forest vegetation after fire and clearcutting. We evaluated residual forest in two locations within the boreal mixedwood region of Quebec, Canada using aerial photo interpretation and ArcGIS 9.1 software. We found residual stands to be larger and more abundant in harvested zones relative to sites affected by fire. Differences with respect to shape and spatial arrangement of residual forest were also observed among disturbance types. Factors such as proximity to watercourses, watercourse shape, and physiography affected residual abundance and spatial distribution. Residual forest in harvested zones tended to be more elongated with greater edge due to rules governing forest operations. Despite greater quantity of residual forest in harvested areas than fires, managers should still be prudent as the surrounding forest matrix is reduced in many managed landscapes.
article id 46, category Research article
From the Arctic Circle to the Canadian prairies – a case study of silver birch acclimation capacity. Silva Fennica vol. 46 no. 3 article id 46. https://doi.org/10.14214/sf.46
Earlier provenance research has indicated poor success even in short distance transfers (> 2–3° latitude) of silver birch (Betula pendula Roth) southward from their origin. These results may indicate poor adaptability of silver birch to a warming climate. Some of the scenarios for a warming climate in Finland suggest effective heat sums are likely to double in the north and increase 1.5 fold in the south for the period of 2070–2099. Consequently, the outlook for silver birch appears bleak. To study the acclimation of birch to this projected change we established a provenance trial in northeastern Alberta, Canada, at the temperature area currently predicted for Central Finland (lat. 64–66°N) at the turn of this century (1400 dd). Our 10-year experiment showed that all the Finnish provenances (origins 61–67°N) have acclimated well to the warmer growth conditions experienced in Alberta at 54°N. These results suggest that silver birch has the potential to acclimate to thermal conditions predicted for Finland at the end of the 21st century. Our results also indicate that silver birch has the potential as a plantation species in Canada, where the Finnish birch grew faster in the boreal forest region of Canada than local paper birch (Betula papyrifera Marsh.) provenances.
article id 45, category Research article
Effect of fall-applied nitrogen on growth, nitrogen storage and frost hardiness of bareroot Larix olgensis seedlings. Silva Fennica vol. 46 no. 3 article id 45. https://doi.org/10.14214/sf.45
Nursery response of evergreen trees to fall fertilization has been studied widely, but little attention has been given to deciduous trees. Bareroot Olga Bay larch (Larix olgensis Henry) seedlings were fertilized in the nursery with urea at four rates (0, 30, 60, 90 kg N ha–1), with half of each rate applied on two dates (September 16 and October 1, 2009). The seedlings were excavated for evaluation on October 15. In the unfertilized (control) treatment, root and shoot dry mass increased by 100% and 57% respectively, while N concentration in the roots and shoots increased by 43% and 40% during the 30 day period. This indicated that substantial biomass growth during this period did not lead to internal nutrient dilution. Root dry mass increased when fall fertilization rates were ≥ 60 kg N ha–1. Fall fertilization increased N concentrations in root tissue by 48–73%. Compared with the control, shoot tissues of fall fertilized seedlings had slightly higher N concentration and content and significantly higher frost hardiness.
article id 44, category Research article
Individual biomass and carbon equations for Mimosa scabrella Benth. (bracatinga) in southern Brazil. Silva Fennica vol. 46 no. 3 article id 44. https://doi.org/10.14214/sf.44
Mimosa scabrella Benth. is an important native species of southern Brazil widely used for energy and promising for reforestation carbon offsets. Quantification of biomass and carbon stock is valuable for both purposes. From a forest inventory conducted in southern Brazil, data of M. scabrella were analyzed. Thirty sample trees were felled, excavated and weighed in the field and brought to laboratory for biomass and carbon determination. The total aboveground biomass represented 85% of the tree biomass, while roots corresponded to 15%. Correlation matrix of diameter at 1.3 m height (D), tree height (H) versus total and compartment biomass (P) indicated strong association between tree dimensions and biomasses. Five regression models were tested and equations were fitted to data of five biomass compartments and total tree biomass. The best fitting model for total biomass was P = –0.49361 + 0.034865 x D2H whereas for the partial biomass of the compartments was lnP = β0 + β1 x ln(D) + β2 lnH. Carbon concentration was statistically significantly different in foliage than in other compartments. Three approaches of calculating carbon stocks were evaluated and compared to actual data: 1) Estimated total biomass x weighted mean carbon concentration; 2) Estimated partial (compartment) biomass x compartment average carbon concentration; and 3) Carbon regression equations. No statistical difference was detected among them. It was concluded that biomass equations fitted in this study were accurate and useful for fuelwood and carbon estimations.
article id 43, category Research article
Polypore communities in broadleaved boreal forests. Silva Fennica vol. 46 no. 3 article id 43. https://doi.org/10.14214/sf.43
The cover and extent of boreal broadleaved forests have been decreasing due to modern forest management practices and fire suppression. As decomposers of woody material, polypores are ecologically important ecosystem engineers. The ecology and conservation biology of polypores have been studied intensively in boreal coniferous forests. However, only a few studies have focused on the species living on broadleaved trees. To increase knowledge on this species group we conducted polypore surveys in 27 broadleaved forests and 303 forest compartments (539 ha) on the southern boreal zone in Finland and measured dead wood and forest characteristics. We detected altogether 98 polypore species, of which 13 are red-listed in Finland. 60% of the recorded species are primarily associated with broadleaved trees. The number of species in a local community present in a broadleaved forest covered approximately 50 species, of which 30–40 were primarily associated with broadleaved trees. The size of the inventoried area explained 67% of the variation in the species richness, but unlike in previous studies conducted in coniferous forests, dead wood variables as well as forest structure had very limited power in explaining polypore species richness on forest stand level. The compartments occupied by red listed Protomerulius caryae had an especially high volume of living birch, but otherwise the occurrences of red-listed species could not be predicted based on the forest structure.
article id 42, category Research article
In vitro and in vivo interactions between Trichoderma viride and Fusarium circinatum. Silva Fennica vol. 46 no. 3 article id 42. https://doi.org/10.14214/sf.42
Fusarium circinatum, a fungus that causes pitch canker disease, has been present in Europe since at least 2003, when it was detected in northern Spain and found to be producing severe damage in tree nurseries and pine plantations. In this study, we tested a method of biological control of the disease with Trichoderma viride, a fungal species successfully used against many other pathogens. In vitro and in vivo assays were carried out to test the efficacy of this antagonist in controlling F. circinatum. The T. viride isolate exerted a significant effect on the growth of F. circinatum in the in vitro assay, reducing the length of the pathogen colony by half. However, although we tested three different concentrations of the T. viride spore solution, no clear conclusions were obtained with regard to the effects on the Pinus radiata seedlings. To our knowledge, this is the first study carried out with the aim of using Trichoderma spp. to control pitch canker disease.
article id 441, category Research article
Factors affecting wind and snow damage of individual trees in a small management unit in Finland: assessment based on inventoried damage and mechanistic modelling. Silva Fennica vol. 46 no. 2 article id 441. https://doi.org/10.14214/sf.441
In this work, we assessed the factors affecting wind and snow damage of individual trees in a small management unit in western Finland. This was done based on inventoried damage and observed wind speeds and snow loading in storms Pyry and Janika in 2001 and Mielikki in 2002 together with mechanistic model. First, we studied which factors explain the observed damage in individual trees. Secondly, we studied how well the mechanistic model (HWIND) could predict the wind speed needed to uproot individual trees at the margins of permanent upwind edges. We found that Pyry storm caused 70% and Janika and Mielikki 18 and 12% of observed damage. In Janika storm, all trees uprooted. In other storms, both uprooting and stem breakage occurred. Scots pine suffered the most damage. Recently thinned stands on the upwind edges of open areas suffered the most damage. But, damage occurred also on soils with relatively shallow anchorage. HWIND predicted correctly damage for 69% of all uprooted trees. No-uprooting was correctly predicted for 45 and 19% of standing trees (all Scots pines), which were measured within and at the immediate upwind edge of same stands. HWIND model needs further validation at the permanent edges and/or on soils with shallow rooting to improve its prediction accuracy in such conditions.
article id 58, category Research article
Factors affecting enlargement of family forest holdings. Silva Fennica vol. 46 no. 2 article id 58. https://doi.org/10.14214/sf.58
This study contributes to the research of enlargement – a counterforce of parcelization – of forest holdings. To help planning policy measures aiming at increased average size of forest holdings, we study the characteristics of family forest owners who acquired additional forestland area during the years 2004–2008. Increases of forestland area due to purchases on the open market, purchases from parents or other relatives, inheritance or gift are studied. Survey data, containing information of 6318 forest owners, are analyzed with logistic regression analysis in order to establish a relationship between the probability of increasing the forestland area and the characteristics of landowners. The results indicate that young male owners, who appreciate economic values of the ownership and are active users of their forest estates, most often expand their forest property. This can be considered as an encouraging result from the point of view of the political objective to boost forest management activity through enlarging family forest holdings.
article id 57, category Research article
Performance modelling in forest operations through partial least square regression. Silva Fennica vol. 46 no. 2 article id 57. https://doi.org/10.14214/sf.57
Partial Least Square (PLS) regression is a recent soft-modelling technique that generalizes and combines features from principal component analysis (PCA) and multiple regression. It is particularly useful when predicting one or more dependent variables from a large set of independent variables, often collinear. The authors compared the potential of PLS regression and ordinary linear regression for accurate modelling of forest work, with special reference to wood chipping, wood extraction and the continuous harvesting of short rotation coppice. Compared to linear regression, PLS regression allowed producing models that better fit the original data. What is more, it allowed handling collinear variables, facilitating the extraction of sound models from large amounts of field data obtained from commercial forest operations. On the other hand, PLS regression analysis is not as easy to conduct, and produces models that are less user-friendly. By producing alternative models, PLS regression may provide additional – and not alternative – ways of reading the data. Ideally, a comprehensive data analysis could include both ordinary and PLS regression and proceed from their results in order to get a better understanding of the phenomenon under examination. Furthermore, the computational complexity of PLS regression may stimulate interdisciplinary team-building, to the greater benefit of scientific research within the field of forest operations.
article id 56, category Research article
Prediction of stem attributes by combining airborne laser scanning and measurements from harvesters. Silva Fennica vol. 46 no. 2 article id 56. https://doi.org/10.14214/sf.56
In this study, a new method was validated for the first time that predicts stem attributes for a forest area without any manual measurements of tree stems by combining harvester measurements and Airborne Laser Scanning (ALS) data. A new algorithm for automatic segmentation of tree crowns from ALS data based on tree crown models was developed. The test site was located in boreal forest (64°06’N, 19°10’E) dominated by Norway spruce (Picea abies) and Scots Pine (Pinus sylvestris).The trees were harvested on field plots, and each harvested tree was linked to the nearest tree crown segment derived from ALS data. In this way, a reference database was created with both stem data from the harvester and ALS derived features for linked tree crowns. To estimate stem attributes for a tree crown segment in parts of the forest where trees not yet have been harvested, tree stems are imputed from the most similar crown segment in the reference database according to features extracted from ALS data. The imputation of harvester data was validated on a sub-stand-level, i.e. 2–4 aggregated 10 m radius plots, and the obtained RMSE of stem volume, mean tree height, mean stem diameter, and stem density (stems per ha) estimates were 11%, 8%, 12%, and 19%, respectively. The imputation of stem data collected by harvesters could in the future be used for bucking simulations of not yet harvested forest stands in order to predict wood assortments.
article id 55, category Research article
Using cost-plus-loss analysis to define optimal forest inventory interval and forest inventory accuracy. Silva Fennica vol. 46 no. 2 article id 55. https://doi.org/10.14214/sf.55
In recent years, optimal inventory accuracy has been analyzed with a cost-plus-loss methodology, where the total costs of inventory include both the measurement costs and the losses from the decisions based on the collected information. Losses occur, when the inaccuracies in the data lead to sub-optimal decisions. In almost all cases, it has been assumed that the accuracy of the once collected data remains the same throughout the planning period, and the period has been from 10 up to 100 years. In reality, the quality of the data deteriorates in time, due to errors in the predicted growth. In this study, we carried out a cost-plus-loss analysis accounting for the errors in (stand-level) growth predictions of basal area and dominant height. In addition, we included the inventory errors of these two variables with several different levels of accuracy, and costs of inventory with several different assumptions of cost structure. Using the methodology presented in this study, we could calculate the optimal inventory interval (life-span of data) minimizing the total costs of inventory and losses through the 30-year planning period. When the inventory costs only to a small extent depended on the accuracy, the optimal inventory period was 5 years and optimal accuracy RMSE 0%. When the costs more and more heavily depended on the accuracy, the optimal interval turned out to be either 10 or 15 years, and the optimal accuracy reduced from RMSE 0% to RMSE 20%. By increasing the accuracy of the growth models, it was possible to reduce the inventory accuracy or lengthen the interval, i.e. obtain clear savings in inventory costs.
article id 54, category Research article
Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54. https://doi.org/10.14214/sf.54
Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.
article id 53, category Research article
Responses of soil carbon and nitrogen transformations to stump removal. Silva Fennica vol. 46 no. 2 article id 53. https://doi.org/10.14214/sf.53
We studied in central Finland whether stump harvesting after clear felling of coniferous forest poses further short-term changes in soil carbon and nitrogen dynamics when compared to the traditional site preparation method, mounding. Exposed mineral soil patches in Norway spruce (Picea abies) dominated clear-cut stands were sampled 1–5 years after the treatments. The extent of the exposed mineral soil surface was significantly larger at the stump removal sites when compared to the mounding sites. No differences were found in soil pH, organic matter content or total concentration of soil C between the treatments or treatment years. Total concentration of soil N was consistently higher and C:N ratio lower in the stump removal plots than in the mounded plots. Further, both net N mineralisation and nitrification were clearly increased in the stump removal plots one year after the treatments. Soil microbial activity (CO2 production) was higher in the stump removal plots but similar difference was not found in sieved soil samples incubated in the laboratory. Fluxes of other important greenhouse gases (CH4 and N2O) did not seem to be affected by stump removal. The differences between the stump removal and mounding procedures were most obviously attributed to more substantial soil disturbance by stump pulling and/or differences in the microbial communities and quality of soil organic matter in the differently treated soil.
article id 444, category Research article
Facilitation of forest landscape restoration on abandoned swidden fallows in Laos using mixed-species planting and biochar application. Silva Fennica vol. 46 no. 1 article id 444. https://doi.org/10.14214/sf.444
The cessation of swidden cultivation and the increasing trend of abandonment of swidden fallows have created an opportunity for forest landscape restoration. However, ways need to be found to improve the poor soil fertility at these sites with affordable materials and to generate short-term socio-economic benefits for small-scale swidden fallow holders. This study assessed the feasibility of using mixed-planting of eight native species and application of rice husk biochar as soil amendment measure at a site in Laos. The effect of biochar application was compared against addition of inorganic (NPK) fertilizer and the control. The establishment and growth of the planted seedlings was then monitored for four years. The addition of rice husk biochar and NPK fertilizer did not significantly (p = 0.578) improve the survival rate of planted seedlings, which ranged from 72% to 91% (depending on the species) compared to the control. No significant growth responses to the soil amendments were observed for most of the species during the first year after planting compared to the control. The biochar effect was, however, more evident at the fourth year for diameter (p < 0.01) and height (p < 0.01) of sapling for all species; particularly its effect was more vivid on the diameter of slow-growing species. The results indicate that the species tested in the mixed-planting showed marked growth variation while application of rice husk biochar boosted their growth. Thus, planting mixed-species in swidden fallows has potential to provide continuous supplies of wood from different species to diversify the livelihood of swidden field owners, while maintaining ecosystem services.
article id 70, category Research article
Firm capabilities in the Finnish forest cluster: comparisons based on self-organizing map. Silva Fennica vol. 46 no. 1 article id 70. https://doi.org/10.14214/sf.70
This paper examines the capability portfolios of Finnish forest cluster firms in 1998–2008. In particular, the focus is on what kind of capabilities the firms in the cluster have developed, whether the firms have developed such capabilities consistently, and whether they have developed similar capability portfolios. Further, a particular focus is on the links between innovativeness and other identified capabilities. We approach the topic with an exploratory quantitative analysis of the annual reports of 11 large firms in the cluster by using computerized content analysis and a self-organizing map as the main research methods. Based on the content analysis and earlier literature, we first identify fifteen capabilities, and then build capability portfolios for the firms on the basis of the results of the self-organizing map. At the firm level, the results reveal both similarities and differences in the capability portfolios of the forest cluster firms. Similarly, we identify both continuity and change in the development of the portfolios. At the cluster level, the focus is on innovativeness capability and its relationship with other capabilities. The results suggest that especially being strategic, market-oriented, and monitoring the external environment are positively related with innovativeness; in contrast, a focus on finance and change seems to suppress innovativeness.
article id 69, category Research article
Analysing the agreement between an Airborne Laser Scanning based forest inventory and a control inventory – a case study in the state owned forests in Finland. Silva Fennica vol. 46 no. 1 article id 69. https://doi.org/10.14214/sf.69
Airborne laser scanning based forest inventories have recently shown to produce accurate results. However, the accuracy varies according to the test area and used methodology and therefore, an unambiguous and practical quality assessment will be needed as a part of each inventory project. In this study, the accuracy of an ALS inventory was evaluated with a field sampling based control inventory. The agreement between the ALS inventory and the control inventory was analysed with four methods: 1) root mean square error (RMSE) and bias, 2) scatter plots with 95% confidence intervals, 3) Bland-Altman plots and 4) tolerance limits within Bland-Altman plots. Each method has its own special features which have to be taken into account when the agreement is analysed. The pre-defined requirements of the ALS inventory were achieved. A simplified control inventory approach with a slightly narrower focus is proposed to be used in the future. The Bland-Altman plots with the tolerance limits are proposed to be used in quality assessments of operational ALS inventories. Further studies to improve the efficiency of quality assessment are needed.
article id 68, category Research article
The suitability of leaf-off airborne laser scanning data in an area-based forest inventory of coniferous and deciduous trees. Silva Fennica vol. 46 no. 1 article id 68. https://doi.org/10.14214/sf.68
This study examined the suitability of airborne laser scanner (ALS) data collected under leaf-off conditions in a forest inventory, in which deciduous and coniferous trees need to be separated. All analyses were carried out with leaf-on and leaf-off ALS data collected from the same study area. Additionally, aerial photographs were utilized in the Nearest Neighbor (NN) imputations. An area-based approach was used in this study. Regression estimates of plot volume were more accurate in the case of leaf-off than leaf-on data. In addition, regression models were more accurate in coniferous plots than in deciduous plots. The results of applying leaf-on models with leaf-off data, and vice versa, indicate that leaf-on and leaf-off data should not be combined since this causes serious bias. The total volume and volume by coniferous and deciduous trees was estimated by the NN imputation. In terms of total volume, leaf-off data provided more accurate estimates than leaf-on data. In addition, leaf-off data discriminated between coniferous and deciduous trees, even without the use of aerial photographs. Accurate results were also obtained when leaf-off ALS data were used to classify sample plots into deciduous and coniferous dominated plots. The results indicate that the area-based method and ALS data collected under leaf-off conditions are suitable for forest inventory in which deciduous and coniferous trees need to be distinguished.
article id 67, category Research article
Impact and productivity of harvesting while retaining young understorey spruces in final cutting of downy birch (Betula pubescens). Silva Fennica vol. 46 no. 1 article id 67. https://doi.org/10.14214/sf.67
Quite often Norway spruce (Picea abies (L.) Karsten) forms an understorey in birch dominated stands in Finland. Advantageous growth conditions for both storeys are present especially in downy birch (Betula pubescens Ehrh.) stands on drained fertile peatland. The most common way of regenerating mature Downy birch forest is clear cutting and replanting with Norway spruce, even if vital spruce seedlings or saplings was already growing under the birch. The aim of this study is to investigate the impact of retaining young understorey spruces on the productivity of harvesting and on the quality of the remaining stands in downy birch dominated stands with modern cut-to-length (CTL) machinery. Retaining undergrowth spruces decreased productivity of cutting in managed stands (600 stems/ha) by 6–9 per cent and in unmanaged stands (1200 stems/ha) by 11–17 per cent compared with clear cutting, where the understorey is not considered. Compared with the case where no understorey was present, the decrease in productivity was 10–17 per cent and 21–30 per cent respectively. In forwarding, retaining the undergrowth decreased the productivity of loading phases by 7–14 per cent. Harvesting treatment where spruces were retained produced an adequate stand structure for the future growing stock. Using this method, 14–24 per cent of the original spruces were totally destroyed while 25–44 per cent of spruces were destroyed when they were not considered for harvesting. The spatial variation of the remaining spruces was much better in the treatment where spruces were retained. Our study results shows that in this kind of two storey birch–spruce forests, the harvesting treatment where spruces are retained while cutting is the most acceptable and profitable method. It allows for a vital spruce sapling to continue growing, and avoids regeneration and tending costs or other harmful effects of clear-cut areas such as the freezing of young spruce plants and an increase in the ground water table.
article id 66, category Research article
Soil CO2 flux during the first years after stump harvesting in two Swedish forests. Silva Fennica vol. 46 no. 1 article id 66. https://doi.org/10.14214/sf.66
One way of increasing the supply of renewable energy, thereby decreasing the use of fossil fuels, is to extract the stumps that remain after final stem harvesting. However, little is known about the environmental consequences of stump harvesting, and how ecosystem services, such as carbon sequestration, are affected by the practice. In the present paper, the effects on the soil carbon pool during the first months and years after stump harvesting in former Norway spruce stands are presented. The study was performed at two sites in mid- and southern Sweden. At both sites, the soil CO2 flux was measured on several occasions with a portable respiration system, to compare plots on which stump harvesting had occurred, with reference plots. At one of the sites, CO2 exchange was also followed continuously by means of eddy-covariance measurements before and after stump harvesting. Since there was no vegetation at the beginning of the study, almost all emitted CO2 could be assumed to come from heterotrophic sources, and the soil CO2 flux was measured. This study shows that the effect of stump harvesting on CO2 flux or soil decomposition processes is small or absent compared to site preparation such as mounding in a short-term perspective of months and years. The long-term consequences of stump harvesting are, however, still uncertain.
article id 65, category Research article
Dynamic response of herbaceous vegetation to gap opening in a Central European beech stand. Silva Fennica vol. 46 no. 1 article id 65. https://doi.org/10.14214/sf.65
Herbaceous ground vegetation in artificially-created gaps was studied in a managed beech (Fagus sylvatica L.) forest over a period of eight years in Northern Hungary, Central Europe. These gaps were being used as an alternative to the regular shelterwood system to create uneven-aged stands. The effects of gap size (15 and 40 m diameter) and canopy openness on herbaceous species colonization and persistence were assessed in a systematic grid of 5 5 m. Overall, herbaceous cover was low before gap creation, increased soon afterwards, and continued to rise over time. The number of herb species increased in the gaps and, to a lesser extent, in adjacent areas under the remaining tree canopy. Colonization of gaps was rapid and there was substantial turnover of species i.e. various species disappeared from the gaps over time whilst others colonized. Species with both long-term persistent seed banks and long distance dispersal abilities were the most successful types colonizing gaps. Six species occurred preferentially in large gaps, while only one species was found to prefer small gaps. Species present before gap creation survived in both gap sizes. Smaller gaps with a diameter of half the height of canopy trees also tended to remain free of common weed species, whereas large cover of Rubus fruticosus L. and Calamagrostis epigejos (L.) Roth could hamper natural regeneration in larger gaps. For the successful regeneration of beech we recommend the use of small gaps complemented by few large gaps.
article id 64, category Research article
Optimization of environmental factors affecting initial growth of Norway spruce seedlings. Silva Fennica vol. 46 no. 1 article id 64. https://doi.org/10.14214/sf.64
The purpose of the study was to create a near optimal environment for seedling establishment and growth, without the restrain of water and nutrients but under climate conditions typical for the region. This to give us valuable knowledge about the growth potential of different seedling types in the field. The experimental site was situated in southern Sweden. Six treatment combinations were applied including two site treatments; 1) soil inversion, i.e. the control treatment, and 2) soil inversion, drip irrigation and fertilization combined with plastic cover mulch, i.e. the optimization treatment, and three seedling types of Norway spruce (Picea abies L. Karst.), (a) a 2-year-old Plug+1 seedling, (b) a 1.5-year-old containerized seedling and (c) a 10-week-old mini seedling. Effects on seedling nutrient status and growth were studied during the first three years after planting. Height, diameter and biomass of the seedlings grown in the optimized environment were significantly greater than for seedlings grown in the control. The Plug+1 seedlings grown in the optimization treatment had, after three years, reached a height of 124 cm, while the containerized seedlings were 104 cm and the mini seedlings 45 cm. In practical plantations, this height is usually gained after 5–10 years depending on planting conditions. Biomass partitioning did not differ between optimization treatments, but between seedling types. The mini seedlings allocated less biomass to the roots and more biomass to needles and stem in comparison with the two other seedling types. Mini seedlings also broke bud earlier. Throughout the experimental period, seedling nutrient status for all treatment combinations was followed and a balanced nutrient supply of macro- and micronutrients was given in the optimization treatment. Nutrient concentrations were constantly higher in seedlings grown in the optimization treatment, but the difference decreased over time. Results from this study shows that, by improving site conditions associated with fast establishment, growth check can be avoided.
article id 63, category Research article
The effect of temperature on seed quality and quantity in crosses between European (Populus tremula) and hybrid aspens (P. tremula x P. tremuloides). Silva Fennica vol. 46 no. 1 article id 63. https://doi.org/10.14214/sf.63
Hybrid aspen (Populus tremula L. Populus tremuloides Michx.) plantations are expanding in Fennoscandia and the Baltic countries; however, the possible effects of plantations on the native European aspen (P. tremula) and the level of gene flow between European and hybrid aspen have not been investigated. We studied seed quantity and quality in intraspecific and interspecific crosses of the European and hybrid aspens over a two year period. In order to study whether elevated temperatures due to climate change would benefit the species differently, we performed the crosses in different temperatures. In both years, interspecific crosses produced more seeds with higher quality than intraspecific crosses. This result was most distinct in crosses between female hybrid aspen and male European aspen. In higher temperatures, relative germination difference between hybrid aspen seeds and seeds from P. tremula P. tremula crosses seems to increase. These results suggest that hybrid aspen may have a significant genetic impact on the European aspen, and this effect may be strengthened by climate warming.
article id 62, category Research article
Microdissection to isolate vascular cambium cells in poplar. Silva Fennica vol. 46 no. 1 article id 62. https://doi.org/10.14214/sf.62
Vascular cambium is the lateral meristem producing xylem cells inwards and phloem cells outwards in plant stem. Thus, in trees, the quality and quantity of wood is a result of highly regulated developmental process depending initially on the vascular cambium cell production. The availability of accurate transcriptomics technologies based on high coverage sequencing raises the level of expectations on tissue sampling to a very high degree. What is the benefit of top-level transcriptomics in wood formation studies if we are using these technologies on raw tissues, mixing cells at the organ level or even higher scale? The presented work describes a nine-step procedure, from standing tree to isolated ray and fusiform cells from cryolyophilized tangential sections of the poplar cambial zone. The aim of this paper is to present a step by step procedure including advices on how to select the optimal tree, how to fell the tree while securing its physiological parameters, how to cryolyophilize and microdissect under binocular, presenting the time schedule of the whole process and RNA analysis.
Category: Review article
article id 923, category Review article
What can molecular markers tell us about the glacial and postglacial histories of European birches? Silva Fennica vol. 46 no. 5 article id 923. https://doi.org/10.14214/sf.923
The last glaciation was one of the most severe of the Pleistocene epoch. The development of the Scandinavian ice sheet forced many species to reduce their ranges to areas with favourable climatic conditions. Most European species survived the Last Glacial Maximum in refugia in southern parts of Europe. Cold-tolerant species, such as birch trees and shrubs, could also inhabit western, eastern or central Europe. After climate warming, Holocene recolonisation began. This paper presents a comparative analysis of the genetic variation of four European Betula species to reconstruct their glacial and postglacial histories. Two chloroplast DNA haplotypes dominate within the ranges of all birch species, one haplotype is the most common in western and northwestern Europe, the second haplotype occurs mainly in the eastern and southeastern parts of the continent. This finding suggests that birches have recolonised Europe from the western and the eastern refugia, respectively. Most of Europe was likely populated from higher latitude refugia because there was no evidence of isolation by distance and weak genetic structures were detected. Similar patterns of haplotype distributions within Betula ranges indicate that postglacial recolonisation may be disturbed by interspecies hybridisation.
Category: Research note
article id 915, category Research note
Comparison of two stump-lifting heads in final felling Norway spruce stand. Silva Fennica vol. 46 no. 4 article id 915. https://doi.org/10.14214/sf.915
The use of stump and root wood chips has increased very rapidly in the 21st century in Finland: in the year 2000, the total consumption of stump wood chips for energy generation was 10 GWh, while in 2010 it was approximately 2 TWh. Metsäteho Oy and TTS Research evaluated two stump-lifting devices for the lifting of Norway spruce (Picea abies) stumps. The productivity and costs of stump lifting were determined. There was one base machine with one operator in the time study. When lifting stumps with a diameter of 30 cm, the effective hour productivity of stump lifting was 11.2 m3 solid over bark (sob)/E0 (4.8 tonD/E0) without site preparation using a Väkevä Stump Processor, and when lifting spruce stumps with a diameter of 40 cm, the productivity was 14.9 m3 sob/E0 (6.5 tonD/E0). When the site preparation (mounding) was integrated into lifting work, the stump-lifting productivity decreased 21–27%. The stump-lifting productivity of the other lifting head (Järvinen) was lower than that of the Väkevä Stump Processor. Some development suggestions for the Järvinen lifting head were presented and discussed. The cost calculations showed that stump-lifting costs are extremely high when stump diameter is less than 20 cm. Therefore, the study recommended a change in the current stump-harvesting guidelines of Finland: The study suggested that all the stumps with a diameter less than 20 cm should be left on the harvesting site.
article id 914, category Research note
Biomass production of dense direct-seeded lodgepole pine (Pinus contorta) at short rotation periods. Silva Fennica vol. 46 no. 4 article id 914. https://doi.org/10.14214/sf.914
Lodgepole pine (Pinus contorta) is a fast-growing species that is suitable for producing woody biomass in Nordic countries. Direct seeding of this species is cheaper than planting and creates dense, stable stands. The objective of this study was to quantify the stem volume and biomass production of direct seeded lodgepole pine stands grown under different site conditions with different stem densities, at an age that would permit extensive harvesting of biomass. A circle-plot inventory was performed in 16 of the oldest direct seeded lodgepole pine stands in mid-northern Sweden. Stemwood production of almost 200 m3/ha was achieved on average on the best sites, rising to about 300 m3/ha for the best circle-plots within 30 years of direct seeding despite the fact that pre-commercial thinning was made once or twice. This corresponds to 100 and 140 tons of dry weight biomass/ha, respectively. Higher stand stem densities (≥3000 st/ha) yielded more biomass with only slight reductions in diameter at breast height. The development of stem volume with respect to dominant height in direct seeded stands was becoming comparable to that in planted stands with similar spacing. It therefore seems that there is an unutilized potential for cost-effectively growing lodgepole pine in dense stands for biomass production after direct seeding. It may be possible to devise regimes for short(er) rotation forestry that would yield substantial amount of inexpensive biomass for biorefineries within a few decades.
article id 442, category Research note
Damage to residual stand caused by mechanized selection harvest in uneven-aged Picea abies dominated stands. Silva Fennica vol. 46 no. 2 article id 442. https://doi.org/10.14214/sf.442
Permanent field plots were established in two uneven-aged Norway spruce (Picea abies (L.) Karst) dominated stands in west-central Sweden. The objective was to quantify level and type of damage caused by harvesting and to quantify the difference between two treatments: T20) only skid road harvest (20 m distance between ca. 4 m wide roads), and T40) skid road harvest (40 m distance between ca. 4 m wide roads) combined with thinning between the roads. In T40, the goal was to harvest approximately the same standing volume as in T20. After harvest, two circular sample plots (radius 18 m, i.e. 1018 m2) were established at random locations within each treated area. All mechanical damage on the stem caused by harvest was measured and registered, including bark stripping larger than 15 cm2, stem broken or split, and tearing of branches causing damage on the stem. About 70–90 per cent of the damaged trees were smaller than 15 cm dbh. Very few trees larger than 25 cm dbh were damaged. In T20, more than 50 per cent of the damaged trees were located less than 5 m from the skid road, compared to less than 25 per cent for T40, in which more than 50 per cent of the damaged trees were located 5–10 m from the skid road. Creating only half the number of skid roads caused no more damage, and was probably more profitable because mean stem volume was about 1.5 times larger than in T20.
article id 61, category Research note
Harvesting of short rotation coppice – harvesting trials with a cut and storage system in Germany. Silva Fennica vol. 46 no. 2 article id 61. https://doi.org/10.14214/sf.61
Short rotation coppice (SRC) harvesting techniques are available in Germany, but broad experience and knowledge about machine performance and the related effective costs of harvesting operations are still missing. This information is crucial, as harvesting costs strongly influence the economic performance of the overall supply chain. Therefore, it was the aim of this study to collect and analyze productivity data of different harvesting systems for SRC. The combined cut and chip system on the one hand and the cut and storage system on the other hand were studied by literature review. Several studies analyze the combined cut and chip systems and the reported machine productivities showed great variations. The average was 30 green tons per scheduled machine hour (gt smh–1). Few studies are analysing the cut and storage system. They report that machines still are under development and that further research is needed. Therefore, time studies of harvesting operations using the cut and storage system were carried out. Five trials were performed with the harvesting machine “Stemster MK III” developed by Nordic Biomass. The share of productive working time was 85% and the average productivity was 21 gt smh–1. These results were compared with values from the literature. Resulting harvesting costs were calculated per oven dry ton (euros odt–1). The advantages and disadvantages of both harvesting systems are highlighted.
article id 60, category Research note
Chipping operations and efficiency in different operational environments. Silva Fennica vol. 46 no. 2 article id 60. https://doi.org/10.14214/sf.60
This research analyses the productivity of energy wood chipping operations at several sites in Austria and Finland. The aim of the work is to examine the differences in productivity and the effects of the operational environment for the chipping of bioenergy at the roadside. Furthermore, the study quantifies the effects of different variables such as forest energy assortments, tree species, sieve size and machines on the overall productivity of chipping. The results revealed that there are significant differences in the chipping productivity in Austria and Finland which are largely based on the use of different sieve sizes. Furthermore, the different operational environments in both countries, as well as the characteristics of the raw material also seem to have an effect on productivity. In order to improve the chipping productivity, particularly in Central European conditions, all relevant stakeholders need to work jointly to find solutions that will allow a greater variation of chip size. Furthermore, in the future more consideration has to be given to the close interlinkage between the chipper, crane and grapple. As a result, investments costs can be optimized and operational costs and stress on the machines reduced.
article id 71, category Research note
Soil preparation reduces pine weevil (Hylobius abietis L.) damage on both peatland and mineral soil sites one year after planting. Silva Fennica vol. 46 no. 1 article id 71. https://doi.org/10.14214/sf.71
We studied pine weevil (Hylobius abietis (L.)) feeding damage to Norway spruce and Scots pine seedlings planted in regeneration areas located on peatlands or on mineral soil sites in Southern and Central Finland. The survey included two planting years and a total of 60 regeneration areas (40 areas on peatlands and 20 on mineral soil sites). Some sites classified as peatland were as transformed or transforming drained peatlands that also contained mineral soil on a prepared surface. The soil preparation method, type of surface material around a seedling, pine weevil, vole-induced or other damage and the health of each seedling were observed in systematically selected circular sample plots. There was slightly more pine weevil damage on peatland than on mineral soil sites. More seedlings were damaged on unprepared peat and humus than on a prepared surface. Seedlings surrounded by a prepared surface had a slightly greater risk of being gnawed by pine weevil when planted on prepared peat compared to planting on prepared mineral soil. Vole damage was observed only in one region during one year. Mounded areas had slightly less vole damage than patched areas. In order to reduce damage caused by pine weevils and voles, it is important to scarify the regeneration area properly before insecticide-treated seedlings are planted. Mounding and patching are recommended so that seedlings can be planted in mineral soil whenever possible, even in the case of peatlands.