Showing papers in "Silva Fennica in 2005"
TL;DR: It is argued that it is necessary to counteract the current shortage in availability of dead wood, concentrate planning at the landscape level in order to minimize isolation and reduce edge effects, and create a variety of dead Wood types to utilise available quantitative analytical tools.
Abstract: Dead wood has been identified as a crucial component for forest biodiversity. Recent research has improved our understanding of habitat relations for many species associated with dead wood. However, the consequences for forest management are yet to be explored. In this review we build upon the growing volume of studies on dead wood dependent species, the dynamics of dead wood and ecological theory in order to identify the challenges for forest management at the landscape level. The review has a Fennoscandian focus, but the problems and challenges are similar in many forest ecosystems. We argue that it is necessary to 1) counteract the current shortage in availability of dead wood, 2) concentrate planning at the landscape level in order to minimize isolation and reduce edge effects, 3) create a variety of dead wood types, and 4) utilise available quantitative analytical tools. This calls for new approaches to management that to a large extent includes available knowledge, and to find platforms for planning forested landscapes with diverse holdings.
419 citations
TL;DR: Investigation of the relations between diameter at breast height and maximum crown diameter, tree height and other possible independent variables available in stand databases found regional models reduced local error and gave better results than the general models.
Abstract: The aim was to investigate the relations between diameter at breast height and maximum crown diameter, tree height and other possible independent variables available in stand databases. Altogether 76 models for estimating stem diameter at breast height and 60 models for tree age were formulated using height and maximum crown diameter as independent variables. These types of models can be utilized in modern remote sensing applications where tree crown dimensions and tree height are measured automatically. Data from Finnish national forest inventory sample plots located throughout the country were used to develop the models, and a separate test site was used to evaluate them. The RMSEs of the diameter models for the entire country varied between 7.3% and 14.9% from the mean diameter depending on the combination of independent variables and species. The RMSEs of the age models for entire country ranged from 9.2% to 12.8% from the mean age. The regional models were formulated from a data set in which the country was divided into four geographical areas. These regional models reduced local error and gave better results than the general models. The standard deviation of the dbh estimate for the separate test site was almost 5 cm when maximum crown width alone was the independent variable. The deviation was smallest for birch. When tree height was the only independent variable, the standard deviation was about 3 cm, and when both height and maximum crown width were included it was under 3 cm. In the latter case, the deviation was equally small (11%) for birch and Norway spruce and greatest (13%) for Scots pine.
133 citations
TL;DR: Evaluation of effects of forwarder tyre inflation pressure on rutting and soil compaction after final felling in Swedish forestry suggests that density increases occur earlier in the 600 kPa treatment than in the other treatments.
Abstract: In Swedish forestry, final felling is usually done by a harvester and a forwarder. These machines are heavy and the risk for rutting and soil compaction can be considerable under unfavourable soil conditions. The aim of this study was to evaluate effects of forwarder tyre inflation pressure on rutting and soil compaction after final felling. Three levels of forwarder tyre pressure were studied, 300, 450 and 600 kPa, after 2 and 5 machine passages. The first passage was driven with a 19.7 Mg harvester, and the second to fifth passages with a fully loaded forwarder totalling 37.8 Mg. Rut depths were not significant affected by tyre pressures but increased significantly with the number of machine passages. Soil density was significantly increased by 0.075 Mg m(-3) by the harvester passage. Soil density increased significantly with increasing number of forwarder passages, and tyre pressure did not significantly influence this increase but the interaction between number of forwarder passages and tyre pressure was almost significant. Data suggest that density increases occur earlier in the 600 kPa treatment than in the other treatments. Only parts of an area harvested are trafficked in a normal harvesting operation. Outside the research area approximately 12.5 per cent of the area harvested was covered with ruts. On primary strip roads, which are heavily trafficked, soil compaction cannot be avoided by reducing the tyre pressure. On secondary strip roads, not passed more than once by the forwarder, a low forwarder tyre pressure may reduce soil compaction. Language: en
119 citations
TL;DR: Both the fixed effects model and the calibrated model mean a substantial improvement when compared with the classical approach, widely used in forest management, of assuming constancy in diameter increment for a short projection period.
Abstract: Diameter increment for stone pine (Pinus pinea L.) is described using a multilevel linear mixed model, where stochastic variability is broken down among period, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, dominant height or site index are included in the model as fixed effects in order to explain residual random variability. The effect of competition on diameter increment is expressed by including distance independent competition indices. The entrance of regional effects within the model is tested to determine whether a single model is sufficient to explain stone pine diameter increment in Spain, or if, on the contrary, regional models are needed. Diameter increment model can be calibrated by predicting random components using data from past growth measurements taken in a complementary sample of trees. Calibration is carried out by using the best linear unbiased predictor (BLUP) theory. Both the fixed effects model and the calibrated model mean a substantial improvement when compared with the classical approach, widely used in forest management, of assuming constancy in diameter increment for a short projection period.
116 citations
TL;DR: The results suggest that, especially in spatial planning problems, it is a benefit if the method performs more complicated moves than selecting one of the neighbouring solutions, and it may also be beneficial to combine two or more heuristic techniques.
Abstract: The existence of multiple decision-makers and goals, spatial and non-linear forest management objectives and the combinatorial nature of forest planning problems are reasons that support the use of heuristic optimisation algorithms in forest planning instead of the more traditional LP methods. A heuristic is a search algorithm that does not necessarily find the global optimum but it can produce relatively good solutions within reasonable time. The performance of different heuristics may vary depending on the complexity of the planning problem. This study tested six heuristic optimisation techniques in five different, increasingly difficult planning problems. The heuristics were evaluated with respect to the objective function value that the techniques were able to find, and the time they consumed in the optimisation process. The tested optimisation techniques were 1) random ascent (RA), 2) Hero sequential ascent technique (Hero), 3) simulated annealing (SA), 4) a hybrid of SA and Hero (SA+Hero), 5) tabu search (TS) and 6) genetic algorithm (GA). The results, calculated as averages of 100 repeated optimisations, were very similar for all heuristics with respect to the objective function value but the time consumption of the heuristics varied considerably. During the time the slowest techniques (SA or GA) required for convergence, the optimisation could have been repeated about 200 times with the fastest technique (Hero). The SA+Hero and SA techniques found the best solutions for non-spatial planning problems, while GA was the best in the most difficult problems. The results suggest that, especially in spatial planning problems, it is a benefit if the method performs more complicated moves than selecting one of the neighbouring solutions. It may also be beneficial to combine two or more heuristic techniques.
98 citations
TL;DR: Geostatistically based methods that utilize textural information are frequently used to analyze remote sensing (RS) images as discussed by the authors, and the role of these methods in analyzing forested areas increased rapidly during the last several years following advancements in high-resolution RS technology.
Abstract: Geostatistically based methods that utilize textural information are frequently used to analyze remote sensing (RS) images. The role of these methods in analyzing forested areas increased rapidly during the last several years following advancements in highresolution RS technology. The results of numerous applications of geostatistical methods for processing RS forest images are encouraging. This paper summarizes such results. Three closely related topics are reviewed: 1) specific properties of geostatistical measures of spatial variability calculated from digital images of forested areas, 2) determination of biophysical forest parameters using semivariograms and characterization of forest ecosystem structure at the stand level, and 3) forest classification methods based on spatial information.
98 citations
TL;DR: In this article, the authors argue that the number of small NIPF owners has increased because a significant amount of forestland is no longer used economically if primarily for timber production, but rather for non-timber forest products and environmental services (particularly where population density is high).
Abstract: The transaction cost approach is used to explain why small non-industrial private forest (NIPF) ownerships are increasing in the U.S. We argue that the number of small NIPF owners have increased because: 1) a significant amount of forestland is no longer used economically if primarily for timber production, but rather for non-timber forest products and environmental services (particularly where population density is high), 2) when a person makes frequent use of non-timber products and services, owning forestland is more efficient for them because it saves the transaction costs involved in getting them from the market, 3) forestland parcelization takes place when non-timber value increases faster than timber value, and 4) marginal value for non-timber product is diminishing much faster than that for timber production. The paper also discusses implications of the parcelization of NIPF ownerships on forest management.
89 citations
TL;DR: In this paper, the authors compare the differences between the definitions used in each study as well as to gain an understanding of the errors and typical differences of the various measuring methods, in order to be able to compare values of canopy cover of forests.
Abstract: Forest canopy cover, frequently defined as the percent area occupied by the vertical projection of tree crowns, is a common concept in forestry and of wide interest in both scientific studies and political decisions. Other, often synonymously used terms include canopy closure, crown closure or crown cover, however, there is no commonly accepted precise definition for the concept. For instance, the United Nations Food and Agricultural Organization has defined forest as land with tree crown cover over 10% and with tree heights over 5 meters covering an area over 0.5 ha (FAO 2000). This definition, which uses the term “tree crown cover”, is used to monitor changes in forest area. The way canopy cover (or any of the similar terms) is defined and measured influences the obtained canopy cover percentage. A central issue in the definitions is whether tree crowns are treated as solids which transmit or which do not transmit radiation, i.e. whether within tree crown gaps are included or excluded. The gaps can sometimes be rather large and thus will affect the canopy cover estimate. In order to be able to compare values of canopy cover of forests, we need to first understand the differences between the definitions used in each study as well as to gain an understanding of the errors and typical differences of the various measuring methods. Estimating Canopy Cover in Scots Pine Stands
78 citations
TL;DR: The moderate and heavy thinnings yielded the highest percentage of heartwood volume and the lowest percentage of stem form factor, while the differences between stem form factors under different treatments were not statistically significant after separating thinning effects from timing effects.
Abstract: The aim of the study was to evaluate the effects of thinning intensity on wood properties, such as heartwood proportion, wood density, and stem form of teak (Tectona grandis L.f.). The thinning trial was established on a teak plantation in a humid tropical site in northern Costa Rica. The moderate and heavy thinnings yielded the highest percentage of heartwood volume (25 to 30% of total stem volume). The differences between stem form factors under different treatments were not statistically significant after separating thinning effects from timing effects. Both the highest (>0.65 g cm-3 (grams per cubic centimeter)) and the lowest (
61 citations
TL;DR: In this article, a multilevel mixed effects model and cross-correlation analysis of prewhitened time series was used to analyse the dependence between height increment and monthly meteorological observations.
Abstract: The effect of temperature and precipitation on the height increment of Pinus sylvestris (L.) was modelled using data gathered from a total of 49 felled sample trees from five stands of Scots pine located along a latitudinal transect from the Arctic Circle up to the northern timberline in Finland. A multilevel mixed effects model and cross-correlation analysis of prewhitened time series was used to analyse the dependence between height increment and monthly meteorological observations. The effect of the mean July temperature of the previous year on height increment proved to be very strong at high latitudes (r > 0.7). The mean November temperature of the year before the previous affected statistically significantly on height increment in the three northernmost stands. There was no correlation between height increment and precipitation in any of the sites. The final height increment model based on all stands included tree age, long-term mean temperature sum of site, and the mean July temperature of the previous year as independent variables. According to the model, one degree’s change in July temperature results on average in 1.8 cm change in the next year’s height increment. There was a modest but significant polynomial age-effect. The proportion of explained variance (at the year level) was 74%. The July temperature dependence on height increment was shown to be very strong, suggesting a high value of height increment in climate modelling at the tree line.
58 citations
TL;DR: Viquez et al. as discussed by the authors reported on the first results of a pruning trial for Tectona grandis L.F. plantations in Costa Rica and found that under an intensive pruning regime, a teak tree at rotation (20 years) may yield over 40% of knot-free volume (over 60% of the merchantable tree volume).
Abstract: Viquez, E. & Perez, D. 2005. Effect of pruning on tree growth, yield, and wood properties of Tectona grandis plantations in Costa Rica. Silva Fennica 39(3): 381–390. Reduced plantation densities have the effect that obtaining natural pruning and stem straightness are less assured. The physiological process of self-pruning is replaced by manual pruning. Generally, plantations are denser and have more uniform spacing than natural forests. In many, if not most species, natural pruning is never a satisfactory option, even after branch senescence, if production of clear wood is a management objective. Natural pruning can only be considered on a species by species basis. This study reports on the first results of a pruning trial for Tectona grandis L.F. plantations in Costa Rica. The treatments consisted of pruning heights of 3.0, 4.0, and 5.0 meters, and the Control without pruning. Differences among treatments in DBH and total height were significant at 3.2, 5.2, and 6.1 years of age, but not at 7.3 years. Under an intensive pruning regime, a teak tree at rotation (20 years) may yield over 40% of knot-free volume (over 60% of the merchantable tree volume). Current findings open a scope for new management options, aiming at improving stem form and wood quality by means of an intensive pruning regime, without having a detrimental effect on tree growth and stand yield.
TL;DR: Stand structural characteristics were examined in old Pinus sylvestris dominated sites in three regions along a broad geographic and human impact gradient in mid-boreal Fennoscandia, demonstrating the higher structural complexity of near-natural stands and stands selectively logged in the past compared to managed stands.
Abstract: Stand structural characteristics were examined in old Pinus sylvestris dominated sites in three regions along a broad geographic and human impact gradient in mid-boreal Fennoscandia. The study regions were: 1) Hame in south-western Finland, with a long history of forest utilization, 2) Kuhmo in north-eastern Finland, with a more recent history of intensive forest utilization, and 3) Vienansalo in Russian Karelia, still characterized by a large near-natural forest landscape. Within each region the sampled sites were divided into three human impact classes: 1) near-natural stands, 2) stands selectively logged in the past, and 3) managed stands treated with thinnings. The near-natural and selectively logged stands in Hame and Kuhmo had a significantly higher Picea proportion compared to stands in Vienansalo. In comparison, the proportions of deciduous tree volumes were higher in near-natural stands in Vienansalo compared to near-natural stands in Hame. The pooled tree diameter distributions, both in near-natural and selectively logged stands, were descending whereas managed stands had a bimodal diameter distribution. Structural diversity characteristics such as broken trunks were most common in near-natural stands and in stands selectively logged in the past. The results demonstrate the higher structural complexity of near-natural stands and stands selectively logged in the past compared to managed stands, and highlight that old near-natural stands and stands selectively logged in the past vary widely in their structures. This obviously reflects both their natural variability but also various combinations of pre-industrial land use and human impact on fire disturbance. These factors need to be acknowledged when using “natural” forest structures as a reference in developing strategies for forest management, restoration and nature conservation.
TL;DR: Repo et al. as mentioned in this paper used electrical impedance spectroscopy (EIS) to measure the root growth of Salix myrsinifolia (Salisb) from cuttings.
Abstract: Repo, T., Laukkanen, J. & Silvennoinen, R. 2005. Measurement of the tree root growth using electrical impedance spectroscopy. Silva Fennica 39(2): 159–166.The non-destructive evaluation of plant root growth is a challenge in root research. In the present study we aimed to develop electrical impedance spectroscopy (EIS) for that purpose. Willows (Salix myrsinifolia Salisb.) were grown from cuttings in a hydroponic culture in a growth chamber. Root growth was monitored at regular intervals by a dis-placement method and compared with the EIS parameters of the plants. To measure its impedance spectrum (IS) (frequency range from 40 Hz to 340 kHz) each plant was set in a measuring cell filled with a solution of the hydroponic culture. The IS was measured using a two-electrode measuring system. A silver needle electrode was connected to the stem immediately above the immersion level and a platinum wire was placed in the solution. The measurements were repeated twice weekly for a root growth period of one month. The IS of the entity consisting of a piece of stem, roots and culture solution were modelled by means of an electric circuit consisting of two ZARC-Cole elements, one constant-phase element, and a resistor. On the plant basis, an increase in root volume by growth correlated with a reduction in the sum of resistances in the ZARC-Cole elements (mean Pearson’s correlation coefficient r = –0.70).Keywords CNLS-curve fitting, displacement method, distributed electric model, hydropon-ics, impedance analysis, willowAuthors’ addresses Repo, The Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FI-80101 Joensuu, Finland; Laukkanen and Silvennoinen, University of Joensuu, Department of Physics, P.O. Box 111, FI-80101 Joensuu, Finland E-mail tapani.repo@metla.fiReceived 28 October 2004 Revised 8 February 2005 Accepted 17 March 2005
TL;DR: In this paper, the authors estimate the height-Diameter models for two shade-intolerant tree species from longitudinal data. But the results show that the parameters of the H-D equation develop over time but the development rate varies between stands.
Abstract: Height-Diameter (H-D) models for two shade-intolerant tree species were estimated from longitudinal data. The longitudinal character of the data was taken into account by estimating the models as random effects models using two nested levels: stand and measurement occasion level. The results show that the parameters of the H-D equation develop over time but the development rate varies between stands. Therefore the development of the parameters is not linked to the stand age but to the median diameter of the basal-area weighted diameter distribution (DGM). Models were estimated with different predictor combinations in order to produce appropriate models for different situations. The estimated models can be localized for a new stand using measured heights and diameters, presumably from different points in time, and the H-D curves can be projected into the future.
TL;DR: Spinelli et al. as mentioned in this paper investigated poplar root recovery operations in plantations with time studies, and determined the productivity and delivery costs of the operations based on general-purpose prime movers.
Abstract: Spinelli, R., Nati, C. & Magagnotti, N. 2005. Harvesting and transport of root biomass from fast-growing poplar plantations. Silva Fennica 39(4): 539–548.Recovery of tree root biomass can be attractive, since the stump-root system represents a substantial portion of the tree mass and its removal may prove instrumental to re-cultiva-tion. Most available studies concern Nordic technologies, particularly suited to mature conifer stands. Unlike spruce, plantation poplar develops a deep taproot, whose extraction requires completely different methods. The aim of the study was to investigate poplar root recovery operations in plantations with time studies, and to determine the productivity and delivery costs of the operations. Seven operation systems developed to work with poplar plantations in Italian condi-tions were studied. Extraction and cleaning units were based on general-purpose prime movers.Under favourable conditions extraction and cleaning units achieved a very high produc-tivity: 150 stumps per hour for the extraction unit and 170 for the cleaning unit. Delivered cost varied widely, ranging from 28 to 66 € Mg
TL;DR: Having a cover crop proved to be an ineffective weed control method both in terms of seedling growth and survival and small seedling size, high shading class, and high vegetation coverage percentage increased the risk of voles damaging the seedlings.
Abstract: Effects of competing vegetation and weed control methods (fibre board mulch, cover crop of clover, various herbicides) on the survival and growth of and vole damage to silver birch (Betula pendula Roth) were analysed based on data from a field experiment established in southern Finland. The cover percentage of competing vegetation and its shading effect were assessed, and seedling size and vitality were recorded several times during the 11-year research period. Mean seedling height and height increment decreased linearly with increasing vegetation cover. Seedling mortality started to significantly increase once the vegetation cover had reached the level of 60–80%. Herbicides significantly retarded increase of weed cover on the initially weedless areas for two to three years, and a cover crop promoted increase in cover percentage. Successful weed control with herbicides significantly increased seedling growth and survival. After 11 years, the average stem volume on the herbicide-treated plots (28.9 m3ha–1) was 2.5-fold as compared to that of the control plots (11.6 m3ha–1). Furthermore, seedling mortality on the control plots (21%) was almost 3.5-fold as compared to the seedling mortality on herbicide-treated plots (6%). Having a cover crop proved to be an ineffective weed control method both in terms of seedling growth and survival. The application of mulch had only a slight effect on height increment (0.6 m in 11 years), but on the other hand, it considerably decreased seedling mortality (control: 21%, mulch treatment: 1.5%). These differences were not, however, statistically significant. Small seedling size, high shading class, and high vegetation coverage percentage increased the risk of voles damaging the seedlings.
TL;DR: The relationships between cut stumps from historical logging activity and forest structural characteristics of today in a total of 385 0.25 ha plots in three boreal coniferous forests which are parts of National Nature Reserves in Norway are studied.
Abstract: Conservation of forest biodiversity has brought about an interest in evaluating the naturalness of forests, and to locate and protect semi-natural and old-growth forests in the Fennoscandian countries. However, it is not always clear how natural these forests really are, and how the past management history has affected their present structural composition. We studied the relationships between cut stumps from historical logging activity (50−100 years ago) and forest structural characteristics of today in a total of 385 0.25 ha plots in three boreal coniferous forests which are parts of National Nature Reserves in Norway. We also studied how forest productivity influenced these relationships. In plots with negligible logging impact we found the amount of living trees, dead wood, and size of the oldest trees mainly to increase with increasing productivity, whereas the age of the oldest trees decreased. The amount of deciduous trees was generally low irrespective of productivity. The intensity of logging did not consistently influence most of these forest structural variables, neither at lownor at high-productive sites. The only consistent relationship in all study areas was a decreasing amount of dead wood with increasing logging intensity at high-productive sites. Also, the decay class distribution of dead wood was more right-skewed (indicating on-going accumulation of dead wood) the more logging had occurred at high-productive sites. Except from the effects on dead wood, previous logging does not show up as a major determinant of other stand structures of today.
TL;DR: In this article, the efficiency of buffer zones to reduce sediment load from peatlands drained for forestry purposes was studied at 7 locations in south-central Finland, and the two largest buffer zones reduced the concentrations of suspended solids by > 70%.
Abstract: In 1995–2001, the efficiency of riparian buffer zone areas to reduce the concentrations of suspended solids in discharge from peatlands drained for forestry purposes was studied at 7 locations in south-central Finland. The two largest buffer zones reduced the concentrations of suspended solids by > 70%. The efficiency of the three medium-sized buffer zones to reduce through-flow sediment concentrations was 50–60%, but no reduction occurred at the smallest two buffer areas. Thus, the capacity of buffer zones to reduce sediment concentrations was strongly related to their size. However, significant correlations were also found between reduction capacity and inflow water sediment concentrations, although the correlations at the two smallest buffer zones were low. The use of buffer zones in reducing sediment load from peatlands drained for forestry purposes is recommended, but relatively large areas for efficient removal capacity are needed.
TL;DR: In this article, the authors developed recruitment models for Norway spruce, Scots pine, birch and other broadleaves in young growth forests in Norway using a two-stage approach that suited the stochastic nature of recruitment in boreal forests.
Abstract: The objective of the present study was to develop recruitment models for Norway spruce, Scots pine, birch and other broadleaves in young growth forests in Norway. The models were developed from permanent sample plots established by the National Forest Inventory, and they will be included in a growth simulator that is part of a large-scale forestry scenario model. The modelling was therefore restricted to independent variables directly or indirectly available from inventories for practical forest management planning. A two-stage modelling approach that suited the stochastic nature of recruitment in boreal forests was used. Models predicting the probability of recruitment were estimated in a first stage, and conditional models for the number of recruits were developed in a second. The probability models as well as the conditional models were biologically realistic and logical. The goodness of fit tests revealed that the probability models fitted the data well, while the coefficients of determination for the conditional models were relatively low. No independent test data were available, but comparisons of predicted and observed number of recruits in different sub-groups of the data revealed few large deviations. The high level of large random errors was probably due to the great variability observed in number of recruits rather than inappropriate specifications of the models. Provided the generally high level of uncertainty connected to analysis performed with large-scale forestry scenario models and the stochastic nature of recruitment, the presented models seem to give satisfactory levels of accuracy.
TL;DR: The modelling approach used proved to be a useful method for examining the sources of variation in development of young plantations and the effects of climatic and site characteristics on height growth.
Abstract: Saksa, T., Heiskanen, J., Miina, J., Tuomola, J. & Kolstrom, T. 2005. Multilevel modelling of height growth in young Norway spruce plantations in southern Finland. Silva Fennica 39(1): 143–153.Height development of Norway spruce (Picea abies (L.) Karst.) transplants was studied on 22 sites prepared by disc trenching or mounding. At the age of 4–9 years the planta-tions were surveyed using a multistage sampling design. For every planted spruce on a plot, the past annual height increments were measured as far into the past as possible. Multilevel mixed linear modelling was used to analyse the variation in growth at different levels (year, stand, cluster, plot, tree) and the effects of climatic and site characteristics on height growth. The within-plantation variation in height growth was higher on mounded sites than on disc-trenched sites. The mean temperature and the precipitation sum of the summer months affected height growth positively. Soil characteristics measured from undisturbed soil did not explain the height growth of seedlings on mounded sites, whereas on disc-trenched sites, the depth of the organic layer and the soil temperature had a positive effect and the depth of the eluvial horizon a negative effect. The modelling approach used proved to be a useful method for examining the sources of variation in development of young plantations.Keywords Picea abies, Norway spruce, container seedlings, mounding, disc trenching, height growth, intra-level correlation, variance-component modelAuthors’ addresses Saksa and Heiskanen, The Finnish Forest Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland; Miina, The Finnish Forest Institute, Joensuu Research Centre, P. O. Box 68, FI-80101 Joensuu, Finland; Tuomola and Kolstrom, The University of Joensuu, Mekrijarvi Research Station, FI-82900 Ilomantsi, FinlandReceived 10 December 2003 Revised 19 November 2004 Accepted 28 December 2004
TL;DR: The results of nearly daily measurements showed that the elongation of Scots pine seedlings was increased by the removal of blue light only at high latitudes.
Abstract: Taulavuori, K., Sarala, M., Karhu, J., Taulavuori, E., Kubin, E., Laine, K., Poikolainen, J. & Pesonen, E. 2005. Elongation of Scots pine seedlings under blue light depletion. Silva Fennica 39(1): 131–136.The effect of blue light (400–500 nm) removal on the elongation of Scots pine (Pinus sylvetris L.) seedlings was investigated in a field experiment in Northern Finland during two growing seasons. The seedlings were grown in plexiglass chambers and ambient control plots. The blue wavelengths were removed from the light spectrum by using chambers made of orange plexiglass. The results of nearly daily measurements showed that the elongation of Scots pine seedlings was increased by the removal of blue light only at high latitudes.Keywords blue light, elongation, high latitude, Scots pineAuthors´ addresses Taulavuori K. & E., Sarala & Laine: Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu, Finland; Karhu, Kubin & Poikolainen: Muhos Research Station, Finnish Forest Research Institute, Kirkkosaarentie 7, FIN-91500 Muhos, Finland; Pesonen: Vantaa Research Centre, Finnish Forest Research Institute, PO Box 18, FIN-01301, Vantaa, FinlandE-mail ktaulavu@cc.oulu.fiReceived 10 June 2004 Revised 15 September 2004 Accepted 24 January 2005
TL;DR: The results indicate that harvester operators’ working technique on the simulator was mainly the same as in the real forest, and indicates that simulators can be used for research purposes.
Abstract: Harvester simulators offer a safe and cost-saving method for studying the basics of harvester controls and working technique. Therefore, harvester simulators are increasingly being used in the education of harvester operators. In this study, the objective was to compare harvester work in real and simulator environments, and to determine how a professional harvester operator’s working technique may have changed in the simulator environment. Specific features of the simulator that encumbered operators’ normal work are also presented; and the correspondence of the simulator to reality is evaluated. The work of six professional harvester operators was studied in thinning and in clear cutting stands in both environments: first in the real forest and thereafter on the simulator. The results indicate that the operators’ working technique on the simulator was mainly the same as in the real forest. This means that the same restrictions are valid on the simulator as in the forest. The basic principles of harvesting must be known so that high productivity and good quality can be obtained. However, certain simulator-specific features encumbered the work of harvester operators. Limited visibility to the side increased the need to reverse and the 3D-visualization caused failed catches. Improvements in software would remove some of the defects, e.g. failed felling and cheating in the felling phase. These results also indicate that simulators can be used for research purposes.
TL;DR: To evaluate the possibilities to extend the planting period, six field experiments were established in four years during which frozen-stored, dormant seedlings and actively growing seedlings targeted for spring planting were planted regularly from mid-May to mid-July or the end of August.
Abstract: Luoranen, J., Rikala, R., Konttinen, K. & Smolander, H. 2005. Extending the planting period of dormant and growing Norway spruce container seedlings to early summer. Silva Fennica 39(4): 481–496. In order to make mechanized planting economically viable, the present spring planting period for Norway spruce (Picea abies (L.) Karst.) seedlings in Scandinavia needs to be extended. To evaluate the possibilities to extend the planting period, six field experiments were established in four years during which frozen-stored, dormant seedlings and actively growing seedlings targeted for spring planting were planted regularly from mid-May to mid-July or the end of August. The survival of actively growing seedlings did not differ between planting dates from mid-May to mid-July. For dormant seedlings, however, the later in summer they were planted the lower was the survival. Oversized seedlings grown in the nursery in containers of too small volume, which were usually planted after mid-June, resulted in reduced growth of seedlings after planting. Root egress (growth of roots from root plugs into the surrounding soil) was most rapid in July and early August and slowest in May and September. Results showed that with dormant seedlings the planting period can be extended from May to mid-June without increasing mortality or reducing growth. The planting period for seedlings stored outdoors and those seedlings that were already growing in June for the purpose of spring plantings can be extended even longer, but it must be kept in mind that the risk of mechanical damage and reduced growth increase due to brittleness of the shoot and increased height. Further research is needed to evaluate the risks in practical scale plantings and with seedlings that are specially targeted for
TL;DR: B fertilization cured the growth disorders and increased height growth within four years, but had no effect on diameter growth, which indicates that B deficiency in fact retards height growth before any disorder symptoms become apparent in individual trees.
Abstract: Growth disturbance symptoms typical of B deficiency have been reported on Norway spruce (Picea abies (L.) Karst.) trees in many parts of eastern Finland. In order to test the B deficiency hypothesis and explore the possibilities of curing the disturbed trees with B fertilization, three experiments were established in October 1999 in young Norway spruce stands growing on fertile sites in eastern Finland. All the stands contained healthy, slightly and severely damaged trees with growth disturbances typical of B deficiency (B < 5 mg kg–1). 40 healthy, 40 slightly damaged, and 40 severely damaged trees were selected as sample trees in each stand. In May 2000, the trees were fertilized with 2.0 kg B ha–1 as borax (B), 2.0 kg B ha–1 and 40 kg P ha–1 as superphosphate (B+P) or 200 kg N ha–1 as urea (N). The control trees were not fertilized (0). The needle response to B fertilization was rapid, relatively high B concentrations being achieved already after one growing season. Boron fertilization cured the growth disorders and increased height growth within four years, but had no effect on diameter growth. The trees also recovered without B fertilization, but to a lesser extent compared to the B fertilized trees. Compared to the control, boron fertilization increased the height growth in all the disorder classes, i.e. 5, 17 and 19 cm yr–1 for healthy, slightly and severely damaged trees, respectively. As the healthy trees also seemed to benefit from B fertilization, this indicates that B deficiency in fact retards height growth before any disorder symptoms become apparent in individual trees. Compared with B alone, the application of P together with B gave no additional benefit. Nitrogen fertilization alone appeared to have a detrimental effect on height growth in the severely disturbed trees.
TL;DR: Results show that Nordic suppliers do not have a strong competitive position in Germany in terms of intangible product quality dimensions, and Nordic suppliers could improve their competitive position by enhancing their service, logistics and other dimensions of the intangible product offering.
Abstract: Toivonen, R., Hansen, E., Jarvinen, E. & Enroth, R.-R. 2005. The competitive position of the Nordic wood industry in Germany – intangible quality dimensions. Silva Fennica 39(2): 277–287 This study examines the importance of various intangible product quality dimensions as perceived by wood-trading retailer and wholesaler companies in Germany. Using perceived importance and perceived performance, the study first examines the dimensionality of intangible product quality and then compares Nordic wood product suppliers with suppliers from other major supply regions. Data was collected from 76 German companies during 2000–2001. Results indicate that intangible product quality can be described in three dimensions, “Behaviour and Image”, “Serviceability and Environment”, and “Reliability”. Results also show that Nordic suppliers do not have a strong competitive position in Germany in terms of intangible product quality dimensions. Thus, Nordic suppliers could improve their competitive position by enhancing their service, logistics and other dimensions of the intangible product offering.
TL;DR: The results suggest that the number of manmade stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.
Abstract: Assessing the human impact on the naturalness and vegetation characteristics of protected areas is one of the key issues when designing forest conservation networks in Fennoscandia. We studied the small-scale, detailed relationship between forest utilization history and the current availability of dead woody material in a protected old-growth forest area in North Karelia, eastern Finland. From the study area of 32.4 ha, all the stumps (diameter ≥ 5 cm and height < 1.3 m, classified as natural, man-made and of undetermined origin) were measured using 25 × 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 × 50 m plots in an area of 7.8 ha. The average number of stumps was 130 per ha, and over half of the stumps were classified as man-made. However, the historical documents since the 1910s showed no logging in the area: some of the largest man-made stumps probably originated from an earlier time, but most of those stumps were made considerably later. The variation in the total number of stumps (per ha) was great (range 0–560/ha, 0–16 m 2 /ha), with no clear clustering in space. However, clustering of man-made stumps was detected. The average volume of pooled standing and fallen trees was 84 m 3 /ha, with a range of 37–146 m 3 /ha. The other noticeable man-made disturbance besides logging was notching of aspens, which has a scatteredly significant influence on the amount of dead trees. In conclusion, the protected old-growth forest was not as a whole in a natural state but showed different degrees of human impact from virtually untouched patches to quite heavily managed patches. The results suggest that the number of manmade stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.
TL;DR: In this study, a voting-theory-based method called multicriteria approval (MA) is introduced to the group decision support of timber-harvesting and is found to be a useful tool for the group decisions of forestry decision-making.
Abstract: The decision support methods most often used in timber-harvesting planning are based on a single criterion. In this study, a voting-theory-based method called multicriteria approval (MA) is introduced to the group decision support of timber-harvesting. The use of voting methods alleviates the problems caused by the multitude of decision objectives involved in forestry decision-making and by the poor quality of information concerning both the preferences of decision-makers and the evaluation of decision alternatives with respect to the objectives often faced in practical timber-harvesting planning. In the case study, the tactical forest management plan of a forest holding jointly owned by three people was specified at the operative timber-harvesting level. The task was to find the best actual operative alternatives for the harvesting that had been proposed in the tactical plan. These timber-harvesting alternatives were combinations of treatment, timber-harvesting system and the timing of logging. Forest owners established multiple criteria under which the alternatives were evaluated. Two versions of MA were tested, one of them based on individual decision analyses and other one based on a composite analysis. The first was markedly modified from the original MA, combining properties of MA and Borda count voting. The other was an original MA with the order of importance for criteria estimated either using Borda count or cumulative voting. The results of the tested MA versions produced were very similar to each other. MA was found to be a useful tool for the group decision support of timber-harvesting.
TL;DR: The hypothesis that the heterogeneity of a stand decreases its optimal prior-thinning density is supported and heterogeneity decreased the soil expectation value, net income and timber harvests.
Abstract: The study presents a method for taking the heterogeneity of the stand into account in the optimisation of stand management. Heterogeneity refers to within-stand variation in stand density and/or other characteristics. A set of plots, corresponding to different sub-areas of the stand, represents the stand in calculations. Cuttings and other treatments of the plots are done simultaneously. The method was used to analyse how the optimal management depends on the heterogeneity of a Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stand. The results supported the hypothesis that the heterogeneity of a stand decreases its optimal prior-thinning density. Also the remaining stand basal areas were lower in heterogeneous stands, especially in spruce. The effect of stand heterogeneity prior to the first commercial thinning still affected the timing of the second thinning, which had to be conducted earlier and at lower prior-thinning basal areas in heterogeneous stands. This happened despite the fact that the first thinning greatly decreased the within-stand variation in stand basal area. In addition, heterogeneity decreased the soil expectation value, net income and timber harvests.
TL;DR: In this paper, the authors compared soil animal communities in planted birch (Betula pendula) stands of different origin with each other and with natural forests, and found that the faunal communities were markedly different in plantations established on spruce forest soil and on arable soil.
Abstract: The aim of this study was to compare soil animal communities in planted birch (Betula pendula) stands of different origin with each other and with natural forests. Six 30-year-old birch stands were investigated, three planted after clear-cutting of spruce stands, and three planted on cultivated soil. The faunal communities were markedly different in plantations established on spruce forest soil and on arable soil. “Birch after Spruce” communities were relatively similar to those of coniferous forests, though the population densities were generally lower. “Birch after Field” communities were sparse and could be characterised as “impoverished forest communities”, except in Lumbricidae and Enchytraeidae that have affinities with deciduous forests and cultural landscapes. Soil conditions are not sufficient to explain the differences between the forests. Colonisation and transport by man may determine the presence of certain species, especially earthworms. These in turn affect soil properties, and compete with or otherwise have negative effects on other soil fauna. Thus the community differences between different forests are an outcome of several factors: soil characteristics, site history, colonisation ability and interspecific interactions.
TL;DR: In this paper, the authors used a Landsat 7 ETM satellite image, a photo mosaic composed of high altitude panchromatic aerial photographs, and a combination of the aforementioned in estimating forest attributes for an area covering approximately 281 000 ha in Forestry Centre Hame-Uusimaa in Southern Finland.
Abstract: Satellite sensor data have traditionally been used in multi-source forest inventory for estimating forest characteristics. Their advantages generally are large geographic coverage and large spectral range. Another remote sensing data source for forest inventories offering a large geographic coverage is high altitude aerial photography. In high altitude aerial photographs the spectral range is very narrow but the spatial resolution is high. This allows the extraction of texture features for forest inventory purposes. In this study we utilized a Landsat 7 ETM satellite image, a photo mosaic composed of high altitude panchromatic aerial photographs, and a combination of the aforementioned in estimating forest attributes for an area covering approximately 281 000 ha in Forestry Centre Hame-Uusimaa in Southern Finland. Sample plots of 9th National Forest Inventory (NFI9) were used as field data. In the estimation, 6 Landsat 7 ETM image channels were used. For aerial photographs, 4 image channels were composed from the spectral averages and texture features. In combining both data sources, 6 Landsat channels and 3 aerial image texture channels were selected for the analysis. The accuracy of forest estimates based on the Landsat image was better than that of estimates based on high altitude aerial photographs. On the other hand, using the combination of Landsat ETM spectral features and textural features on high altitude aerial photographs improved the estimation accuracy of most forest attributes.