Category: Research article
article id 400, category Research article
Finnish sawlog market under forest taxation reform. Silva Fennica vol. 39 no. 1 article id 400. https://doi.org/10.14214/sf.400
The stepwise transition in forest taxation from site productivity tax to taxation of profits from timber sales was one of the major institutional changes to impact Finnish non-industrial private forest owners in the 1990s. In this study the effect of the forest taxation reform on the aggregate supply of sawlogs was investigated using time series analysis and quarterly data. In particular, we estimated two simultaneous equations systems for the pine and the spruce sawlog markets. According to the results, the forest taxation reform strengthened the supply of spruce and pine sawlogs in the anticipatory stage of the taxation reform in 1992. Also during the fiscal transition period, which started in 1993, the supply effect of the taxation reform has clearly been positive. The strong own-price elasticity of sawlog supply found in this study indicates high sensitivity to actual and expected wood price changes in the determination of sawlog supply in Finland. Furthermore, the results indicate that the theoretical assumption of a competitive market is suitable for the Finnish sawlog market, but that separate analysis of pine and spruce sawlogs provides additional insights into market behaviour.
article id 399, category Research article
Projecting pulpwood prices under different assumptions on future capacities in the pulp and paper industry. Silva Fennica vol. 39 no. 1 article id 399. https://doi.org/10.14214/sf.399
Capacity changes in the pulp and paper industry affect demand for pulpwood and thus pulpwood prices. This paper analyzes the impacts on roundwood prices in Norway of two possible capacity changes (one new machine and one close-down) that currently are high on the agenda in the Norwegian paper industry, and assesses the generality of the results obtained from these case studies. The two cases are implemented exogenously into a regionalized partial equilibrium forest sector model, and the capacity change scenarios are compared with a business as usual scenario assuming no demand shocks. The projected pulpwood prices change significantly in regions near mills where capacity shifts, at least for the close-down case, but only moderately at an aggregated national level. The reduction in prices under the close-down studied is higher than the price increase from the possible capacity increase case. The asymmetric price responses projected for the two case studies are supported by sensitivity analyses on other regions and cases (technologies). For the capacity increase case it is shown that the level of the projected pulpwood price is sensitive to assumptions on base-year prices and transport costs of imported roundwood, but the magnitudes of the price increases projected as a result of increased demand are less affected by these assumptions.
article id 398, category Research article
Comparison of harvester work in forest and simulator environments. Silva Fennica vol. 39 no. 1 article id 398. https://doi.org/10.14214/sf.398
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.
article id 397, category Research article
Pricing the risk of the quality-guarantee in a stand establishment service. Silva Fennica vol. 39 no. 1 article id 397. https://doi.org/10.14214/sf.397
A stand-establishment service concept with quality guarantee was analysed. Here, the quality of stand establishment was assessed as the density of good quality seedlings evenly distributed on the plantation three years after planting. The amount of adequate premiums for the guarantee service and the risks accumulating to the service provider were studied. Monte Carlo simulation was used as a tool for analyzing the risks accumulating to the service provider of the stand-establishment in operational environments of different sizes. The premiums calculated to cover the expected amount of claims caused by the plantations not meeting the pre-set criteria were about 4–8% in addition to the approximated costs of stand establishment. The criteria used for determining the success or failure in a stand have a marked effect on the amount of premiums with a reasonable risk of ruin.
article id 396, category Research article
Examining the performance of six heuristic optimisation techniques in different forest planning problems. Silva Fennica vol. 39 no. 1 article id 396. https://doi.org/10.14214/sf.396
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.
article id 395, category Research article
Height-diameter models for Scots pine and birch in Finland. Silva Fennica vol. 39 no. 1 article id 395. https://doi.org/10.14214/sf.395
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.
article id 394, category Research article
Multilevel linear mixed model for tree diameter increment in stone pine (Pinus pinea): a calibrating approach. Silva Fennica vol. 39 no. 1 article id 394. https://doi.org/10.14214/sf.394
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.
article id 393, category Research article
A relation between historical forest use and current dead woody material in a boreal protected old-growth forest in Finland. Silva Fennica vol. 39 no. 1 article id 393. https://doi.org/10.14214/sf.393
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 x 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 x 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 m2/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 m3/ha, with a range of 37–146 m3/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 man-made stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.
article id 392, category Research article
Soil animal communities of planted birch stands in central Finland. Silva Fennica vol. 39 no. 1 article id 392. https://doi.org/10.14214/sf.392
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.
Category: Research note
article id 403, category Research note
Multilevel modelling of height growth in young Norway spruce plantations in southern Finland. Silva Fennica vol. 39 no. 1 article id 403. https://doi.org/10.14214/sf.403
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 plantations 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.
article id 402, category Research note
Estimating canopy cover in Scots pine stands. Silva Fennica vol. 39 no. 1 article id 402. https://doi.org/10.14214/sf.402
The way canopy cover is defined and measured influences the obtained canopy cover percentage. Estimates of canopy cover are needed, for example, in canopy radiation modelling and remote sensing applications and as a tool for political decision-making. In this paper, we demonstrated the use of two methods, the LAI-2000 Plant Canopy Analyzer instrument and the Cajanus tube, in Scots pine stands for canopy cover estimation, and also assessed the number of measurement points required for reliable estimates. The Cajanus tube yielded slightly larger canopy closure values than the LAI-2000 instrument, but the values were nevertheless in good agreement. Both of the methods required approximately 250 measurement points for canopy closure estimates of a stand to become relatively stable. We also present the first measured effective canopy transmittance values for Scots pine stands in Finland and an example of tree pattern mapping with the Cajanus tube.
article id 401, category Research note
Elongation of Scots pine seedlings under blue light depletion. Silva Fennica vol. 39 no. 1 article id 401. https://doi.org/10.14214/sf.401
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.