Modelling stand structure in young Scots pine dominated stands

The purpose of this study was to construct models for predicting the structure of young Scots pine (Pinus sylvestris L.) stands. The two-parameter Weibull function characterized the height distribution of the stands. In young stands height was preferred to dbh as a random variable because of its continuous feature. Tree diameters were predicted using a multiplicative model, fitted as a linearized mixed-effect model. The modelling data consisted of repeatedly measured Scots pine dominated juvenile stands, carried out on a sub-sample of the 7th National Forest Inventory. The data covered a dominant height range from 0.2 up to 17 m. Two independent data sets were used to validate the models. The Weibull function was fitted using the maximum likelihood method. Four methods for predicting the distributions were compared: (1) parameter prediction models (PPM) consisting of seemingly unrelated regression equations, (2) a generalized linear model (GLM) which was a one-stage distribution and model fitting procedure, (3) a hybrid method including PPM for the shape parameter together with moment-based parameter recovery for the scale parameter, and (4) inclusion of moment-based parameter recovery for the scale parameter in the estimated GLM. Goodness-of-fit were tested in terms of Kolmogorov–Smirnov and error index statistics. Parameter recovery showed no improvement when used with PPM, but it improved GLM and gave the overall best performance for this new method. The constructed diameter–height model showed quite flexible and unbiased behaviour. Models are recommended as practical tools for Finnish forest management planning purposes.     

A comparison of carbon assessment methods for optimizing timber production and carbon sequestration in Scots pine stands

Projected changes in forest carbon stocks and carbon balance differ according to the choice of estimation methods and the carbon pools considered. Here, we compared three carbon assessment methods for optimizing timber production and carbon sequestration in six example Scots pine (Pinus sylvestris L.) stands in Finland. The forest carbon stock was assessed, with three methods: stem carbon, biomass expansion factors (BEFs), and a process-based model. Given a carbon price of 40 € t⁻¹ (equivalent to 10.9 € t⁻¹ CO₂) and a 3% discount rate, the highest average carbon stock and mean annual increment (MAI) were obtained with the BEF method. Increasing the carbon price from 0 to 200 € t⁻¹ resulted in longer optimal rotations and higher MAI, and increased the average carbon stock, especially when carbon was assessed by the BEF method. Comparison of these carbon assessment methods, using economic sensitivity analyses, indicated that optimal thinning regimes and average carbon stocks are strongly dependent on the assessment method. The process-based method led to less frequent thinnings and shorter rotations than the BEF method, due to different predictions of biomass production. As a cost-effective option, optimal thinning regimes play a very important role in timber production and carbon sequestration.     

A new multivariate approach to foliar analyses for diagnostic purposes in mature Scots pine stands

The relationship between the needle dry weight and the contents of particular nutrients in pine needles is studied using multiple regression and path coefficient analysis. By joint use of all the information thus obtained it is possible to reach an objective assessment of the nutrient status of mature pine stands and to plan adequate fertilization without recourse to uncertain critical nutrient levels and to the difficult-to-interpret tree growth response. An example is presented of the application of this approach to a 72-year-old Scots pine stand.     

Stability of height positions in young naturally regenerated stands of Scots pine

The stability of height positions of saplings in young stands of Scots pine (Pinus sylvestris L.) was examined by comparing the height order of trees at successive measurements. The data consisted of six naturally regenerated stands and one planted stand for comparison. The length of the examination period was approximately 20 years, covering the mean height development of stands from 0.5 to 5.5 m. For each stand, a structural equation model was fitted by which the covariance structure occurring in the data could be described. In terms of the stability coefficients between the variables produced by the model, the height position of the saplings was very stable. The height positions had mainly been established during the first 5–10 years of age and at a mean height of less than 0.5–1 m. In the naturally regenerated stands, stability was virtually complete from the stage of 15–20 years and 1.5–2 m onwards. In the planted stand, stability became complete slightly later than in the naturally regenerated stands. According to the results, the height of the sapling can be emphasized as a selection criterion in precommercial thinning.     

Fine root biomass and production in Scots pine stands in relation to stand age

We determined fine root biomass and production of 15-, 35- and 100-year-old Scots pine (Pinus sylvestris L.) stands during three growing seasons. Fine roots were sampled by the soil core method. Mean (+/- SE) annual fine root biomass of Scots pine in the 15-, 35- and 100-year-old stands was 220 +/- 25, 357 +/- 21 and 259 +/- 26 g m(-2), respectively. Fine root biomass of the understory vegetation was 159 +/- 54 g m(-2), 244 +/- 30 and 408 +/- 81 g m(-2), and fine root necromass was 500 +/- 112, 1,047 +/- 452 and 1,895 +/- 607 g m(-2) in the sapling, pole stage and mature stands, respectively. Both understory and Scots pine fine root production increased with stand age. Mean annual Scots pine fine root production was 165 +/- 131, 775 +/- 339 and 860 +/- 348 g m(-2) year(-1) in the sapling, pole stage and mature stand, respectively. The respective mean annual production of all fine roots (Scots pine and understory) was 181 +/- 129, 1,039 +/- 497 and 1,360 +/- 869 g m(-2) year(-1). The Scots pine and understory fine root biomass, necromass and production varied in relation to stand age, although the variation was not statistically significant.     

Browsing and damage inflicted by moose in young Scots pine stands subjected to high-stump precommercial thinning

In Fennoscandia, young stands of Scots pine (Pinus sylvestris L.) are intensively used by moose (Alces alces L.) during winter. We studied whether forage amounts on high-cut pines in high-stump commercial thinning influenced browsing intensity and damage incidence on retained (i.e. uncut) pine stems. High-cut pines were browsed, but to a lesser extent than retained pines. At a scale corresponding to individual feeding sites (≈40 m²), browsing intensity on retained pines was not influenced by the amount of forage on high-cut pines but was positively related to moose pellet group counts. The incidence of lower-height damage (stem breakage and bark stripping) was positively related to the amount of forage on high-cut pines, whereas higher damage (leader shoot browsing) was not. Overall browsing damage incidence on retained pines was positively related to the density of deciduous trees and negatively related to the amount of forage on retained pines. Our results suggest that although high-stump thinning supplies additional food resources for moose, larger amounts of forage on high-cut pines may increase the risk for bark stripping and stem breakage on retained trees. Further research is needed at larger spatial scales to assess the feasibility of high-stump thinning as a damage mitigation measure.     

Associations between Pityogenes bidentatus and fungi in young managed Scots pine stands in Poland

The association between Pityogenes bidentatus and fungi was studied in young, managed Pinus sylvestris stands in Poland. Fungi were isolated from emerged adults and their galleries collected from four populations. In total, 2089 fungal isolates including 42 species, were obtained. Penicillium sp. 1 and Geosmithia sp. 1 were the most commonly isolated fungi from beetles (49% and 41% of beetles respectively). Geosmithia sp. 1 species was the dominant species in P. bidentatus galleries with a frequency of occurrence of 57.9%. Hormonema dematioides was the second most abundant fungus in gallery systems (17.1% of wood samples). Two of the isolated Geosmithia species were previously undescribed. Pityogenes bidentatus also vectored three ophiostomatoid species: Ophiostoma minus, O. piceae and Graphium sp. ‘W’. These species were occasionally isolated from beetles and their galleries, suggesting a non-specific relationship.     

Identifying the biological effects of pre-commercial thinning on diameter growth in young Scots pine stands

Data from seven Scots pine (Pinus sylvestris L.) stands in central Sweden that had undergone pre-commercial thinning (PCT) were used to investigate the biological effect of PCT on the diameter at breast height (DBH) growth of the remaining trees. Two treatments were considered: a PCT treatment and a control (C) with no PCT. The DBH of the trees in each stand was measured on up to four occasions over 15 years. We examined mean DBH and DBH growth of the largest 300, 600, 900 and 1200 trees ha^?1. Two methods of selecting the trees used to calculate the mean DBH values for each measurement occasion were considered: the actual mean DBH (Dma), which is based on the DBH distribution of the trees on the measurement occasion in question, and the genuine mean DBH (Dmg), which is based on the DBH distribution of the trees on the final measurement occasion of the study and therefore focuses on the same set of trees for all measurement occasions. There was no clear difference between the Dma- and Dmg-based DBH increments, but the Dmg values tended to be somewhat larger both for the C and PCT treatments. Over a 15-year period, the relative mean yearly increments (Dma/Dmg) for different tree size classes ranged from 0.91 to 0.98, with lower values for the C treatment and larger DBH size classes. We found that PCT promotes DBH growth: over a 15-year period, the increased growth amounted to about 2.0 mm year^?1 compared to the trees in unthinned plots.     

Photosynthetic utilization efficiency of absorbed photosynthetically active radiation by Scots pine and birch forest stands in the southern Taiga

Absorption and utilization of photosynthetically active radiation (PAR) were investigated in Scots pine (Pinus sylvestris L.) and birch (Betula pendula Roth.) stands that were 41 years old at the end of the experimental period. Canopy depth of the Scots pine stand was about half that of the birch stand (6.5 versus 11.0 m), but absorption of PAR was similar in the two stands. The Scots pine forest canopy, with a leaf area index of 8.9, absorbed 90% of the incoming PAR (APAR), whereas the birch forest canopy, with a leaf area index of 5.9, absorbed 92% of APAR. During maximum foliage development, the upper Scots pine canopy absorbed more PAR than the upper birch canopy (75 versus 66%). The upper, middle and lower layers of the Scots pine canopy contained 37, 48 and 15% of the total needle surface area, respectively. The corresponding distribution of foliage surface area in the three layers of the birch canopy was 50, 30 and 20%, respectively. Measurements of photosynthetic rate were combined with estimates of leaf area index and stand phytomass to determine rates of primary production on a sunny day, a cloudy day, and on an annual basis. The energy equivalents of short- and long-term carbon gain were used with determinations of APAR to calculate photosynthetic utilization efficiency. Throughout the growing season, photosynthetic utilization efficiency of APAR in the upper canopy layer of the Scots pine forest was almost twice that in the lower canopy layer. In the birch forest, photosynthetic utilization efficiency was greater in the lower canopy layer than in the upper canopy layer. In all cases, utilization efficiency was higher in the birch stand than in the Scots pine stand (52 versus 29 J kJ(-1)). Taking account of respiration of the non-photosynthetic parts of each stand (night respiration of needles or leaves; respiration of branches, trunk and roots), estimated utilization efficiency of APAR for net primary production was 11 J kJ(-1) for Scots pine and 19 J kJ(-1) for birch. Solar conversion ratios, expressed as whole-plant net primary productivity per unit of APAR for the growing season, were 0.81 g MJ(-1) for Scots pine and 0.93 g MJ(-1) for birch.     

Above- and belowground biomass and net primary production in a 73-year-old Scots pine forest

We estimated above- and belowground biomass and net primary production (NPP) of a 73-year-old Scots pine (Pinus sylvestris L.) forest stand in the Belgian Campine region. Total biomass for the stand was 176 Mg ha(-1), of which 74.4% was found in stems. The root system contained 12.6% of total biomass, most of it in coarse roots (> 5 mm). Fine roots (< 5 mm) comprised only about 1.7% of total biomass, and more than 50% of fine root biomass was retrieved in the litter layer and the upper 15 cm of the mineral soil. The ratio of belowground biomass to aboveground biomass was 0.14, which is lower than that of other Scots pine forests and other coniferous forests. Between 1995 and 2001, mean annual NPP was 11.2 Mg ha(-1) year(-1), of which 68.7% was allocated to aboveground compartments. Stems, needles and cones made relatively high contributions to total NPP compared with branches. However, branch NPP was possibly underestimated because litterfall of big branches was neglected. The proportion of total NPP in belowground components was 31.3%. Coarse root NPP (2% of total) was low compared with its biomass. Fine root NPP was 3.3 Mg ha(-1) year(-1), representing about 29.5% of total NPP; however, the estimate of fine root NPP is much more uncertain than NPP of aboveground compartments. The ratio NPP/GPP (gross primary production) was 0.32, which was low compared with other coniferous forests.     

Simulated effects of browsing on the production and economic values of Scots pine (Pinus sylvestris) stands

Effects of browsing damage on Scots pine (Pinus sylvestris) production and economic value were simulated on sites ranging in fertility from relatively poor to relatively high. Effects of browsing damage on growth and survival after trees had exceeded browsing-height were estimated using data from a browsing study. Stem lists were produced when stems had reached a height of about 4?m. Individual tree data were then imported into the Heureka simulation system to generate predictions about stand production and economic value. Six browsing levels were simulated: 0, 2, 5, 10, 15 and 27% browsing damage annually. The 2% and 5% browsing levels had only minor effects on production, whilst higher browsing levels significantly reduced production. However, the effect on economic value was more pronounced and even the 2% browsing level had significant effects on estimated land expectation values. Results from this simulation may support discussions about acceptable browsing levels in young Scots pine stands.     

Water limitations to carbon exchange in old-growth and young ponderosa pine stands

We investigated the impact of seasonal soil water deficit on the processes driving net ecosystem exchange of carbon (NEE) in old-growth and recently regenerating ponderosa pine (Pinus ponderosa Doug. ex Laws.) stands in Oregon. We measured seasonal patterns of transpiration, canopy conductance and NEE, as well as soil water, soil temperature and soil respiration. The old-growth stand (O) included two primary age classes (50 and 250 years), had a leaf area index (LAI) of 2.1 and had never been logged. The recently regenerating stand (Y) consisted predominantly of 14-year-old ponderosa pine with an LAI of 1.0. Both stands experienced similar meteorological conditions with moderately cold wet winters and hot dry summers. By August, soil volumetric water content within the upper 30 cm had declined to a seasonal minimum of 0.07 at both sites. Between April and June, both stands showed similar rates of transpiration peaking at 0.96 mm day(-1); thereafter, trees at the Y site showed increasing drought stress with canopy stomatal resistance increasing 6-fold by mid-August relative to values for trees at the O site. Over the same period, predawn water potential (psi(pd)) of trees at the Y site declined from -0.54 to -1.24 MPa, whereas psi(pd) of trees at the O site remained greater than -0.8 MPa throughout the season. Soil respiration at the O site showed a strong seasonal correlation with soil temperature with no discernible constraints imposed by declining soil water. In contrast, soil respiration at the Y site peaked before seasonal maximal soil temperatures and declined thereafter with declining soil water. No pronounced seasonal pattern in daytime NEE was observed at either site between April and September. At the Y site this behavior was driven by concurrent soil water limitations on soil respiration and assimilation, whereas there was no evidence of seasonal soil water limitations on either process at the O site.     

An integrated approach to assess carbon credit from improved forest management

Fossil fuel consumption in recent decades has caused the rise of CO₂ concentration in the atmosphere, with negative consequences on the environment and human health. This study develops a methodological framework to quantify carbon credits from carbon-oriented forest management and evaluates the economic sustainability of their sale. Application of the framework to two forest compartments with long-lasting active management in the Western Italian Alps showed the feasibility of the methodology and provided insights on its replication in other contexts. Particularly, the Carbon-oriented scenario led to a reduction of both the extracted wood volume (10% and 6.5% CASE1 and CASE2, respectively) and Net Present Value (32% and 29%), leading to a carbon credit price of 19.6 € MgCO_2eq^?1? and 44.1 € MgCO_2eq^?1 to counteract these losses.

This work allows us to highlight the factors needed to design and evaluate alternative forest management options while considering the consequences of climate change. Moreover, the hypothesized scenarios include an economic remuneration of the positive externalities provided by sustainable forest management.

Finally, the proposed workflow entails undeniable environmental benefits while contrasting climate change but still looks undesirable with respect to the traditional timber-oriented management in compartments where high-quality wood products can be obtained.     

Spatial optimization for dispersion of remnant trees in seed-tree cuttings and retention-tree stands of Scots pine

Abstract

In this study, optimal spatial patterns for seed-tree cuttings and green-tree retention in Scots pine stands were investigated. The optimization approach is based on functions that describe the effects of single, retained trees on Scots pine regeneration. Two spatial optimization techniques were applied to this intrastand-level problem. The model approach assumes smooth, non-convex optimization problems with a convex set of feasible solutions. These problems were solved with a deterministic optimization algorithm with 500 initial tree position sets, also taking into account different forest management objectives such as high, homogeneous seed and seedling density. This required the use of multicriteria optimization procedures. The best spatial patterns identified differed significantly according to the objective functions considered. This was demonstrated by aggregation index values of stem maps and from visualization. Thus, the objective functions must be defined carefully to obtain best solutions for the management aims. A small degree of clumping in seed-tree cuttings did not appear detrimental to seedling density objectives. Therefore, short-term retention trees should be selected primarily by phenotype, not solely by a specific distribution scheme.     

Replacing coniferous monocultures with mixed-species production stands: An assessment of the potential benefits for forest biodiversity in northern Europe

Conifer dominated plantations in central and northern Europe are associated with relatively low ecological values, and in some cases, may be vulnerable to disturbances caused by anthropogenic climate change. This has prompted the consideration of alternative tree species compositions for use in production forestry in this region. Here we evaluate the likely biodiversity costs and benefits of supplanting Norway spruce (Picea abies) monocultures with polycultures of spruce and birch (Betula spp.) in southern Sweden. This polyculture alternative has previously been evaluated in terms of economic, recreational, and silvicultural benefits. By also assessing the ecological implications we fill a gap in our understanding of the range of socio-ecological benefits that can be achieved from a single polyculture alternative. We project likely broad scale changes to species richness and abundance within production stands for five taxonomic groups including ground vegetation, tree-living bryophytes, lichens, saproxylic beetles, and birds. Our research leads us to three key findings. First, the replacement of spruce monocultures with spruce–birch polycultures in the managed forest landscapes of southern Sweden can be expected to result in an increase in biological diversity for most but not all taxa assessed, but it is unlikely to improve conditions for many red-listed forest species. Second, modification of other aspects of forest management (i.e. rotation length, dead wood and green tree retention, thinning regimes) is likely to contribute to further biodiversity gains using spruce–birch polycultures than spruce monocultures. Third, the paucity of empirical research which directly compares the biodiversity of different types of managed production stands, limits the extent to which policy relevant conclusions can be extracted from the scientific literature. We discuss the wider implications of our findings, which indicate that some climate change adaptation strategies, such as risk-spreading, can be readily integrated with the economic, environmental and social goals of multi-use forestry.     

Fine root biomass in relation to site and stand characteristics in Norway spruce and Scots pine stands

Variations in fine root biomass of trees and understory in 16 stands throughout Finland were examined and relationships to site and stand characteristics determined. Norway spruce fine root biomass varied between 184 and 370 g m(-2), and that of Scots pine ranged between 149 and 386 g m(-2). In northern Finland, understory roots and rhizomes (< 2 mm diameter) accounted for up to 50% of the stand total fine root biomass. Therefore, the fine root biomass of trees plus understory was larger in northern Finland in stands of both tree species, resulting in a negative relationship between fine root biomass and the temperature sum and a positive relationship between fine root biomass and the carbon:nitrogen ratio of the soil organic layer. The foliage:fine root ratio varied between 2.1 and 6.4 for Norway spruce and between 0.8 and 2.2 for Scots pine. The ratio decreased for both Norway spruce and Scots pine from south to north, as well as from fertile to more infertile site types. The foliage:fine root ratio of Norway spruce was related to basal area and stem surface area. The strong positive correlations of these three parameters with fine root nitrogen concentration implies that more fine roots are needed to maintain a certain amount of foliage when nutrient availability is low. No significant relationships were found between stand parameters and fine root biomass at the stand level, but the relationships considerably improved when both fine root biomass and stand parameters were calculated for the mean tree in the stand. When the northern and southern sites were analyzed separately, fine root biomass per tree of both species was significantly correlated with basal area and stem surface area per tree. Basal area, stem surface area and stand density can be estimated accurately and easily. Thus, our results may have value in predicting fine root biomass at the tree and stand level in boreal Norway spruce and Scots pine forests.     

Probability models for pine twisting rust (Melampsora pinitorqua) damage in Scots pine (Pinus sylvestris) stands in Finland

Factors affecting the probability that pine twisting rust (Melampsora pinitorqua) damage occur in a Scots pine (Pinus sylvestris) stand were analysed using the 7th Finnish National Forest Inventory data (NFI7) from southern Finland in 1977–1983. The inventory was based on systematic sampling. The NFI7 data was measured in clusters, each of which consisted of 21 sample plots. In addition to the stand and site characteristics measured for forest management planning purposes, the data included records of damage by pine twisting rust and occurrence of aspens (Populus tremula, the other host plant of the pathogen) in the stands. Two multilevel logit models were developed for predicting the overall probability of pine twisting rust damage and the probability of severe pine twisting rust damage. Site and stand characteristics were used as explanatory variables in the models. Residual variance in the models was studied on the inventory crew, cluster and year levels. The occurrence of aspens and site fertility were the most important factors increasing the probability that pine twisting rust damage will occur in a stand. The damage probability also decreased with increasing effective temperature sum calculated for the location. The overall damage probability was equally high on peatlands and on mineral soil if there were aspens in the stand. If, however, there were no aspens in the stand, the probability of damage was higher on mineral soils than on peatlands. In addition, the overall probability was lower in naturally regenerated stands than in planted or sown stands, and it decreased with increasing mean age of pines. In both models, the residual variance was significant on the both the inventory crew and the cluster levels.     

Linear programming approach for optimal forest plantation

The aim of this research was to identify species suitable for plantation. We first identified species for potentially suitable for plantation based on ecological capabilities regarding soil properties. We determined the area of plantation for different species based on ecological capabilities. Then, we collected relevant data such as growth patterns of different species, labor requirements for plantation and plantation cost. A linear programming model and two integer linear programming models were used for optimization. The appropriate species based on ecological capabilities were ash, elm, maple, oak and bald cypress. A linear programming model was used based on ecological capabilities classification to determine the land area of different species for plantation. Then, two integer linear programming models were employed to select the species for plantation. We set ecological properties unequal for all of the species in the first run of the integer programming model. Two groups were classified: group one included maple and ash; group two included bald cypress, oak and elm. The second integer programming model assumed equal ecological properties for all the species. Results of linear programming showed that maple and bald cypress were appropriate for plantation at the site and their plantation areas should be 151.3 and 355.3 ha, respectively. Results of the first integer linear programming model showed that maple and bald cypress would be economically profitable for plantation. The results of the second integer linear programming model showed that only bald cypress would be appropriate for plantation.     

松兰山景区松材线虫病综合治理研究

研究分析了浙江宁波市象山松兰山景区松材线虫病发生规律与防治效果。结果表明：只采取“封锁”措施，会使松材线虫病迅速爆发毁灭全林。从1992年到1998年，松兰山枯死松树从6株增到5893l株，增长了9820．8倍；采用皆伐松林防治松材线虫病并改造成板栗、杨梅的方法，会导致逆向演替，使松林最后成为以疏花野青茅为主的荒山。而采取综合防治措施就可有效地控制松材线虫病的危害。从1998年到2002年，松兰山枯死松树下降到137株，缩小了430倍，使松兰山仍然保持着葱郁的松林群落。     

新造未成林兔害几种防治方法的效果初探

选择兔害危害较重的造林地块,依草兔的生活习性,采取不同的几种环保型防治技术方法,对实施的方法进行效果调查对比和评估,找出操作简便、适用、防治效果好的兔害防治技术方法,以此指导新造未成林兔害防治技术的应用。