Search

Understanding the growth efficiency of individual trees, or growth per unit of resource utilization, can inform silvicultural management strategies to maximize tree and stand growth. Stand structure—the size and spatial distributions of trees within the stand—strongly influences water, light, and nutrient availability, as well as the resource-use efficiency of each tree. Key silvicultural tools for stand management include manipulating tree density, size distribution, and arrangement by controlling natural regeneration, artificial seeding, planting seedlings, and/or subsequent thinning of established trees. We analyzed two sets of plots from even-aged stands of common coniferous species in central Spain, 106 pure Scots pine (Pinus sylvestris) and 92 pure Mediterranean pine (Pinus pinaster), to examine the dynamics of the dominance hypothesis, the relationship between stand structure and growth, and the relationship between structure and growth efficiency. Our main findings revealed a negative impact of size-class uniformity on stand growth in both Scots pine and Mediterranean pine, while the positive effect of tree size on growth efficiency was supported for Mediterranean pine stands but uncertain for Scots pine. At the operational level, our results highlight how thinning intensity is more important than the thinning method in Mediterranean pinewoods and how thinning can benefit the provision of multiple ecosystem services. We also recommend integrating dominance effects on growth into individual tree modelling. [ABSTRACT FROM AUTHOR]

Sapindus mukorossi Gaertn., an important oleaginous woody plant, has garnered increasing research attention owing to its potential as a source of renewable energy (biodiesel). Leaf structural traits are closely related to plant size, and they affect the fruit yield and oil quality. However, plant size factors that predominantly contribute to leaf structural traits remain unknown. Therefore, the purpose of this study was to understand the associations between leaf structural traits and plant size factors in even-aged stands of S. mukorossi. Results showed that leaf length (LL) and leaf area (LA) markedly increased with the increasing diameter at breast height (DBH) and tree height (TH), although other leaf structural traits did not show noticeable changes. Difference in slopes also indicated that the degree of effect of plant size factors on leaf structural traits was in the order of TH > DBH. Leaf structural traits showed no systematic variation with crown width (CW). LA was significantly positively correlated with LL, leaf width (LW), LL/LW, and leaf thickness (LT) and was significantly but negatively correlated with leaf tissue density (LTD) and leaf dry mass content (LDMC). Specific leaf area showed a significantly negative correlation with LT, LDMC, and LTD. LTD showed a significantly positive correlation with LDMC, but a negative correlation with LT. The results were critical to understand the variability of leaf structural traits with plant size, can provide a theoretical foundation for further study in the relationship between leaf structural traits and fruit yield, and regulate leaf traits through artificial management measures to promote plant growth and fruit yield.

Sapindus mukorossi Gaertn., an important oleaginous woody plant, has garnered increasing research attention owing to its potential as a source of renewable energy (biodiesel). Leaf structural traits are closely related to plant size, and they affect the fruit yield and oil quality. However, plant size factors that predominantly contribute to leaf structural traits remain unknown. Therefore, the purpose of this study was to understand the associations between leaf structural traits and plant size factors in even-aged stands of S. mukorossi. Results showed that leaf length (LL) and leaf area (LA) markedly increased with the increasing diameter at breast height (DBH) and tree height (TH), although other leaf structural traits did not show noticeable changes. Difference in slopes also indicated that the degree of effect of plant size factors on leaf structural traits was in the order of TH > DBH. Leaf structural traits showed no systematic variation with crown width (CW). LA was significantly positively correlated with LL, leaf width (LW), LL/LW, and leaf thickness (LT) and was significantly but negatively correlated with leaf tissue density (LTD) and leaf dry mass content (LDMC). Specific leaf area showed a significantly negative correlation with LT, LDMC, and LTD. LTD showed a significantly positive correlation with LDMC, but a negative correlation with LT. The results were critical to understand the variability of leaf structural traits with plant size, can provide a theoretical foundation for further study in the relationship between leaf structural traits and fruit yield, and regulate leaf traits through artificial management measures to promote plant growth and fruit yield. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Faculty of Forestry, University of Banja Luka / Glasnik Šumarskog Fakulteta Univerziteta u Banjoj Luci is the property of University of Banja Luka, Faculty of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Forest regeneration is a key element in achieving sustainable forest management. Partial harvest methods have been used extensively in temperate broadleaf and mixedwood ecosystems to promote regeneration on poorly stocked sites and to maintain forest composition and productivity. However, their effectiveness in promoting conifer establishment has yet to be demonstrated in unmanaged boreal forests, especially those dominated by black spruce (Picea mariana (Mill.) BSP) where constraints for regeneration differ from those found in more meridional regions. We aimed to evaluate conifer seedling density and dimensions, 10 years after the onset of a gradient of silvicultural treatments varying in harvesting intensities, and to identify the critical factors driving the regeneration process. Study blocks of even-aged black spruce stands in the eastern Canadian boreal forest were submitted to three variants of shelterwood harvesting: a seed-tree harvest, a clear-cut and an untreated control. Shelterwood and seed-tree harvesting were combined with spot scarification to promote regeneration. Shelterwood and seed-tree harvesting produced a density of conifer regeneration sufficient to maintain forest productivity, but they did not promote seedling growth. Black spruce was the predominant species in terms of regeneration density, with proportions 3–5× higher than that for balsam fir (Abies balsamea (L.) Mill.). Ten years after treatment, seed-origin black spruce seedlings were abundant in skidding trails, while layers dominated the residual strips. Balsam fir density was not influenced by treatment nor by tree position relative to skidding trails. Balsam fir and black spruce had different responses to treatment in terms of height and diameter, the former exhibiting a better growth performance and larger diameter in the residual strips. Spot scarification created micro-sites that had a significant impact on the regeneration process. Overall, our results support that shelterwood and seed-tree harvesting combined with scarification enable adequate regeneration in black spruce stands, confirming these treatments as viable silvicultural alternatives to clear-cutting when required by sustainable forest management objectives.

Forest regeneration is a key element in achieving sustainable forest management. Partial harvest methods have been used extensively in temperate broadleaf and mixedwood ecosystems to promote regeneration on poorly stocked sites and to maintain forest composition and productivity. However, their effectiveness in promoting conifer establishment has yet to be demonstrated in unmanaged boreal forests, especially those dominated by black spruce (Picea mariana (Mill.) BSP) where constraints for regeneration differ from those found in more meridional regions. We aimed to evaluate conifer seedling density and dimensions, 10 years after the onset of a gradient of silvicultural treatments varying in harvesting intensities, and to identify the critical factors driving the regeneration process. Study blocks of even-aged black spruce stands in the eastern Canadian boreal forest were submitted to three variants of shelterwood harvesting: a seed-tree harvest, a clear-cut and an untreated control. Shelterwood and seed-tree harvesting were combined with spot scarification to promote regeneration. Shelterwood and seed-tree harvesting produced a density of conifer regeneration sufficient to maintain forest productivity, but they did not promote seedling growth. Black spruce was the predominant species in terms of regeneration density, with proportions 3–5× higher than that for balsam fir (Abies balsamea (L.) Mill.). Ten years after treatment, seed-origin black spruce seedlings were abundant in skidding trails, while layers dominated the residual strips. Balsam fir density was not influenced by treatment nor by tree position relative to skidding trails. Balsam fir and black spruce had different responses to treatment in terms of height and diameter, the former exhibiting a better growth performance and larger diameter in the residual strips. Spot scarification created micro-sites that had a significant impact on the regeneration process. Overall, our results support that shelterwood and seed-tree harvesting combined with scarification enable adequate regeneration in black spruce stands, confirming these treatments as viable silvicultural alternatives to clear-cutting when required by sustainable forest management objectives. [ABSTRACT FROM AUTHOR]

O objetivo deste estudo foi avaliar as funções de Weibull e Hiperbólica quanto à capacidade de descrição da estrutura diamétrica de povoamentos de eucalipto submetidos a desbaste. As funções com quatro e três parâmetros foram ajustadas a dados de 48 parcelas permanentes instaladas em um povoamento desbastado de um clone híbrido de eucalipto (Eucalyptus grandis x Eucalyptus urophylla), localizado na região Nordeste do Estado da Bahia. Essas parcelas foram mensuradas em 10 ocasiões, a partir de 27 meses de idade. Foi avaliado, também, o ajuste da função Weibull de dois parâmetros por aproximação linear. A aderência foi avaliada pelo teste de Kolmogorov-Smirnov. Também, foram comparadas as somas de quadrados dos resíduos (SQR), dos diferentes ajustamentos. Todas as funções apresentaram aderência aos dados (P>0,01). A função hiperbólica apresentou menor soma de quadrados de resíduos e menores valores para o teste de aderência. A função Weibull, quando ajustada por aproximação linear, apresentou os maiores valores de soma de quadrado de resíduos e de significância no teste de aderência. Foi comprovada a ineficiência do ajuste da função Weibull por aproximação linear.The objective of this study was to evaluate the Weibull and Hyperbolic fitting functions for describing the diametric structure of eucalyptus stands submitted to thinning. The four- and three-parameter functions were fit to data of 48 permanent plots set up in a thinned eucalyptus hybrid clone (Eucalyptus grandis x Eucalyptus urophylla) stand located in northeastern Bahia. The fitting of the two-parameter Weibull function was also evaluated by linear approximation. Adherence was evaluated by the Kolmogorov-Smirnov test. The sum of squares of the residues (SSR) from the different fittings also was compared. All the functions presented adherence to the data (P>0.01). The hyperbolic function presented the smallest sum of squares of the residues and smallest adherence test values. The Weibull function, when fit by linear approximation, presented the largest sum of squares of the residues and significance values for the adherence test.

Our investigation aims (1) to derive a dynamic model for mean volume and biomass growth projection over time, considering the competition-induced tree mortality (dynamic size-density model), (2) to design a compatible two-component modelling system composed of the dynamic size-density model and an appropriate density decrease function, and (3) to examine the applicability of this composite natural thinning model to describe the growth dynamics of even-aged coniferous and broadleaved stands. The stand growth projection system was formulated to include three dynamic equations: a density decrease model expressing the reduction in tree number with dominant height growth, and two dynamic size-density models, for mean stem volume and tree biomass respectively. Two size-density formulations (M1 and M2) were derived, each including one local (site- or stand-specific) and three global (common to all stands of the species) parameters. Model M1 suggests a polymorphic set of size-density curves, while model M2 describes size-density curves with variable asymptotes. The goodness-of-fit statistics showed that for radiata pine ( Pinus radiata D. Don) and Scots pine ( Pinus sylvestris L.) datasets the three-model-system based on M1 performed better than the one based on M2. The growth trajectories of downy birch ( Betula pubescens Ehrh.) and English oak ( Quercus robur L.) stands were described only by model M2. The systems of projection equations explained more than 95% of the variation in most cases. The two-component modelling system is implicitly defined by the stand density and mean tree size (biomass and/or volume) values for a given dominant stand height and set of global model parameters; it does not require any additional stand variables, constants of contested universality or standard-base variable values. It uses stand dominant height as a proxy for time, and inclusion of this growth stage indicator enables the bidirectional dependence between stand density and tree size to be reflected. The composite natural thinning model estimates sets of polymorphic curves with multiple asymptotes. Together with the stand-specific rate of density decrease, this also yields the stand-specific rate of size increase over time and the reduction in tree number, thus enabling prediction of contrasting individual growth patterns of stands of similar initial densities. It accounts for the isometric relationship between plant volume and biomass and can be considered for incorporation as a principal component of a dynamic Stand Density Management Diagram. [ABSTRACT FROM AUTHOR]

Partial cutting is thought to be an alternative to achieve sustainable management in boreal forests. However, the effects of intermediate harvest intensity (45%-80%) on growth remain unknown in black spruce (Picea mariana (Mill.) B.S.P.) stands, one of the most widely distributed boreal species with great commercial interest. In this study, we analysed the effect of three experimental shelterwood and one seed-tree treatments on tree radial growth in even-aged black spruce stands, 10 years after intervention. Our results show that radial growth response 8-10 years after cutting was 41% to 62% higher than in untreated plots, with stand structure, treatment, tree position relative to skidding trails, growth before cutting and time having significant interactions. The stand structure conditioned tree growth after cutting, being doubled in younger and denser stands. Tree spatial position had a pronounced effect on radial growth; trees at the edge of the skidding trails showed twice the increase in growth compared to interior trees. Dominant trees before cutting located close to the skidding trails manifested the highest growth response after cutting. This research suggests that the studied treatments are effective to enhance radial wood production of black spruce especially in younger stands, and that the edge effect must be considered in silvicultural management planning. [ABSTRACT FROM AUTHOR]

Unlike most plants that increase size with age, species in bamboo subfamily have a unique growth pattern and their vegetative sprouts reach adult size during the first growing season. However, the adult size of bamboo varies greatly among species, and the range of sizes among different bamboo species may be an analog to the range of size of a non-bamboo tree species due to its growth with age. Therefore, we hypothesize that the self-thinning rule developed for individual plant species can be applied to describe the size–density relationship among different bamboo species. To test this hypothesis, we quantified the size–density relationship using data collected from 50 bamboo species in fully stocked stands and compared this relationship with the self-thinning rule. The 50 bamboo species included 10 dwarf bamboo species, 20 shrubby bamboo species, and 20 woody bamboo species, with their size covered almost the entire size range within the bamboo subfamily. In addition to biomass, ground diameter (GD) was also used as a measure of size in our study because of its close relationship with biomass. Our results indicate that the self-thinning rule described the size–density relationship very well, with a slope of −1.184 that is slightly lower than −3/2. We conclude that size differences among bamboo species, instead of the conventional size differences due to growth with age within a single species, can be used to develop the self-thinning rule for bamboo subfamily. Compared to the biomass, the ground diameter resulted in a better fit with density, suggesting that ground diameter should be used as the measure of size when studying size–density relationship for bamboos. [ABSTRACT FROM AUTHOR]

The findings regarding the self-thinning rule in forest stands indicate that the rule may have a sort of 'asymptotic' status. It means the admittance of two theses: (1) the slopes of self-thinning trajectories may deviate from −3/2 value; (2) in the space 'size-density,' a limiting line exists that serves as a 'goal' for population dynamics which this dynamics tends to. An application of the simple geometrical model to the Douglas-fir and Scots pine data suggests that the slope of the self-thinning curve will not remain constant during the course of growth and self-thinning of a single forest stand. Most probably, at the initial stages of stand growth, the slope will be less than −3/2, and at old ages of the stand, the slope will be higher than −3/2. The slope −3/2 is thus an obligatory state in the course of self-thinning of a forest stand. At the very time of −3/2 slope, two particular features fit together. One is that the total bole surface area remains constant. Another feature of the −3/2 slope time is that geometric similarity holds in the growth of the forest stand, which is not in a contradiction with the '−3/2' rule as it had been formulated by its authors. That is, the slope −3/2 (1) is a very specific and obligatory state in the process of forest stand growth and (2) is not an asymptote-like 'goal' but rather a transitional point (or may be a span) in the time of growth. These two assertions may be called a transitional status of the '−3/2' rule. [ABSTRACT FROM AUTHOR]

A geometrical model of a forest stand has been analyzed. A forest stand has been modeled as a population of cones which was described by the change of total bole surface area with density $$\hat{S}(N)$$ , relation between density and a horizontal dimension (radius r) r( N), and the relation between vertical dimension (generatrix l) and radius l( r). It has been shown that there are close relationships between $$\hat{S}(N)$$ , l( r) and r( N). In case of $$\hat{S}(N) = const$$ , power exponent of l( r) can be predicted from the power exponent of r( N) and vice versa. A comparison of the model analysis with the data available on Scots pine ( Pinus sylvestris L.) stands has been performed. In spite of the model simplicity, its inferences proved to be workable in many cases where the data can be interpreted as a dynamics of an even-aged forest stand. In particular, if the estimation of total bole surface area is constant, the power exponent in the relation of diameter and stand density DBH(SD) can be calculated on the basis of the power exponent in the relation of height and diameter H(DBH) and vice versa. Possible limitations and the meaning of the analysis are discussed. [ABSTRACT FROM AUTHOR]

Because Sharp-shinned Hawks (Accipiter striatus) are among the most secretive of North America's forest-breeding raptors, little is known about their breeding biology, including the characteristics of their nesting habitat. In 2009 and 2010, we searched forest stands in Kentucky and located 11 nests, all in pines (Pinus spp.). Nests were at a mean height of 18.6 ± 1.4 m in trees with a mean height of 23.7 m. Comparison of the characteristics of nest sites and randomly selected unused sites revealed significant differences (P = 0.021). Discriminant analysis revealed that six variables (foliage cover, mean tree height, basal area, percent deciduous canopy cover, distance from edge, and distance from road) permitted the best discrimination between used and random sites. Sharp-shinned Hawks nested in areas closer to edges and in areas with denser stands of taller conifers and denser understory. All nests were in stands of young (~25-50 years), even-aged conifers about 18-25 m in height. Nest sites were also closer to edges where stands of dense pines transitioned into areas with more, shorter deciduous trees and less foliage cover than nest sites. These adjacent areas may provide better foraging habitat for nesting Sharp-shinned Hawks because small birds, their primary prey, are more abundant in mixed stands than in dense stands of conifers where they nested [ABSTRACT FROM AUTHOR]

Context: Regular mortality (or self-thinning) is an integral part of woody plant dynamics, and the mortality model is one of the most important transition functions within dynamic growth models. Aims: The main objectives of the present study were to derive one-step stand-level mortality models for estimating the reduction in stand density with stand dominant height growth and to examine the applicability of the models in predicting regular mortality trends in even-aged natural stands and plantations. Methods: Four model formulations based on graphical examination of the main trends in the data and on defined desired properties of the selected mathematical functions were proposed and tested in algebraic difference equation form with two datasets from pine plantations and two datasets from natural broadleaved even-aged stands. Results: The mortality patterns of three of the datasets were characterized by reverse sigmoid curves, while the forth dataset exhibited a reverse J-shaped trajectory. The models analyzed adequately represented the density decrease trends of the data through sets of polymorphic curves with multiple asymptotes. Conclusion: The dominant height-dependent mortality equations provide a simple and reliable approach to modeling the regular density decrease trends and can be considered for incorporation as a submodel within the framework of a dynamic Stand Density Management Diagram. [ABSTRACT FROM AUTHOR]

Aboveground biomass predictive equations were developed for a highly productive 47-year-old mixed Douglas-fir and western hemlock stand in southwest Washington State to characterize the preharvest stand attributes for the Fall River Long-Term Site Productivity Study. The equations were developed using detailed biomass data taken from 31 Douglas-fir and 11 western hemlock trees within the original stand. The stand had an average of 615 live trees per hectare, with an average dbh of 35.6 cm (39.1 cm for Douglas-fir and 33.3 cm for western hemlock) and an average total tree height of 31.6 m (32.8 m for Douglas-fir and 30.2 m for western hemlock). Equations developed were of the form ln Y = b1 + b2 ln dbh, where Y = biomass in kg, dbh = diameter in cm at 1.3 m height, b1 = intercept, and b2 = slope of equation. Each tree part was estimated separately and also combined into total aboveground biomass. The total aboveground biomass estimation equations were ln Y=-0.9950 + 2.0765 ln dbh for Douglas-fir, and ln Y= -1.6612 = 2.2321 ln dbh for western hemlock. The estimate of the aboveground live-tree biomass was of 395 Mg ha-1 (235 Mg ha-1 for Douglas-fir and 160 Mg ha-1 for western hemlock), with 9.5, 29.3, 12.9, 308, and 32.7 Mg ha-1 in the foliage, live branches, dead branches, stem wood, and stem bark, respectively. When compared with biomass estimates from six other studies, ranging in age from 22 to 110 years and from 96.3 to 636 Mg ha-1, the biomass of the Fall River site was relatively high for its age, indicating very high productivity. [ABSTRACT FROM AUTHOR]

Abstract: The ability of cyanolichens to sustain growth in even-aged forests that develop after clear-cut harvesting is a major conservation biology concern in British Columbia''s inland rainforest. This and other conservation issues have led to proposals advocating partial-cut rather than clear-cut harvesting to better maintain the structures that support biodiversity in old-growth forest stands. However, evaluating the potential impacts of alternative harvesting practices cannot occur without first understanding lichen growth responses to the existing range of natural variability in canopy structure. Using transplant experiments with thalli of Lobaria pulmonaria (a tripartite foliose cyanolichen), we evaluate growth responses to canopy structure in both naturally occurring 120 year old small-patch even-aged stands and in adjacent old-growth uneven-aged forest stands. Canopy microclimate was also measured in old-growth reference trees, allowing calculation of energy conversion efficiency for old-growth L. pulmonaria thalli. Growth rates of L. pulmonaria transplants showed a strong correlation with canopy light transmission (CLT). Mean annual lichen dry matter gain over the 2-year measurement period ranged from less than 5% on branches in closed canopy even-aged stands (<1molm−2 day−1 CLT) to near 20% on branches under canopy gaps in old-growth stands (>18molm−2 day−1 CLT). Intercepted irradiance of hydrated L. pulmonaria thalli (I wet) under old-growth stand conditions was 24.7 and 45.5MJm−2 annually in years 2 and 3 of the study, resulting in an energy conversion efficiency of 1.33 and 0.61%, respectively. Open sky (gap fraction) above lichen transplants in old-growth stands was much greater than that found in even-aged stands, allowing for longer duration sunfleck events in the lower canopy of the old-growth forest stands. These findings suggest that the creation of small openings by partial-cut harvesting in the inland rainforest may result in conditions favourable to continued growth of the dominant canopy cyanolichen, L. pulmonaria. They also support existing concerns about future cyanolichen growth in even-aged forests regenerating after clear-cut harvesting. [Copyright &y& Elsevier]

The objectives of this study were to examine the effects of stand development and soil nutrient supply on processes affecting the productivity of loblolly pine (Pinus taeda L.) over a period approximately equal to a pulpwood rotation (18 years). The experiment consisted of a 2×2 factorial combination of complete and sustained weed control and annual fertilization treatments (C: control treatment, F: fertilization, W: weed control, FW: combined fertilization and weed control), located on a Spodosol in north-central Florida, USA. The reduction of soil nutrient limitations through fertilization or control of competing vegetation resulted in dramatic increases in almost every measure of productivity investigated, including height (19.7 m in the FW treatment versus 12.5 m in the C treatment at age 18 years), basal area (FW=44.2 m2 ha−1, F=39.6 m2 ha−1, W=36.6 m2 ha−1, C=19.9 m2 ha−1 at age 16 years), stemwood biomass accumulation (114 Mg ha−1 in FW versus 42.8 Mg ha−1 in C at age 18 years), foliar nitrogen concentration (1.53% in plots receiving fertilization versus 1.06% in unfertilized plots at age 17 years) and leaf area index (age 16-year peak projected of approximately 3.3 at age 9–10 years in F and FW plots, 2.5 in the W treatment and 1.5 in the C plots). Cultural treatments also decreased the growth ring earlywood/latewood ratio, and accelerated the juvenile wood to mature wood transition. While soil nutrient supply was a major determinant of productivity, production changes that occurred within treatments over the course of stand development were equally dramatic. For example, between age 8 and 15 years, stemwood PAI in the FW treatment declined by 275%; similarly large reductions occurred in the F and W treatments over the same time period. The reductions in PAI in the treated plots were linearly related to stand BA, suggesting the decline in productivity was associated with the onset of inter-tree competition. Responses of stemwood PAI to re-fertilization treatments at age 15 years suggests that the declines in growth and growth efficiency with time were partially attributable to nutrient limitations. [Copyright &y& Elsevier]

This mini-review is concerned with one of the facets of the sensory physiology of plants that, in the last decade, has been intensively studied using genetically altered plants and eco-physiological techniques -- the perception of the proximity of neighbouring plants through specific informational photoreceptors. We focus on the signalling mechanisms that allow individual shoots to 'forage' for light in patchy and highly dynamic canopy environments. We present evidence from recent experiments suggesting that the fitness of each individual plant in the population, the growth of the population as a whole, and the degree of growth inequality among neighbours are all strongly dependent on the timing and precision of foraging mechanisms controlled, at least partially, by phytochrome-B-like phytochromes. This evidence is discussed in the context of potential impacts on yield of agricultural crops resulting from the artificial alteration of plant sensitivity to proximity photo-signals. Directed overexpression of phytochrome genes appears to be an interesting avenue to explore in order to alter the photomorphogenesis of specific organs (or developmental stages) without affecting the overall ability of the plants to forage for light. [ABSTRACT FROM AUTHOR]

Boreal forests, which are often undeveloped, are a major source of raw materials for many countries. They are circumpolar in extent and occupy a belt to a width of 1000 km in certain regions. Various conifer and hardwood species ranging from true firs to poplars grow in boreal forests. These species exhibit a wide range of shade tolerance and growth characteristics, and occupy different successional positions. The climate is subarctic, with short growing seasons, and the soils are shallow. Both wildfires and timber harvesting play an important role in shaping the structure and composition of boreal forests. Both uneven-aged and even-aged silvicultural systems can be used to produce commercial harvests, but systems can also be designed to meet a variety of other forest management objectives. Wildlife habitat maintenance, water production or conservation, and fire hazard reduction are only some of the objectives for which silvicultural systems can be designed. Coarse wood debris, snags, shrubs, canopy layers, and species composition are examples of forest attributes that can be managed using silvicultural systems. Systems can be designed to sustain predator habitat, yet provide a continual production of wood products. Uneven-aged systems tend to favor the regeneration and development of shade-tolerant species, whereas even-aged systems tend to favor shade-intolerant species. These systems and all of their permutations can create and maintain a suite of different stand compositions and structures that can be used to meet a wide variety of management objectives.

The article presents research which assessed the role of silviculture in the efficient management of boreal forests. The researchers examined the effects of timber harvesting and wildfires on the composition of the forests. They also analyzed the importance of silvicultural systems to wildlife habitat maintenance, fire hazard reduction as well as water conservation.