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Pontus M.f. Lindgren - One of the best experts on this subject based on the ideXlab platform.
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Influence of variable retention harvests on forest ecosystems: Plant and mammal responses up to 8 years post-harvest
Forest Ecology and Management, 2008Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Abstract Green-Tree retention systems are an important management component of variable retention harvests in temperate zone coniferous forests. Residual live Trees (“legacy Trees”) provide mature forest habitat, increase structural diversity, and provide continuity in the regenerating stand. This study was designed to test the hypotheses that, at up to 8 years after harvest, abundance and species diversity of communities of (i) understory plants and (ii) forest-floor small mammals, and (iii) relative habitat use by mule deer ( Odocoileus hemionus ), will decline with decreasing levels of Tree retention. Communities of plants and forest floor small mammals were sampled in replicated clearcut, single Seed-Tree, group Seed-Tree, patch cut, and uncut forest sites in mixed Douglas-fir ( Pseudotsuga menziesii )—lodgepole pine ( Pinus contorta ) forest in southern British Columbia, Canada from 2000 to 2003 (5–8 years post-harvest). Habitat use by mule deer was measured during summer and winter periods each year from 1999 to 2003 in these same sites. Mean total abundance (crown volume index) of herbs, shrubs, mosses, and lichens was similar among sites. Mean species richness of herbs, shrubs, and total plants was similar among sites, but total species diversity and structural diversity were significantly lower in the patch cut and uncut forest sites than in the other harvesting treatments. Thus, hypothesis (i) was not supported. Mean total abundance, species richness, and species diversity of small mammals were similar among sites, contrary to hypothesis (ii). However, the southern red-backed vole ( Clethrionomys gapperi ) declined in abundance as conditions became intolerable for this microtine to persist at numbers > 1/ha in the clearcut and Seed-Tree sites. The early successional and mycophagist northwestern chipmunk ( Tamias amoenus ) occurred at 2.3–4.4 times higher abundance on the Seed-Tree sites than the other sites. Relative habitat use by mule deer was highest in the Seed-Tree sites during summer periods and highest in the group Seed-Tree, patch cut and uncut sites in winter periods. The responses to our treatments were species specific, and hence a range of different harvesting systems should be used to maintain plant and mammal diversity across forest landscapes.
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Influence of variable retention harvests on forest ecosystems. I. Diversity of stand structure
Journal of Applied Ecology, 2001Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Summary 1 Variable retention harvests or ‘green-Tree retention systems’ are important to the management of coniferous forests in the temperate zone. Green-Tree retention leaves large live Trees after harvest (i.e. residual Trees) to increase structural diversity of the regenerating stand and provide mature forest habitat that develops sooner than in typical even-aged management by clear-cutting. The Seed-Tree system is one method of harvesting that leaves a few wind-firm Seed Trees standing singly, or in groups, to provide Seed to regenerate an area naturally. Green-Tree retention may increase biological diversity and help to enhance functional links among forest structures or ecological processes. 2 This study was designed to test the hypothesis that the abundance (e.g. basal area and density of residual Trees and amount of vegetation) and diversity (e.g. species diversity and structural diversity of the herb, shrub and Tree layers) of various aspects of stand structure will decline with lower levels of Tree retention. In particular, abundance and diversity should be greater in sites with green-Tree retention than in clear-cut sites. 3 Stand structure attributes were measured from 1996 (immediately after harvesting) to 1999 in replicated clear-cut, single Seed-Tree, group Seed-Tree, patch-cut and uncut forest sites in mixed forests of Douglas fir Pseudotsuga menziesii–lodgepole pine Pinus contorta in southern British Columbia, Canada. 4 In terms of abundance, clear-cut, single Seed-Tree and group Seed-Tree sites had similar mean basal areas of residual Trees, ranging from 0·1 to 2·5 m2 ha−1, with significantly higher levels on patch-cut (23·4 m2 ha−1) and uncut forest (39·0 m2 ha−1) sites. Mean densities of residual Trees also followed this pattern, ranging from 0·7 to 16·3 stems ha−1 on the clear-cut to group Seed-Tree sites, to 769·4 and 2050·0 stems ha−1 on the patch-cut and uncut forest sites, respectively. However, mean volume (m3 ha−1) of fallen wood (i.e. dead wood or woody debris) was similar among sites, ranging from 116·7 in the single Seed-Tree to 210·2 in the patch-cut sites. Contrary to our hypothesis, the mean index of total crown volume of herbs, shrubs, mosses and lichens was similar among sites. 5 Mean species richness of herbs, shrubs and total plants was similar among sites. Mean richness of Trees in Seed-Tree sites was similar to that in uncut forest in three of four post-harvest years. The mean species diversity of herbs was similar among sites, but that of shrubs and Trees was generally lowest in the patch-cut sites and similar among the other sites. 6 The mean structural richness and diversity of herbs was lowest in the uncut forest and similar at the other sites 3 and 4 years post-harvest. The mean structural richness of Trees and total plants in the patch-cut and uncut forest sites had more vegetation layers than the other sites. 7 Our hypothesis was partly supported in terms of basal area and density of residual Trees and structural richness of total vegetation layers across a gradient of Tree retention from uncut forest to clear-cut sites. However, this pattern was not supported for abundance or diversity of understorey vegetation. Thus, the structural attributes of residual Trees and layers of vegetation, but not the abundance, species richness or species diversity of understorey vegetation, lend support to the aims of variable retention harvesting, at least up to 4 years post-harvest.
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SMALL MAMMALS AND STAND STRUCTURE IN YOUNG PINE, Seed-Tree, AND OLD-GROWTH FOREST, SOUTHWEST CANADA
Ecological Applications, 2000Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Alternative silvicultural systems to clearcutting are receiving considerable attention in Pacific Northwest forests of North America. Understanding the implications of these harvesting systems on stand structure and biodiversity through time is a fundamental aspect of forest ecosystem management. This study was designed to test the hypothesis that diversity of stand-structure attributes and forest floor small-mammal communities will increase from young pine to Seed Tree to old-growth forest. The study area was within mixed Douglas-fir (Pseudotsuga menziesii)–lodgepole pine (Pinus contorta) forests within the Montane Spruce biogeoclimatic zone near Summerland in south-central British Columbia, Canada. This retrospective study had three replicate stands each of 17-yr-old “young pine” (clear-cut harvested), “Seed Tree” composed of young pine with Douglas-fir Seed Trees, and uncut “old-growth” composed primarily of Douglas-fir and lodgepole pine. Stand-structure attributes (coniferous Tree layers and understo...
Thomas P. Sullivan - One of the best experts on this subject based on the ideXlab platform.
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Influence of variable retention harvests on forest ecosystems: Plant and mammal responses up to 8 years post-harvest
Forest Ecology and Management, 2008Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Abstract Green-Tree retention systems are an important management component of variable retention harvests in temperate zone coniferous forests. Residual live Trees (“legacy Trees”) provide mature forest habitat, increase structural diversity, and provide continuity in the regenerating stand. This study was designed to test the hypotheses that, at up to 8 years after harvest, abundance and species diversity of communities of (i) understory plants and (ii) forest-floor small mammals, and (iii) relative habitat use by mule deer ( Odocoileus hemionus ), will decline with decreasing levels of Tree retention. Communities of plants and forest floor small mammals were sampled in replicated clearcut, single Seed-Tree, group Seed-Tree, patch cut, and uncut forest sites in mixed Douglas-fir ( Pseudotsuga menziesii )—lodgepole pine ( Pinus contorta ) forest in southern British Columbia, Canada from 2000 to 2003 (5–8 years post-harvest). Habitat use by mule deer was measured during summer and winter periods each year from 1999 to 2003 in these same sites. Mean total abundance (crown volume index) of herbs, shrubs, mosses, and lichens was similar among sites. Mean species richness of herbs, shrubs, and total plants was similar among sites, but total species diversity and structural diversity were significantly lower in the patch cut and uncut forest sites than in the other harvesting treatments. Thus, hypothesis (i) was not supported. Mean total abundance, species richness, and species diversity of small mammals were similar among sites, contrary to hypothesis (ii). However, the southern red-backed vole ( Clethrionomys gapperi ) declined in abundance as conditions became intolerable for this microtine to persist at numbers > 1/ha in the clearcut and Seed-Tree sites. The early successional and mycophagist northwestern chipmunk ( Tamias amoenus ) occurred at 2.3–4.4 times higher abundance on the Seed-Tree sites than the other sites. Relative habitat use by mule deer was highest in the Seed-Tree sites during summer periods and highest in the group Seed-Tree, patch cut and uncut sites in winter periods. The responses to our treatments were species specific, and hence a range of different harvesting systems should be used to maintain plant and mammal diversity across forest landscapes.
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Influence of variable retention harvests on forest ecosystems. I. Diversity of stand structure
Journal of Applied Ecology, 2001Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Summary 1 Variable retention harvests or ‘green-Tree retention systems’ are important to the management of coniferous forests in the temperate zone. Green-Tree retention leaves large live Trees after harvest (i.e. residual Trees) to increase structural diversity of the regenerating stand and provide mature forest habitat that develops sooner than in typical even-aged management by clear-cutting. The Seed-Tree system is one method of harvesting that leaves a few wind-firm Seed Trees standing singly, or in groups, to provide Seed to regenerate an area naturally. Green-Tree retention may increase biological diversity and help to enhance functional links among forest structures or ecological processes. 2 This study was designed to test the hypothesis that the abundance (e.g. basal area and density of residual Trees and amount of vegetation) and diversity (e.g. species diversity and structural diversity of the herb, shrub and Tree layers) of various aspects of stand structure will decline with lower levels of Tree retention. In particular, abundance and diversity should be greater in sites with green-Tree retention than in clear-cut sites. 3 Stand structure attributes were measured from 1996 (immediately after harvesting) to 1999 in replicated clear-cut, single Seed-Tree, group Seed-Tree, patch-cut and uncut forest sites in mixed forests of Douglas fir Pseudotsuga menziesii–lodgepole pine Pinus contorta in southern British Columbia, Canada. 4 In terms of abundance, clear-cut, single Seed-Tree and group Seed-Tree sites had similar mean basal areas of residual Trees, ranging from 0·1 to 2·5 m2 ha−1, with significantly higher levels on patch-cut (23·4 m2 ha−1) and uncut forest (39·0 m2 ha−1) sites. Mean densities of residual Trees also followed this pattern, ranging from 0·7 to 16·3 stems ha−1 on the clear-cut to group Seed-Tree sites, to 769·4 and 2050·0 stems ha−1 on the patch-cut and uncut forest sites, respectively. However, mean volume (m3 ha−1) of fallen wood (i.e. dead wood or woody debris) was similar among sites, ranging from 116·7 in the single Seed-Tree to 210·2 in the patch-cut sites. Contrary to our hypothesis, the mean index of total crown volume of herbs, shrubs, mosses and lichens was similar among sites. 5 Mean species richness of herbs, shrubs and total plants was similar among sites. Mean richness of Trees in Seed-Tree sites was similar to that in uncut forest in three of four post-harvest years. The mean species diversity of herbs was similar among sites, but that of shrubs and Trees was generally lowest in the patch-cut sites and similar among the other sites. 6 The mean structural richness and diversity of herbs was lowest in the uncut forest and similar at the other sites 3 and 4 years post-harvest. The mean structural richness of Trees and total plants in the patch-cut and uncut forest sites had more vegetation layers than the other sites. 7 Our hypothesis was partly supported in terms of basal area and density of residual Trees and structural richness of total vegetation layers across a gradient of Tree retention from uncut forest to clear-cut sites. However, this pattern was not supported for abundance or diversity of understorey vegetation. Thus, the structural attributes of residual Trees and layers of vegetation, but not the abundance, species richness or species diversity of understorey vegetation, lend support to the aims of variable retention harvesting, at least up to 4 years post-harvest.
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Influence of variable retention harvests on forest ecosystems. II. Diversity and population dynamics of small mammals
Journal of Applied Ecology, 2001Co-Authors: Thomas P. Sullivan, Druscilla S. SullivanAbstract:Summary 1 Variable retention harvests in temperate coniferous forests provide various intensities and sizes of disturbance across a gradient, from clear-cutting to single-Tree harvesting. These ‘green-Tree retention systems’ leave large live Trees after harvest (i.e. residual Trees) to increase structural diversity of the regenerating stand. It is unclear what effect these harvesting patterns will have on wildlife in general, and small mammals in particular. 2 This study was designed to test the hypotheses that: (i) the abundance and diversity of forest-floor small mammals will decline with lower levels of Tree retention; (ii) the abundance, reproduction and survival of Microtus spp. and southern red-backed vole Clethrionomys gapperi populations will decline and increase, respectively, with the basal area and density of residual Trees after harvest; and (iii) habitat heterogeneity generated by variable retention harvesting will limit population size of Microtus, thereby reducing feeding damage to Tree Seedlings planted on harvested areas. 3 Small mammals were intensively live-trapped from 1996 to 1999 in replicated clear-cut, single Seed-Tree, group Seed-Tree, patch-cut and uncut forest sites in mixed natural forests of Douglas fir Pseudotsuga menziesii–lodgepole pine Pinus contorta in southern British Columbia, Canada. The Seed-Tree harvesting system leaves a few wind-firm Seed Trees standing singly, or in groups, to provide Seed to regenerate an area naturally. The patch-cut system harvests timber from small (
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SMALL MAMMALS AND STAND STRUCTURE IN YOUNG PINE, Seed-Tree, AND OLD-GROWTH FOREST, SOUTHWEST CANADA
Ecological Applications, 2000Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Alternative silvicultural systems to clearcutting are receiving considerable attention in Pacific Northwest forests of North America. Understanding the implications of these harvesting systems on stand structure and biodiversity through time is a fundamental aspect of forest ecosystem management. This study was designed to test the hypothesis that diversity of stand-structure attributes and forest floor small-mammal communities will increase from young pine to Seed Tree to old-growth forest. The study area was within mixed Douglas-fir (Pseudotsuga menziesii)–lodgepole pine (Pinus contorta) forests within the Montane Spruce biogeoclimatic zone near Summerland in south-central British Columbia, Canada. This retrospective study had three replicate stands each of 17-yr-old “young pine” (clear-cut harvested), “Seed Tree” composed of young pine with Douglas-fir Seed Trees, and uncut “old-growth” composed primarily of Douglas-fir and lodgepole pine. Stand-structure attributes (coniferous Tree layers and understo...
Druscilla S. Sullivan - One of the best experts on this subject based on the ideXlab platform.
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Influence of variable retention harvests on forest ecosystems: Plant and mammal responses up to 8 years post-harvest
Forest Ecology and Management, 2008Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Abstract Green-Tree retention systems are an important management component of variable retention harvests in temperate zone coniferous forests. Residual live Trees (“legacy Trees”) provide mature forest habitat, increase structural diversity, and provide continuity in the regenerating stand. This study was designed to test the hypotheses that, at up to 8 years after harvest, abundance and species diversity of communities of (i) understory plants and (ii) forest-floor small mammals, and (iii) relative habitat use by mule deer ( Odocoileus hemionus ), will decline with decreasing levels of Tree retention. Communities of plants and forest floor small mammals were sampled in replicated clearcut, single Seed-Tree, group Seed-Tree, patch cut, and uncut forest sites in mixed Douglas-fir ( Pseudotsuga menziesii )—lodgepole pine ( Pinus contorta ) forest in southern British Columbia, Canada from 2000 to 2003 (5–8 years post-harvest). Habitat use by mule deer was measured during summer and winter periods each year from 1999 to 2003 in these same sites. Mean total abundance (crown volume index) of herbs, shrubs, mosses, and lichens was similar among sites. Mean species richness of herbs, shrubs, and total plants was similar among sites, but total species diversity and structural diversity were significantly lower in the patch cut and uncut forest sites than in the other harvesting treatments. Thus, hypothesis (i) was not supported. Mean total abundance, species richness, and species diversity of small mammals were similar among sites, contrary to hypothesis (ii). However, the southern red-backed vole ( Clethrionomys gapperi ) declined in abundance as conditions became intolerable for this microtine to persist at numbers > 1/ha in the clearcut and Seed-Tree sites. The early successional and mycophagist northwestern chipmunk ( Tamias amoenus ) occurred at 2.3–4.4 times higher abundance on the Seed-Tree sites than the other sites. Relative habitat use by mule deer was highest in the Seed-Tree sites during summer periods and highest in the group Seed-Tree, patch cut and uncut sites in winter periods. The responses to our treatments were species specific, and hence a range of different harvesting systems should be used to maintain plant and mammal diversity across forest landscapes.
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Influence of variable retention harvests on forest ecosystems. I. Diversity of stand structure
Journal of Applied Ecology, 2001Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Summary 1 Variable retention harvests or ‘green-Tree retention systems’ are important to the management of coniferous forests in the temperate zone. Green-Tree retention leaves large live Trees after harvest (i.e. residual Trees) to increase structural diversity of the regenerating stand and provide mature forest habitat that develops sooner than in typical even-aged management by clear-cutting. The Seed-Tree system is one method of harvesting that leaves a few wind-firm Seed Trees standing singly, or in groups, to provide Seed to regenerate an area naturally. Green-Tree retention may increase biological diversity and help to enhance functional links among forest structures or ecological processes. 2 This study was designed to test the hypothesis that the abundance (e.g. basal area and density of residual Trees and amount of vegetation) and diversity (e.g. species diversity and structural diversity of the herb, shrub and Tree layers) of various aspects of stand structure will decline with lower levels of Tree retention. In particular, abundance and diversity should be greater in sites with green-Tree retention than in clear-cut sites. 3 Stand structure attributes were measured from 1996 (immediately after harvesting) to 1999 in replicated clear-cut, single Seed-Tree, group Seed-Tree, patch-cut and uncut forest sites in mixed forests of Douglas fir Pseudotsuga menziesii–lodgepole pine Pinus contorta in southern British Columbia, Canada. 4 In terms of abundance, clear-cut, single Seed-Tree and group Seed-Tree sites had similar mean basal areas of residual Trees, ranging from 0·1 to 2·5 m2 ha−1, with significantly higher levels on patch-cut (23·4 m2 ha−1) and uncut forest (39·0 m2 ha−1) sites. Mean densities of residual Trees also followed this pattern, ranging from 0·7 to 16·3 stems ha−1 on the clear-cut to group Seed-Tree sites, to 769·4 and 2050·0 stems ha−1 on the patch-cut and uncut forest sites, respectively. However, mean volume (m3 ha−1) of fallen wood (i.e. dead wood or woody debris) was similar among sites, ranging from 116·7 in the single Seed-Tree to 210·2 in the patch-cut sites. Contrary to our hypothesis, the mean index of total crown volume of herbs, shrubs, mosses and lichens was similar among sites. 5 Mean species richness of herbs, shrubs and total plants was similar among sites. Mean richness of Trees in Seed-Tree sites was similar to that in uncut forest in three of four post-harvest years. The mean species diversity of herbs was similar among sites, but that of shrubs and Trees was generally lowest in the patch-cut sites and similar among the other sites. 6 The mean structural richness and diversity of herbs was lowest in the uncut forest and similar at the other sites 3 and 4 years post-harvest. The mean structural richness of Trees and total plants in the patch-cut and uncut forest sites had more vegetation layers than the other sites. 7 Our hypothesis was partly supported in terms of basal area and density of residual Trees and structural richness of total vegetation layers across a gradient of Tree retention from uncut forest to clear-cut sites. However, this pattern was not supported for abundance or diversity of understorey vegetation. Thus, the structural attributes of residual Trees and layers of vegetation, but not the abundance, species richness or species diversity of understorey vegetation, lend support to the aims of variable retention harvesting, at least up to 4 years post-harvest.
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Influence of variable retention harvests on forest ecosystems. II. Diversity and population dynamics of small mammals
Journal of Applied Ecology, 2001Co-Authors: Thomas P. Sullivan, Druscilla S. SullivanAbstract:Summary 1 Variable retention harvests in temperate coniferous forests provide various intensities and sizes of disturbance across a gradient, from clear-cutting to single-Tree harvesting. These ‘green-Tree retention systems’ leave large live Trees after harvest (i.e. residual Trees) to increase structural diversity of the regenerating stand. It is unclear what effect these harvesting patterns will have on wildlife in general, and small mammals in particular. 2 This study was designed to test the hypotheses that: (i) the abundance and diversity of forest-floor small mammals will decline with lower levels of Tree retention; (ii) the abundance, reproduction and survival of Microtus spp. and southern red-backed vole Clethrionomys gapperi populations will decline and increase, respectively, with the basal area and density of residual Trees after harvest; and (iii) habitat heterogeneity generated by variable retention harvesting will limit population size of Microtus, thereby reducing feeding damage to Tree Seedlings planted on harvested areas. 3 Small mammals were intensively live-trapped from 1996 to 1999 in replicated clear-cut, single Seed-Tree, group Seed-Tree, patch-cut and uncut forest sites in mixed natural forests of Douglas fir Pseudotsuga menziesii–lodgepole pine Pinus contorta in southern British Columbia, Canada. The Seed-Tree harvesting system leaves a few wind-firm Seed Trees standing singly, or in groups, to provide Seed to regenerate an area naturally. The patch-cut system harvests timber from small (
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SMALL MAMMALS AND STAND STRUCTURE IN YOUNG PINE, Seed-Tree, AND OLD-GROWTH FOREST, SOUTHWEST CANADA
Ecological Applications, 2000Co-Authors: Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M.f. LindgrenAbstract:Alternative silvicultural systems to clearcutting are receiving considerable attention in Pacific Northwest forests of North America. Understanding the implications of these harvesting systems on stand structure and biodiversity through time is a fundamental aspect of forest ecosystem management. This study was designed to test the hypothesis that diversity of stand-structure attributes and forest floor small-mammal communities will increase from young pine to Seed Tree to old-growth forest. The study area was within mixed Douglas-fir (Pseudotsuga menziesii)–lodgepole pine (Pinus contorta) forests within the Montane Spruce biogeoclimatic zone near Summerland in south-central British Columbia, Canada. This retrospective study had three replicate stands each of 17-yr-old “young pine” (clear-cut harvested), “Seed Tree” composed of young pine with Douglas-fir Seed Trees, and uncut “old-growth” composed primarily of Douglas-fir and lodgepole pine. Stand-structure attributes (coniferous Tree layers and understo...
Wenchao Zhou - One of the best experts on this subject based on the ideXlab platform.
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Risk-based selection of forest regeneration methods
Forest Ecology and Management, 1999Co-Authors: Wenchao ZhouAbstract:Abstract A stochastic optimization model is developed to select between planting and Seed-Tree regeneration methods. The model considers the uncertainty of, and the legal requirement on, the stocking level of the established Seedlings in a given year after regeneration. Uncertainty is quantified as a variation of the mortality rate of the planted Seedlings for the planting method and as the prediction error for the Seed-Tree method. The objective of the forest landowner is assumed to maximize the expected net present value (NPV). Numerical simulations show that the landowner should select the Seed-Tree method rather than planting for a sample site with a Scots pine stand. In addition, if a risk-free selection model is used, it over-estimates the financial return by about +1.8%. Sensitivity analysis shows that a less restrictive forest act may improve the expected NPV for both planting and the Seed-Tree method. Sensitivity analysis also shows that a decrease in the variation of the mortality rate (or prediction error) increases the expected NPV. Since these results are obtained only for the sample site, more work is needed to be done until a general conclusion has been drawn.
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Optimal natural regeneration of Scots pine with Seed Trees
Journal of Environmental Management, 1998Co-Authors: Wenchao ZhouAbstract:In this study a model for the economic optimization of natural regeneration with Seed Trees is presented. The objective is maximization of the present value of profits. The model is used, given an initial stand, to determine the optimal harvesting time of the initial stand, the number of Seed Trees, the length of Seed Tree period, the density of the future stand after precommercial thinning, the timing and intensities of thinnings in the future stand and the rotation age of the future stand, simultaneously. The results obtained in the numerical analysis of Scots pine (Pinus silvestris) stands in northern Sweden show that: (1) A combination of a low number of Seed Trees with a long Seed Tree period is better than a combination of a high number of Seed Trees with a short Seed Tree period; (2) The optimal density of the future stand after precommercial thinning depends on the cleaning cost function. A higher average cost of precommercial thinning leads to a denser stand after this treatment; and (3) It is economically optimal not to thin the Scots pine stand established with Seed Trees.1998 Academic Press
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Risk-based Selection of Forest Regeneration Methods
1997Co-Authors: Wenchao ZhouAbstract:A stochastic optimization model is developed to make a selection between the planting method and the Seed-Tree method, taking into account the uncertainty of, and the legal requirement on, the stocking level of the established Seedlings in a given year after regeneration action. Uncertainty is quantified as the variation of the mortality rate of planted Seedlings for the planting method, and as the prediction error for the Seed-Tree method. The objective of the forest landowner is assumed to maximize the expected net present value (NPV). Numerical simulations show that the owner should prefer the Seed-Tree method to the planting method for Scots pine stand. However, if the risk-free selection model is used, it overestimates the expected NPV by about 2\%. Sensitivity analysis shows that a less restrictive forest act could improve the expected net present value both for the planting method and the Seed-Tree method. Sensitivity analysis also shows that decreasing the level of variation of the mortality rate (or prediction error) increases the expected NPV.
Miklós Csűrös - One of the best experts on this subject based on the ideXlab platform.
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CPM - Performing Local Similarity Searches with Variable Length Seeds
Combinatorial Pattern Matching, 2004Co-Authors: Miklós CsűrösAbstract:This paper describes a general method for controlling the running time of similarity search algorithms. Our method can be used in conjunction with the Seed-and-extend paradigm employed by many search algorithms, including BLAST. We introduce the concept of a Seed Tree, and provide a Seed Tree-pruning algorithm that affects the specificity in a predictable manner. The algorithm uses a single parameter to control the speed of the similarity search. The parameter enables us to reach arbitrary levels between the exponential increases in running time that are typical of Seed-and-extend methods.