A case study was conducted in beech forests of northern Iran to determine the effect of the created gaps on some soil properties in beech stand. Changes of soil properties in small (60-150 mE), medium (151-241 mE)...A case study was conducted in beech forests of northern Iran to determine the effect of the created gaps on some soil properties in beech stand. Changes of soil properties in small (60-150 mE), medium (151-241 mE), large (242-332 m^2) and very large (333-550 m^2) gaps, as well as under closed stands were studied eight years after-the gap creation. Soil samples were taken from three depths, 0-10, 10-20 and 20-30 cm. The gaps were different from their around undisturbed stands in terms of the following soil parameters: Mg^+2 concentration of 0-10 cm at medium gap size, bulk density of 10-20 cm at very large gap size as well as K^+ and Ca^+2 concentrations at 20-30 cm at small and large gap sizes, respectively. Furthermore, the size of the gaps had no effect on soil characteristics through the whole profile. Water saturation percent (Sp %) at 0-10cm as well as P and Mg^+2 at 20--30 cm was different amongst undisturbed stands around different gap sizes. The center and the edges of the gap were different only in terms of organic carbon at the depth of 10-20 cm. Significant differences were observed between gaps and closed canopy regarding P and Ca^+2 at depth 0--10 cm and 10-20 cm, respectively. It can be concluded that applied silvicultural system for harvesting trees which created these gaps might be suitable for conservation and forest management in the region.展开更多
To verify if the response by Eucalyptus clones in a single-tree plot is influenced by neighboring plants and to determine the effect of missing and/or dominated plants,seven eucalyptus trials in four Brazilian states ...To verify if the response by Eucalyptus clones in a single-tree plot is influenced by neighboring plants and to determine the effect of missing and/or dominated plants,seven eucalyptus trials in four Brazilian states were analyzed in a randomized complete block design with one plant/plot and 30 replications.Mean annual increment(MAI,m^(3)ha^(-1)per year)was determined for three-year-old clones.The influence of neighboring clones was estimated by a linear regression coefficient between the MAI of each clone/plot and the average of a clonal MAI and its eight neighbors.To determine the effect of missing and/or dominated trees,a correction between the MAI and the area available/plant was applied.Subsequent analysis considered unadjusted and adjusted data for missing and dominated trees.Estimate of accuracy and index of coincidence were used to compare the adjustments.In single-tree plots,clone performances were not influenced by neighboring plants.Experimental accuracy was not increased by any of the adjustments employed and the clone ranking was not altered,and therefore did not justify their use.展开更多
Forest resource management and ecological assessment have been recently supported by emerging technologies.Terrestrial laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional fore...Forest resource management and ecological assessment have been recently supported by emerging technologies.Terrestrial laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional forest information,and create good representations of forest vertical structure.TLS data can be exploited for highly significant tasks,particularly the segmentation and information extraction for individual trees.However,the existing single-tree segmentation methods suffer from low segmentation accuracy and poor robustness,and hence do not lead to satisfactory results for natural forests in complex environments.In this paper,we propose a trunk-growth(TG)method for single-tree point-cloud segmentation,and apply this method to the natural forest scenes of Shangri-La City in Northwest Yunnan,China.First,the point normal vector and its Z-axis component are used as trunk-growth constraints.Then,the points surrounding the trunk are searched to account for regrowth.Finally,the nearest distributed branch and leaf points are used to complete the individual tree segmentation.The results show that the TG method can effectively segment individual trees with an average F-score of 0.96.The proposed method applies to many types of trees with various growth shapes,and can effectively identify shrubs and herbs in complex scenes of natural forests.The promising outcomes of the TG method demonstrate the key advantages of combining plant morphology theory and LiDAR technology for advancing and optimizing forestry systems.展开更多
Time and motion studies were conducted to evaluate the impact of selective cutting type on Chainsaw productivity in Caspian forests, the selective cutting performed as single and group selection cutting in the region....Time and motion studies were conducted to evaluate the impact of selective cutting type on Chainsaw productivity in Caspian forests, the selective cutting performed as single and group selection cutting in the region. The selective cutting was performed on a 42-ha tract with an average slope of 30%. The results indicate that felling time for per tree is most affected by diameter at breast height, the distance among harvested trees in single-tree selection method and diameter at breast height in group selection method. The production rate in single and group selection cutting were 21.2 m^3·h^-1 and 28.4 m^3·h^-1 for one person, respectively. Considering the gross and net production rate in single and group selection cutting, the unit cost was 1.11 USD.m^-3 and 0.88 USD.m^-3, respectively. The results indicate that group selection cutting can be more profitable than single-tree selection method.展开更多
In 1958, a demonstrational cutting trial totaling 22.2 ha was established in a northern hardwood forest in Alberta, MI. Eight different treatments were installed, including four diameter-limit treatments (56 cm, 41 cm...In 1958, a demonstrational cutting trial totaling 22.2 ha was established in a northern hardwood forest in Alberta, MI. Eight different treatments were installed, including four diameter-limit treatments (56 cm, 41 cm, 30 cm, and 13 cm), three single-tree selection treatments with residual basal areas of 21 m2·ha–1, 16 m2·ha–1, and 11 m2·ha–1, and an uncut control. Within each treatment, a 0.4-ha permanent plot was established and subdivided into 0.04-ha square subplots. Harvests have been implemented every ten years with the most recent harvest occurring during the winter of 2008 - 2009. We quantified ground layer vegetation response before and after the most recent harvest. Nonmetric multidimensional scaling (NMS) ordination showed a very distinct separation between the most intensive management treatment (13-cm diameter-limit treatment) and the uncut control. Compositionally, the diameter-limit treatments moved with greater directionality and magnitude towards the 13-cm diameter-limit treatment following harvest, while compositional change in the residual basal area treatments was less pronounced and lacked strong directionality. Herbaceous species percent cover generally decreased with increasing residual overstory basal area across treatments. Weedy and early successional species were most abundant under lower residual basal area and diameter-limit treatments. Results based on 50 years of continuous management suggest that diameter-limit harvests likely have a greater impact on the herbaceous community than single-tree selection or no management.展开更多
文摘A case study was conducted in beech forests of northern Iran to determine the effect of the created gaps on some soil properties in beech stand. Changes of soil properties in small (60-150 mE), medium (151-241 mE), large (242-332 m^2) and very large (333-550 m^2) gaps, as well as under closed stands were studied eight years after-the gap creation. Soil samples were taken from three depths, 0-10, 10-20 and 20-30 cm. The gaps were different from their around undisturbed stands in terms of the following soil parameters: Mg^+2 concentration of 0-10 cm at medium gap size, bulk density of 10-20 cm at very large gap size as well as K^+ and Ca^+2 concentrations at 20-30 cm at small and large gap sizes, respectively. Furthermore, the size of the gaps had no effect on soil characteristics through the whole profile. Water saturation percent (Sp %) at 0-10cm as well as P and Mg^+2 at 20--30 cm was different amongst undisturbed stands around different gap sizes. The center and the edges of the gap were different only in terms of organic carbon at the depth of 10-20 cm. Significant differences were observed between gaps and closed canopy regarding P and Ca^+2 at depth 0--10 cm and 10-20 cm, respectively. It can be concluded that applied silvicultural system for harvesting trees which created these gaps might be suitable for conservation and forest management in the region.
基金This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior-Brasil(CAPES)-Finance Code 001,and by the National Council for Scientific and Technological Development(CNPq).
文摘To verify if the response by Eucalyptus clones in a single-tree plot is influenced by neighboring plants and to determine the effect of missing and/or dominated plants,seven eucalyptus trials in four Brazilian states were analyzed in a randomized complete block design with one plant/plot and 30 replications.Mean annual increment(MAI,m^(3)ha^(-1)per year)was determined for three-year-old clones.The influence of neighboring clones was estimated by a linear regression coefficient between the MAI of each clone/plot and the average of a clonal MAI and its eight neighbors.To determine the effect of missing and/or dominated trees,a correction between the MAI and the area available/plant was applied.Subsequent analysis considered unadjusted and adjusted data for missing and dominated trees.Estimate of accuracy and index of coincidence were used to compare the adjustments.In single-tree plots,clone performances were not influenced by neighboring plants.Experimental accuracy was not increased by any of the adjustments employed and the clone ranking was not altered,and therefore did not justify their use.
基金The work was supported by the National Natural Science Foundation of China(Grant Number 41961060)the Key Program of Basic Research of Yunnan Province,China(Grant Number 2019FA017)+1 种基金the Multi-government International Science and Technology Innovation Cooperation Key Project of National Key Research and Development Program of China(Grant Number 2018YFE0184300)the Program for Innovative Research Team in Science and Technology research and innovation fund(ysdyjs 2020058)in the University of Yunnan Province.
文摘Forest resource management and ecological assessment have been recently supported by emerging technologies.Terrestrial laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional forest information,and create good representations of forest vertical structure.TLS data can be exploited for highly significant tasks,particularly the segmentation and information extraction for individual trees.However,the existing single-tree segmentation methods suffer from low segmentation accuracy and poor robustness,and hence do not lead to satisfactory results for natural forests in complex environments.In this paper,we propose a trunk-growth(TG)method for single-tree point-cloud segmentation,and apply this method to the natural forest scenes of Shangri-La City in Northwest Yunnan,China.First,the point normal vector and its Z-axis component are used as trunk-growth constraints.Then,the points surrounding the trunk are searched to account for regrowth.Finally,the nearest distributed branch and leaf points are used to complete the individual tree segmentation.The results show that the TG method can effectively segment individual trees with an average F-score of 0.96.The proposed method applies to many types of trees with various growth shapes,and can effectively identify shrubs and herbs in complex scenes of natural forests.The promising outcomes of the TG method demonstrate the key advantages of combining plant morphology theory and LiDAR technology for advancing and optimizing forestry systems.
文摘Time and motion studies were conducted to evaluate the impact of selective cutting type on Chainsaw productivity in Caspian forests, the selective cutting performed as single and group selection cutting in the region. The selective cutting was performed on a 42-ha tract with an average slope of 30%. The results indicate that felling time for per tree is most affected by diameter at breast height, the distance among harvested trees in single-tree selection method and diameter at breast height in group selection method. The production rate in single and group selection cutting were 21.2 m^3·h^-1 and 28.4 m^3·h^-1 for one person, respectively. Considering the gross and net production rate in single and group selection cutting, the unit cost was 1.11 USD.m^-3 and 0.88 USD.m^-3, respectively. The results indicate that group selection cutting can be more profitable than single-tree selection method.
文摘In 1958, a demonstrational cutting trial totaling 22.2 ha was established in a northern hardwood forest in Alberta, MI. Eight different treatments were installed, including four diameter-limit treatments (56 cm, 41 cm, 30 cm, and 13 cm), three single-tree selection treatments with residual basal areas of 21 m2·ha–1, 16 m2·ha–1, and 11 m2·ha–1, and an uncut control. Within each treatment, a 0.4-ha permanent plot was established and subdivided into 0.04-ha square subplots. Harvests have been implemented every ten years with the most recent harvest occurring during the winter of 2008 - 2009. We quantified ground layer vegetation response before and after the most recent harvest. Nonmetric multidimensional scaling (NMS) ordination showed a very distinct separation between the most intensive management treatment (13-cm diameter-limit treatment) and the uncut control. Compositionally, the diameter-limit treatments moved with greater directionality and magnitude towards the 13-cm diameter-limit treatment following harvest, while compositional change in the residual basal area treatments was less pronounced and lacked strong directionality. Herbaceous species percent cover generally decreased with increasing residual overstory basal area across treatments. Weedy and early successional species were most abundant under lower residual basal area and diameter-limit treatments. Results based on 50 years of continuous management suggest that diameter-limit harvests likely have a greater impact on the herbaceous community than single-tree selection or no management.