Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth (diameter at breast height, total height), natural pruning (height to fir...Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth (diameter at breast height, total height), natural pruning (height to first dead and first live branch and branchiness) and stem and crown form of 24-year-old pedunculate oak (Quercus robur [L.]) and European ash (Fraxinus excelsior [L.]) were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha?1. Mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots and inadequate self-pruning can be controlled with trainer species, the initial stocking may be reduced significantly in oak.展开更多
Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources ha...Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.展开更多
For sustainable forest management, understanding the ecological factors that determine vegetation composition are important. Here, the relation between the vegetation composition and environmental factors(elevation, a...For sustainable forest management, understanding the ecological factors that determine vegetation composition are important. Here, the relation between the vegetation composition and environmental factors(elevation, aspect, slope, CaCO3, K, P, C, N, C/N, bulk density,soil porosity, saturation moisture content, EC, pH, sand, silt and clay) was investigated in the Khonj forests, Fars Province, Iran. Characteristic land units, each 200 m2, were chosen for sampling to analyze species composition, soil characteristics and topographic factors. The floristic data were classified using a two-way indicator species analysis(TWINSPAN). Means were then compared using an ANOVA and Duncan multiple range test to detect any variations between groups. Also, the Kaiser–Meyer–Olkin index and Bartlett test were used to measure sampling adequacy. The four vegetation groups identified comprised the species Achillea wilhelmsii, Tanacetum parthenium,Convolvulus spinosus, Capparis spinosa. A detrended canonical correspondence analysis(DCCA) ordination diagram clearly illustrated the relationship between vegetation and environmental factors. According to the results,group 1 with A. wilhelmsii as the indicator species has a positive relation with slope and elevation. T. parthenium was the indicator species of group 2, that appears in areas with high silt and low bulk density and sand. The results showed that group 3 with Convolvulus spinosus as the indicator species was distributed in soils with high bulk density, low silt and pH as well. Group 4 with C. spinosa as the indicator species occurs in sandy soils and low slopes.Using DCCA, we determined the relationship between species and environmental factors more accurately. Results of this study can be used to restore vegetation or maintain species composition in ecological sensitive areas.展开更多
Tropical forests contain many tree species that have supplied edible fruits for centuries.These fruits have contributed to human diets due to their richness in nutrients,vitamins,minerals,antioxidants and their low an...Tropical forests contain many tree species that have supplied edible fruits for centuries.These fruits have contributed to human diets due to their richness in nutrients,vitamins,minerals,antioxidants and their low antinutrients content.We investigated the antioxidant,nutritional and anti-nutritional composition of Garcinia kola and Chrysophyllum albidum fruit parts.The nutritional,anti-nutritional and antioxidant compositions differed depending on the fruit part.Irrespective of fruit part,moisture content was high(72–93 %).While the edible part(fruit pulp) of C.albidum proved a better source of protein(4),fibre(17 %) and fat(2 %),the seed kernel was a better source of ash(2 %) and carbohydrate(15 %).Carbohydrate(22 %),protein(2 %),fat(1 %) and fibre(3 %) were higher in G.kola seed kernel(edible part) than in the pulp and pod.Anti-nutrient content in G.kola and C.albidum fruits was low,indicating that their consumption would not pose nutritional or health problems.The antioxidant compositions(especially phenolic content(10–21 mg g-1) and DPPH(1,1-diphenyl–2 picrylhydrazyl)(26–55 %)) of C.albidum fruit pulp and G.kola seed kernel were high,implying that they could be good sources of natural antioxidants and could be used as supplements in food manufacturing.展开更多
The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer a...The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^(-2), 795.4 trees·hm^(-2) and 3.9 m2·hm-2, 5.8 m^2·hm^(-2), respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.展开更多
English yew Taxus baccata L. has been catalogued as endangered tree species and prone to extinction in Austria as well as many other parts of Europe. The present work is based on the comparison of the natural populati...English yew Taxus baccata L. has been catalogued as endangered tree species and prone to extinction in Austria as well as many other parts of Europe. The present work is based on the comparison of the natural population of two gene conservation forests from different geographic locations in Austria where the spatial structure, regeneration status and possible conservation measures are examined. The pole stand distribution varied distinctly in each sites. The total no of individuals per ha (DBH ≥5 cm), average DBH and average height were 492 n.hm^-2, 8.8 cm and 6.3 m in Stiwollgraben whereas in Leininger Riese 45 n.hm^-2, 16.3 cm and 7.6 m respectively. Over 79% of the Stiwollgraben population were represented the good health condition, while in Leininger Riese it was less then 49 % which means population of Stiwollgraben is in better condition compared to Leininger Riese. The sites differed considerably in the pattern of regeneration but pattern were consistent with the dynamics depicted by the age distribution. Considering the one-year-old seedlings Stiwollgraben contains 13 019 individuals.hm^-2 whereas Leininger Riese only 1 368. Surprisingly there were no any saplings in respect of 51 to 150 cm height classes in both sites and 30 to 50 cm in Stiwollgraben. In that context the conservation of English yew on the forest level may require well-managed reserves and long-term rotations between harvest events, protection from the herbivore and reduction of competition, which will enhance the long-term viability of the species.展开更多
This paper addresses the final stage of the study concerning the practical use of the best Russian methods,technologies and means for detecting and extinguishing forest fires in Russia.In general,the work is aimed at ...This paper addresses the final stage of the study concerning the practical use of the best Russian methods,technologies and means for detecting and extinguishing forest fires in Russia.In general,the work is aimed at increasing the effectiveness of the forest fire protection system by improving the methodological and technical support for the use of the best new innovations.In the course of the study,analytical methods have been applied,tested and used in silviculture,while developing and improving the regulatory legal and methodological frameworks.Based on the selection of research directions in the preliminary stages of work,analysis of the current state,use,and the development forecast of the most effective and promising technologies was carried out.In addition,for detecting,controlling and extinguishing forest fires,including a comparative analysis of their economic efficiency,methods for practical use of the best Russian innovations was developed.A significant number of new developments have accumulated which,for a number of reasons,have not been implemented.Taking into account the current state and dynamics of these promising methods,technologies,means of detecting and extinguishing forest fires,this study substantiates the development forecast of these promising innovations and their content.Its structure includes general provisions,concepts and terminology,regulatory support,the procedure for assessing the feasibility and effectiveness of the innovations,as well as a list of recommended documents for studying the use of technology for detecting,controlling and extinguishing forest fires.These methods will help meet modern requirements for the protection of forests from wildfires,and present an algorithm for their implementation in practice.展开更多
Anthropogenic disturbances influence plant regeneration and species diversity, which impact the conservation status of protected areas. A study was conducted in the Sitakund Botanical Garden and Eco-park(SBGE), Chitta...Anthropogenic disturbances influence plant regeneration and species diversity, which impact the conservation status of protected areas. A study was conducted in the Sitakund Botanical Garden and Eco-park(SBGE), Chittagong,Bangladesh to analyze the natural regeneration and tree species diversity in disturbed and less disturbed zones. Stratified and systematic random sampling was used to select 50 sample plots from each of the two zones. A total number of 109 plant species from 43 families were recorded in the study; of which 93 species were of natural origin while the rest were planted. From the species with natural origin 66 were tree species, 9 were shrub species and 18 were climbers. Species richness, density of regeneration and disturbance index in the height classes(0- 0.5 m)and(dbh > 6 cm) indicated significant differences between the zones. The study analyzed how disturbances affect species diversity in the area. It was found that species richness and basal area are negatively related with disturbances. Moreover,density(N/ha) of trees was more likely to decrease with increasing tree height that reflects the huge demand of local people to harvest large trees as part of their income generating activities. The study findings have implications for future management decisions of the SGBE. To restore these ecosystems, management should focus on both biodiversity conservation and providing benefits to local people without hampering forest ecosystems.展开更多
We examined the impact of picnic activities on forest diversity, structure, regeneration and vitality of tree species in the Bhawal National Park of Bangladesh. The study area was classified as a non-used, occasionall...We examined the impact of picnic activities on forest diversity, structure, regeneration and vitality of tree species in the Bhawal National Park of Bangladesh. The study area was classified as a non-used, occasionally used and frequently used area on the basis of the intensity of the picnic activities. A total of 43 plant species were enumerated in the whole study area. The highest plant species richness (41 species) was observed in the non-used area whereas the lowest species richness (11 species) in the frequently used area. The diversity index decreased with the increase of picnic intensity whereas the concentration of dominance increased. Density of all plant groups except mature trees, and the basal area of the mature trees showed a declining trend from the non-used to frequently used area. The frequently used area exhibited very poor regeneration. Tree vitality decreased with the increase of picnic intensity. The relevance of our study as a basis for further research to determine the impact of tourism on biodiversity in Bangladesh is discussed.展开更多
The original version of this article unfortunately contained three mistakes. (1) The spelling of the [A. Nishad'] name was incorrect. The corrected spelling is given below.
A novel but simple approach for describing stand structure in natural and managed forests driven by small-scaled disturbances is introduced. A primeval beech forest reserve in Slovakia and two beech stands in Germany ...A novel but simple approach for describing stand structure in natural and managed forests driven by small-scaled disturbances is introduced. A primeval beech forest reserve in Slovakia and two beech stands in Germany with different management histories were studied, and their forest stand texture was analysed in terms of tree coordinates, stem diameter, and crown radius. Neigh-bouring trees of similar size with estimated contact of their crowns were assigned to tree groups. The study goal was to estimate the number and size of such homogeneous patches. In all cases, the number of tree groups in a particular diameter class decreased exponentially as group size increased. Single trees were predominant. Compared to simulated random tree distributions, the natural stand exhibited a more clumped distribution of small trees and more regular distribution of larger ones. The natural forest generally had smaller groups than the managed even aged stand, but the smallest group sizes were found in the uneven-aged selection forest. The simple analytical approach provided new spatial insights into neighbourhood relations of trees. The continuous scale from single trees to larger tree groups is an important achievement compared to other analytical methods applied in this field. The findings may even indicate a certain degree of self-organization in natural forests. Due to the limitations associated with each method or statistical models, a joint consideration of 1) gap dynamics, 2) forest developmental stages, and 3) size classes of homogeneous tree groups is recommended. Relevant to forest practitioners, the size class distributions enhance an understanding of the complex stand structures in natural forests and therewith support an emulation of natural forest dynamics in managed beech forests.展开更多
采用BIOME-BGC模型对广东鹤山的马占相思(Acacia mangium)人工林生态系统1985-2100年间的碳格局及其动态变化进行了模拟。结果表明,马占相思生物量在前12a增长较快,之后增长缓慢,最终达到300t hm^-2;预计2100年马占相思生物量在...采用BIOME-BGC模型对广东鹤山的马占相思(Acacia mangium)人工林生态系统1985-2100年间的碳格局及其动态变化进行了模拟。结果表明,马占相思生物量在前12a增长较快,之后增长缓慢,最终达到300t hm^-2;预计2100年马占相思生物量在于、根、叶中的分配分别为73.91%、21.74%和4.35%。马占相思人工林的碳贮量在前12a增长较快,之后增长缓慢并最终维持在325t C hm^-2左右,在造林初始阶段主要分布于土壤中,之后在植被、土壤和凋落物3大碳库中的分配分别为43.08%、52.30%和4.62%;马占相思净初级生产力(NPP)在4-12a较大,最大可达11t C hm^-2,之后下降至3-6t C hm^-2;马占相思叶面积指数(LAX)前3a增长迅速,5a达到7.84,之后下降,约为2.7-5.0;LAJ与NPP的回归分析结果显示LAI可能是限制马占相思林NPP增长的主要因子。模拟结果还显示马占相思林前期生长迅速,但随后生长缓慢,叶生物量还出现负增长现象。因此,我国南亚热带地区在以马占相思作为先锋树种进行地带性森林植被恢复时,可在12a后进行林分改造。展开更多
Annual discharge and annual suspended sediment loads of Beipei Hydrological Station of the Jialing River catchment were analyzed to describe the trend of Jialing River over the last five decades (1956-2006). These loa...Annual discharge and annual suspended sediment loads of Beipei Hydrological Station of the Jialing River catchment were analyzed to describe the trend of Jialing River over the last five decades (1956-2006). These loads were also analyzed to ascertain the influential factors associated with its variation with the help of Kendall's Tau-b correlation analysis and regression analysis. The results indicated that the Jialing River annual discharge showed no significant trend at >95% confidence level while the annual sediment load appeared to have a significant decrease trend over the last 50 years. A decrease in the annual sediment load was particularly apparent after the year 1985, at which a substantial shift in the sediment level occurred. This shift is attributed to the construction of numerous dams in 1980s. However, after the year of 1985, two periodical stages (1986-1991 and 1992-2006) with distinct sediment load and sediment-runoff ratio were identified. The period 1992-2006 is characterised by low sediment load, which is most probably due to the impact of large scale of soil and water conservation, which took place at the end of the 1980s. Last, models describing the relationship between the discharge and the sediment load, discharge and sediment-runoff ratio as well as between the sediment load and sediment-runoff ratio were constructed.展开更多
The present study was conducted within the frame of the Sino-German project "Rehabilitation of degraded land ecosystems in the mountainous area of the Southern Shaanxi Province,China".The study deals with th...The present study was conducted within the frame of the Sino-German project "Rehabilitation of degraded land ecosystems in the mountainous area of the Southern Shaanxi Province,China".The study deals with the assessment of the potential of oak coppices as well as the evaluation of the socioeconomic conditions in the Shangnan County.The ultimate objective of the study is to provide recommendations on the sustainable management of forest resources,which does not only aim to improve the environmental situation but also to satisfy the demands of the local rural residents.The study was based on 30 samples of oak coppices stands,which were randomly selected within an area of a size of 20 km × 20 km.In each selected stand,the mature stand and understory regeneration were investigated in depth.For the socio-economic survey,175 households from 11 villages were randomly selected.Results revealed that the stocking capacity of the cork oak coppices reaches 120 m3/ha in average at the older age classes(≥25 years) even after frequent timber harvest.High potential for productivity was indicated by the availability of sufficient vigorous individuals at different age classes.In addition,the understory regeneration was sufficient in density(19,000±133 individual/ha) and consisted of diverse valuable native-species(17 species within a survey area of 400 m2).The results of the assessment of the oak coppices provided possibilities for some practices that can be recommended towards sustainable management of such stands.On the other hand,results of the socioeconomic study showed a high degree of acceptance among the local inhabitants(79% of the total households) to change traditional land use,providing an enhancement of their economic situation.展开更多
Siberian moth Dendcrolimus superans sibiricus Tschetw. is the main important insect pest not only in Siberian coniferous taiga, but it often forms foci of mass reproduction in larch stands in the Russian Far East. Thi...Siberian moth Dendcrolimus superans sibiricus Tschetw. is the main important insect pest not only in Siberian coniferous taiga, but it often forms foci of mass reproduction in larch stands in the Russian Far East. This article has described outbreaks of the Siberian moth and other insect pests since 1960 till now.展开更多
文摘Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth (diameter at breast height, total height), natural pruning (height to first dead and first live branch and branchiness) and stem and crown form of 24-year-old pedunculate oak (Quercus robur [L.]) and European ash (Fraxinus excelsior [L.]) were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha?1. Mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots and inadequate self-pruning can be controlled with trainer species, the initial stocking may be reduced significantly in oak.
文摘Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh's hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.
文摘For sustainable forest management, understanding the ecological factors that determine vegetation composition are important. Here, the relation between the vegetation composition and environmental factors(elevation, aspect, slope, CaCO3, K, P, C, N, C/N, bulk density,soil porosity, saturation moisture content, EC, pH, sand, silt and clay) was investigated in the Khonj forests, Fars Province, Iran. Characteristic land units, each 200 m2, were chosen for sampling to analyze species composition, soil characteristics and topographic factors. The floristic data were classified using a two-way indicator species analysis(TWINSPAN). Means were then compared using an ANOVA and Duncan multiple range test to detect any variations between groups. Also, the Kaiser–Meyer–Olkin index and Bartlett test were used to measure sampling adequacy. The four vegetation groups identified comprised the species Achillea wilhelmsii, Tanacetum parthenium,Convolvulus spinosus, Capparis spinosa. A detrended canonical correspondence analysis(DCCA) ordination diagram clearly illustrated the relationship between vegetation and environmental factors. According to the results,group 1 with A. wilhelmsii as the indicator species has a positive relation with slope and elevation. T. parthenium was the indicator species of group 2, that appears in areas with high silt and low bulk density and sand. The results showed that group 3 with Convolvulus spinosus as the indicator species was distributed in soils with high bulk density, low silt and pH as well. Group 4 with C. spinosa as the indicator species occurs in sandy soils and low slopes.Using DCCA, we determined the relationship between species and environmental factors more accurately. Results of this study can be used to restore vegetation or maintain species composition in ecological sensitive areas.
基金supported by Alexander von Humboldt Foundation(Av H),Bonn,Germany
文摘Tropical forests contain many tree species that have supplied edible fruits for centuries.These fruits have contributed to human diets due to their richness in nutrients,vitamins,minerals,antioxidants and their low antinutrients content.We investigated the antioxidant,nutritional and anti-nutritional composition of Garcinia kola and Chrysophyllum albidum fruit parts.The nutritional,anti-nutritional and antioxidant compositions differed depending on the fruit part.Irrespective of fruit part,moisture content was high(72–93 %).While the edible part(fruit pulp) of C.albidum proved a better source of protein(4),fibre(17 %) and fat(2 %),the seed kernel was a better source of ash(2 %) and carbohydrate(15 %).Carbohydrate(22 %),protein(2 %),fat(1 %) and fibre(3 %) were higher in G.kola seed kernel(edible part) than in the pulp and pod.Anti-nutrient content in G.kola and C.albidum fruits was low,indicating that their consumption would not pose nutritional or health problems.The antioxidant compositions(especially phenolic content(10–21 mg g-1) and DPPH(1,1-diphenyl–2 picrylhydrazyl)(26–55 %)) of C.albidum fruit pulp and G.kola seed kernel were high,implying that they could be good sources of natural antioxidants and could be used as supplements in food manufacturing.
文摘The structural diversity of different tree-crop associations were studied at Gachabari Sal forest area of Madhupur Garh on Buffer and Peripheral Zone during 2006. The total density, basal area of trees in the Buffer and Peripheral Zone were 155.5 trees·hm^(-2), 795.4 trees·hm^(-2) and 3.9 m2·hm-2, 5.8 m^2·hm^(-2), respectively. No regeneration and natural trees were found in Peripheral Zone and the Zone is totally occupied by exotic species where the Buffer Zone comprised of both natural and exotic trees. The Peripheral Zone belonged to younger and smaller trees whereas the Buffer Zone belonged to mixture of smaller, taller, younger and mature trees simultaneously. For the practicing of different agroforestry systems both Zones have lost their original characters of Sal forest.
文摘English yew Taxus baccata L. has been catalogued as endangered tree species and prone to extinction in Austria as well as many other parts of Europe. The present work is based on the comparison of the natural population of two gene conservation forests from different geographic locations in Austria where the spatial structure, regeneration status and possible conservation measures are examined. The pole stand distribution varied distinctly in each sites. The total no of individuals per ha (DBH ≥5 cm), average DBH and average height were 492 n.hm^-2, 8.8 cm and 6.3 m in Stiwollgraben whereas in Leininger Riese 45 n.hm^-2, 16.3 cm and 7.6 m respectively. Over 79% of the Stiwollgraben population were represented the good health condition, while in Leininger Riese it was less then 49 % which means population of Stiwollgraben is in better condition compared to Leininger Riese. The sites differed considerably in the pattern of regeneration but pattern were consistent with the dynamics depicted by the age distribution. Considering the one-year-old seedlings Stiwollgraben contains 13 019 individuals.hm^-2 whereas Leininger Riese only 1 368. Surprisingly there were no any saplings in respect of 51 to 150 cm height classes in both sites and 30 to 50 cm in Stiwollgraben. In that context the conservation of English yew on the forest level may require well-managed reserves and long-term rotations between harvest events, protection from the herbivore and reduction of competition, which will enhance the long-term viability of the species.
基金The project is funded by All-Russian Research Institute of Silviculture and Mechanization of Forestry(ARRISMF).
文摘This paper addresses the final stage of the study concerning the practical use of the best Russian methods,technologies and means for detecting and extinguishing forest fires in Russia.In general,the work is aimed at increasing the effectiveness of the forest fire protection system by improving the methodological and technical support for the use of the best new innovations.In the course of the study,analytical methods have been applied,tested and used in silviculture,while developing and improving the regulatory legal and methodological frameworks.Based on the selection of research directions in the preliminary stages of work,analysis of the current state,use,and the development forecast of the most effective and promising technologies was carried out.In addition,for detecting,controlling and extinguishing forest fires,including a comparative analysis of their economic efficiency,methods for practical use of the best Russian innovations was developed.A significant number of new developments have accumulated which,for a number of reasons,have not been implemented.Taking into account the current state and dynamics of these promising methods,technologies,means of detecting and extinguishing forest fires,this study substantiates the development forecast of these promising innovations and their content.Its structure includes general provisions,concepts and terminology,regulatory support,the procedure for assessing the feasibility and effectiveness of the innovations,as well as a list of recommended documents for studying the use of technology for detecting,controlling and extinguishing forest fires.These methods will help meet modern requirements for the protection of forests from wildfires,and present an algorithm for their implementation in practice.
基金supported by the OG (sterreichische Orient-Gesellschaft Hammer Purgstall) Vienna, Austria
文摘Anthropogenic disturbances influence plant regeneration and species diversity, which impact the conservation status of protected areas. A study was conducted in the Sitakund Botanical Garden and Eco-park(SBGE), Chittagong,Bangladesh to analyze the natural regeneration and tree species diversity in disturbed and less disturbed zones. Stratified and systematic random sampling was used to select 50 sample plots from each of the two zones. A total number of 109 plant species from 43 families were recorded in the study; of which 93 species were of natural origin while the rest were planted. From the species with natural origin 66 were tree species, 9 were shrub species and 18 were climbers. Species richness, density of regeneration and disturbance index in the height classes(0- 0.5 m)and(dbh > 6 cm) indicated significant differences between the zones. The study analyzed how disturbances affect species diversity in the area. It was found that species richness and basal area are negatively related with disturbances. Moreover,density(N/ha) of trees was more likely to decrease with increasing tree height that reflects the huge demand of local people to harvest large trees as part of their income generating activities. The study findings have implications for future management decisions of the SGBE. To restore these ecosystems, management should focus on both biodiversity conservation and providing benefits to local people without hampering forest ecosystems.
文摘We examined the impact of picnic activities on forest diversity, structure, regeneration and vitality of tree species in the Bhawal National Park of Bangladesh. The study area was classified as a non-used, occasionally used and frequently used area on the basis of the intensity of the picnic activities. A total of 43 plant species were enumerated in the whole study area. The highest plant species richness (41 species) was observed in the non-used area whereas the lowest species richness (11 species) in the frequently used area. The diversity index decreased with the increase of picnic intensity whereas the concentration of dominance increased. Density of all plant groups except mature trees, and the basal area of the mature trees showed a declining trend from the non-used to frequently used area. The frequently used area exhibited very poor regeneration. Tree vitality decreased with the increase of picnic intensity. The relevance of our study as a basis for further research to determine the impact of tourism on biodiversity in Bangladesh is discussed.
文摘The original version of this article unfortunately contained three mistakes. (1) The spelling of the [A. Nishad'] name was incorrect. The corrected spelling is given below.
文摘A novel but simple approach for describing stand structure in natural and managed forests driven by small-scaled disturbances is introduced. A primeval beech forest reserve in Slovakia and two beech stands in Germany with different management histories were studied, and their forest stand texture was analysed in terms of tree coordinates, stem diameter, and crown radius. Neigh-bouring trees of similar size with estimated contact of their crowns were assigned to tree groups. The study goal was to estimate the number and size of such homogeneous patches. In all cases, the number of tree groups in a particular diameter class decreased exponentially as group size increased. Single trees were predominant. Compared to simulated random tree distributions, the natural stand exhibited a more clumped distribution of small trees and more regular distribution of larger ones. The natural forest generally had smaller groups than the managed even aged stand, but the smallest group sizes were found in the uneven-aged selection forest. The simple analytical approach provided new spatial insights into neighbourhood relations of trees. The continuous scale from single trees to larger tree groups is an important achievement compared to other analytical methods applied in this field. The findings may even indicate a certain degree of self-organization in natural forests. Due to the limitations associated with each method or statistical models, a joint consideration of 1) gap dynamics, 2) forest developmental stages, and 3) size classes of homogeneous tree groups is recommended. Relevant to forest practitioners, the size class distributions enhance an understanding of the complex stand structures in natural forests and therewith support an emulation of natural forest dynamics in managed beech forests.
文摘采用BIOME-BGC模型对广东鹤山的马占相思(Acacia mangium)人工林生态系统1985-2100年间的碳格局及其动态变化进行了模拟。结果表明,马占相思生物量在前12a增长较快,之后增长缓慢,最终达到300t hm^-2;预计2100年马占相思生物量在于、根、叶中的分配分别为73.91%、21.74%和4.35%。马占相思人工林的碳贮量在前12a增长较快,之后增长缓慢并最终维持在325t C hm^-2左右,在造林初始阶段主要分布于土壤中,之后在植被、土壤和凋落物3大碳库中的分配分别为43.08%、52.30%和4.62%;马占相思净初级生产力(NPP)在4-12a较大,最大可达11t C hm^-2,之后下降至3-6t C hm^-2;马占相思叶面积指数(LAX)前3a增长迅速,5a达到7.84,之后下降,约为2.7-5.0;LAJ与NPP的回归分析结果显示LAI可能是限制马占相思林NPP增长的主要因子。模拟结果还显示马占相思林前期生长迅速,但随后生长缓慢,叶生物量还出现负增长现象。因此,我国南亚热带地区在以马占相思作为先锋树种进行地带性森林植被恢复时,可在12a后进行林分改造。
基金supported by the National Natural Science Foundation (40901135)973 program (2007CB40720301)+1 种基金National Key Technology R&D Program (2008BAD98B02)the open fund of Institute of Changjiang River Scientific Research program (YWF0716/TB01)
文摘Annual discharge and annual suspended sediment loads of Beipei Hydrological Station of the Jialing River catchment were analyzed to describe the trend of Jialing River over the last five decades (1956-2006). These loads were also analyzed to ascertain the influential factors associated with its variation with the help of Kendall's Tau-b correlation analysis and regression analysis. The results indicated that the Jialing River annual discharge showed no significant trend at >95% confidence level while the annual sediment load appeared to have a significant decrease trend over the last 50 years. A decrease in the annual sediment load was particularly apparent after the year 1985, at which a substantial shift in the sediment level occurred. This shift is attributed to the construction of numerous dams in 1980s. However, after the year of 1985, two periodical stages (1986-1991 and 1992-2006) with distinct sediment load and sediment-runoff ratio were identified. The period 1992-2006 is characterised by low sediment load, which is most probably due to the impact of large scale of soil and water conservation, which took place at the end of the 1980s. Last, models describing the relationship between the discharge and the sediment load, discharge and sediment-runoff ratio as well as between the sediment load and sediment-runoff ratio were constructed.
基金funded by German Federal Ministry of Education and Research(BMBF)(0330803)Robert Bosch Foundation(32.5.8003.0064.0)National Natural Science Foundation of China(NSFC)(40901135)
文摘The present study was conducted within the frame of the Sino-German project "Rehabilitation of degraded land ecosystems in the mountainous area of the Southern Shaanxi Province,China".The study deals with the assessment of the potential of oak coppices as well as the evaluation of the socioeconomic conditions in the Shangnan County.The ultimate objective of the study is to provide recommendations on the sustainable management of forest resources,which does not only aim to improve the environmental situation but also to satisfy the demands of the local rural residents.The study was based on 30 samples of oak coppices stands,which were randomly selected within an area of a size of 20 km × 20 km.In each selected stand,the mature stand and understory regeneration were investigated in depth.For the socio-economic survey,175 households from 11 villages were randomly selected.Results revealed that the stocking capacity of the cork oak coppices reaches 120 m3/ha in average at the older age classes(≥25 years) even after frequent timber harvest.High potential for productivity was indicated by the availability of sufficient vigorous individuals at different age classes.In addition,the understory regeneration was sufficient in density(19,000±133 individual/ha) and consisted of diverse valuable native-species(17 species within a survey area of 400 m2).The results of the assessment of the oak coppices provided possibilities for some practices that can be recommended towards sustainable management of such stands.On the other hand,results of the socioeconomic study showed a high degree of acceptance among the local inhabitants(79% of the total households) to change traditional land use,providing an enhancement of their economic situation.
文摘Siberian moth Dendcrolimus superans sibiricus Tschetw. is the main important insect pest not only in Siberian coniferous taiga, but it often forms foci of mass reproduction in larch stands in the Russian Far East. This article has described outbreaks of the Siberian moth and other insect pests since 1960 till now.