The objective was to examine the effects of optimal leaf nitrogen levels>2.0%and suboptimal levels<2.0%,nitrogen nutrition on net photo synthetic rate,stem diameter increment,height growth increment and acorn ma...The objective was to examine the effects of optimal leaf nitrogen levels>2.0%and suboptimal levels<2.0%,nitrogen nutrition on net photo synthetic rate,stem diameter increment,height growth increment and acorn mass of pedunculate oak during 2010 in the absence of drought stress and during 2011 under the impact of moderate drought stress.According to the results,moderate drought stress significantly reduced net photo synthetic rate,stem diameter increment and height growth increment,while acorn mass was not affected.Suboptimal nitrogen nutrition significantly reduced the net photo synthetic rate and stem diameter increment only in the wet year,acorn mass in both wet and dry years,while height growth increment was not significantly reduced by suboptimal nitrogen nutrition in either year.The results indicate that optimal nitrogen levels can stimulate photo synthetic rate and stem diameter increment of pedunculate oak only in the absence of moderate drought stress.Moreover,the results show that moderate drought stress is a more dominant stressor for photosynthesis and growth of pedunculate oak than suboptimal nitrogen nutrition,while for acorn development,it is the more dominant stressor.展开更多
The aim of this study was to estimate a basal area growth model for individual trees in uneven-aged Caspian forests.A survey was conducted in order to find a natural forest without any harvesting activities,a so call...The aim of this study was to estimate a basal area growth model for individual trees in uneven-aged Caspian forests.A survey was conducted in order to find a natural forest without any harvesting activities,a so called ＇untouched forest＇ and an area was selected from the Iranian Caspian forest.Three sample plots in the same aspect and of the same forest type were selected.In each plot,total tree height,diameter at breast height,distance of neighbor trees and azimuth were measured.Thirty trees were selected and drilled with increment borer to determine the increment model.Regression analysis was used to estimate the growth model.Results show that,for individual trees,there is a significant nonlinear relationship between the annual basal area increment,as the dependent variable,and the basal area.The results also show that the basal area of competing trees has a positive influence on growth.That the increment is higher with more competing neighboring trees is possibly because plots with higher volume per hectare and more competition,most likely also have higher site index or better soil or better site productivity than the plot with lower volume per hectare.展开更多
Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectiv...Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectives were to assess relative seedling performance(survival and growth)with respect to plantation age,and to analyze the influence of specific climatic factors during the early stages of Scots pine(Pinus sylvestris L.)plantations.The study was carried out in reforested areas of the Tujyin Nars region of northern Mongolia on six Scots pine plantations ranging from 5 to 10 years.In each of the six plantations,five 900 m^2 permanent sample plots were established and survival rates and growth performance measured annually over 7 years.Results show high variation in survival among the plantations(p<0.001,F=29.7).Seedling survival in the first year corresponded directly to the number of dry days in May.However,survival rate appeared to stabilize after the second year.The insignificant variation of height categories throughout the observation period indicated low competition among individuals.Two linear mixed-effect models show that height and radial growth were best explained by relative air humidity,which we consider to be a reliable indicator of site-specific water availability.Insufficient amounts and uneven distribution of rainfall pose a major threat during the first year of plantation establishment.Humidity and water availability are decisive factors for a successful seedling plantation.This highlights the impact of drought on forest plantations in northern Mongolia and the importance of developing climate resilient reforestation strategies.展开更多
The analysis of growth bands in the eyestalk has been increasingly used for estimating crustacean ageing and molting.In this study,we developed an effective method to process and observe the eyestalk microstructure of...The analysis of growth bands in the eyestalk has been increasingly used for estimating crustacean ageing and molting.In this study,we developed an effective method to process and observe the eyestalk microstructure of the swimming crab(Portunus trituberculatus).We found that dark pigmentation as a result of boiling has an influence on the observation of the eyestalk microstructure.Choosing an unboiled eyestalk,this study compared the cross section and longitudinal section,and concluded that the cross section is suitable for the observation of growth increments with 6.1%CV(coefficient of variation),and growth bands are suitable for the observation of the longitudinal section with 5.4%CV.The width of growth increments near the edge of the endocuticle is small,and the width of growth increments of the middle part of the endocuticle is large.Relationship of number of growth bands to molting time was fitted to a linear function with the slope not significantly different from 1,indicating that growth bands are formed associated with molting.Periodicity of growth increment formation was calculated as 3.7 d,however was not verified.Our results provide a new improved technique for identification of crustacean molting and growth.展开更多
Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obta...Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country-and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil and nutrient deposition.Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from10% to 53% depending on the species. Variables related to forest structure(basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species.Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etc.展开更多
Since the reform and opening up in 1978, the improving efficiency of resource allocation, particularly the flow and migration of agricultural workforce to non-agricultural sectors, has contributed greatly to China'...Since the reform and opening up in 1978, the improving efficiency of resource allocation, particularly the flow and migration of agricultural workforce to non-agricultural sectors, has contributed greatly to China's economic growth. However, scholars have seldom carried out continuous empirical study on the extent of such contribution mainly due to limited methods for the calculation of labor allocation effect. This paper employs the incremental analysis method of index to separate labor allocation effect from economic growth in order to conduct an analysis on such effect under the framework of economic growth. Using this approach, this paper has calculated the labor allocation effect during various periods of time in China between 1978 and 2014 and the results indicate that the flow and migration of labor constituted the major source of China's economic growth during the periods between 1978 and 1987, between 1992 and 1998 and between 2003 and 2014 and still have great potentials in the coming decade. After 2025, the labor allocation effect will diminish and is likely to become a factor that hinders economic growth.展开更多
基金conducted as part of the research project“Reproductive physiology of pedunculate oak(Quercus robur L.)in Spa?va”fully supported and funded by“Croatian Forests Ltd”。
文摘The objective was to examine the effects of optimal leaf nitrogen levels>2.0%and suboptimal levels<2.0%,nitrogen nutrition on net photo synthetic rate,stem diameter increment,height growth increment and acorn mass of pedunculate oak during 2010 in the absence of drought stress and during 2011 under the impact of moderate drought stress.According to the results,moderate drought stress significantly reduced net photo synthetic rate,stem diameter increment and height growth increment,while acorn mass was not affected.Suboptimal nitrogen nutrition significantly reduced the net photo synthetic rate and stem diameter increment only in the wet year,acorn mass in both wet and dry years,while height growth increment was not significantly reduced by suboptimal nitrogen nutrition in either year.The results indicate that optimal nitrogen levels can stimulate photo synthetic rate and stem diameter increment of pedunculate oak only in the absence of moderate drought stress.Moreover,the results show that moderate drought stress is a more dominant stressor for photosynthesis and growth of pedunculate oak than suboptimal nitrogen nutrition,while for acorn development,it is the more dominant stressor.
文摘The aim of this study was to estimate a basal area growth model for individual trees in uneven-aged Caspian forests.A survey was conducted in order to find a natural forest without any harvesting activities,a so called ＇untouched forest＇ and an area was selected from the Iranian Caspian forest.Three sample plots in the same aspect and of the same forest type were selected.In each plot,total tree height,diameter at breast height,distance of neighbor trees and azimuth were measured.Thirty trees were selected and drilled with increment borer to determine the increment model.Regression analysis was used to estimate the growth model.Results show that,for individual trees,there is a significant nonlinear relationship between the annual basal area increment,as the dependent variable,and the basal area.The results also show that the basal area of competing trees has a positive influence on growth.That the increment is higher with more competing neighboring trees is possibly because plots with higher volume per hectare and more competition,most likely also have higher site index or better soil or better site productivity than the plot with lower volume per hectare.
基金supported by the Partnerships for Enhanced Engagement in Research(PEER)Science Cycle 2 Grant#296’Building research and teaching capacity to aid climate change and natural resource management at the National University of Mongolia(NUM)’
文摘Environmental factors play vital roles in successful plantation and cultivation of tree seedlings.This study focuses on problems associated with reforestation under extreme continental climatic conditions.The objectives were to assess relative seedling performance(survival and growth)with respect to plantation age,and to analyze the influence of specific climatic factors during the early stages of Scots pine(Pinus sylvestris L.)plantations.The study was carried out in reforested areas of the Tujyin Nars region of northern Mongolia on six Scots pine plantations ranging from 5 to 10 years.In each of the six plantations,five 900 m^2 permanent sample plots were established and survival rates and growth performance measured annually over 7 years.Results show high variation in survival among the plantations(p<0.001,F=29.7).Seedling survival in the first year corresponded directly to the number of dry days in May.However,survival rate appeared to stabilize after the second year.The insignificant variation of height categories throughout the observation period indicated low competition among individuals.Two linear mixed-effect models show that height and radial growth were best explained by relative air humidity,which we consider to be a reliable indicator of site-specific water availability.Insufficient amounts and uneven distribution of rainfall pose a major threat during the first year of plantation establishment.Humidity and water availability are decisive factors for a successful seedling plantation.This highlights the impact of drought on forest plantations in northern Mongolia and the importance of developing climate resilient reforestation strategies.
基金The National Key R&D Program of China under contract No.2019YFD0901404the National Natural Science Foundation of China under contract No.41876141+3 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning under contract No.0810000243the Shanghai Pujiang Program under contract No.18PJ1404100the Shanghai Science and Technology Innovation Action Plan under contract No.19DZ1207502Programs Foundation of Ministry of Education of China under contract No.20133104120001。
文摘The analysis of growth bands in the eyestalk has been increasingly used for estimating crustacean ageing and molting.In this study,we developed an effective method to process and observe the eyestalk microstructure of the swimming crab(Portunus trituberculatus).We found that dark pigmentation as a result of boiling has an influence on the observation of the eyestalk microstructure.Choosing an unboiled eyestalk,this study compared the cross section and longitudinal section,and concluded that the cross section is suitable for the observation of growth increments with 6.1%CV(coefficient of variation),and growth bands are suitable for the observation of the longitudinal section with 5.4%CV.The width of growth increments near the edge of the endocuticle is small,and the width of growth increments of the middle part of the endocuticle is large.Relationship of number of growth bands to molting time was fitted to a linear function with the slope not significantly different from 1,indicating that growth bands are formed associated with molting.Periodicity of growth increment formation was calculated as 3.7 d,however was not verified.Our results provide a new improved technique for identification of crustacean molting and growth.
基金funded by the SIMWOOD project(Grant Agreement No.613762)of the EU H2020 Programmefacilitated by the Alter For project(Grant Agreement No.676754)+3 种基金the VERIFY project(Grant Agreement No.776810)Co-funding was received from the topsector Agri&Food under No.AF-EU-15002The Dutch National Forest Inventory is funded by the Ministry of Economic AffairsThe regional forest inventory in Piemonte was produced with the support of EU structural funds
文摘Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country-and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil and nutrient deposition.Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from10% to 53% depending on the species. Variables related to forest structure(basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species.Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etc.
文摘Since the reform and opening up in 1978, the improving efficiency of resource allocation, particularly the flow and migration of agricultural workforce to non-agricultural sectors, has contributed greatly to China's economic growth. However, scholars have seldom carried out continuous empirical study on the extent of such contribution mainly due to limited methods for the calculation of labor allocation effect. This paper employs the incremental analysis method of index to separate labor allocation effect from economic growth in order to conduct an analysis on such effect under the framework of economic growth. Using this approach, this paper has calculated the labor allocation effect during various periods of time in China between 1978 and 2014 and the results indicate that the flow and migration of labor constituted the major source of China's economic growth during the periods between 1978 and 1987, between 1992 and 1998 and between 2003 and 2014 and still have great potentials in the coming decade. After 2025, the labor allocation effect will diminish and is likely to become a factor that hinders economic growth.
