In this study, the approach of conditional nonlinear optimal perturbation related to initial perturbation （CNOP-I） was employed to investigate the maximum variations in plant amount for three main woody plants （a t...In this study, the approach of conditional nonlinear optimal perturbation related to initial perturbation （CNOP-I） was employed to investigate the maximum variations in plant amount for three main woody plants （a temperate broadleaved evergreen, a temperate broadleaved summergreen, and a boreal needleleaved evergreen） in China. The investigation was conducted within a certain range of land use intensity using a state-of-the-art Lund-Potsdam-Jena dynamic global vegetation model （LPJ DGVM）. CNOP-I represents a class of deforestation and can be considered a type of land use with respect to the initial perturbation. When deforestation denoted by the CNOP-I has the same intensity for all three plants, the variation in plant amount of the boreal needleleaved evergreen in northern China is greater than the variation in plant amount of both the temperate broadleaved evergreen and temperate broadleaved summergreen in southern China. As deforestation intensity increases, the plant amount variation in the three woody plant functional types carbon changes, in a nonlinear fashion. The impact of land use on plant functional types is minor because the interaction between climate condition and land use is not considered in the LPJ model. Finally, the different impacts of deforestation on net primary production of the three plant functional types were analyzed by modeling gross primary production and autotrophic respiration. Our results suggest that the CNOP-I approach is a useful tool for exploring the nonlinear and different responses of terrestrial ecosystems to land use.展开更多
Miyun County,located in the northeast of Chinese capital Beijing,was underwent remarkable variations in land use in recent years.This paper aimed to detect changes in land use of Miyun from 1997 to 2005,and to qualify...Miyun County,located in the northeast of Chinese capital Beijing,was underwent remarkable variations in land use in recent years.This paper aimed to detect changes in land use of Miyun from 1997 to 2005,and to qualify the response of ecosystem to LUCC based on ecosystem services valuation.With two-periods TM images,we got land use change data,and then ecosystem services values were calculated using ecosystem services valuation coefficients proposed by Chinese scholar Xie Gaodi.Results showed that water area,farm land and unused land decreased while residential land,forest land,grassland and orchard land increased during the study period.The loss of ESV was RMB 206 million and the main reason was the decrease of water area and farm land area.As for spatial variation,there were most dramatically land use change and ESV decline in reservoir ecological protection region.The coefficient sensitivity analysis indicates that valuation coefficients used in the study are suitable and results are reasonable.The driving forces of ESV loss were rapid population growth and economic development.More work should be done to make eco-environment stay healthy.展开更多
Context dependence arises when ecological relationships vary with the conditions under which they are observed. Context dependence of interactions involving parasites is poorly known, even if it is key to understandin...Context dependence arises when ecological relationships vary with the conditions under which they are observed. Context dependence of interactions involving parasites is poorly known, even if it is key to understanding host–parasite relationships and food web dynamics. This paper investigates to which extent predation pressure on an avian ectoparasite (Carnus hemapterus) is context-dependent. Based on a predator-exclusion experiment, predation pressure on C. hemapterus pupae in the host's nest for 3 years, and its variation between habitat types are quantified. Variation in precipitation and normalized difference vegetation index (NDVI) is also explored as a likely cause of context dependency. We hypothesize that predation pressure should fluctuate with such surrogates of food availability, so that inter-annual and intra-annual differences may emerge. The number of nests with significant reduction of pupae varied widely among years ranging from 24% to 75%. However, average pupae reduction in nests where a significant reduction occurred did not vary between years. No differences in predation rates between habitat types were detected. Precipitation and NDVI varied widely between years and NDVI was consistently lower around nests on cliffs than around nests on trees and farmhouses. Parallels were found between variation in predation pressure and precipitation/NDVI at a wide scale (highest predation the driest year, and much lower the 2 rainier ones), but not at the nest scale. This paper shows clear context-dependent insect predation pressure on an ectoparasite under natural conditions, and that such interaction changes in signs rather than magnitude between years. The causes for these variations require longer-term studies and/or well-designed, large-scale experiments.展开更多
Based on the characteristics of colony emer-gence of artificial organisms,their dynamic interaction with the environment,and the food-chain crucial to the life system,the rules of local activities of artificial organ-...Based on the characteristics of colony emer-gence of artificial organisms,their dynamic interaction with the environment,and the food-chain crucial to the life system,the rules of local activities of artificial organ-isms at different levels are defined.The article proposes an artificial life-based algorithm,which is referred to as the food-chain algorithm.This algorithm optimizes computa-tion by simulating the evolution of natural ecosystems and the information processing mechanism of natural organ-isms.The definition,idea and flow of the algorithm are introduced,and relevant rules on metabolic energy and change in the surroundings where artificial-life individuals live are depicted.Furthermore,key parameters of the algorithm are systematically analyzed.Test results show that the algorithm has quasi-life traits that include being autonomous,evolutionary,and self-adaptive.These traits are highly fit for optimization problems of life-like sys-tems such as the location-allocation problem of a distri-bution network system.展开更多
基金Funding was provided from the State Key Development Program for Basic Research，National Natural Science Foundation of China，the KZCX3-SW-230 of the Chinese Academy of Sciences
文摘In this study, the approach of conditional nonlinear optimal perturbation related to initial perturbation （CNOP-I） was employed to investigate the maximum variations in plant amount for three main woody plants （a temperate broadleaved evergreen, a temperate broadleaved summergreen, and a boreal needleleaved evergreen） in China. The investigation was conducted within a certain range of land use intensity using a state-of-the-art Lund-Potsdam-Jena dynamic global vegetation model （LPJ DGVM）. CNOP-I represents a class of deforestation and can be considered a type of land use with respect to the initial perturbation. When deforestation denoted by the CNOP-I has the same intensity for all three plants, the variation in plant amount of the boreal needleleaved evergreen in northern China is greater than the variation in plant amount of both the temperate broadleaved evergreen and temperate broadleaved summergreen in southern China. As deforestation intensity increases, the plant amount variation in the three woody plant functional types carbon changes, in a nonlinear fashion. The impact of land use on plant functional types is minor because the interaction between climate condition and land use is not considered in the LPJ model. Finally, the different impacts of deforestation on net primary production of the three plant functional types were analyzed by modeling gross primary production and autotrophic respiration. Our results suggest that the CNOP-I approach is a useful tool for exploring the nonlinear and different responses of terrestrial ecosystems to land use.
基金supported by the Hi-tech Research and Development Program of China(Grant No.2006AA120108)
文摘Miyun County,located in the northeast of Chinese capital Beijing,was underwent remarkable variations in land use in recent years.This paper aimed to detect changes in land use of Miyun from 1997 to 2005,and to qualify the response of ecosystem to LUCC based on ecosystem services valuation.With two-periods TM images,we got land use change data,and then ecosystem services values were calculated using ecosystem services valuation coefficients proposed by Chinese scholar Xie Gaodi.Results showed that water area,farm land and unused land decreased while residential land,forest land,grassland and orchard land increased during the study period.The loss of ESV was RMB 206 million and the main reason was the decrease of water area and farm land area.As for spatial variation,there were most dramatically land use change and ESV decline in reservoir ecological protection region.The coefficient sensitivity analysis indicates that valuation coefficients used in the study are suitable and results are reasonable.The driving forces of ESV loss were rapid population growth and economic development.More work should be done to make eco-environment stay healthy.
文摘Context dependence arises when ecological relationships vary with the conditions under which they are observed. Context dependence of interactions involving parasites is poorly known, even if it is key to understanding host–parasite relationships and food web dynamics. This paper investigates to which extent predation pressure on an avian ectoparasite (Carnus hemapterus) is context-dependent. Based on a predator-exclusion experiment, predation pressure on C. hemapterus pupae in the host's nest for 3 years, and its variation between habitat types are quantified. Variation in precipitation and normalized difference vegetation index (NDVI) is also explored as a likely cause of context dependency. We hypothesize that predation pressure should fluctuate with such surrogates of food availability, so that inter-annual and intra-annual differences may emerge. The number of nests with significant reduction of pupae varied widely among years ranging from 24% to 75%. However, average pupae reduction in nests where a significant reduction occurred did not vary between years. No differences in predation rates between habitat types were detected. Precipitation and NDVI varied widely between years and NDVI was consistently lower around nests on cliffs than around nests on trees and farmhouses. Parallels were found between variation in predation pressure and precipitation/NDVI at a wide scale (highest predation the driest year, and much lower the 2 rainier ones), but not at the nest scale. This paper shows clear context-dependent insect predation pressure on an ectoparasite under natural conditions, and that such interaction changes in signs rather than magnitude between years. The causes for these variations require longer-term studies and/or well-designed, large-scale experiments.
基金supported by the National Natural Science Foundation of China(Grant Nos.70431003,70571077,75103012).
文摘Based on the characteristics of colony emer-gence of artificial organisms,their dynamic interaction with the environment,and the food-chain crucial to the life system,the rules of local activities of artificial organ-isms at different levels are defined.The article proposes an artificial life-based algorithm,which is referred to as the food-chain algorithm.This algorithm optimizes computa-tion by simulating the evolution of natural ecosystems and the information processing mechanism of natural organ-isms.The definition,idea and flow of the algorithm are introduced,and relevant rules on metabolic energy and change in the surroundings where artificial-life individuals live are depicted.Furthermore,key parameters of the algorithm are systematically analyzed.Test results show that the algorithm has quasi-life traits that include being autonomous,evolutionary,and self-adaptive.These traits are highly fit for optimization problems of life-like sys-tems such as the location-allocation problem of a distri-bution network system.
