Awareness of the adverse ecological effects of road and other large construction projects has resulted in a rapidly growing demand to quantitatively predict and evaluate the effects on gene flow among plants and anima...Awareness of the adverse ecological effects of road and other large construction projects has resulted in a rapidly growing demand to quantitatively predict and evaluate the effects on gene flow among plants and animals in natural habitats.In this study,we evaluated the effects of different road construction scenarios on animal species movement by using the methods of ecological landscape connectivity in the typical regions of Yunnan Province,China.The results showed landscape connectivity levels(Probability of Connectivity(PC))decreased after road construction and species with lower dispersal abilities were more affected to the subsequent habitat fragmentation.First level roads affected landscape connectivity most significantly.At a distance of 100 m,the PC index decreased more than 50%.Further analysis suggested that the use of landscape connectivity to assess landscape processes revealed the adverse effects on the species movement more effectively compared with the traditional landscape pattern analysis.In addition,we conducted a graph theory and a least-cost modeling discussion,it is obvious that they are powerful tools to represent and analyze landscape networks with respect to related species movement.Network analysis offers a quantitative and simple but effective tool for ecological process assessment and biological conservation on large scales.展开更多
Understanding habitat requirements and identifying landscape linkages are essential for the survival of isolated populations of endangered species.Currently,some of the giant panda populations are isolated,which...Understanding habitat requirements and identifying landscape linkages are essential for the survival of isolated populations of endangered species.Currently,some of the giant panda populations are isolated,which threatens their long-term survival,particularly in the Xiaoxiangling mountains.In the present study,we quantified niche requirements and then identified potential linkages of giant panda subpopulations in the most isolated region,using ecological niche factor analysis and a least-cost path model.Giant pandas preferred habitat with conifer forest and gentle slopes(>20 to≤30°).Based on spatial distribution of suitable habitat,linkages were identified for the Yele subpopulation to 4 other subpopulations(Liziping,Matou,Xinmin and Wanba).Their lengths ranged from 15 to 54 km.The accumulated cost ranged from 693 to 3166 and conifer forest covered over 31%.However,a variety of features(e.g.major roads,human settlements and large unforested areas)might act as barriers along the linkages for giant panda dispersal.Our analysis quantified giant panda subpopulation connectivity to ensure long-term survival.展开更多
The protecting requirements and functional connectivity of species in isolated habitat patches are crucial factors of eco-network planning.This study aimed to improve the method of eco-network planning for species con...The protecting requirements and functional connectivity of species in isolated habitat patches are crucial factors of eco-network planning.This study aimed to improve the method of eco-network planning for species conservation.Ecoprofiling was used to group the species by similar behavior types,namely,choice of ecosystem,area requirement,and short distance dispersal abilities.A least-cost model was used to simulate the optimal corridor location to maintain functional connectivity.A combination of ecoprofile and least-cost model was hired to develop an eco-network that promoted species conservation.A case study was also conducted in Beijing,China.In addition to the required ecosystem,habitat area is an important parameter for habitat extraction.Habitat area can remove noise habitat patches because of lacking area.Short-distance dispersal can be used to identify corridor requirements and avoid unnecessary building requirements.Species with various dispersal abilities exhibit significant differences in terms of corridor length and location requirement.Habitat isolation is the main threat for weakly mobile species,and habitat loss is the major risk of mobile species protection.Different species groups also exhibit distinct landscape pattern demands for an eco-network,and the eco-network planning based on specific species can not protect other species.We proposed that a combination of ecoprofile and least-cost model improved the efficiency of species conservation by eco-network planning.展开更多
Aims Resistance distance(RD),based on circuit theory,is a promising metric for modelling effects of landscape configuration on dispersal of organ-isms and the resulting population and community patterns.The values of ...Aims Resistance distance(RD),based on circuit theory,is a promising metric for modelling effects of landscape configuration on dispersal of organ-isms and the resulting population and community patterns.The values of RD reflect the likelihood of a random walker to reach from a source to a certain destination in the landscape.Although it has successfully been used to model genetic structures of animal populations,where it most often outperforms other isolation metrics,there are hardly any applications to plants and,in particular,to plant community data.Our aims were to test if RD was a suitable metric for studying dispersal processes of plants in narrow habitat corridors(linear landscape ele-ments[LLE]).This would be the case,if dispersal processes(seed dis-persal and migration)resembled random walks.Further,we compared the model performance of RD against least-cost distance(LCD)and Euclidean distance(ED).Finally,we tested the suitability of different cost surfaces for calculations of LCD and RD.Methods We used data from 50 vegetation plots located on semi-natural LLE(field margins,ditches,road verges)in eight agricultural landscapes of Northwest Germany.We mapped LLE,including hedges and tree rows,from aerial images in a Geographic Information System,con-verted the maps into raster layers,and assigned resistance values to the raster cells,where all cells outside of LLE received infinite resist-ance and,thus,represented barriers to dispersal.For all pairs of plots within study areas,we calculated Jaccard similarity assuming that it was a proxy(or correlate)of dispersal events between plots.Further,we calculated RD and LCD of the network of LLE and ED between the plots.We modelled the effects of distance metrics on community similarity using binomial generalized linear mixed models.Important Findings ED was clearly the least suitable isolation metrics.Further,we found that RD performed better than LCD at modelling Jaccard similar-ity.Predictions varied markedly between the two distance metrics suggesting that RD co展开更多
Hancang River is a river on the eastern border of Jinan City. In recent years, with the development of cities, river flow has dropped sharply, river water has been polluted, and the ecological environment of the basin...Hancang River is a river on the eastern border of Jinan City. In recent years, with the development of cities, river flow has dropped sharply, river water has been polluted, and the ecological environment of the basin has declined. Improving the water ecological environment and enhancing the resilience of the water ecology of the river basin were set as the research goals, especially coupling of hydrological and ecological processes and the recycling of sewage resources. The “patch-corridor-matrix” theory of landscape ecology, the Least-cost distance model and the Arc Hydro Tools module of the ArcGIS platform were used to describe the river system and basin boundaries, optimize the current water network and the path network of the ecosystem. A novel ecological network and water network were proposed to form the final aquatic ecosystem, which combines the hydrological process with the ecosystem, and three decentralized wastewater treatment systems were designed to reduce the wastewater directly flowing into the river. The ecosystem resilience of the basin will be enhanced.展开更多
Geospatial technology is a useful tool when identifying land corridors for transportation networks. The primary transit corridor between Los Angeles, CA and Las Vegas, NV is Interstate-15, approximately a four-hour au...Geospatial technology is a useful tool when identifying land corridors for transportation networks. The primary transit corridor between Los Angeles, CA and Las Vegas, NV is Interstate-15, approximately a four-hour automobile trip without traffic. Virgin Trains USA LLC proposes an alternative means of travel by constructing a high-speed railway along Interstate-15 connecting Las Vegas and Victorville, CA. This study uses least-cost path analysis to propose an optimized alternative corridor for Virgin Trains’ proposed high-speed railway through a system facilitated road and rail accessibility analysis. Previous research using least-cost path and accessibility methodologies evaluated the results of proposed high-speed railway corridors and the system facilitated accessibility changes by visually inspecting deviations from a planned corridor using single or multiple cost criteria as inputs for a weighted cost surface. However, robust analyses of previous least-cost path studies’ corridors are lacking. This proof-in-concept study proposes a less costly corridor through least-cost path analysis and measures the social impact on the stakeholders of a high-speed railway transportation system through system facilitated accessibility. This study’s proposed alternative corridor is 31% shorter than Virgin Trains’ planned corridor and system facilitated accessibility to Las Vegas, NV is increased in 99.74% of Los Angeles County’s census tracts. These results support this study’s position that geospatial technology can support transportation planning in a comprehensive method that considers the transportation corridor and benefits its stakeholders.展开更多
Background:Connectivity is an important landscape attribute in ecological studies and conservation practices and is often expressed in terms of effective distance.If the cost of movement of an organism over a landscap...Background:Connectivity is an important landscape attribute in ecological studies and conservation practices and is often expressed in terms of effective distance.If the cost of movement of an organism over a landscape is effectively represented by a raster surface,effective distances can be equated with the cost-weighted distance of least-cost paths.It is generally recognized that this measure is sensitive to the grid’s cell size,but little is known if it is always sensitive in the same way and to the same degree and if not,what makes it more(or less)sensitive.We conducted computational experiments with both synthetic and real landscape data,in which we generated and analyzed large samples of effective distances measured on cost surfaces of varying cell sizes derived from those data.The particular focus was on the statistical behavior of the ratio—referred to as‘accuracy indicator’—of the effective distance measured on a lower-resolution cost surface to that measured on a higher-resolution cost surface.Results:In the experiment with synthetic cost surfaces,the sample values of the accuracy indicator were generally clustered around 1,but slightly greater with the absence of linear sequences(or barriers)of high-cost or inadmissible cells and smaller with the presence of such sequences.The latter tendency was more dominant,and both tendencies became more pronounced as the difference between the spatial resolutions of the associated cost surfaces increased.When two real satellite images(of different resolutions with fairly large discrepancies)were used as the basis of cost estimation,the variation of the accuracy indicator was found to be substantially large in the vicinity(1500 m)of the source but decreases quickly with an increase in distance from it.Conclusions:Effective distances measured on lower-resolution cost surfaces are generally highly correlated with—and useful predictors of—effective distances measured on higher-resolution cost surfaces.This relationship tends to be weakened when linear ba展开更多
In this paper,we propose a method of cost distribution analysis of new consumer connections to a city power grid by accounting for spatial restrictions and characteristics of existing networks.In practice,the calculat...In this paper,we propose a method of cost distribution analysis of new consumer connections to a city power grid by accounting for spatial restrictions and characteristics of existing networks.In practice,the calculation of connection costs for each new consumer includes the network design and financial expenditure.We suggest that connection costs should be calculated for the whole city based on the normative parameters at the stage when the object location is selected by investors and when power grid development is planned by power companies.The proposed method enables the modeling of new power line connection routes from every parcel of city land to possible points of connection to the operating networks based on the raster design of the area.The optimal path is chosen by one criterion consisting of two components:the costs of both laying new power lines and providing sufficient power reserve in the chosen network connection point.Realized as a computer program,the method has been used to calculate the costs of connections to low-voltage power lines.展开更多
基金Under the auspices of Nonprofit Environment Protection Specific Project of China(No.201209029-4)
文摘Awareness of the adverse ecological effects of road and other large construction projects has resulted in a rapidly growing demand to quantitatively predict and evaluate the effects on gene flow among plants and animals in natural habitats.In this study,we evaluated the effects of different road construction scenarios on animal species movement by using the methods of ecological landscape connectivity in the typical regions of Yunnan Province,China.The results showed landscape connectivity levels(Probability of Connectivity(PC))decreased after road construction and species with lower dispersal abilities were more affected to the subsequent habitat fragmentation.First level roads affected landscape connectivity most significantly.At a distance of 100 m,the PC index decreased more than 50%.Further analysis suggested that the use of landscape connectivity to assess landscape processes revealed the adverse effects on the species movement more effectively compared with the traditional landscape pattern analysis.In addition,we conducted a graph theory and a least-cost modeling discussion,it is obvious that they are powerful tools to represent and analyze landscape networks with respect to related species movement.Network analysis offers a quantitative and simple but effective tool for ecological process assessment and biological conservation on large scales.
基金supported by the National Nature Science Foundation(30830020)Key Program of Knowledge Innovation Program of Chinese Academy of Sciences(KSCX2-EW-Z-4)the China Postdoctoral Science Foundation(200904501111).
文摘Understanding habitat requirements and identifying landscape linkages are essential for the survival of isolated populations of endangered species.Currently,some of the giant panda populations are isolated,which threatens their long-term survival,particularly in the Xiaoxiangling mountains.In the present study,we quantified niche requirements and then identified potential linkages of giant panda subpopulations in the most isolated region,using ecological niche factor analysis and a least-cost path model.Giant pandas preferred habitat with conifer forest and gentle slopes(>20 to≤30°).Based on spatial distribution of suitable habitat,linkages were identified for the Yele subpopulation to 4 other subpopulations(Liziping,Matou,Xinmin and Wanba).Their lengths ranged from 15 to 54 km.The accumulated cost ranged from 693 to 3166 and conifer forest covered over 31%.However,a variety of features(e.g.major roads,human settlements and large unforested areas)might act as barriers along the linkages for giant panda dispersal.Our analysis quantified giant panda subpopulation connectivity to ensure long-term survival.
基金Under the auspices of National Natural Science Foundation of China(No.41271198)
文摘The protecting requirements and functional connectivity of species in isolated habitat patches are crucial factors of eco-network planning.This study aimed to improve the method of eco-network planning for species conservation.Ecoprofiling was used to group the species by similar behavior types,namely,choice of ecosystem,area requirement,and short distance dispersal abilities.A least-cost model was used to simulate the optimal corridor location to maintain functional connectivity.A combination of ecoprofile and least-cost model was hired to develop an eco-network that promoted species conservation.A case study was also conducted in Beijing,China.In addition to the required ecosystem,habitat area is an important parameter for habitat extraction.Habitat area can remove noise habitat patches because of lacking area.Short-distance dispersal can be used to identify corridor requirements and avoid unnecessary building requirements.Species with various dispersal abilities exhibit significant differences in terms of corridor length and location requirement.Habitat isolation is the main threat for weakly mobile species,and habitat loss is the major risk of mobile species protection.Different species groups also exhibit distinct landscape pattern demands for an eco-network,and the eco-network planning based on specific species can not protect other species.We proposed that a combination of ecoprofile and least-cost model improved the efficiency of species conservation by eco-network planning.
文摘Aims Resistance distance(RD),based on circuit theory,is a promising metric for modelling effects of landscape configuration on dispersal of organ-isms and the resulting population and community patterns.The values of RD reflect the likelihood of a random walker to reach from a source to a certain destination in the landscape.Although it has successfully been used to model genetic structures of animal populations,where it most often outperforms other isolation metrics,there are hardly any applications to plants and,in particular,to plant community data.Our aims were to test if RD was a suitable metric for studying dispersal processes of plants in narrow habitat corridors(linear landscape ele-ments[LLE]).This would be the case,if dispersal processes(seed dis-persal and migration)resembled random walks.Further,we compared the model performance of RD against least-cost distance(LCD)and Euclidean distance(ED).Finally,we tested the suitability of different cost surfaces for calculations of LCD and RD.Methods We used data from 50 vegetation plots located on semi-natural LLE(field margins,ditches,road verges)in eight agricultural landscapes of Northwest Germany.We mapped LLE,including hedges and tree rows,from aerial images in a Geographic Information System,con-verted the maps into raster layers,and assigned resistance values to the raster cells,where all cells outside of LLE received infinite resist-ance and,thus,represented barriers to dispersal.For all pairs of plots within study areas,we calculated Jaccard similarity assuming that it was a proxy(or correlate)of dispersal events between plots.Further,we calculated RD and LCD of the network of LLE and ED between the plots.We modelled the effects of distance metrics on community similarity using binomial generalized linear mixed models.Important Findings ED was clearly the least suitable isolation metrics.Further,we found that RD performed better than LCD at modelling Jaccard similar-ity.Predictions varied markedly between the two distance metrics suggesting that RD co
文摘Hancang River is a river on the eastern border of Jinan City. In recent years, with the development of cities, river flow has dropped sharply, river water has been polluted, and the ecological environment of the basin has declined. Improving the water ecological environment and enhancing the resilience of the water ecology of the river basin were set as the research goals, especially coupling of hydrological and ecological processes and the recycling of sewage resources. The “patch-corridor-matrix” theory of landscape ecology, the Least-cost distance model and the Arc Hydro Tools module of the ArcGIS platform were used to describe the river system and basin boundaries, optimize the current water network and the path network of the ecosystem. A novel ecological network and water network were proposed to form the final aquatic ecosystem, which combines the hydrological process with the ecosystem, and three decentralized wastewater treatment systems were designed to reduce the wastewater directly flowing into the river. The ecosystem resilience of the basin will be enhanced.
文摘Geospatial technology is a useful tool when identifying land corridors for transportation networks. The primary transit corridor between Los Angeles, CA and Las Vegas, NV is Interstate-15, approximately a four-hour automobile trip without traffic. Virgin Trains USA LLC proposes an alternative means of travel by constructing a high-speed railway along Interstate-15 connecting Las Vegas and Victorville, CA. This study uses least-cost path analysis to propose an optimized alternative corridor for Virgin Trains’ proposed high-speed railway through a system facilitated road and rail accessibility analysis. Previous research using least-cost path and accessibility methodologies evaluated the results of proposed high-speed railway corridors and the system facilitated accessibility changes by visually inspecting deviations from a planned corridor using single or multiple cost criteria as inputs for a weighted cost surface. However, robust analyses of previous least-cost path studies’ corridors are lacking. This proof-in-concept study proposes a less costly corridor through least-cost path analysis and measures the social impact on the stakeholders of a high-speed railway transportation system through system facilitated accessibility. This study’s proposed alternative corridor is 31% shorter than Virgin Trains’ planned corridor and system facilitated accessibility to Las Vegas, NV is increased in 99.74% of Los Angeles County’s census tracts. These results support this study’s position that geospatial technology can support transportation planning in a comprehensive method that considers the transportation corridor and benefits its stakeholders.
基金This work was part of the doctoral study of Rachel Mundeli Murekatete,which was supported by the Swedish International Development Cooperation Agency(Sida)(grant number:51160059-06)This work was also part of the research project“Drawing with Geography”,which was fully supported by the Swedish Research Council for Sustainable Development Formas(grant number:942-2015-1513).
文摘Background:Connectivity is an important landscape attribute in ecological studies and conservation practices and is often expressed in terms of effective distance.If the cost of movement of an organism over a landscape is effectively represented by a raster surface,effective distances can be equated with the cost-weighted distance of least-cost paths.It is generally recognized that this measure is sensitive to the grid’s cell size,but little is known if it is always sensitive in the same way and to the same degree and if not,what makes it more(or less)sensitive.We conducted computational experiments with both synthetic and real landscape data,in which we generated and analyzed large samples of effective distances measured on cost surfaces of varying cell sizes derived from those data.The particular focus was on the statistical behavior of the ratio—referred to as‘accuracy indicator’—of the effective distance measured on a lower-resolution cost surface to that measured on a higher-resolution cost surface.Results:In the experiment with synthetic cost surfaces,the sample values of the accuracy indicator were generally clustered around 1,but slightly greater with the absence of linear sequences(or barriers)of high-cost or inadmissible cells and smaller with the presence of such sequences.The latter tendency was more dominant,and both tendencies became more pronounced as the difference between the spatial resolutions of the associated cost surfaces increased.When two real satellite images(of different resolutions with fairly large discrepancies)were used as the basis of cost estimation,the variation of the accuracy indicator was found to be substantially large in the vicinity(1500 m)of the source but decreases quickly with an increase in distance from it.Conclusions:Effective distances measured on lower-resolution cost surfaces are generally highly correlated with—and useful predictors of—effective distances measured on higher-resolution cost surfaces.This relationship tends to be weakened when linear ba
基金This work was supported by the Ministry Education and Science of the Russian Federation[grant number 2278].
文摘In this paper,we propose a method of cost distribution analysis of new consumer connections to a city power grid by accounting for spatial restrictions and characteristics of existing networks.In practice,the calculation of connection costs for each new consumer includes the network design and financial expenditure.We suggest that connection costs should be calculated for the whole city based on the normative parameters at the stage when the object location is selected by investors and when power grid development is planned by power companies.The proposed method enables the modeling of new power line connection routes from every parcel of city land to possible points of connection to the operating networks based on the raster design of the area.The optimal path is chosen by one criterion consisting of two components:the costs of both laying new power lines and providing sufficient power reserve in the chosen network connection point.Realized as a computer program,the method has been used to calculate the costs of connections to low-voltage power lines.
