Landscape fragmentation is generally viewed as an indicator of environmental stresses or risks,but the fragmentation intensity assessment also depends on the scale of data and the definition of spatial unit.This study...Landscape fragmentation is generally viewed as an indicator of environmental stresses or risks,but the fragmentation intensity assessment also depends on the scale of data and the definition of spatial unit.This study aimed to explore the scale-dependence of forest fragmentation intensity along a moisture gradient in Yinshan Mountain of North China,and to estimate environmental sensitivity of forest fragmentation in this semi-arid landscape.We developed an automatic classification algorithm using simple linear iterative clustering(SLIC)and Gaussian mixture model(GMM),and extracted tree canopy patches from Google Earth images(GEI),with an accuracy of 89.2%in the study area.Then we convert the tree canopy patches to forest category according to definition of forest that tree density greater than 10%,and compared it with forest categories from global land use datasets,FROM-GLC10 and GlobeLand30,with spatial resolutions of 10 m and 30 m,respectively.We found that the FROM-GLC10 and GlobeLand30 datasets underestimated the forest area in Yinshan Mountain by 16.88%and 21.06%,respectively;and the ratio of open forest(OF,10%<tree coverage<40%)to closed forest(CF,tree coverage>40%)areas in the underestimated part was 2:1.The underestimations concentrated in warmer and drier areas occupied mostly by large coverage of OFs with severely fragmented canopies.Fragmentation intensity of canopies positively correlated with spring temperature while negatively correlated with summer precipitation and terrain slope.When summer precipitation was less than 300 mm or spring temperature higher than 4℃,canopy fragmentation intensity rose drastically,while the forest area percentage kept stable.Our study suggested that the spatial configuration,e.g.,sparseness,is more sensitive to drought stress than area percentage.This highlights the importance of data resolution and proper fragmentation measurements for forest patterns and environmental interpretation,which is the base of reliable ecosystem predictions with regard to the future climate scenarios.展开更多
The intensified conflict between island urbanization and lagging supervision deserves special attention worldwide.Zhoushan Island has been an outstanding center of marine economic development in China but also one of ...The intensified conflict between island urbanization and lagging supervision deserves special attention worldwide.Zhoushan Island has been an outstanding center of marine economic development in China but also one of the areas most threatened by recent human activities.To cope with this challenge,the development of a retrospective understanding of the spatiotemporal dynamics of island urban growth is a key prerequisite.Detailed,multi-scales,long-term studies on island urban expansion are relatively rare.Remote sensing data,landscape metrics,and spatial statistics were used to characterize the urban landscape changes during the years from 1980 to 2013.Then,the potential determinants of island urban expansion were analyzed by integrating socioeconomic drivers,population factors,topographic variables,and policy guidance.The results indicate that Zhoushan Island has experienced a considerable urban expansion with an evident acceleration during the last period.Landscape changes in response to urban expansion varied with time,region,and scale.A general understanding of landscape metrics failed to reveal accurate dynamics for the urban landscape at a local level.At a block size of1 km,the urban landscape was more compact around the island urban center and the new developing zone,in contrast to the extensive and scattered pattern present across the entire region.Urban land primarily expanded from the urban center to the coastal regions due to topographic constraints and support from policy and economic benefits.The potential impact of the population factor decreased with urban growth,a finding that differs from several previous studies.The island urban dynamics observed in this study involved characteristics and differences that will guide future planning decisions and will provide a scientific case for urban development and sustainability with respect to islands and coastal regions in China.展开更多
基金the Natural Science Foundation of China(Grant No.41790425).
文摘Landscape fragmentation is generally viewed as an indicator of environmental stresses or risks,but the fragmentation intensity assessment also depends on the scale of data and the definition of spatial unit.This study aimed to explore the scale-dependence of forest fragmentation intensity along a moisture gradient in Yinshan Mountain of North China,and to estimate environmental sensitivity of forest fragmentation in this semi-arid landscape.We developed an automatic classification algorithm using simple linear iterative clustering(SLIC)and Gaussian mixture model(GMM),and extracted tree canopy patches from Google Earth images(GEI),with an accuracy of 89.2%in the study area.Then we convert the tree canopy patches to forest category according to definition of forest that tree density greater than 10%,and compared it with forest categories from global land use datasets,FROM-GLC10 and GlobeLand30,with spatial resolutions of 10 m and 30 m,respectively.We found that the FROM-GLC10 and GlobeLand30 datasets underestimated the forest area in Yinshan Mountain by 16.88%and 21.06%,respectively;and the ratio of open forest(OF,10%<tree coverage<40%)to closed forest(CF,tree coverage>40%)areas in the underestimated part was 2:1.The underestimations concentrated in warmer and drier areas occupied mostly by large coverage of OFs with severely fragmented canopies.Fragmentation intensity of canopies positively correlated with spring temperature while negatively correlated with summer precipitation and terrain slope.When summer precipitation was less than 300 mm or spring temperature higher than 4℃,canopy fragmentation intensity rose drastically,while the forest area percentage kept stable.Our study suggested that the spatial configuration,e.g.,sparseness,is more sensitive to drought stress than area percentage.This highlights the importance of data resolution and proper fragmentation measurements for forest patterns and environmental interpretation,which is the base of reliable ecosystem predictions with regard to the future climate scenarios.
基金Zhejiang Provincial Academy of Social Sciences of China(No.2015N076)the Funding from Chinese Ministry of Environmental Protection,China(No.STSN-05-11)+2 种基金National Science-Technology Support Plan Project,China(No.2015BAC02B06)Natural Science Foundation of Zhejiang Province,China(No.LQ14D010003)Zhejiang Provincial Social Science Foundation of China(No.16NDJC145YB)
文摘The intensified conflict between island urbanization and lagging supervision deserves special attention worldwide.Zhoushan Island has been an outstanding center of marine economic development in China but also one of the areas most threatened by recent human activities.To cope with this challenge,the development of a retrospective understanding of the spatiotemporal dynamics of island urban growth is a key prerequisite.Detailed,multi-scales,long-term studies on island urban expansion are relatively rare.Remote sensing data,landscape metrics,and spatial statistics were used to characterize the urban landscape changes during the years from 1980 to 2013.Then,the potential determinants of island urban expansion were analyzed by integrating socioeconomic drivers,population factors,topographic variables,and policy guidance.The results indicate that Zhoushan Island has experienced a considerable urban expansion with an evident acceleration during the last period.Landscape changes in response to urban expansion varied with time,region,and scale.A general understanding of landscape metrics failed to reveal accurate dynamics for the urban landscape at a local level.At a block size of1 km,the urban landscape was more compact around the island urban center and the new developing zone,in contrast to the extensive and scattered pattern present across the entire region.Urban land primarily expanded from the urban center to the coastal regions due to topographic constraints and support from policy and economic benefits.The potential impact of the population factor decreased with urban growth,a finding that differs from several previous studies.The island urban dynamics observed in this study involved characteristics and differences that will guide future planning decisions and will provide a scientific case for urban development and sustainability with respect to islands and coastal regions in China.
