Land use change and landscape patterns have a large effect on land productivity and ecosystem biodiversity. Based on geographical information system technology and remote sensing data related to land use and land cove...Land use change and landscape patterns have a large effect on land productivity and ecosystem biodiversity. Based on geographical information system technology and remote sensing data related to land use and land cover of Jiangsu and Zhejiang provinces and Shanghai （Jiang-Zhe-Hu area）, we analyzed patterns of landscape change and predicted land use dynamics using the CA-MARKOV model. We also analyzed the conversion rate and area among landscape classes using the CA-Markov model. We found that from 1980 to 2005, there was a significant decrease in the area of farmland, and much of this landscape was transformed into settlements. Most of the landscape classes have become fragmented and isolated. The areas of farmland, settlement land and water tend to be complex in their shape and spatial clustering. The shapes of other land class patches have become simpler, and overall landscape fragmentation has increased. Landscape diversity and heterogeneity have increased. The CAMARKOV model predicted that settlement land will continue to grow from 2005 to 2015, but the speed of conversion will be reduced. The speed of the reduction in farmland and forest has increased, and increased settlement areas are clustered along the Yangtze River. Land use dynamics and change in the landscape pattern have affected land productivity and made the ecosystem more sensitive and fragile in this study region.展开更多
Bush encroachment is widely distributed in arid and semi-arid regions, and it has a serious impact on livestock production, especially in Africa where livestock is a primary source for the livelihoods of many people. ...Bush encroachment is widely distributed in arid and semi-arid regions, and it has a serious impact on livestock production, especially in Africa where livestock is a primary source for the livelihoods of many people. In this study, methods of supervised classification and decision tree classification, and indexes of a land use change significance index（Ci） and a single land use dynamic degree, were applied to remote sensing imagery of Ethiopia for 1986–2016. The results show the dynamic characteristics of grassland bush encroachment in low altitude areas（pastures 1500 m above sea level） of Ethiopia in the 30 year period studied. The results revealed several interesting features of this phenomenon.（1） The area of bush encroachment showed an increasing trend, with a maximum of 3.74×10^3 km^2 in 2003, which represented 68.97% of the total area, and declined slightly from 2003~2016.（2） Among classification types, the area of severe shrub grassland was the largest, accounting for 28.36–49.10% of the total area, while the area of moderate bush encroachment accounted for 9.77–16.68%, and slight bush encroachment accounted for 5.52–7.57%.（3） The expansion rate of shrubby grassland was 0.74% for the 30 year period, while the average annual expansion rate was 2.16% for the 8 years from 1995–2003.（4） Forest land and grassland were the two main land use types of shrub grassland transformation in low altitude areas and bush encroachment changed large amounts of forest land into grassland due to shrub grassland management. The results of this study provide basic data for revealing the impacts of development processes on subsequent bush encroachment and can inform better management for the sustainable development of grasslands in low altitude systems.展开更多
基金National Natural Science Foundation of China (41271556)the National Basic Research Priorities Program of China (2007FY110300)
文摘Land use change and landscape patterns have a large effect on land productivity and ecosystem biodiversity. Based on geographical information system technology and remote sensing data related to land use and land cover of Jiangsu and Zhejiang provinces and Shanghai （Jiang-Zhe-Hu area）, we analyzed patterns of landscape change and predicted land use dynamics using the CA-MARKOV model. We also analyzed the conversion rate and area among landscape classes using the CA-Markov model. We found that from 1980 to 2005, there was a significant decrease in the area of farmland, and much of this landscape was transformed into settlements. Most of the landscape classes have become fragmented and isolated. The areas of farmland, settlement land and water tend to be complex in their shape and spatial clustering. The shapes of other land class patches have become simpler, and overall landscape fragmentation has increased. Landscape diversity and heterogeneity have increased. The CAMARKOV model predicted that settlement land will continue to grow from 2005 to 2015, but the speed of conversion will be reduced. The speed of the reduction in farmland and forest has increased, and increased settlement areas are clustered along the Yangtze River. Land use dynamics and change in the landscape pattern have affected land productivity and made the ecosystem more sensitive and fragile in this study region.
基金China–Africa Joint Research Centre Project of the Chinese Academy of Sciences(SAJC201610)Science and Technology partnership ProgramMinistry of Science and Technology of China(KY201702010)
文摘Bush encroachment is widely distributed in arid and semi-arid regions, and it has a serious impact on livestock production, especially in Africa where livestock is a primary source for the livelihoods of many people. In this study, methods of supervised classification and decision tree classification, and indexes of a land use change significance index（Ci） and a single land use dynamic degree, were applied to remote sensing imagery of Ethiopia for 1986–2016. The results show the dynamic characteristics of grassland bush encroachment in low altitude areas（pastures 1500 m above sea level） of Ethiopia in the 30 year period studied. The results revealed several interesting features of this phenomenon.（1） The area of bush encroachment showed an increasing trend, with a maximum of 3.74×10^3 km^2 in 2003, which represented 68.97% of the total area, and declined slightly from 2003~2016.（2） Among classification types, the area of severe shrub grassland was the largest, accounting for 28.36–49.10% of the total area, while the area of moderate bush encroachment accounted for 9.77–16.68%, and slight bush encroachment accounted for 5.52–7.57%.（3） The expansion rate of shrubby grassland was 0.74% for the 30 year period, while the average annual expansion rate was 2.16% for the 8 years from 1995–2003.（4） Forest land and grassland were the two main land use types of shrub grassland transformation in low altitude areas and bush encroachment changed large amounts of forest land into grassland due to shrub grassland management. The results of this study provide basic data for revealing the impacts of development processes on subsequent bush encroachment and can inform better management for the sustainable development of grasslands in low altitude systems.
