Urban growth is a key indicator of economic development.At the same time,haphazard urban growth creates serious socioeconomic,environmental and urban land management problems.In this context,understanding the process ...Urban growth is a key indicator of economic development.At the same time,haphazard urban growth creates serious socioeconomic,environmental and urban land management problems.In this context,understanding the process of urban landscape change is important for guiding the sustainable growth of urban areas.This study analyzes the urban land changes during 1990–2018 in two metropolitan cities of Gandaki basin:Pokhara and Bharatpur.Landsat satellite images were analyzed using supervised classification methods.The results revealed that the built-up area has increased significantly by 300%in Pokhara and by nearly 500%in the Bharatpur during the past 28 years.Population growth,migration from surrounding areas due to urban facilities and the easy lifestyle in cities were found to be major determinants of urban growth within the study area.In addition,the changing urban definition and expansion of municipal boundaries are key factors for rapid urban growth.Both cities are likely to grow in the future as they are both located in areas that encompass the high levels of commercial activity and modern service facilities.The haphazard urban growth should be minimized through planning and policies for sustainable urban development.展开更多
Biological invasion is one of the leading causes of global biodiversity loss and the degradation of ecosystem services.Wetlands situated within human-dominated landscapes are particularly vulnerable to these invasions...Biological invasion is one of the leading causes of global biodiversity loss and the degradation of ecosystem services.Wetlands situated within human-dominated landscapes are particularly vulnerable to these invasions.However,extent of plant invasions in many wetlands remains insufficiently known for guiding effective management.This study aimed to analyze the status of plant invasions in the Lake Cluster of the Pokhara Valley(LCPV),a Ramsar site encompassing nine wetlands in the rapidly urbanizing region of central Nepal.A total of 89 plots(20 m×5 m)along the lakeshore were surveyed to record the richness and coverage of both native and naturalized plant species.Water samples were also collected from each plot to measure nitrogen and phosphorus levels.Data were analyzed using analysis of variance,generalized linear models,multiple regression,and canonical correspondence analysis.The results revealed significant variation in native and naturalized species richness and composition across the wetlands.Naturalized species richness was positively correlated with native species richness.Species richness was the highest in the smallest wetlands site(i.e.,Kamalpokhari)and the species composition of the largest wetland site with the highest tourist visitation(i.e.,Phewa lake)was distinctly different from the rest of the other wetlands.Species composition similarity increased when only the naturalized species were accounted,relative to the scenario when only native species were considered,suggesting increased homogenization due to plant invasions.No significant effects of nitrogen or phosphorus levels on species richness or coverage were found.Understanding these local drivers that affect naturalized plant diversity in the LCPV can inform management strategies to protect these wetlands from further invasion by alien species.展开更多
基金The National Natural Science Foundation of China(41761144081)The Second Tibetan Plateau Scientific Expedition and Research(2019QZKK2203)+1 种基金The International Partnership Program of Chinese Academy of Sciences(131C11KYSB20160061)The Chinese Academy of Sciences-The World Academy of Sciences(CAS-TWAS)President’s Fellowship Program for Ph D Study
文摘Urban growth is a key indicator of economic development.At the same time,haphazard urban growth creates serious socioeconomic,environmental and urban land management problems.In this context,understanding the process of urban landscape change is important for guiding the sustainable growth of urban areas.This study analyzes the urban land changes during 1990–2018 in two metropolitan cities of Gandaki basin:Pokhara and Bharatpur.Landsat satellite images were analyzed using supervised classification methods.The results revealed that the built-up area has increased significantly by 300%in Pokhara and by nearly 500%in the Bharatpur during the past 28 years.Population growth,migration from surrounding areas due to urban facilities and the easy lifestyle in cities were found to be major determinants of urban growth within the study area.In addition,the changing urban definition and expansion of municipal boundaries are key factors for rapid urban growth.Both cities are likely to grow in the future as they are both located in areas that encompass the high levels of commercial activity and modern service facilities.The haphazard urban growth should be minimized through planning and policies for sustainable urban development.
基金The Hariyoban Program,WWF-Nepal(under grant agreement#GX67)the Rector’s Office,Tribhuvan University provided partial financial support for this work。
文摘Biological invasion is one of the leading causes of global biodiversity loss and the degradation of ecosystem services.Wetlands situated within human-dominated landscapes are particularly vulnerable to these invasions.However,extent of plant invasions in many wetlands remains insufficiently known for guiding effective management.This study aimed to analyze the status of plant invasions in the Lake Cluster of the Pokhara Valley(LCPV),a Ramsar site encompassing nine wetlands in the rapidly urbanizing region of central Nepal.A total of 89 plots(20 m×5 m)along the lakeshore were surveyed to record the richness and coverage of both native and naturalized plant species.Water samples were also collected from each plot to measure nitrogen and phosphorus levels.Data were analyzed using analysis of variance,generalized linear models,multiple regression,and canonical correspondence analysis.The results revealed significant variation in native and naturalized species richness and composition across the wetlands.Naturalized species richness was positively correlated with native species richness.Species richness was the highest in the smallest wetlands site(i.e.,Kamalpokhari)and the species composition of the largest wetland site with the highest tourist visitation(i.e.,Phewa lake)was distinctly different from the rest of the other wetlands.Species composition similarity increased when only the naturalized species were accounted,relative to the scenario when only native species were considered,suggesting increased homogenization due to plant invasions.No significant effects of nitrogen or phosphorus levels on species richness or coverage were found.Understanding these local drivers that affect naturalized plant diversity in the LCPV can inform management strategies to protect these wetlands from further invasion by alien species.
