Introduction:The ecological processes underlying the suppressive impacts of invasive species on native species diversity,both above-and below-ground,in non-native regions are not well understood.We therefore aimed to ...Introduction:The ecological processes underlying the suppressive impacts of invasive species on native species diversity,both above-and below-ground,in non-native regions are not well understood.We therefore aimed to investigate the cross-city biogeographic patterns of arbuscular mycorrhizal(AM)diversity in Conyza canadensis rhizosphere in native(North American)and non-native(Kashmir Himalayan)regions.Methods:We recovered AMF spores from rhizospheric soils of Conyza in native and non-native ranges,besides doing so from the uninvaded sites in the introduced region.DNA extracted from AMF spores was processed for cloning and PCR-RFLP of SSU rRNA gene to yield the restriction groups(RGs)followed by their sequence analysis to determine the sequence groups(SGs).Results:The results indicated greater diversity of RGs and SGs in Conyza rhizosphere in native than in non-native sites.In the introduced region,however,the AMF diversity was more in uninvaded than in invaded sites.The species composition of AMF varied significantly between native and non-native regions and so also between invaded and uninvaded habitats.Conclusions:Though difference in AMF diversity between Conyza invaded and uninvaded sites may be attributed to invasion,the role of other evolutionary factors seems likely for differences between the native and non-native regions.We suggest that the ecological processes underlying these evolutionary differences in two biogeographic regions,besides the intensity of urbanization,might play some role in these differences.展开更多
Introduction:Special economic zones(SEZs)emerge as new forces driving Asian economic transformation and triggering rapid landscape fragmentation.It is imperative to map out the present and future spatial patterns of S...Introduction:Special economic zones(SEZs)emerge as new forces driving Asian economic transformation and triggering rapid landscape fragmentation.It is imperative to map out the present and future spatial patterns of SEZs in order to understand how they undermine sustainability.Drawing from the experience of Iskandar Malaysia,one of the most successful SEZs in Southeast Asia,this study measures how biophysical and cultural landscapes are being affected by the most recent accelerated land development in the area.Methods:With aid of a hybrid model,namely the special economic zone landscape fragmentation measurement(SeLaFragment),which combines Geographic Information System(GIS),FRAGSTATS and NetLogo,the current and future fragmentation dynamics were analysed using land use data of the study area from the beginning of intensive landscape transformation in 2007 until 2010.Iskandar Malaysia’s cultural and biophysical landscapes were extensively fragmented.Results:The analysis showed that urban built-up areas increased from 13%in 2006 to 24%in 2010.Mangrove swamps were the worst affected ecosystem as they lost 20%of their areal coverage between 2006 and 2010.The simulation of the future scenarios suggested that,in the future,fragmentation and landscape homogenisation will intensify and pose more risks to landscape quality,functions and socio-ecological services.Conclusions:It is obvious that rapid landscape fragmentation compromises sustainability of a wide range of ecosystems and their functions and services in and around urban areas.It is difficult to see how existing environmental strategies have been effective in addressing the emerging sustainability challenges of rapid landscape change.The best way to respond to this kind of situation in the SEZs is by focusing on holistic approach to landscape sustainability.展开更多
Introduction:Karachi,a city of unique terrain and moderate tropical climate,is home to several mosquito species.The geographical distribution and density of these species may vary within the city,owing to their intera...Introduction:Karachi,a city of unique terrain and moderate tropical climate,is home to several mosquito species.The geographical distribution and density of these species may vary within the city,owing to their interaction with an ever-increasing population and urban settings.As a consequence,the prevalence of vector-borne diseases is unpredictable within the geographical limits of Karachi city.In this spatiotemporal study,1,156 mosquito samples were collected from 50 study sites with unique ecological characteristics within the city and a taxonomical exercise was conducted to investigate different vector species thriving in different months and seasons of the year.The main genera of mosquitoes were identified and categorized using a pictorial key based on the standard guidelines of the Walter Reed Biosystematics Unit,substantiated with ancillary literature.Results:Three important genera were found in Karachi:Anopheles,Aedes and Culex.Important subgenera were subsequently identified,based on their susceptibility to major vector-borne diseases.January had the highest concentration of adult mosquitoes,as the colder weather conditions were suitable for breeding.May recorded the lowest number,owing to excessively hot weather when most of the breeding pockets had dried out;less vegetation(in pre-monsoon conditions)prevented mosquito growth.Conclusions:Slum areas showed an abundance of malaria and dengue vectors,owing to poor hygiene conditions caused by open sewage drains.Hence,a major precaution is to raise awareness among people about mosquito-borne diseases.The breeding habitats of these vectors should be studied using geospatial technologies to improve spatial and temporal coverage.展开更多
基金by the Department of Foreign Affairs and International Trade(DFAIT)through the Canadian Bureau for International Education(CBIE)at the University Laval,Quebec,Canada.
文摘Introduction:The ecological processes underlying the suppressive impacts of invasive species on native species diversity,both above-and below-ground,in non-native regions are not well understood.We therefore aimed to investigate the cross-city biogeographic patterns of arbuscular mycorrhizal(AM)diversity in Conyza canadensis rhizosphere in native(North American)and non-native(Kashmir Himalayan)regions.Methods:We recovered AMF spores from rhizospheric soils of Conyza in native and non-native ranges,besides doing so from the uninvaded sites in the introduced region.DNA extracted from AMF spores was processed for cloning and PCR-RFLP of SSU rRNA gene to yield the restriction groups(RGs)followed by their sequence analysis to determine the sequence groups(SGs).Results:The results indicated greater diversity of RGs and SGs in Conyza rhizosphere in native than in non-native sites.In the introduced region,however,the AMF diversity was more in uninvaded than in invaded sites.The species composition of AMF varied significantly between native and non-native regions and so also between invaded and uninvaded habitats.Conclusions:Though difference in AMF diversity between Conyza invaded and uninvaded sites may be attributed to invasion,the role of other evolutionary factors seems likely for differences between the native and non-native regions.We suggest that the ecological processes underlying these evolutionary differences in two biogeographic regions,besides the intensity of urbanization,might play some role in these differences.
文摘Introduction:Special economic zones(SEZs)emerge as new forces driving Asian economic transformation and triggering rapid landscape fragmentation.It is imperative to map out the present and future spatial patterns of SEZs in order to understand how they undermine sustainability.Drawing from the experience of Iskandar Malaysia,one of the most successful SEZs in Southeast Asia,this study measures how biophysical and cultural landscapes are being affected by the most recent accelerated land development in the area.Methods:With aid of a hybrid model,namely the special economic zone landscape fragmentation measurement(SeLaFragment),which combines Geographic Information System(GIS),FRAGSTATS and NetLogo,the current and future fragmentation dynamics were analysed using land use data of the study area from the beginning of intensive landscape transformation in 2007 until 2010.Iskandar Malaysia’s cultural and biophysical landscapes were extensively fragmented.Results:The analysis showed that urban built-up areas increased from 13%in 2006 to 24%in 2010.Mangrove swamps were the worst affected ecosystem as they lost 20%of their areal coverage between 2006 and 2010.The simulation of the future scenarios suggested that,in the future,fragmentation and landscape homogenisation will intensify and pose more risks to landscape quality,functions and socio-ecological services.Conclusions:It is obvious that rapid landscape fragmentation compromises sustainability of a wide range of ecosystems and their functions and services in and around urban areas.It is difficult to see how existing environmental strategies have been effective in addressing the emerging sustainability challenges of rapid landscape change.The best way to respond to this kind of situation in the SEZs is by focusing on holistic approach to landscape sustainability.
文摘Introduction:Karachi,a city of unique terrain and moderate tropical climate,is home to several mosquito species.The geographical distribution and density of these species may vary within the city,owing to their interaction with an ever-increasing population and urban settings.As a consequence,the prevalence of vector-borne diseases is unpredictable within the geographical limits of Karachi city.In this spatiotemporal study,1,156 mosquito samples were collected from 50 study sites with unique ecological characteristics within the city and a taxonomical exercise was conducted to investigate different vector species thriving in different months and seasons of the year.The main genera of mosquitoes were identified and categorized using a pictorial key based on the standard guidelines of the Walter Reed Biosystematics Unit,substantiated with ancillary literature.Results:Three important genera were found in Karachi:Anopheles,Aedes and Culex.Important subgenera were subsequently identified,based on their susceptibility to major vector-borne diseases.January had the highest concentration of adult mosquitoes,as the colder weather conditions were suitable for breeding.May recorded the lowest number,owing to excessively hot weather when most of the breeding pockets had dried out;less vegetation(in pre-monsoon conditions)prevented mosquito growth.Conclusions:Slum areas showed an abundance of malaria and dengue vectors,owing to poor hygiene conditions caused by open sewage drains.Hence,a major precaution is to raise awareness among people about mosquito-borne diseases.The breeding habitats of these vectors should be studied using geospatial technologies to improve spatial and temporal coverage.
