Background One issue in invasive plant ecology is identification of the factors related to the invasion process that increase number of non-native species.When invasion by non-native species increases,so does the prob...Background One issue in invasive plant ecology is identification of the factors related to the invasion process that increase number of non-native species.When invasion by non-native species increases,so does the probability that some non-native species will become harmful,or classified as invasive species,which disrupt natural ecosystems with attendant economic and social costs.I quantified patterns of how non-native species richness varied with vegetation types and human populations.To evaluate the relative importance of different predictor variables for invasion pathways in the conterminous United States,I modeled non-native plant species richness by county compared to current and historical human populations;greenhouses and nurseries;railroads,pipelines,transmission lines,and oil and gas wells;and land covers of impervious surface,development intensity categories,agriculture,and vegetation types.I also modeled these variables within vegetation types,excluding vegetation variables.Results To summarize patterns,non-native plant species richness increased from 72 to 200 with increasing human population density classes.Forests and forest land use mosaics had the greatest mean number of non-native plant species,ranging from 121 to 166,whereas grasslands and grassland mosaics had the least number of non-native plant species,about 70.For modeling variable importance,all combined variables had R^(2)values of 56%(random forests regressor)and 54%(cubist regressor)for predictions of withheld observations of non-native plant species rich-ness,with greenhouse density and percent forestlands as most influential variables.Single variables of greenhouses(R^(2)=29%),historical and current human populations(R^(2)=27%and 23%),impervious surface(25%),and medium intensity development(23%)were most associated with non-native plant species richness.For vegetation types,greenhouse and historical human population densities were influential variables particularly in forestlands,shrublands,and wetlands.Conclusions Based on these models展开更多
Embedded in an INTERREG IVc project called Flexible Transport Services （FTS） and Information and Communication Technology （ICT） platform for Eco-Mobility in urban and rural European areas （acronym： FLIPPER）, th...Embedded in an INTERREG IVc project called Flexible Transport Services （FTS） and Information and Communication Technology （ICT） platform for Eco-Mobility in urban and rural European areas （acronym： FLIPPER）, the University of Natural Resources and Applied Life Sciences in Vienna, Austria, analysed impacts of Flexible Transport Services focusing on Demand Responsive Public Transport （DRT）. This includes the analysis of site characteristics, the existing mobility demand, accessibility, area needs, current environmental impact, operational, financial and organisational constraints; designing of the service and definition of the supporting organisational measures required. Examples of realised services in Alpine areas in Austria confirm the effects on people＇s daily mobility and all its consequences towards society and environment. Main effects are the decrease of public funding needs and ensuring a basic transport supply even in rural areas. Additionally, there is a strong component of social inclusion in this service, increasing the quality of life capable to contribute to the deceleration of the out migration. As secondary effects, economic effects and environmental effects can be observed. The potential of these services are not fully utilised today and can be achieved through further extensions of service area as well as technical developments.展开更多
基金supported by the USDA Forest Service,Rocky Mountain Research Station.
文摘Background One issue in invasive plant ecology is identification of the factors related to the invasion process that increase number of non-native species.When invasion by non-native species increases,so does the probability that some non-native species will become harmful,or classified as invasive species,which disrupt natural ecosystems with attendant economic and social costs.I quantified patterns of how non-native species richness varied with vegetation types and human populations.To evaluate the relative importance of different predictor variables for invasion pathways in the conterminous United States,I modeled non-native plant species richness by county compared to current and historical human populations;greenhouses and nurseries;railroads,pipelines,transmission lines,and oil and gas wells;and land covers of impervious surface,development intensity categories,agriculture,and vegetation types.I also modeled these variables within vegetation types,excluding vegetation variables.Results To summarize patterns,non-native plant species richness increased from 72 to 200 with increasing human population density classes.Forests and forest land use mosaics had the greatest mean number of non-native plant species,ranging from 121 to 166,whereas grasslands and grassland mosaics had the least number of non-native plant species,about 70.For modeling variable importance,all combined variables had R^(2)values of 56%(random forests regressor)and 54%(cubist regressor)for predictions of withheld observations of non-native plant species rich-ness,with greenhouse density and percent forestlands as most influential variables.Single variables of greenhouses(R^(2)=29%),historical and current human populations(R^(2)=27%and 23%),impervious surface(25%),and medium intensity development(23%)were most associated with non-native plant species richness.For vegetation types,greenhouse and historical human population densities were influential variables particularly in forestlands,shrublands,and wetlands.Conclusions Based on these models
文摘Embedded in an INTERREG IVc project called Flexible Transport Services （FTS） and Information and Communication Technology （ICT） platform for Eco-Mobility in urban and rural European areas （acronym： FLIPPER）, the University of Natural Resources and Applied Life Sciences in Vienna, Austria, analysed impacts of Flexible Transport Services focusing on Demand Responsive Public Transport （DRT）. This includes the analysis of site characteristics, the existing mobility demand, accessibility, area needs, current environmental impact, operational, financial and organisational constraints; designing of the service and definition of the supporting organisational measures required. Examples of realised services in Alpine areas in Austria confirm the effects on people＇s daily mobility and all its consequences towards society and environment. Main effects are the decrease of public funding needs and ensuring a basic transport supply even in rural areas. Additionally, there is a strong component of social inclusion in this service, increasing the quality of life capable to contribute to the deceleration of the out migration. As secondary effects, economic effects and environmental effects can be observed. The potential of these services are not fully utilised today and can be achieved through further extensions of service area as well as technical developments.
