@article {753,
	title = {Human impacts, plant invasion, and imperiled plant species in California},
	journal = {Ecological Applications},
	volume = {16},
	year = {2006},
	month = {2006},
	pages = {1338-1350},
	abstract = {Invasive species are one of the fastest growing conservation problems. These species homogenize the world{\textquoteright}s flora and fauna, threaten rare and endemic species, and impose large economic costs. Here, we examine the distribution of 834 of the more than 1000 exotic plant taxa that have become established in California, USA. Total species richness increases with productivity; however, the exotic flora is richest in low-lying coastal sites that harbor large numbers of imperiled species, while native diversity is highest in areas with high mean elevation. Weedy and invasive exotics are more tightly linked to the distribution of imperiled species than the overall pool of exotic species. Structural equation modeling suggests that while human activities, such as urbanization and agriculture, facilitate the initial invasion by exotic plants, exotics spread ahead of the front of human development into areas with high numbers of threatened native plants. The range sizes of exotic taxa are an order of magnitude smaller than for comparable native taxa. The current small range size of exotic species implies that California has a significant {\textquoteleft}{\textquoteleft}invasion debt{\textquoteright}{\textquoteright} that will be paid as exotic plants expand their range and spread throughout the state.},
	keywords = {California, dispersal, exotic plants, extinction, global biodiversity hotspot, habitat loss, invasive species, rare species, species richness, structural equation models},
	url = {http://www.esajournals.org/esaonline/?request=get-abstract\&issn=1051-0761\&volume=016\&issue=04\&page=1338},
	author = {Seabloom, E. W. and Williams, J. W. and Slayback, D. and Stoms, D. M. and Viers, J. H. and Dobson, A. P.}
}
@article {832,
	title = {Anthropogenic impacts upon plant species richness and NPP in California},
	journal = {Ecology Letters},
	volume = {8},
	year = {2005},
	month = {2005},
	pages = {127-137},
	abstract = {We assess the importance of anthropogenic land-use, altered productivity, and species invasions for observed productivity-richness relationships in California. To this end, we model net primary productivity (NPP) c. 1750 AD and at present (1982-1999) and map native and exotic vascular plant richness for 230 subecoregions. NPP has increased up to 105\% in semi-arid areas and decreased up to 48\% in coastal urbanized areas. Exotic invasions have increased local species diversity up to 15\%. Human activities have reinforced historical gradients in species richness but reduced the spatial heterogeneity of NPP. Structural equation modelling suggests that, prior to European settlement, NPP and richness were primarily controlled by precipitation and other abiotic variables, with NPP mediating richness. Abiotic variables remain the strongest predictors of present NPP and richness, but intermodel comparisons indicate a significant anthropogenic impact upon statewide distributions of NPP and richness. Exotic and native species each positively correlate to NPP after controlling for other variables, which may help explain recent reports of positively associated native and exotic richness.},
	keywords = {California, human impacts, Land cover change, net primary productivity, species richness, structural equation models},
	url = {<Go to ISI>://000226491200001},
	author = {Williams, J. W. and Seabloom, E. W. and Slayback, D. and Stoms, D. M. and Viers, J. H.}
}
