| Biological invasions are one of the most detrimental aspects of global change, and a main factor of ecosystem degradation and biodiversity loss. Housing growth can foster biological invasions, but the relationship of housing growth and invasions is not well understood. The objective of my dissertation was to analyze the relationship between housing and the distribution of exotic invasive plants in forested areas to inform management and to understand the ecological consequences of future housing growth.My results showed first, that in New England's counties, housing was equally or more strongly related to richness of invasive exotic plants than other human and environmental factors. Suburban areas in contact with areas dominated by native vegetation were particularly important.Second, In the Baraboo Hills, Wisconsin, richness of invasive exotic plants was higher closer to houses and in area surrounded by more houses, as was invasive plant species cover. At the landscape scale, the distribution of invasive exotic plants was as strongly related to rural housing as to forest fragmentation (distance to roads and distance to forest edges). Invasive plant species with a history of ornamental use were most strongly related to housing.Third, ecological legacies of past housing patterns affect present distributions of invasive exotic plants. In the Baraboo Hills, invasive exotic plants were more strongly associated with housing in 1938 (particularly plant species with the longest use as landscaping plants), than with housing in 2001.Finally, I examined the spread of the invasive tree glossy privet ( Ligustrum lucidum) in Argentina using Landsat satellite imagery. Glossy privet has expanded greatly between 1983 and 2001. The proportion of glossy privet decreased with distance from the urban area.In summary, my results show that housing should be considered as a primary factor when managing for invasive exotic plants and as a main focus of research to clarify the role of humans in fostering exotic plant invasions. Expected urban growth could result in more invasions of exotic plants, and present housing patterns will determine exotic plant invasions for decades. |
