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The Southwest Exotic Plant Mapping Program (SWEMP) is a collaborative effort between the United States Geological Survey and federal, tribal, state, county and non-governmental organization (NGO) partners in the southwest. This project is an ongoing effort to compile and distribute regional data on the occurrence of non-native invasive plants in the southwestern United States. The database represents the known sites (represented by a point location, i.e. site) of non-native invasive plant infestations within Arizona and New Mexico, and adjacent portions of California, Colorado, Nevada and Utah. These data, collected from 1911 to 2006, represent the field observations of various state, federal, tribal and county...
Categories: Data;
Types: Citation;
Tags: Alien plants,
Arizona,
California,
Colorado,
Exotic plants,
At the Appleton-Whittell Research Ranch, an ungrazed grassland preserve in southeastern Arizona, soil seed banks were sampled in June, August, and October 2002 and June 2003. Wildfire had previously burned 90% of the research ranch in May 2002. Seed density and species richness in burned native grassland (2 plots) were compared to those in burned exotic grassland (2 plots). Averaged over 4 sample dates, seed densities were as follows: burned native grassland, 591 ± 243.1 seeds ⋅ m–2 and 784 ± 334.9 seeds ⋅ m–2; burned exotic grassland, 501 ± 198.9 seeds ⋅ m–2 and 196 ± 123.8 seeds ⋅ m–2. Species richness in the seed bank, also averaged over 4 sample dates, was as follows: burned native grassland, 16.3 ± 1.7 species...
Categories: Publication;
Types: Citation;
Tags: Eragrostis curvula,
alien plants,
seed,
seed density
A gridline survey for exotic plant species was undertaken in 1983 and repeated in 2005 at the Desert Laboratory, a 352-ha natural area just west of downtown Tucson, Arizona, USA. Coordinate data gathered during the surveys were used to plot distributions, determine frequencies (number of coordinate locations), and assess percent change. Fifty-two exotic species were encountered in all, 34 in the first survey, 44 in the second. The proportion of ornamental exotics doubled over time, reaching 50% in 2005. Casual, naturalized, and invasive exotics comprised 44%, 40%, and 15% of species found during the surveys. Minimum residence time increased significantly from casual to naturalized to invasive species, suggesting...
Categories: Publication;
Types: Citation;
Tags: alien plants,
distribution maps,
invasions,
nonnative
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