Landscape correlates of forest plant invasions: A high‐resolution analysis across the eastern United States |
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| Authors: | Kurt Riitters Kevin Potter Basil V Iannone III Christopher Oswalt Songlin Fei Qinfeng Guo |
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| Affiliation: | 1. USDA Forest Service, Southern Research Station, Research Triangle Park, NC, USA;2. Department of Forestry and Environmental Resources, North Carolina State University, Research Triangle Park, NC, USA;3. School of Forest Resources and Conservation, University of Florida, Gainesville, FL, USA;4. USDA Forest Service, Southern Research Station, Knoxville, TN, USA;5. Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA |
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| Abstract: | Aim Invasive species occurrence is often related to the anthropogenic context of a given area. Quantifying the effects of roads is of particular interest as roads are a major vector for invasion. Our objective was to further quantify the effects of roads on forest plant invasion through a macroscale, high‐resolution investigation to assist effective invasion control and mitigation. Location Eastern United States. Methods Using invasive plant data from 23,039 forest inventory plots in 13 ecological provinces, we employed logistic regression to relate the odds of invasion to distance from a road, with adjustments for broadscale differences attributable to ecological provinces, and local scale differences in productivity, forest fragmentation and land use. Results The overall proportion (P) of invaded plots was 0.58 (0.65 for plots within 50 m of a road), and the highest odds (P/1 ? P) of invasion were found in relatively more productive, fragmented forest in landscapes with more than 10% agriculture or developed land cover. Wald chi‐square statistics indicated the best predictor of the odds of invasion was ecological province, followed by land use, productivity, forest fragmentation and distance from a road. Depending on the province, the adjusted odds of invasion decreased by up to 23% (typically 4%–10%) per 100 m distance from a road. The adjusted probability of invasion approached zero in only three provinces, for the least productive, least fragmented forest that was at least 2,000 m from a road in landscapes with less than 10% agricultural or developed land cover. Main conclusions In the eastern United States, the existence of a nearby road is less important than the landscape context associated with the road. A purely road‐mediated effect has little practical meaning because anthropogenic activities and roads are pervasive and confounded. |
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| Keywords: | fragmentation invasive species land use macroscale road ecology |
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