Abstract
The current loss of biodiversity has put 50,000 plant species at an elevated risk of extinction worldwide. Conserving at-risk species is often complicated by covariance or nonadditivity among threats, which makes it difficult to determine optimal management strategies. We sought to demographically quantify covariance and nonadditive effects of more threats on more rare plant species than ever attempted in a single analysis. We used 1082 population reports from 186 populations across 3 U.S. states of 27 rare, herbaceous plant species collected over 15 years by citizen scientists. We used a linear mixed-effects model with 4 threats and their interactions as fixed predictors, species as a random predictor, and annual growth rates as the response. We found a significant 3-way interaction on annual growth rates; rare plant population sizes were reduced by 46% during the time immediately after disturbance when populations were also browsed by deer (Odocoileus virginianus) and had high levels of encroachment by woody species. This nonadditive effect should be considered a major threat to the persistence of rare plant species. Our results highlight the need for comprehensive, multithreat assessments to determine optimal conservation actions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1029-1034 |
| Number of pages | 6 |
| Journal | Conservation Biology |
| Volume | 34 |
| Issue number | 4 |
| DOIs | |
| State | Published - Aug 1 2020 |
Funding
We thank the hundreds of POC volunteers for the countless hours of data collection that contributed to this work. We thank M. Albrecht, A. Smith, S. Mangan, and C. Stein for their thoughtful reviews on a previous version of this article. Funding was provided by the Alexander von Humboldt Foundation as part of the Alexander von Humboldt Professorship of T.M.K. Funding for the POC program was provided by Illinois Department of Natural Resources, Cook County Forest Preserves, Openlands of Chicago, U.S. Forest Service, Toyota TogetherGreen, The Nature Conservancy of Illinois, Great Lakes Restoration Initiative, National Fish and Wildlife Foundation, U.S. Environmental Protection Agency, Gaylord and Dorothy Donnelley Foundation, Garden Club of America, Root‐Pike Watershed Initiative Network, U.S. Fish and Wildlife Service through the Chicago Wilderness Alliance, Wisconsin Department of Natural Resources, CorLands, and Illinois Department of Agriculture.
Keywords
- disturbance
- especies leñosas
- especies raras de plantas
- evaluación de amenazas
- habitat management
- herbivoría de mamíferos
- human intrusion
- intrusión humana
- invasión
- mammalian herbivory
- manejo de hábitat
- perturbación
- species’ viability
- threat assessment
- viabilidad de especies
- woody species encroachment
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Ecology
- Nature and Landscape Conservation
