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- Title
Life-history strategy and extinction risk in the warm desert perennial spring ephemeral Astragalus holmgreniorum (Fabaceae).
- Authors
Van Buren, Renée; Searle, Allyson B.; Meyer, Susan E.
- Abstract
This study of Astragalus holmgreniorum examines its adaptations to the warm desert environment and whether these adaptations will enable it to persist. Its spring ephemeral hemicryptophyte life-history strategy is unusual in warm deserts. We used data from a 22-year demographic study supplemented with reproductive output, seed bank, and germinant survival studies to examine the population dynamics of this species using discrete-time stochastic matrix modeling. The model showed that A. holmgreniorum is likely to persist in the warm desert in spite of high dormant-season mortality. It relies on a stochastically varying environment with high inter-annual variation in precipitation for persistence, but without a long-lived seed bank, environmental stochasticity confers no advantage. Episodic high reproductive output and frequent seedling recruitment along with a persistent seed bank are adaptations that facilitate its survival. These adaptations place its life-history strategy further along the spectrum from "slower" to "faster" relative to other perennial spring ephemerals. The extinction risk for small populations is relatively high even though mean λs > 1 because of the high variance in year quality. This risk is also strongly dependent on seed bank starting values, creating a moving window of extinction risk that varies with population size through time. Astragalus holmgreniorum life-history strategy combines the perennial spring ephemeral life form with features more characteristic of desert annuals. These adaptations permit persistence in the warm desert environment. A promising conclusion is that new populations of this endangered species can likely be established through direct seeding.
- Subjects
MOJAVE Desert; ENDANGERED species; ASTRAGALUS (Plants); LEGUMES; SOWING; DESERTS
- Publication
Ecology & Evolution (20457758), 2021, Vol 11, Issue 22, p16188
- ISSN
2045-7758
- Publication type
Article
- DOI
10.1002/ece3.8301