Cattle trampling increases dormant season mortality of a globally endangered desert milkvetch

Autor: Susan E. Meyer, Allyson B. Searle
Rok vydání: 2020
Předmět:
Zdroj: Journal for Nature Conservation. 56:125868
ISSN: 1617-1381
DOI: 10.1016/j.jnc.2020.125868
Popis: Conflicting priorities for livestock grazing management in the context of rare plant conservation are common worldwide, especially in semiarid and arid ecosystems, where open-range livestock grazing is a primary land use. Detailed information on the interaction between livestock impacts and rare plant demography would facilitate improved management, yet this information is most often not available. In this study we examined the direct impacts of cattle trampling on dormant season survival of Astragalus holmgreniorum (Fabaceae), a globally endangered perennial spring ephemeral of the northeastern Mojave Desert, USA. Current management restricts livestock access to the dormant season, when plants are not active above-ground, but monitoring indicates possible population decline under this regime. We tagged >2100 A. holmgreniorum plants to document dormant season survival and quantified cattle trampling and other disturbance impacts in small plots at six sites with contrasting disturbance regimes. We documented disturbance impacts on survival at the site, plot, and individual plant level across two dormant season iterations. We consistently found significant negative relationships between plant dormant season survival and cattle impacts. Plants at sites with heavy cattle trampling were up to five times more likely to experience mortality than those at sites with low cattle impact. Other surface disturbances (rodent activity, human impacts, water erosion) were also quantified but contributed substantially to reduced survival in only one case of water erosion disturbance. We conclude that grazing management in A. holmgreniorum critical habitat on federal land may require modification to reduce extinction risk for this federally listed endangered species.
Databáze: OpenAIRE