Astragalus mulfordiae (Mulford’s milkvetch): modeling population growth rates and the effects of climate

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This study aims to identify relationships between Mulford’s milkvetch (Astragalus mulforidae) demographic trends and climatic variables over multiple years, based on data collected both in Idaho and Oregon. Overall, populations are decreasing in both states, more accentuated in Idaho than Oregon. Count-based extinction probability was somewhat slower for Oregon populations, even though the tendency is for a collapse of the populations. Detailed data from Oregon populations allowed for a more thorough demographic analysis, arriving to the same conclusions of the species being under imminent risk. Compared to other climate variables, years with extreme hot and dry conditions showed less of a negative effect on simulated stochastic growth, and a deacceleration on quasi-extinction probability. Climate projections for the area indicate an increase in the number of dry hot years, which potentially could delay the forthcoming collapse of the species, but not avoid it. While the projected increase in drought conditions will likely alter community composition and productivity, disturbance requirements, and erosion; Mulford’s milkvetch adaptation to new climate regimes is unknown. <br>

Mulford’s milkvetch populations are in clear decline throughout its range, and projections for the near future suggest a collapse of the species in the near future.

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Reference Code: U22DIA01IDUS <br>

Full Citation: Diaz, Soledad, Scott Harris and Tom Kaye. 2022. Astragalus mulfordiae (Mulford’s milkvetch): modeling population growth rates and the effects of climate. Unpublished report for USDI Bureau of Land Management, Vale District. Institute for Applied Ecology, Corvallis, Oregon. 17 pp. plus appendices <br>

Location: ELECTRONIC FILE - BOTANY: PLANT SPECIES: Astragalus mulfordiae <br>

Keywords: Astragalus mulfordiae, Mulford’s milkvetch, Idaho, Oregon <br>