Skip to content

Herbaceous plant communities respond more to seasonal precipitation than cumulative drought in the hot deserts of the United States

Published Article

United States, Mexico

Publication date: August 12, 2025

File format: URL

View resource

Hot deserts of the southwestern United States are facing more frequent and intense drought under climate change, yet plant communities may respond differently depending on their composition. In a four‑year rain‑exclusion experiment across six sites in the Chihuahuan, Sonoran and Mojave Deserts, researchers reduced ambient rainfall by 66% and measured herbaceous plant responses. Vegetative cover consistently tracked seasonal precipitation, while species richness and evenness varied among sites. At half the sites, richness increased with rainfall; at others, evenness declined. Overall, community structure was shaped more by seasonal precipitation than by cumulative drought, revealing high resilience of herbaceous desert communities even under prolonged, extreme drought conditions.

Subject Tags

  • Climate resilience
  • Desert

Abstract

  • The hot deserts of the southwestern United States are experiencing increased frequency, severity, and duration of drought due to anthropogenic climate change. Plant communities in these deserts differ in composition, specifically the abundance of annual and perennial species, which could differentiate responses among these ecosystems to drought. Thus, identifying how these desert plant communities respond to prolonged, severe drought is critical to assess vulnerability to climate change. We measured the response of herbaceous plant communities to 4 years of experimentally imposed severe drought in Chihuahuan, Sonoran, and Mojave Desert sites in the southwestern U.S.
  • We imposed year-round passive rain exclusion treatments with a 66% reduction in ambient rainfall for 4 years at two sites in each of the three US hot deserts. We measured plant species composition and abundance in treatment and control plots during the peak growing season.
  • Vegetative cover increased with seasonal precipitation at all six sites. Species richness and evenness varied in response to drought across all sites over the duration of the experiment. At three of the six sites, species richness increased with seasonal precipitation and at three sites species evenness decreased with seasonal precipitation.
  • In general, we found that community structure was linked to seasonal precipitation more so than cumulative drought in these herbaceous communities of southwestern U.S. deserts, and that these desert communities are highly resilient following prolonged, extreme drought.

Citation

Ohlert, T., Patton, M., Hallmark, A., Hamilton, G., & Collins, S. L. (2025). Herbaceous plant communities respond more to seasonal precipitation than cumulative drought in the hot deserts of the United States. Plant Biology. https://doi.org/10.1111/plb.70083

TNC Authors