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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #423053
Research Project: Developing Precision Management Strategies to Enhance Productivity, Biodiversity, and Climate Resilience in Rangeland Social-ecological Systems

Location: Rangeland Resources & Systems Research

Title: Flexible phenology of a C4 grass linked to resiliency to seasonal and multiyear drought events in the American Southwest

Author
item FINGER-HIGGENS, REBECCA - Us Geological Survey (USGS)
item Hoover, David
item KNIGHT, ANNA - Us Geological Survey (USGS)
item SCHLAEPFER, DANIEL - Northern Arizona University
item DUNIWAY, MICHAEL - Us Geological Survey (USGS)

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2025
Publication Date: 5/14/2025
Citation: Finger-Higgens, R., Hoover, D.L., Knight, A.C., Schlaepfer, D.R., Duniway, M.C. 2025. Flexible phenology of a C4 grass linked to resiliency to seasonal and multiyear drought events in the American Southwest. New Phytologist. 15(5). Article e71435. https://doi.org/10.1002/ece3.71435.
DOI: https://doi.org/10.1002/ece3.71435

Interpretive Summary: Increasing droughts and aridity may cause shifts in plant phenology and caused increased mortality. We examined the responses of two dominant Colorado Plateau grasses species to experimental droughts. We measured plant phenology and mortality biweekly during the four years of experimental drought and for two years of recovery to examine the impacts on these key species. Our results suggest that the grasses differed in their sensitivity; the cool-season grass (Indian Ricegrass) showed low drought resilience and high mortality, while the warm-season grass (James' galleta grass) had higher drought resilience and greater phenological flexibility. These results suggest that drought may not affect all grasses equally, and that a hotter drier future may lead to a different plant community on the Colorado Plateau.

Technical Abstract: 1. Rising temperatures are predicted to further limit dryland water availability as droughts become more intense and frequent and seasonal precipitation patterns shift. Vegetation drought stress may increase mortality and cause declines and delays in phenological events, thereby impacting species’ capacity for persistence and recovery from extreme drought conditions. 2. We compare phenological responses of two common dryland perennial grass species, Achnatherum hymenoides (C3) and Pleuraphis jamesii (C4), to four years of experimentally imposed precipitation drought treatments (cool season, warm season, ambient), followed by two years of recovery on the Colorado Plateau, USA. Tagged individual grasses from both species were monitored biweekly and assessed for phenological metrics and mortality. 3. The C3 grass exhibited less phenological flexibility to both seasonal and interannual drought conditions and experienced high rates of mortality, thus reducing resiliency. Conversely, the C4 grass showed more phenological plasticity during imposed drought treatments, with treatment effects diminishing in the two-year recovery period despite a severe ambient drought. 4. Results suggest that plant photosynthetic strategies may impact plant resistance and resiliency to drought. Here, C3 grass populations may decline, potentially shifting cool dryland ecosystem into a system comprised predominantly of warm season adapted species.