Effective rangeland management requires planning for the impacts of climate change. Against a backdrop of rising temperature, the US Southwest is experiencing fewer, larger precipitation events, and longer dry intervals between these events. While abundant research addresses chronic temperature and precipitation shifts, we lack the ability to forecast the impacts of extreme-duration drought on rangeland ecosystem services. There is a critical need for improved prediction of rangeland plant community composition, annual forage production, and seasonal shifts in production timing under this ongoing “temporal repackaging” of rainfall.

To address this knowledge gap, we have constructed a transformative, large-scale, long-term, rainfall manipulation experiment in the Santa Rita Experimental Range (RainManSR). The location provides novel opportunities to study in-depth the impact of extreme-duration drought on soil hydrology, plant community composition, ecosystem function, and total above- and below-ground vegetation production.

Significance

Key ecosystem services provided by Southwest rangelands include wildlife habitat, forage and grazing, soil conservation, and taking up atmospheric carbon, thereby slowing climate change. In particular, Arizona desert rangelands are highly vulnerable to climate extremes. Assessing resilience of grassland biodiversity and forage production to longer droughts will empower ranchers and other land managers to make climate adaptation decisions. This research will also improve our ability to represent climate extremes in operational forecasting tools such as Grass-Cast — a regional decision support tool produced in part by members of our team and used widely by public and private stakeholders. Our long-term goal is decision support to Southwest land managers on grazing rotations and allotments, woody vegetation management, wildlife habitat, wildfire management, agricultural planning, and land restoration. This work addresses multiple AIR themes including (1) Applied Carbon Science and Management, (2) Climate Science, Adaptation and Resilience Solutions; (3) Biodiversity, Conservation & Ecosystems; and (4) Arid Lands & Resources. Because the proposed work will measure mechanisms of grassland response to temporal changes in rainfall, it can readily be scaled to predicting climate resilience across the Southwest.