Sagebrush Ecosystems in a Changing Climate
Climate responses of sagebrush are needed to inform land managers on the stability and restoration of sagebrush ecosystems, which are an important but threatened habitat type. We evaluated climate responses of sagebrush using two approaches: 1) experimental manipulations of temperature and precipitation for natural plants in the field, and 2) assessment of how climate adaptation and weather have affected sagebrush seeding efforts on nearly 25 large-scale sagebrush seeding projects done over the past several decades.
Experimental warming increased growth of sagebrush in high-elevation meadows in the Teton Mountains, but had marginal or no effects at lower elevations sites (near Twin Falls and Boise, Idaho, respectively). Increased precipitation enhanced sagebrush abundance, along with flowering and stem growth, particularly when added in winter on deep soils. In the post-fire seeding study, we found sagebrush abundances to be highly variable across different seeding projects, and the variation was partly related to the climate of seeding and seed-source sites, and weather. Sagebrush seeds typically traveled hundreds of km and nearly 1000 m downhill from seed source/origins to seeding sites, from sites with colder minimum temperatures than the seeding sites. Big sagebrush is comprised of subspecies that differ in their climate adaptation, and many seeding projects received a subspecies that differed from the native type requested by the land managers. These climate transfers appeared important to the success of seedings: successful seedings imported seeds from sites having the same minimum temperatures. In failed seedings, seeds originated from relatively colder sites and, moreover, years having relatively warm minimum temperatures prevailed following planting.
These results suggest minimum temperature and winter precipitation responses are important factors in the climate adaptation and ecology of this desert shrub, and their consideration in climate vulnerability analyses and selection of seed sources is likely to improve land planning and restoration.