Local adaptation to precipitation in the perennial grass Elymus elymoides: Trade‐offs between growth and drought resistance traits

Abstract

Understanding local adaptation to climate is critical for managing ecosystems in the face of climate change. While there have been many provenance studies in trees, less is known about local adaptation in herbaceous species, including the perennial grasses that dominate arid and semiarid rangeland ecosystems. We used a common garden study to quantify variation in growth and drought resistance traits in 99 populations of Elymus elymoides from a broad geographic and climatic range in the western United States. Ecotypes from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance: small leaves with low osmotic potential and high integrated water use efficiency (δ13C). Seasonality also influenced plant traits. Plants from regions with relatively warm, wet summers had large seeds, large leaves, and low δ13C. Irrespective of climate, we also observed trade‐offs between biomass production and drought resistance traits. Together, these results suggest that much of the phenotypic variation among E. elymoides ecotypes represents local adaptation to differences in the amount and timing of water availability. In addition, ecotypes that grow rapidly may be less able to persist under dry conditions. Land managers may be able to use this variation to improve restoration success by seeding ecotypes with multiple drought resistance traits in areas with lower precipitation. The future success of this common rangeland species will likely depend on the use of tools such as seed transfer zones to match local variation in growth and drought resistance to predicted climatic conditions.

Plant functional trait responses to cope with drought in seven cool-season grasses

“…Summer dormancy (S/SP) is acknowledged as one of the avoidance mechanisms in some perennial cool-season grasses, which enables plant survival by reducing water loss and reallocation of energy and storage in meristems to keep the plant alive and to support regrowth 34 . High genetic variation was observed between and within species for S/SP.…”

Local adaptation of seed and seedling traits along a natural aridity gradient may both predict and constrain adaptive responses to climate change

“…Thus, our observed result may stem from the interaction of abiotic and biotic selection pressures. Overall, our findings indicate that average aridity as well as precipitation variability both represent important selective forces structuring local adaptation across abiotic gradients (Pratt and Mooney, 2013;Muir and Angert, 2017;Blumenthal et al, 2021).…”

Cover-based allometric estimate of aboveground biomass of a non-native, invasive annual grass (Bromus tectorum L.) in the Great Basin, USA

“…Cheatgrass mitigates the effects of seasonal drought by germinating in early spring as soon as moisture is available and completing its life cycle before soil moisture decreases, and atmospheric vapor pressure deficit increases, during summer (Mack and Pyke, 1983). Perennial grasses like Elymus elymoides and Poa secunda, in contrast, must allocate fewer resources to aboveground growth during the period when moisture availability is high, and more to underground carbon storage to survive the summer drought (Blumenthal et al, 2021;Johnson et al, 2015). These differences in resource allocation strategies may explain why the SLA of cheatgrass, unlike the SLA of other grasses, does not appear to be as sensitive to precipitation.…”