Abstract Detail


Mount, Hailey [1], Laughlin, Daniel [2], Smith, Melinda [3], Atkins, Dave [4], Griffin-Nolan, Robert [5], Knapp, Alan [3], Collins, Scott [6].

Evidence for a consistent trade-off between response to drought and neighbors in grasslands along a precipitation gradient.

Across their ranges plant species are dually limited by resource availability and competition. Investment in highly acquisitive tissues or highly conservative structural tissues pose a physiological trade-off for plants. Conservative populations should have higher fitness under belowground limitation from drought while acquisitive populations have higher fitness under light limitation from neighbors. Understanding how multiple populations with different resource acquisition strategies respond to these two key drivers concurrently will be key to predicting the future of grasslands in extreme drought. However, it remains unclear how fitness responses to abiotic and biotic contexts combine to structure grassland communities and how these dynamics change along gradients of resource availability. To address these knowledge gaps, we compared low density population growth rates (LDGR) between ambient and four-year extreme experimental drought treatments within plant communities representing five grassland types across the West-central US to evaluate species-level effects of drought on fitness. We observed a strong trade-off between species LDGR response to drought and LDGR response to neighbors within each grassland where the spread of strategies was equally broad in the most xeric and most mesic grasslands. Responses to drought were positively related to the average SLA of the local neighborhood and the leaf area or root diameter of the focal species, but the latter effects varied by grassland type. Perhaps most surprisingly, one species could exhibit opposite responses to drought and neighbor density at different grasslands despite exhibiting little intraspecific trait variation between populations. Our results suggest that individual species may vary in their trade-offs between response to drought and competition strategies depending on abiotic and biotic conditions at the neighborhood level, which may be related to local resource heterogeneity or frequency dependent interactions. We provide evidence for a consistent trade-off structuring communities across multiple grasslands and address a critical challenge facing plant ecologists in predicting how regionally diverse grasslands will respond to unprecedented anthropocentric climate change.

1 - 162 N Railroad St, Unit B, Laramie, WY, 82072, United States
2 - University Of Wyoming, Department Of Botany, 1000 E University Ave, Laramie, WY, 82071, United States
3 - Colorado State University, Biology, 1878 Campus Delivery, Fort Collins, CO, 80523, USA
4 - University of Wyoming, 1000 E University Ave, Laramie, WY, 82072, United States
5 -
6 - Department Of Biology, University Of New Mexico, Albuquerque, NM, 87131, United States

community ecology
low density population growth rates

Presentation Type: Poster
Number: PEC027
Abstract ID:916
Candidate for Awards:None

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