CAREER: Feedbacks From Drought on the Phytochemical Landscape

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The western United States is suffering from the worst drought in centuries. To predict how drought will affect the environment, the effects of drought studies must include natural variation across space in resources and in food webs. Plants produce mixtures of nutrients and toxins, and this chemistry varies genetically and with changes in the environment. Because plants use resources to form the base of food webs on land, plant chemistry can link variation in resources with variation in food webs. An understanding of how plant chemistry responds to extreme drought could help in understanding plants in these larger systems. This CAREER award will improve understanding of (a) how plant chemistry changes in response to drought at the scales of individual plants and of plant communities, and (b) the relationship of these changes to changes in plant-animal interactions and decomposition. The project is based in the Great Basin Desert on the border between Nevada and California, where extreme drought is now commonplace. The award will test the hypothesis that extreme drought reduces environmental variation, with consequences for system function. The project includes training and research participation of first generation students, outdoor science experience for grade school students, and research opportunities for community scientists in Nevada. Drought imposes acute stress on plant metabolism, which may reduce the strength of feedbacks between trophic interactions and soil carbon dynamics, simplifying ecological communities. To test this hypothesis, the award will support drought experiments on focal plant individuals and on plant communities. Using outdoor gardens of western milkweed, the research will assess how the amount and variability of water impacts plant-herbivore-predator interactions, as well as how plant tissues from different watering treatments influence decomposition and soil respiration. Using drought shelters and rainfall additions in plant communities in sagebrush ecosystems, the research will assess how drought affects plant chemistry at the plot scale, including changes in the chemistry of individuals and changes due to differential survival and recruitment in the community. These measurements will then be related to changes in arthropod communities and in soil carbon dynamics in a spatially explicit design. Plant chemistry will be assessed using untargeted metabolomics approaches that consider the composition and diversity of compounds as well as their concentrations. The complexity of plant-animal interactions will be also manipulated in the milkweed gardens using factorial combinations of herbivores and their predators to test the importance of such trophic feedbacks. The work will provide insight into the dynamics of future ecosystems in the American West and the extent to which we can predict those dynamics through an understanding of plant chemistry. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.