Grassland responses to seasonal shifts in water availability
Date
2023
Authors
Hajek, Olivia Louise, author
Knapp, Alan K., advisor
von Fischer, Joseph, committee member
Cusack, Daniela, committee member
Schumacher, Russ, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Climate change is altering seasonal dynamics across a wide range of ecosystems with consequences that include shifts in phenology, timing of nutrient availability, and changes in plant community composition. Current research has primarily focused on temperature as the key driver for these shifts because of the strong directional trend with climate warming, however, alterations in the availability of water across seasons is an unappreciated aspect of climate change that can significantly influence ecosystem functioning. While changes in the seasonal availability of water are expected to be globally pervasive, grasslands may be particularly vulnerable because these ecosystems are often water-limited and have species with distinct seasons of growth. Therefore, my dissertation examined how seasonal patterns of water availability may shift with climate change in the grasslands of the US Great Plains and the ecological consequences of these shifts. I first explored several mechanisms by which climate change is altering the seasonal water balance, using the Great Plains as a case study. Building on that, I then designed two field experiments in semi-arid grasslands that altered seasonal patterns of water availability to understand how these shifts affected ecosystem function and structure (primarily C3 vs C4 grasses). Overall, the results from both field experiments suggest that shifts in the seasonality of water availability with climate change will alter carbon cycling dynamics, shift seasonal patterns of canopy albedo, and differentially impact C3 vs. C4 species in the semi-arid grasslands of the US Great Plains. Thus, my research confirms the importance of this aspect of climate change and provides evidence that seasonal shifts in water availability can alter ecosystem processes and drive compositional changes. Since grasslands provide many economically and ecologically valuable services, understanding how climate change will impact these systems is critical for land managers and policymakers to make informed decisions.