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ARS Home » Plains Area » El Reno, Oklahoma » Oklahoma and Central Plains Agricultural Research Center » Livestock, Forage and Pasture Management Research Unit » Research » Publications at this Location » Publication #413152
Research Project: Integrated Research to Enhance Forage and Food Production from Southern Great Plains Agroecosystems

Location: Livestock, Forage and Pasture Management Research Unit

Title: Influence of weather variability on vegetation dynamics and eddy fluxes in tallgrass prairie

Author
item Wagle, Pradeep
item Northup, Brian
item Moffet, Corey
item Gunter, Stacey

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/18/2024
Publication Date: 7/28/2024
Citation: Wagle, P., Northup, B.K., Moffet, C., Gunter, S.A. 2024. Influence of weather variability on vegetation dynamics and eddy fluxes in tallgrass prairie [abstract]. 2024 Ecological Society of America Meeting.

Interpretive Summary:

Technical Abstract: Native tallgrass prairie ecosystems, once covering millions of hectares in North America, are threatened by development and agriculture, with less than 4% of the original prairie (pre-European settlement) now remaining. However, it is one of the major ecosystems in the Southern Great Plains of the United States of America (USA). The influence of diverse weather conditions on the vegetation dynamics (enhanced vegetation index, EVI and land surface water index, LSWI) obtained through satellite remote sensing and the dynamics of carbon dioxide (CO2) fluxes, evapotranspiration (ET), and ecosystem water use efficiency (EWUE) obtained through eddy covariance (EC) in a native tallgrass prairie pasture was studied. The study was conducted from 2019 to 2022, considering varying growing conditions. Peak net ecosystem CO2 exchange (NEE), gross primary production (GPP), and ET were -8.7 g C m-2 d-1, 15.1 g C m-2 d-1, and 5.9 mm d-1, respectively. Dynamics of eddy fluxes aligned with the dynamics of vegetation, indicating the accuracy and reliability of satellite-based vegetation indices in tallgrass prairie. Both CO2 fluxes and ET rates showed little variation over the years during the dormant season (November to March). However, eddy fluxes exhibited diverse patterns during growing seasons. During the regrowth phase after hay harvest, the differences in eddy fluxes were particularly substantial due to large variations in late-season rainfall. Consequently, the strength and duration of carbon gain during growing seasons varied substantially by year (i.e., carbon sink for six months in 2019 vs. two months in 2022). The LSWI followed the patterns of GPP and showed its potential to successfully track drought-impacted prairie vegetation. The highly variable magnitude of EWUE over the years illustrates that EWUE is not a constant property of this prairie ecosystem. A greater reduction in GPP than ET during dry years led to reduced EWUE. Strong relationships between eddy fluxes and vegetation indices suggest that CO2 fluxes and ET can be estimated from satellite imagery alone for tallgrass prairie across large spatial scales. The findings of this study are important for informing management about the impacts of variable weather conditions on these important tallgrass prairie ecosystems.