Response of Tallgrass Prairie to Management in the U.S. Southern Great
Plains: Site Descriptions, Management Practices, and Eddy Covariance
Instrumentation for a Long-Term Experiment
Abstract
Understanding the consequences of different management practices on
vegetation phenology, forage production and quality, plant and microbial
species composition, greenhouse gas emissions, and water budgets in
tallgrass prairie systems is vital to identify best management
practices. As part of the Southern Plains Long-Term Agroecosystem
Research (SP-LTAR) grassland study, a long-term integrated
Grassland-LivestOck Burning Experiment (iGLOBE) has been established
with a cluster of six eddy covariance (EC) systems on differently
managed (i.e., different burning and grazing regimes) native tallgrass
prairie systems located in different landscape positions. The purpose of
this paper is to describe this long-term experiment, report preliminary
results on the responses of differently managed tallgrass prairies under
variable climates using satellite remote sensing and EC data, and
present future research directions. In general, vegetation greened-up
and peaked early, and produced greater forage yields in burned years.
However, drought impacts were greater in burned sites due to reductions
in soil water availability by burning. The impact of grazing on
vegetation phenology was confounded by several factors (e.g., cattle
size, stocking rate, precipitation). Moreover, prairie systems located
in different landscapes responded differently, especially in dry years
due to differences in water availability. The strong correspondence
between vegetation phenology and eddy fluxes was evidenced by strong
linear relationships of greenness index (i.e., enhanced vegetation
index) with evapotranspiration and gross primary production. Results
indicate that impacts of climate and management practices on vegetation
phenology may profoundly impact carbon and water budgets of tallgrass
prairie. Interacting effects of multiple management practices and
inter-annual climatic variability on the responses of tallgrass prairie
highlight the necessity of establishing an innovative and comprehensive
long-term experiment to address inconsistent responses of tallgrass
prairie to different intensities, frequencies, timing, and duration of
management practices, and to identify best management practices.