Timing and Magnitude of Drought Impacts on Carbon Uptake Across a Grassland Biome

Authors

Andrew Felton, Chapman UniversityFollow
Gregory R. Goldsmith, Chapman UniversityFollow

Document Type

Article

Publication Date

2-15-2023

Abstract

Although drought is known to negatively impact grassland functioning, the timing and magnitude of these impacts within a growing season remains unresolved. Previous small-scale assessments indicate grasslands may only respond to drought during narrow periods within a year; however, large-scale assessments are now needed to uncover the general patterns and determinants of this timing. We combined remote sensing datasets of gross primary productivity and weather to assess the timing and magnitude of grassland responses to drought at 5 km² temporal resolution across two expansive ecoregions of the western US Great Plains biome: the C₄-dominated shortgrass steppe and the C₃-dominated northern mixed prairies. Across over 700,000 pixel-year combinations covering more than 600,000 km², we studied how the driest years between 2003-2020 altered the daily and bi-weekly dynamics of grassland carbon (C) uptake. Reductions to C uptake intensified into the early summer during drought and peaked in mid- and late June in both ecoregions. Stimulation of spring C uptake during drought was small and insufficient to compensate for losses during summer. Thus, total grassland C uptake was consistently reduced by drought across both ecoregions; however, reductions were twice as large across the more southern and warmer shortgrass steppe. Across the biome, increased summer vapor pressure deficit was strongly linked to peak reductions in vegetation greenness during drought. Rising vapor pressure deficit will likely exacerbate reductions in C uptake during drought across the western US Great Plains, with these reductions greatest during the warmest months and in the warmest locations. High spatiotemporal resolution analyses of grassland response to drought over large areas provide both generalizable insights and new opportunities for basic and applied ecosystem science in these water-limited ecoregions amid climate change.

Comments

This article was originally published in Global Change Biology, volume 29, issue 10, in 2023. https://doi.org/10.1111/gcb.16637

Recommended Citation

Felton, A.J. and Goldsmith, G.R. (2023), Timing and magnitude of drought impacts on carbon uptake across a grassland biome. Glob Change Biol, 29, 2790– 2803. https://doi.org/10.1111/gcb.16637

Copyright

Wiley

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 License.