The sensitivity of carbon exchanges in Great Plains grasslands to precipitation variability

TitleThe sensitivity of carbon exchanges in Great Plains grasslands to precipitation variability
Publication TypeJournal Article
Year of Publication2016
AuthorsPetrie MD, Brunsell NA, Vargas R, Collins SL, Flanagan LB, Hanan NP, Litvak ME, Suyker AE
JournalJournal of Geophysical Research: Biogeosciences
Start Page1
Pagination19
Date Published01/2016
Accession NumberSEV.751
Keywordscarbon, Grasslands, Great Plains, precipitation
Abstract

In the Great Plains, grassland carbon dynamics differ across broad gradients of precipitation and temperature, yet finer-scale variation in these variables may also affect grassland processes. Despite the importance of grasslands, there is little information on how fine-scale relationships compare between them regionally. We compared grassland C exchanges, energy partitioning and precipitation variability in eight sites in the eastern and western Great Plains using eddy covariance and meteorological data. During our study, both eastern and western grasslands varied between an average net carbon sink and a net source. Eastern grasslands had a moderate vapor pressure deficit (VPD = 0.95 kPa) and high growing season gross primary productivity (GPP = 1010 ± 218 g C m−2 yr−1). Western grasslands had a growing season with higher VPD (1.43 kPa) and lower GPP (360 ± 127 g C m−2 yr−1). Western grasslands were sensitive to precipitation at daily timescales, whereas eastern grasslands were sensitive at monthly and seasonal timescales. Our results support the expectation that C exchanges in these grasslands differ as a result of varying precipitation regimes. Because eastern grasslands are less influenced by short-term variability in rainfall than western grasslands, the effects of precipitation change are likely to be more predictable in eastern grasslands because the timescales of variability that must be resolved are relatively longer. We postulate increasing regional heterogeneity in grassland C exchanges in the Great Plains in coming decades.

DOI10.1002/2015JG003205