The sensitivity of carbon exchanges in Great Plains grasslands to precipitation variability
نویسندگان
چکیده
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.
منابع مشابه
Litter decomposition in grasslands of Central North America (US Great Plains)
One of the major concerns about global warming is the potential for an increase in decomposition and soil respiration rates, increasing CO2 emissions and creating a positive feedback between global warming and soil respiration. This is particularly important in ecosystems with large belowground biomass, such as grasslands where over 90% of the carbon is allocated belowground. A better understan...
متن کاملContrasting above- and belowground sensitivity of three Great Plains grasslands to altered rainfall regimes.
Intensification of the global hydrological cycle with atmospheric warming is expected to increase interannual variation in precipitation amount and the frequency of extreme precipitation events. Although studies in grasslands have shown sensitivity of aboveground net primary productivity (ANPP) to both precipitation amount and event size, we lack equivalent knowledge for responses of belowgroun...
متن کاملPhysiological and environmental regulation of interannual variability in CO2 exchange on rangelands in the western United States
For most ecosystems, net ecosystem exchange of CO2 (NEE) varies within and among years in response to environmental change. We analyzed measurements of CO2 exchange from eight native rangeland ecosystems in the western United States (58 site-years of data) in order to determine the contributions of photosynthetic and respiratory (physiological) components of CO2 exchange to environmentally caus...
متن کاملDynamical connection between Great Plains low-level winds and variability of central Gulf States precipitation
The Great Plains low-level jet has been related to summer precipitation over the northern Great Plains and Midwest through its moisture transport and convergence at the jet exit area. Much less studied has been its negative relationship with precipitation over the southern Great Plains and the Gulf coastal area. This work shows that the southerly low-level winds at 30°–40°N over the southern Gr...
متن کاملVariability of the Great Plains Low-Level Jet: Large Scale Circulation Context and Hydroclimate Impacts
Title of Document: VARIABILITY OF THE GREAT PLAINS LOW-LEVEL JET: LARGE SCALE CIRCULATION CONTEXT AND HYDROCLIMATE IMPACTS Scott J. Weaver, Doctor of Philosophy, 2007 Directed By: Professor Sumant Nigam, Department of Atmospheric and Oceanic Science Variability of the Great Plains Low-Level Jet (GPLLJ) is analyzed from the perspective of larger-scale, lower-frequency influences and regional hyd...
متن کامل