01833nas a2200145 4500008004100000245009700041210006900138300001500207490000600222520134300228100001701571700002301588700001501611856006101626 2014 eng d00aImpacts of seasonality and surface heterogeneity on water-use efficiency in mesic grasslands0 aImpacts of seasonality and surface heterogeneity on wateruse eff a1223 -12330 v73 a
Woody encroachment is occurring in grasslands worldwide, with largely unknown effects on local carbon and water fluxes and the energy balance. Water-use efficiency (λ) is a measure of carbon assimilation per evapotranspiration. Here, a was compared among three different grassland ecosystems in eastern KS, USA, by using the eddy covariance technique. Variation in λ was examined at multiple timescales and across different burning regimes. Site-specific variations in λ were more readily observed at seasonal and inter-annual timescales rather than daily and monthly averages. Annually burned grassland with homogeneous C4 grass cover had less negative values of λ [lower water-use efficiency (WUE)] than infrequently burned grassland that is presently undergoing woody encroachment and a transition to a shrub-dominated ecosystem. The most likely explanation for differences in λ are differences in rooting depth and source-water acquisition between encroaching woody plants and the native grass community. Reliance on a deeper water source by the woody community may buffer the negative consequences of forecasted climate variability and drought, resulting in greater landscape WUE and reduced susceptibility to water stress when compared with the coexisting grass species. Copyright © 2013 John Wiley & Sons, Ltd.
1 aBrunsell, N.1 aNippert, Jesse, B.1 aBuck, T.L. uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/eco.1455