In semiarid regions, vegetation constraints on plant growth responses to precipitation (
Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (
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- Global Change Biology
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- p. 4376-4385
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- National Science Foundation
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In semiarid regions, vegetation constraints on plant growth responses to precipitation (
PPT) are hypothesized to place an upper limit on net primary productivity ( NPP), leading to predictions of future shifts from currently defined linear to saturating NPP– PPTrelationships as increases in both dry and wet PPTextremes occur. We experimentally tested this prediction by imposing a replicated gradient of growing season PPT( GSP, n= 11 levels, n= 4 replicates), ranging from the driest to wettest conditions in the 75‐yr climate record, within a semiarid grassland. We focused on responses of two key ecosystem processes: aboveground NPP( ANPP) and soil respiration ( Rs). ANPPand Rsboth exhibited greater relative responses to wet vs. dry GSPextremes, with a linear relationship consistently best explaining the response of both processes to GSP. However, this responsiveness to GSPpeaked at moderate levels of extremity for both processes, and declined at the most extreme GSPlevels, suggesting that greater sensitivity of ANPPand Rsto wet vs. dry conditions may diminish under increased magnitudes of GSPextremes. Underlying these responses was rapid plant compositional change driven by increased forb production and cover as GSPtransitioned to extreme wet conditions. This compositional shift increased the magnitude of ANPPresponses to wet GSPextremes, as well as the slope and variability explained in the ANPP– GSPrelationship. Our findings suggest that rapid plant compositional change may act as a mediator of semiarid ecosystem responses to predicted changes in GSPextremes.
Changing precipitation patterns are predicted to alter ecosystem structure and function with potential carbon cycle feedbacks to climate change. Influenced by both land and sea, salt marshes are unique ecosystems and their productivity and respiration responses to precipitation change differ from those observed in terrestrial ecosystems. How salt marsh greenhouse gas fluxes and sediment microbial communities will respond to climate‐induced precipitation changes is largely unknown. We conducted 1‐year precipitation manipulation experiments in the
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Succession theory predicts altered sensitivity of ecosystem functions to disturbance (i.e., climate change) due to the temporal shift in plant community composition. However, empirical evidence in global change experiments is lacking to support this prediction. Here, we present findings from an 8‐year long‐term global change experiment with warming and altered precipitation manipulation (double and halved amount). First, we observed a temporal shift in species composition over 8 years, resulting in a transition from an annual C3‐dominant plant community to a perennial C4‐dominant plant community. This successional transition was independent of any experimental treatments. During the successional transition, the response of aboveground net primary productivity (
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