How do variations in the temporal distribution of rainfall events affect ecosystem fluxes in seasonally water-limited Northern Hemisphere shrublands and forests?

[摘要] Rainfall regimes became more extreme over the course of the 20thcentury, characterised by fewer and larger rainfall events.Suchchanges are expected to continue throughout the current century.The effect of changes in the temporal distribution of rainfall onecosystem carbon fluxes is poorly understood, with most availableinformation coming from experimental studies of grasslandecosystems.Here, continuous measurements of ecosystem carbonfluxes and precipitation from the worldwide FLUXNET network ofeddy-covariance sites are exploited to investigate the effects ofdifferences in rainfall distribution on the carbon balance ofseasonally water-limited shrubland and forest sites.Once thestrong dependence of ecosystem fluxes on total annual rainfallamount is accounted for, results show that sites with rainfalldistributions characterised by fewer and larger rainfall events havesignificantly lower gross primary productivity, slightly lowerecosystem respiration and consequently a smaller net ecosystemproductivity.

[学科分类] 地球化学与岩石