Submitted to: Geophysical Research Letters
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/9/2006
Publication Date: 8/4/2006
Citation: Porporato, A., Vico, G., Fay, P.A. 2006. Superstatistics of hydro-climatic fluctuations and interannual ecosystem productivity. Geophysical Research Letters. 33:15402-15405. Interpretive Summary: Extreme weather events, such as droughts and floods, increasingly appear to be impacting the natural and human systems on which we rely for food, fiber, aesthetic value, and clean air and water. However, the consequences of extreme events for terrestrial ecosystems are poorly understood. We have shown that in a grassland, several key indicators of its productivity were less efficient when watered to simulate more extreme rain events likely with climate change, compared to less extreme events providing equal total rainfall. We suggest that rainfall patterns will greatly affect ecosystem responses to climate change, and the provision of ecosystem services of benefit to humans.
Technical Abstract: Water limited ecosystems are highly sensitive to climatic variability, and are likely to be impacted by the increased rainfall variability and extreme event frequency expected with climate change. The impacts of increased rainfall variability on key carbon cycling processes such as photosynthetic carbon gain [ACO2], soil CO2 efflux [JCO2], or aboveground net primary production [ANPP] will depend on how rainfall total quantity, event size, and inter-event intervals change, but the interactions among these factors are poorly understood. Here we show that the interactions between rain event interval and event size are crucial determinants of ecosystem responses to rainfall variability. We found that larger individual rain events, occurring at longer intervals as predicted in climate change scenarios, were less efficiently captured by the ecosystem, thus decreasing the resource use efficiencies for processes as diverse as ACO2, JCO2, and ANPP. The outcome of interactions between rainfall variability and other elements of climate change will depend greatly on the distribution of rain event sizes and intervals, because of their strong effects on ecosystem function and resource use efficiency.