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Insight: precipitation frequency regulates summer soil moisture

Last modified June 25, 2012 11:31

Future precipitation patterns will typically be characterized by more intense periods of rainfall and longer dry periods. It is therefore important to understand how these patterns will affect ecosystem processes.

Using 415 site-year measurements from 75 locations worldwide, we have now shown that changes in precipitation on a daily scale play an important role in regulating water content in soil from one year to the next for non-forests, deciduous forests and evergreen forests. The frequency of precipitation was found to be a better indicator of summer soil-moisture content than the total amount of precipitation, but these results were only observed in non-forest ecosystems, demonstrating just how important soil characteristics are.

Several broad implications can be drawn from our analyses. Precipitation frequency highlights the importance of precipitation patterns, rather than just the quantity of precipitation, when it comes to ecological processes in soil water. It also provides insights into how to improve the accuracy of ecosystem models that do not incorporate such mechanisms, but which tend to link together precipitation and soil moisture.

Our results may provide a new way to analyse changes in precipitation over time that can lead to substantial differences in precipitation patterns over the long term, even if the total amount of precipitation remains stable. With longer and more severe periods of drought expected, we advise that future climate-change models take precipitation frequency into account. Our group is currently working on understanding the impact of precipitation on carbon sequestration in Canadian forests using the Integrated Terrestrial Ecosystem C-budget model (InTEC).

About the author

Chaoyang Wu is a postdoctoral fellow in Jing M Chen's group in the Department of Geography, University of Toronto, Canada. His research focuses on climate change and carbon cycling, especially the impacts of future climate change (for example precipitation, carbon dioxide and temperature) on carbon sequestration in ecosystems.

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