The importance of precipitation timing for grassland productivity
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Future climate change is likely to involve changes in the amount and intensity of precipitation, but also its timing during the year. To better understand how the timing of precipitation impacts plant productivity, a 27-year dataset on grass productivity for a mesic North American grassland was analyzed. Along with other climate parameters, the ability of the average date precipitation fell during different climate periods to explain grass productivity was tested. Across the 27 years, grass productivity was greater in years with more precipitation between April 15 and August 2. After accounting for differences in the total amount of precipitation during this time period, in years when precipitation between May 9 and August 27 fell later, measured grass productivity was less. Variation among years in precipitation timing was of similar importance as temperatures during critical climate periods and about 40 % of the importance of the total amount of precipitation. In all, although the mechanisms generating these responses are uncertain, precipitation timing within a growing season has substantial effects on productivity.
KeywordsGrasslands Konza Prairie Precipitation Timing Primary productivity Critical climate period
Collection of the productivity and climate data was supported by grants from the National Science Foundation in support of the Konza Long-Term Ecological Research program. Jesse Nippert and anonymous reviewers provided valuable comments to earlier manuscripts and Troy Ocheltree inspiration for the linear density plots of the critical climate periods in Fig. 1.
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