Researchers at the Konza Prairie (KNZ) Long Term Ecological Research (LTER) site have discovered that the severity of climate effects such as droughts and heat waves depends on when they occur. The findings derive from more than 25 years of productivity data that looked at how drought and heat affect grass growth during different times of the year.
In a paper published in the February 13, 2012 issue of the journal Proceedings of the National Academy of Sciences (PNAS), lead author Joseph M. Craine and co-authors Jesse B. Nippert, Adam M. Skibbe (all of Kansas State University (KSU) and KNZ), Stacy L. Hutchinson (KSU), Andrew J. Elmore (University of Maryland) and Nathaniel A. Brunsell (University of Kansas) found that droughts reduced grass growth mostly in early June, while heat waves reduced grass growth during late July. Interestingly, neither effect had significant impact on grass growth in later months, the study found.
The researchers suggest that if these patterns turn out to be true in general across ecosystems, then predictions of ecosystem response to climate change should account for both the magnitude and timing of climate variability. Indeed, the researchers are now looking at long-term records from other LTER sites to determine whether there is uniformity to their findings in Konza. Considering that future climates are forecast to include greater precipitation variability and more frequent heat waves, this finding, if confirmed to be widespread, may provide resource planners and managers a better way to anticipate the impacts of droughts and heat waves.
More information and pdf download instructions are available at Timing of climate variability and grassland productivity.abstract. Also see the NSF news release about the finding at Time of Year Important in Projections of Climate Change Effects on Ecosystems.