Publication Date:
2017-12-20
Description:
There is uncertainty in the magnitude and direction of changes in precipitation associated with climate change, and ecosystem responses are also uncertain. Multi-year periods of above- and below-average rainfall may foretell consequences of changes in rainfall regime. We compiled long-term aboveground net primary productivity (ANPP) and precipitation (PPT) data for eight North American grasslands, and quantified relationships between ANPP and PPT at each site, and in 1-3 year periods of above- and below-average rainfall for mesic, semiarid cool and semiarid warm grassland types. Our objectives were to improve understanding of PPT-ANPP relationships in above- and below-average years, and to contrast the importance of current conditions, prior-year legacies, and emergent responses to ANPP during sequences of above- and below-average years to provide insights into ANPP dynamics associated with changing climatic conditions. We found differences in PPT-ANPP relationships in above- and below-average years compared to long-term site averages, and variation in ANPP not explained by PPT totals that likely is attributed to legacy effects. The correlation between ANPP and current- and prior-year conditions changed from year to year throughout multi-year periods, with some legacy effects declining, and new responses emerging. Thus, ANPP in every year was influenced by sequences of conditions that varied across grassland types and climates. Most importantly, the influence of prior year ANPP often increased with the length of multi-year periods, whereas the influence of the amount of PPT declined, but often not until after the first above- or below-average year. Although it is not fully clear how a directional change in the frequency of above- and below-average years could impose a persistent change in grassland ANPP, our results emphasize the importance of legacy effects on productivity for sequences of above- versus below-average years, and illustrate the utility of long-term data to examine these patterns. This article is protected by copyright. All rights reserved.
Print ISSN:
1354-1013
Electronic ISSN:
1365-2486
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Geography
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