@article {JRN54907, title = {Regional grassland productivity responses to precipitation during multiyear above- and below-average rainfall periods}, journal = {Global Change Biology}, volume = {24:1935-1951}, year = {2018}, month = {05/2018}, abstract = {

There is considerable uncertainty in the magnitude and direction of changes in precipitation associated with climate change, and ecosystem responses are also uncertain. Multiyear 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 objective was to improve understanding of ANPP dynamics associated with changing climatic conditions by contrasting PPT-ANPP relationships in above- and below-average PPT years to those that occurred during sequences of multiple above- and below-average years. 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 are attributed to legacy effects. The correlation between ANPP and current- and prior-year conditions changed from year to year throughout multiyear periods, with some legacy effects declining, and new responses emerging. Thus, ANPP in a given 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 multiyear periods, whereas the influence of the amount of current-year PPT declined. Although the mechanisms by which a directional change in the frequency of above- and below-average years imposes a persistent change in grassland ANPP require further investigation, our results emphasize the importance of legacy effects on productivity for sequences of above- vs. below-average years, and illustrate the utility of long-term data to examine these patterns.

}, doi = {10.1111/gcb.14024}, url = {files/bibliography/18-012_0.pdf}, author = {Matthew D. Petrie and Debra C. Peters and Jin Yao and John M Blair and N. Dylan Burruss and S.L. Collins and J. D. Derner and Laureano A. Gherardi and John Hendrickson and O. E. Sala and Paul F. Starrs and Jean Steiner} } @conference {JRN54910, title = {Regional telecoupling and impacts of wet periods across the Chihuahuan Desert of the United States and northern Mexico}, booktitle = {Ecological Society of America}, year = {2018}, month = {08/2018}, publisher = {Ecological Society of America}, organization = {Ecological Society of America}, address = {New Orleans, LA}, abstract = {

Telecoupling of environmental and ecological conditions in aridlands is associated with the Land Surface Template (LST) and precipitation (PPT) patterns. Variation in telecoupling may be shaped by multiple factors, and local (\< 1 km2) observations may be similar to regional (\> 250 km2) patterns under some conditions and different under others. For example, extreme drought events can influence vegetation over large regions, and overwhelm the effects of many LST factors. Multi-year high PPT periods that resulted in perennial grass production on some sites have received less attention. In the Chihuahuan Desert region, individual rainfall events in the monsoon season are stochastic, suggesting that high PPT is localized and widespread positive telecoupling is improbable. Yet, multi-year high PPT periods may homogenize stochastic rainfall patterns through time and across space to overwhelm local LST conditions, and in this way promote positive telecoupling that is not possible in single years.

Using remote sensing data from 1983-present and a suite of harmonized LST datasets, we sought to quantify telecoupling beginning locally at the Jornada LTER site in New Mexico and expanding to the Chihuahuan Desert in the US and northern Mexico. Our goal was to determine if patterns in climate are coupled to patterns in vegetation response during a wet period or if local heterogeneity in soils and land use decouple climate and vegetation response. We hypothesized that high PPT would aggregate through time to become more regionally-similar and/or more probable, and that increasing duration of a local forcing event at JRN would increase its similarity to the larger region. Our results show that telecoupling in this region is instigated by the aggregation of sustained high PPT and/or extreme high PPT events through time, but its pattern within the rainfall area is contingent on local factors. Wet periods are changing and will play an important role in shaping the future pattern and dynamics of aridlands. By identifying and quantifying patterns in telecoupling, we develop new insight on how climate and landscapes interact, and how these landscapes may respond to future climates.

}, author = {Matthew D. Petrie and Debra C. Peters and N. Dylan Burruss and W Ji and Niall Hanan and Heather Savoy} }