Theme 1: Grassland Ecology
Description
Grasslands in the central United States span large temperature and aridity gradients and regionally differ in their drivers of water availability. These differences likely determine how drought event periodicity and duration can influence grassland growth, and are important to consider as global warming changes energy and water distribution across these systems. Here, we explored frequency patterns in annual grassland plant growth (aboveground net primary productivity (ANPP)) and precipitation (PPT) relationships for over 20 years at six long-term research sites spatially distributed across the central grassland region. We identified the periods (>1 year) these relationships are strongest- and when they occur- with wavelet coherence analyses. We found disturbance events such as severe drought lowered ANPP and preceded strong coherence at 2-4 year periods at two sites, potentially by increasing ANPP sensitivity to PPT. All sites showed strong coherence at 1-2 years periods, however this coherence was not consistent through time for two sites, where declines in ANPP did not correspond with PPT variability. In addition to strong coherence at 1-2 year periods, at southern desert and central tallgrass grasslands there was also strong coherence at 5-10 year periods over the entire record, indicating that long-term PPT and ANPP dynamics are important. Pacific ocean-atmosphere drivers of regional precipitation were found to influence coherence at all sites, and could potentially explain the long-term 5- 10 year coherence at the sites mentioned above. Contextualizing ANPP-PPT relationships through time at sites with different drivers of precipitation requires understanding of site-dependent production dynamics and is key to forecasting grassland responses to climate change.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Length of Multi-Year Precipitation and Primary Production Relationships Vary Regionally Across Grasslands in the Central U.S.
Grasslands in the central United States span large temperature and aridity gradients and regionally differ in their drivers of water availability. These differences likely determine how drought event periodicity and duration can influence grassland growth, and are important to consider as global warming changes energy and water distribution across these systems. Here, we explored frequency patterns in annual grassland plant growth (aboveground net primary productivity (ANPP)) and precipitation (PPT) relationships for over 20 years at six long-term research sites spatially distributed across the central grassland region. We identified the periods (>1 year) these relationships are strongest- and when they occur- with wavelet coherence analyses. We found disturbance events such as severe drought lowered ANPP and preceded strong coherence at 2-4 year periods at two sites, potentially by increasing ANPP sensitivity to PPT. All sites showed strong coherence at 1-2 years periods, however this coherence was not consistent through time for two sites, where declines in ANPP did not correspond with PPT variability. In addition to strong coherence at 1-2 year periods, at southern desert and central tallgrass grasslands there was also strong coherence at 5-10 year periods over the entire record, indicating that long-term PPT and ANPP dynamics are important. Pacific ocean-atmosphere drivers of regional precipitation were found to influence coherence at all sites, and could potentially explain the long-term 5- 10 year coherence at the sites mentioned above. Contextualizing ANPP-PPT relationships through time at sites with different drivers of precipitation requires understanding of site-dependent production dynamics and is key to forecasting grassland responses to climate change.
