Signatures of autumn deluges revealed during spring drought in a semi-arid grassland

Increases in extremely large precipitation events (deluges) and shifts in seasonal patterns of water availability with climate change will both have important consequences for ecosystem function, particularly in water-limited regions. While previous work in the semi-arid shortgrass steppe of northeastern Colorado has demonstrated this ecosystem’s strong sensitivity to growing season deluges, our understanding of ecosystem responses to deluges during the dormant season is limited. Here, we imposed experimental 100 mm deluges (~ 30% of mean annual precipitation) in either September or October in a native C4-dominated shortgrass steppe ecosystem to evaluate the impact of this post-growing season shift in water availability during the autumn and the following growing season. Soil moisture for both deluge treatments remained elevated compared with ambient levels through April as spring precipitation was atypically low. Despite overall low levels of productivity with spring drought, these del..., Methods
Site Description
Our study site was in the North American shortgrass steppe at the USDA Central Plains Experimental Range in northeastern Colorado, USA (N 40.8422°, W 104.7156°). Mean annual temperature is 8.6°C (Lauenroth and Sala 1992), and mean annual precipitation is 342 mm with only ~20% of annual precipitation occurring during the autumn season (Sept. – Nov.; Hermance et al. 2015). Growing season precipitation (May – Aug.) accounts for majority (~75%) of the annual total. Long-term ANPP is ~75 g m-2 with the majority comprised of perennial C4 grasses (~75%, primarily Bouteloua gracillis and Bouteloua dactyloides) and the remainder including perennial C3 grasses, cool-season annual grasses, forbs, and cacti (Hoover et al. 2021). Soil texture at the study site is sandy clay loam (Sala et al. 1992), and although the site has a history of moderate cattle grazing, the area where this experiment was conducted has been protected from large ruminant grazers since 2011 (Post and Kn..., , # Data associated with \"Signatures of autumn deluges revealed during spring drought in a semi-arid grassland\"

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Abstract:
Increases in extremely large precipitation events (deluges) and shifts in seasonal patterns of water availability with climate change will both have important consequences for ecosystem function, particularly in water-limited regions. While previous work in the semi-arid shortgrass steppe of northeastern Colorado has demonstrated this ecosystems strong sensitivity to growing season deluges, our understanding of ecosystem responses to deluges during the dormant season is limited. Here, we imposed experimental 100 mm deluges (~ 30% of mean annual precipitation) in either September or October in a native C4- dominated shortgrass steppe ecosystem to evaluate the impact of this post-growing season shift in water availability during the autumn as well the following growing season. Soil moisture for both deluge treatments remained elevated compared with ambient levels t...