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Data associated with “How Big is Big Enough? Surprising Responses of a Semi-arid Grassland to Increasing Deluge Size”


Climate change has intensified the hydrologic cycle globally, increasing the magnitude and frequency of large precipitation events, or deluges. Dryland ecosystems are expected to be particularly responsive to increases in deluge size, as their ecological processes are largely dependent on distinct soil moisture pulses. To better understand how increasing deluge size will affect ecosystem function, we conducted a field experiment in a native semi-arid shortgrass steppe (Colorado, USA). We quantified ecological responses to a range of deluge sizes, from moderate to extreme, with the goal of identifying response patterns and thresholds beyond which ecological processes would not increase further (saturate). Using a replicated regression approach, we imposed single deluges that ranged in size from 20 to 120 mm (82.3rd to > 99.9th percentile of historical event size) on undisturbed grassland plots. We quantified pre- and post-deluge responses in soil moisture, soil respiration, and canopy greenness, as well as leaf water potential, growth, and flowering of the dominant grass species (Bouteloua gracilis). We also measured end of season above- and below-ground net primary production (ANPP, BNPP). As expected, this water-limited ecosystem responded strongly to the applied deluges, but surprisingly, most variables increased linearly with deluge size. We found little evidence for response thresholds within the range of deluge sizes imposed, at least during a dry year. Instead, response patterns reflected the linear increase in the duration of elevated soil moisture (2-22 days) with increasing event size. Flowering of B. gracilis and soil respiration responded particularly strongly to deluge size (14- and 4-fold increases, respectively), as did ANPP and BNPP (~60% increase for both). Overall, our results suggest that this semi-arid grassland will respond positively and linearly to predicted increases in deluge size, and that event sizes will need to exceed historical magnitudes before responses saturate.


Data used in manuscript “How Big is Big Enough? Surprising Responses of a Semi-arid Grassland to Increasing Deluge Size.” This study quantifies the impact of deluge size on various ecosystem processes in the shortgrass steppe of Eastern Colorado.
Graduate Degree Program in Ecology

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Net Primary Production
precipitation extremes
semi-arid grassland
shortgrass steppe
soil respiration


Associated Publications

Post, A.K. & Knapp, A.K. How big is big enough? Surprising responses of a semiarid grassland to increasing deluge size. Glob Change Biol. 2021; 27: 1157–1169.