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Title: Repeated extreme droughts decrease root production, but not the potential for post‐drought recovery of root production, in a mesic grassland

Global climate change is expected to cause more frequent extreme droughts in many parts of the world. Despite the crucial role of roots in water acquisition and plant survival, our understanding of ecosystem vulnerability to drought is primarily based on aboveground impacts. As return intervals between droughts decrease, root responses to one drought might alter responses to subsequent droughts, but this remains unresolved. We conducted a seven‐year experiment that imposed extreme drought (growing season precipitation reduced 66%) in a mesic grassland. Plots were droughted during years 1–2 (‘Drought 1'), or years 5–6 (‘Drought 2') or both. We quantified root production during year 6 (final year of Drought 2) and year 7 (first year after Drought 2), when all plots received ambient precipitation. We found that repeated drought decreased root mass production more than twice as much as a single drought (−63% versus −27%, respectively, relative to ambient precipitation). Root mass production of the dominant C4grassAndropogon gerardiidid not decrease significantly with either one or two droughts.A. gerardiiroot traits differed from subdominant species on average across all treatments, but drought did not alter root traits of eitherA. gerardiior the subdominant species (collectively). In year 6, root production in plots droughted 4 years ago had not recovered (−21% versus control), but root production recovered in all formerly droughted plots in year 7, when precipitation was above average. Our results highlight the complexity of root responses to drought. Drought‐induced reductions in root production can persist for years after drought and repeated drought can reduce production even further, but this does not preclude rapid recovery of root production in a wet year.

 
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Award ID(s):
2025849
NSF-PAR ID:
10467479
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Oikos
Date Published:
Journal Name:
Oikos
Volume:
2023
Issue:
1
ISSN:
0030-1299
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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