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Title: Plant responses to changing rainfall frequency and magnitude

item FELDMAN, A.F. - Nasa Goddard Institute For Space Studies
item FENG, X. - University Of Minnesota
item FELTON, A.J. - Montana State University
item KONINGS, A.G. - Stanford University
item KNAPP, A.K. - Colorado State University
item Biederman, Joel
item POULTER, B. - Nasa Goddard Institute For Space Studies

Submitted to: Nature Reviews Earth & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2024
Publication Date: 4/9/2024
Citation: Feldman, A., Feng, X., Felton, A., Konings, A., Knapp, A., Biederman, J.A., Poulter, B. 2024. Plant responses to changing rainfall frequency and magnitude. Nature Reviews Earth & Environment. 5:276-294.

Interpretive Summary: : In many parts of the world, rain storms are delivering greater rainfall amounts, but there are longer dry periods in between storms. It is unknown how this temporal repackaging of precipitation affects plant growth. Here we review the evidence from experiments, environmental observations, and plant models to determine how fewer, larger rainstorms affect plants globally. We find that increased precipitation variability generally decreases plant growth in regions with relatively wet climates (average of 53% negative). In dryland regions, increased precipitation variability can have either positive (38% of drylands) or negative (29%) impacts on plant growth. Key knowledge gaps for future research included exploration of extreme rainfall events and extreme-duration droughts.

Technical Abstract: Under climate change, rainfall events are larger in magnitude but less frequent, regardless of annual rainfall amount changes. Such facets of hydrologic cycle intensification ¬– longer dry spells between higher-magnitude events ¬– have complex and sometimes competing effects on plant photosynthesis and growth, challenging our ability to understand broader carbon cycle consequences. In this Review, we evaluate global plant responses to rainfall regimes characterized by fewer, larger rainfall events. Based on evidence from diverse approaches, average plant function changes between -30% to 30% under fewer, larger rainfall events, with responses contingent on climate; productivity decreases are common in wetter systems (53% negative), while responses are variable and often positive in drier ecosystems (38% positive; 29% negative). Contrasting responses in dry and wet ecosystems are attributed to non-linear plant responses to soil moisture driven by several ecohydrologic mechanisms. Key knowledge gaps are determining if there are optimal rainfall frequencies for photosynthesis, assessing the relative dominance of rainfall pulse and dry spell mechanisms, and evaluating the disproportionate role of extreme rainfall pulses on plants. Ultimately, daily rainfall frequency and magnitude may be of similar importance to annual rainfall amounts in regulating terrestrial vegetation response to global carbon cycle changes.