title: Legacies of precipitation fluctuations on primary production: theory and data synthesis.
abstract: Variability of above-ground net primary production (ANPP) of arid to sub-humid ecosystems displays a closer association with precipitation when considered across space (based on multiyear averages for different locations) than through time (based on year-to-year change at single locations). Here, we propose a theory of controls of ANPP based on four hypotheses about legacies of wet and dry years that explains space versus time differences in ANPP-precipitation relationships. We tested the hypotheses using 16 long-term series of ANPP. We found that legacies revealed by the association of current- versus previous-year conditions through the temporal series occur across all ecosystem types from deserts to mesic grasslands. Therefore, previous-year precipitation and ANPP control a significant fraction of current-year production. We developed unified models for the controls of ANPP through space and time. The relative importance of current-versus previous-year precipitation changes along a gradient of mean annual precipitation with the importance of current-year PPT decreasing, whereas the importance of previous-year PPT remains constant as mean annual precipitation increases. Finally, our results suggest that ANPP will respond to climate-change-driven alterations in water availability and, more importantly, that the magnitude of the response will increase with time.
authors.affiliation: School of Sustainability, Arizona State University, Tempe, AZ, USA. osvaldo.sala@asu.edu
authors.forename: Osvaldo E
authors.initials: OE
authors.lastname: Sala
authors.forename: Laureano A
authors.initials: LA
authors.lastname: Gherardi
authors.forename: Lara
authors.initials: L
authors.lastname: Reichmann
authors.forename: Esteban
authors.initials: E
authors.lastname: Jobbágy
authors.forename: Debra
authors.initials: D
authors.lastname: Peters
mesh_terms: D057486:Carbon Cycle; D057231:Climate Change; D055864:Droughts; D017753:Ecosystem; D005843:Geography; D008954:Models, Biological; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D006109:Poaceae / Q000737:chemistry*; D013223:Statistics as Topic / Q000379:methods*; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water