title: Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change.
abstract: Amazon forests, which store ∼ 50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale die-back of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size- and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem's resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest's response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138; Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0371;
authors.forename: Naomi M
authors.identifier: http://orcid.org/0000-0002-4963-0535
authors.initials: NM
authors.lastname: Levine
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138; Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, Norman, OK 73072;
authors.forename: Ke
authors.identifier: http://orcid.org/0000-0001-5288-9372
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138;
authors.forename: Marcos
authors.initials: M
authors.lastname: Longo
authors.affiliation: The Woods Hole Research Center, Falmouth, MA 02540-1644;
authors.forename: Alessandro
authors.initials: A
authors.lastname: Baccini
authors.affiliation: School of Geography, University of Leeds, Leeds LS2 9JT, United Kingdom;
authors.forename: Oliver L
authors.initials: OL
authors.lastname: Phillips
authors.affiliation: School of Geography, University of Leeds, Leeds LS2 9JT, United Kingdom; Department of Geography, University College London, London WC1E 6BT, United Kingdom;
authors.forename: Simon L
authors.initials: SL
authors.lastname: Lewis
authors.affiliation: Jardín Botánico de Medellín, Grupo de Investigación en Servicios Ecosistémicos y Cambio Climático, 14 Medellin, Colombia;
authors.forename: Esteban
authors.initials: E
authors.lastname: Alvarez-Dávila
authors.affiliation: Instituto Nacional de Pesquisas da Amazônia, Manaus - AM, 69067-375, Brazil;
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Segalin de Andrade
authors.affiliation: School of Geography, University of Leeds, Leeds LS2 9JT, United Kingdom;
authors.forename: Roel J W
authors.initials: RJ
authors.lastname: Brienen
authors.affiliation: Department of Entomology, Smithsonian Institution, Washington, DC 20013-7012;
authors.forename: Terry L
authors.initials: TL
authors.lastname: Erwin
authors.affiliation: College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4SB, United Kingdom;
authors.forename: Ted R
authors.initials: TR
authors.lastname: Feldpausch
authors.affiliation: Jardín Botánico de Missouri, Oxapampa, Peru;
authors.forename: Abel Lorenzo
authors.initials: AL
authors.lastname: Monteagudo Mendoza
authors.affiliation: Universidad Nacional de San Antonio Abad del Cusco, Cusco, Peru;
authors.forename: Percy
authors.initials: P
authors.lastname: Nuñez Vargas
authors.affiliation: Instituto de Ciencias Naturales, Bogota, Colombia;
authors.forename: Adriana
authors.initials: A
authors.lastname: Prieto
authors.affiliation: Universidad Nacional de San Antonio Abad del Cusco, Cusco, Peru;
authors.forename: Javier Eduardo
authors.initials: JE
authors.lastname: Silva-Espejo
authors.affiliation: School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, United Kingdom.
authors.forename: Yadvinder
authors.initials: Y
authors.lastname: Malhi
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138; paul_moorcroft@harvard.edu.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Moorcroft
mesh_terms: D018533:Biomass; D001938:Brazil; D057231:Climate Change; D003681:Dehydration; D017753:Ecosystem; D058998:Remote Sensing Technology; D012621:Seasons; D012987:Soil
chemical_list: D012987:Soil
keywords: Amazon forests; biomass; climate change; ecological resilience; ecosystem heterogeneity