Journal Article

Evaluating theories of drought-induced vegetation mortality using a multimodel–experiment framework

Martinez-Vilálta, Jordi, Yepez, Enrico A, Hölttä T., Teemu, Sperry, John S, National Center for Atmospheric Research [Boulder] (NCAR), Mencuccini, Maurizio, Gehres, Nathan, Sevanto, Sanna, College of Forestry ; Oregon State University (OSU), Pockman, William T, United States Department of Agriculture (USDA), Instituto Tecnológico de Sonora (ITSON), Boutz, Amanda, Domec, Jean-Christophe, State University of New York (SUNY), Earth and Environmental Sciences Division [Los Alamos] (EES) ; Los Alamos National Laboratory (LANL), Mcdowell, Nate G, Department of Forest Sciences [Helsinki] ; Faculty of Agriculture and Forestry [Helsinki] ; Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Xu, Chonggang, Transfert Sol-Plante et Cycle des Eléments Minéraux dans les Ecosystèmes Cultivés (TCEM) ; Institut National de la Recherche Agronomique (INRA)-École Nationale d'Ingénieurs des Travaux Agricoles - Bordeaux (ENITAB), Écologie fonctionnelle et p

2013

Overview

Model–data comparisons of plant physiological processes provide an understanding of mechanisms underlying vegetation responses to climate. We simulated the physiology of a piñon pine–juniper woodland (Pinus edulis–Juniperus monosperma) that experienced mortality during a 5 yr precipitation-reduction experiment, allowing a framework with which to examine our knowledge of drought-induced tree mortality. We used six models designed for scales ranging from individual plants to a global level, all containing state-of-the-art representations of the internal hydraulic and carbohydrate dynamics of woody plants. Despite the large range of model structures, tuning, and parameterization employed, all simulations predicted hydraulic failure and carbon starvation processes co-occurring in dying trees of both species, with the time spent with severe hydraulic failure and carbon starvation, rather than absolute thresholds per se, being a better predictor of impending mortality. Model and empirical data suggest that limited carbon and water exchanges at stomatal, phloem, and below-ground interfaces were associated with mortality of both species. The model–data comparison suggests that the introduction of a mechanistic process into physiology-based models provides equal or improved predictive power over traditional process-model or empirical thresholds. Both biophysical and empirical modeling approaches are useful in understanding processes, particularly when the models fail, because they reveal mechanisms that are likely to underlie mortality. We suggest that for some ecosystems, integration of mechanistic pathogen models into current vegetation models, and evaluation against observations, could result in a breakthrough capability to simulate vegetation dynamics.

• Publisher: Wiley,CCSD,New Phytologist Trust,Wiley Subscription Services, Inc
• Subject: Carbohydrates / Carbon / Carbon - metabolism / carbon starvation / cavitation / climate / die‐off / Drought / Droughts / dynamic global vegetation models (DGVMs) / Dynamics / Ecosystem models / Environment models / Evaluation / hydraulic failure / Hydraulics / Interfaces / Juniperus - growth & development / Juniperus - physiology / Juniperus monosperma / Life Sciences / Model testing / Modeling / Models, Biological / Mortality / Parameterization / Pathogens / Phloem / Phloem - growth & development / Phloem - physiology / photosynthesis / Physiology / Pine trees / Pinus / Pinus - growth & development / Pinus - physiology / Pinus edulis / Plant Stomata - growth & development / Plant Stomata - physiology / Plant Transpiration - physiology / Plants / process‐based models / Rain / Simulation / Simulations / Starvation / Stomata / Stress, Physiological / Tansley reviews / Temperature / Thresholds / tree mortality / Trees / Vegetal Biology / Vegetation / Water - physiology / Woodlands / Woody plants
• ISBN: 0003246216000