Experimental drought and heat can delay phenological development and reduce foliar and shoot growth in semiarid trees
Adams, Henry D. (Los Alamos National Laboratory. Earth and Environmental Sciences Division)
Collins, Adam D. (Los Alamos National Laboratory. Earth and Environmental Sciences Division)
Briggs, Samuel P. (Los Alamos National Laboratory. Earth and Environmental Sciences Division)
Vennetier, Michel (Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (França))
Dickman, L. Turin (Los Alamos National Laboratory. Earth and Environmental Sciences Division)
Sevanto, Sanna A. (Los Alamos National Laboratory. Earth and Environmental Sciences)
Garcia-Forner, Núria (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Powers, Heath H. (Los Alamos National Laboratory. Earth and Environmental Sciences Division)
McDowell, Nate G. (Los Alamos National Laboratory. Earth and Environmental Sciences Division)

Data:	2015
Resum:	Higher temperatures associated with climate change are anticipated to trigger an earlier start to the growing season, which could increase the terrestrial C sink strength. Greater variability in the amount and timing of precipitation is also expected with higher temperatures, bringing increased drought stress to many ecosystems. We experimentally assessed the effects of higher temperature and drought on the foliar phenology and shoot growth of mature trees of two semiarid conifer species. We exposed field-grown trees to a ~45% reduction in precipitation with a rain-out structure ('drought'), a ~4. 8 °C temperature increase with open-top chambers ('heat'), and a combination of both simultaneously ('drought + heat'). Over the 2013 growing season, drought, heat, and drought + heat treatments reduced shoot and needle growth in piñon pine (Pinus edulis) by ≥39%, while juniper (Juniperus monosperma) had low growth and little response to these treatments. Needle emergence on primary axis branches of piñon pine was delayed in heat, drought, and drought + heat treatments by 19-57 days, while secondary axis branches were less likely to produce needles in the heat treatment, and produced no needles at all in the drought + heat treatment. Growth of shoots and needles, and the timing of needle emergence correlated inversely with xylem water tension and positively with nonstructural carbohydrate concentrations. Our findings demonstrate the potential for delayed phenological development and reduced growth with higher temperatures and drought in tree species that are vulnerable to drought and reveal potential mechanistic links to physiological stress responses. Climate change projections of an earlier and longer growing season with higher temperatures, and consequent increases in terrestrial C sink strength, may be incorrect for regions where plants will face increased drought stress with climate change.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Climate change ; Juniper ; Juniperus monosperma ; Nonstructural carbohydrate ; Phenology ; Pinus edulis ; Piñon pine ; Water potential
Publicat a:	Global change biology, Vol. 21 Issue 11 (Nov. 2015) , p. 4210-4220, ISSN 1365-2486

DOI: 10.1111/gcb.13030

Article. Post-print 44 p, 3.2 MB

Material addicional. Post-print 14 p, 2.3 MB

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