Experimental drought and heat can delay phenological development and reduce foliar and shoot growth in semiarid trees

Sécheresse et réchauffement expérimentaux peuvent retarder le développement phénologique et réduire la croissance des feuilles et branches chez des arbres de milieux semi-arides

Adams, H.D. ; Collins, A.D. ; Briggs, S.P. ; Vennetier, M. ; Dickman, L.T. ; Sevanto, S.A. ; Garcia Forner, N. ; Heath, P. ; McDowell, N.G.

Type de document
Article de revue scientifique à comité de lecture
Langue
Anglais
Affiliation de l'auteur
LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA ; LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA ; LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA ; IRSTEA AIX EN PROVENCE UR EMAX FRA ; LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA ; LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA ; CENTRE DE RECERCA ECOLÒGICA I APLICACIONS FORESTALS UNIVERSITAT AUTÒNOMA DE BARCELONA ESP ; LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA ; LOS ALAMOS NATIONAL LABORATORY EARTH AND ENVIRONMENTAL SCIENCES DIVISION LOS ALAMOS USA
Année
2015
Résumé / Abstract
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 are 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 semi-arid 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 to 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 non-structural 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.
Source
Global Change Biology, vol. 21, num. 11, p. 4210 - 4220

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