Contrasting impacts of continuous moderate drought and episodic severe droughts on the aboveground-biomass increment and litterfall of three coexisting Mediterranean woody species
Liu, Daijun (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Ogaya Inurrigarro, Romà (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)
Barbeta i Margarit, Adrià (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Yang, Xiaohong (Chongqing da xue. Key Laboratory of Horticulture Science for SouthernMountainous Regions)
Peñuelas, Josep (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)

Fecha:	2015
Resumen:	Climate change is predicted to increase the aridity in the Mediterranean Basin and severely affect forest productivity and composition. The responses of forests to different timescales of drought, however, are still poorly understood because extreme and persistent moderate droughts can produce nonlinear responses in plants. We conducted a rainfall-manipulation experiment in a Mediterranean forest dominated by Quercus ilex, Phillyrea latifolia, and Arbutus unedo in the Prades Mountains in southern Catalonia from 1999 to 2014. The experimental drought significantly decreased forest aboveground-biomass increment (ABI), tended to increase the litterfall, and decreased aboveground net primary production throughout the 15 years of the study. The responses to the experimental drought were highly species-specific. A. unedo suffered a significant reduction in ABI, Q. ilex experienced a decrease during the early experiment (1999-2003) and in the extreme droughts of 2005-2006 and 2011-2012, and P. latifolia was unaffected by the treatment. The drought treatment significantly increased branch litterfall, especially in the extremely dry year of 2011, and also increased overall leaf litterfall. The drought treatment reduced the fruit production of Q. ilex, which affected seedling recruitment. The ABIs of all species were highly correlated with SPEI in early spring, whereas the branch litterfalls were better correlated with summer SPEIs and the leaf and fruit litterfalls were better correlated with autumn SPEIs. These species-specific responses indicated that the dominant species (Q. ilex) could be partially replaced by the drought-resistant species (P. latifolia). However, the results of this long-term study also suggest that the effect of drought treatment has been dampened over time, probably due to a combination of demographic compensation, morphological and physiological acclimation, and epigenetic changes. However, the structure of community (e. g. , species composition, dominance, and stand density) may be reordered when a certain drought threshold is reached.
Ayudas:	European Commission 610028 Ministerio de Economía y Competitividad CGL2013-48074-P Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-274
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió acceptada per publicar
Materia:	Aboveground-biomass increment ; Droughts ; Extreme episodes ; Forest acclimation ; Global warming ; Litterfall ; Netprimary production
Publicado en:	Global change biology, Vol. 21, issue 11 (Nov. 2015) , p. 4196-4209, ISSN 1365-2486

DOI: 10.1111/gcb.13029

Post-print 43 p, 1.5 MB

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