The combined effects of a long-term experimental drought and an extreme drought on the use of plant-water sources in a Mediterranean forest
Barbeta i Margarit, Adrià (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Mejía Chang, Monica (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)
Voltas, Jordi (Universitat de Lleida. Departament de Producció Vegetal i Ciència Forestal)
Dawson, Todd E. (University of California, Berkeley. Department of Integrative Biology)
Peñuelas, Josep (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)

Fecha:	2015
Resumen:	Vegetation in water-limited ecosystems relies strongly on access to deep water reserves to withstand dry periods. Most of these ecosystems have shallow soils over deep groundwater reserves. Understanding the functioning and functional plasticity of species-specific root systems and the patterns of or differences in the use of water sources under more frequent or intense droughts is therefore necessary to properly predict the responses of seasonally dry ecosystems to future climate. We used stable isotopes to investigate the seasonal patterns of water uptake by a sclerophyll forest on sloped terrain with shallow soils. We assessed the effect of a long-term experimental drought (12 years) and the added impact of an extreme natural drought that produced widespread tree mortality and crown defoliation. The dominant species, Quercus ilex, Arbutus unedo and Phillyrea latifolia, all have dimorphic root systems enabling them to access different water sources in space and time. The plants extracted water mainly from the soil in the cold and wet seasons but increased their use of groundwater during the summer drought. Interestingly, the plants subjected to the long-term experimental drought shifted water uptake toward deeper (10-35 cm) soil layers during the wet season and reduced groundwater uptake in summer, indicating plasticity in the functional distribution of fine roots that dampened the effect of our experimental drought over the long term. An extreme drought in 2011, however, further reduced the contribution of deep soil layers and groundwater to transpiration, which resulted in greater crown defoliation in the drought-affected plants. The present study suggests that extreme droughts aggravate moderate but persistent drier conditions (simulated by our manipulation) and may lead to the depletion of water from groundwater reservoirs and weathered bedrock, threatening the preservation of these Mediterranean ecosystems in their current structures and compositions.
Ayudas:	European Commission 610028 Ministerio de Ciencia e Innovación CSD2008-00040 Ministerio de Ciencia e Innovación CGC2010-17172 Agència de Gestió d'Ajuts Universitaris i de Recerca 2009/SGR-458
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió acceptada per publicar
Materia:	Holm oak ; Experimental drought ; Stable isotopes ; Water uptake ; Mediterranean forest ; Climate change ; Extreme drought ; Water-use strategies ; Arbatus unedo ; Quercus ilex ; Phillyrea latifolia
Publicado en:	Global change biology, Vol. 21, no. 3 (March 2015) , p. 1213-1225, ISSN 1365-2486

DOI: 10.1111/gcb.12785

Post-print 41 p, 629.6 KB

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Documentos de investigación > Documentos de los grupos de investigación de la UAB > Centros y grupos de investigación (producción científica) > Ciencias > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals) > Imbalance-P
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