title: Physiological adjustments of a Mediterranean shrub to long-term experimental warming and drought treatments.
abstract: Warmer temperatures and extended drought in the Mediterranean Basin are becoming increasingly important in determining plant physiological processes and affecting the regional carbon budget. The responses of plant physiological variables such as shoot water potential (Ψ), carbon-assimilation rates (A), stomatal conductance (gs) and intrinsic water-use efficiency (iWUE) to these climatic regimes, however, are not well understood. We conducted long-term (16 years) field experiments with mild nocturnal warming (+0.6°C) and drought (-20% soil moisture) in a Mediterranean early-successional shrubland. Warming treatment moderately influenced Ψ, A and gs throughout the sampling periods, whereas drought treatment strongly influenced these variables, especially during the summer. The combination of a natural drought in summer 2003 and the treatments significantly decreased A and iWUE. Foliar δ13C increased in the treatments relative to control, but not significantly. The values of Ψ, A and gs were correlated negatively with vapor-pressure deficit (VPD) and positively with soil moisture and tended to be more dependent on the availability of soil water. The plant, however, also improved the acclimation to drier and hotter conditions by physiological adjustments (gs and iWUE). Understanding these physiological processes in Mediterranean shrubs is crucial for assessing further climate change impacts on ecosystemic functions and services.
authors.affiliation: CSIC, Global Ecology Unit, CREAF-CEAB-CSIC-Universitat Autònoma de Barcelona, Cerdanyola del Vallés (Catalonia), E-08193, Spain; CREAF, Cerdanyola del Vallès (Catalonia), E-08193, Spain,. Electronic address: d.liu@creaf.uab.cat.
authors.forename: Daijun
authors.initials: D
authors.lastname: Liu
authors.affiliation: CSIC, Global Ecology Unit, CREAF-CEAB-CSIC-Universitat Autònoma de Barcelona, Cerdanyola del Vallés (Catalonia), E-08193, Spain; CREAF, Cerdanyola del Vallès (Catalonia), E-08193, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Llusia
authors.affiliation: CSIC, Global Ecology Unit, CREAF-CEAB-CSIC-Universitat Autònoma de Barcelona, Cerdanyola del Vallés (Catalonia), E-08193, Spain; CREAF, Cerdanyola del Vallès (Catalonia), E-08193, Spain.
authors.forename: Romà
authors.initials: R
authors.lastname: Ogaya
authors.affiliation: CSIC, Global Ecology Unit, CREAF-CEAB-CSIC-Universitat Autònoma de Barcelona, Cerdanyola del Vallés (Catalonia), E-08193, Spain; CREAF, Cerdanyola del Vallès (Catalonia), E-08193, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Estiarte
authors.affiliation: Department of Environmental Sciences, Faculty of Sciences, University of Girona, Campus de Montilivi s/n, E-17071 Girona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Llorens
authors.affiliation: Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Southwest University, Chongqing 400716, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Yang
authors.affiliation: CSIC, Global Ecology Unit, CREAF-CEAB-CSIC-Universitat Autònoma de Barcelona, Cerdanyola del Vallés (Catalonia), E-08193, Spain; CREAF, Cerdanyola del Vallès (Catalonia), E-08193, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Peñuelas
mesh_terms: D000064:Acclimatization; D000222:Adaptation, Physiological; D057231:Climate Change; D055864:Droughts; D029791:Ericaceae / Q000502:physiology*; D019083:Mediterranean Region; D010788:Photosynthesis; D012621:Seasons; D013030:Spain; D013696:Temperature; D013997:Time Factors
keywords: Frequent droughts; Global warming; Long-term experiments; Physiological response; Plant acclimation