title: Ecophysiological responses of Betula pendula, Pinus uncinata and Rhododendron ferrugineum in the Catalan Pyrenees to low summer rainfall.
abstract: Climate change is producing modifications in the intensity and frequency of rainfall in some regions of the planet. According to predictions, annual rainfall distribution in Western Europe will result in an increase in episodes of drought, thereby negatively affecting nutrient availability. Since high mountain systems will be particularly vulnerable, the physiological and nutritional responses to changes in summer rainfall were monitored over the course of two consecutive summers on three species, which are representative of subalpine forests: birch (Betula pendula Roth.), rhododendron (Rhododendron ferrugineum L.) and mountain pine (Pinus uncinata Mill.). Birch was especially susceptible to scarce precipitation showing alterations in leaf morphology and a decline in net photosynthesis (A) due to stomatal closure, which led to photoinhibition and to early leaf senescence as shown by the photosynthetic nitrogen-use efficiency (PNUE), carbon/nitrogen (C/N) ratio, foliar N and13C isotope discrimination (Δ13C) results. The Δ13C of the soluble fraction is a good estimator of intrinsic water-use efficiency in this species. Rhododendron and mountain pine had sclerophyllous leaves, as indicated by leaf mass per area, Δ13C, PNUE and C/N results. Rhododendron was particularly affected by short periods of scarce rainfall, which negatively affected gas exchange and photochemistry, and reduced the remobilization of leaf N and P. Mountain pine was the most tolerant species since alterations of gas exchange, photochemistry and Δ13C were not observed. Its highest investment of N in RuBisCo and highest potassium, iron and magnesium leaf concentration contributed to the highest A rates observed.
authors: Departament de Biologia Vegetal, Unitat de Fisiologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Diagonal 643, E-08028 Barcelona, Spain.
authors: Jordi
authors: J
authors: Fernàndez-Martínez
authors: Medi Ambient i Serveis Urbans-Ecologia Urbana, Ajuntament de Barcelona, Torrent de l'Olla, 218-220, E-08012 Barcelona, Spain.
authors: M Alba
authors: MA
authors: Fransi
authors: Departament de Biologia Vegetal, Unitat de Fisiologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Diagonal 643, E-08028 Barcelona, Spain ifleck@ub.edu.
authors: Isabel
authors: I
authors: Fleck
mesh_terms: D029662:Betula / Q000502:physiology*; D044822:Biodiversity; D002244:Carbon / Q000378:metabolism; D002734:Chlorophyll / Q000502:physiology; D057231:Climate Change; D065928:Forests; D010788:Photosynthesis; D028223:Pinus / Q000502:physiology*; D018526:Plant Transpiration; D011891:Rain; D029793:Rhododendron / Q000502:physiology*; D012621:Seasons; D013030:Spain
chemical_list: D002734:Chlorophyll; D002244:Carbon
keywords: birch; drought; nutrients; pine; rhododendron