Per citar aquest document: http://ddd.uab.cat/record/131594
Foliar photochemical processes and carbon metabolism under favourable and adverse winter conditions in a Mediterranean mixed forest, Catalonia (Spain)
Sperlich, Dominik (Centre de Recerca Ecològica i Aplicacions Forestals)
Chang, C. T. (Centre de Recerca Ecològica i Aplicacions Forestals)
Peñuelas, Josep (Centre de Recerca Ecològica i Aplicacions Forestals)
Gracia, Carles (Centre de Recerca Ecològica i Aplicacions Forestals)
Sabaté i Jorba, Santi (Centre de Recerca Ecològica i Aplicacions Forestals)

Data: 2014
Resum: Evergreen trees in the Mediterranean region must cope with a wide range of environmental stresses from summer drought to winter cold. The mildness of Mediterranean winters can periodically lead to favourable environmental conditions above the threshold for a positive carbon balance, benefitting evergreen woody species more than deciduous ones. The comparatively lower solar energy input in winter decreases the foliar light saturation point. This leads to a higher susceptibility to photoinhibitory stress especially when chilly (< 12 °C) or freezing temperatures (< 0 °C) coincide with clear skies and relatively high solar irradiances. Nonetheless, the advantage of evergreen species that are able to photosynthesize all year round where a significant fraction can be attributed to winter months, compensates for the lower carbon uptake during spring and summer in comparison to deciduous species. We investigated the ecophysiological behaviour of three co-occurring mature evergreen tree species (Quercus ilex L. , Pinus halepensis Mill. , and Arbutus unedo L. ). Therefore, we collected twigs from the field during a period of mild winter conditions and after a sudden cold period. After both periods, the state of the photosynthetic machinery was tested in the laboratory by estimating the foliar photosynthetic potential with CO² response curves in parallel with chlorophyll fluorescence measurements. The studied evergreen tree species benefited strongly from mild winter conditions by exhibiting extraordinarily high photosynthetic potentials. A sudden period of frost, however, negatively affected the photosynthetic apparatus, leading to significant decreases in key physiological parameters such as the maximum carboxylation velocity (V_(c,max)), the maximum photosynthetic electron transport rate (J(max)), and the optimal fluorometric quantum yield of photosystem II (F_v/F_m). The responses of V_(c,max) and J(max) were highly species specific, with Q. ilex exhibiting the highest and P. halepensis the lowest reductions. In contrast, the optimal fluorometric quantum yield of photosystem II (F_v/_Fm) was significantly lower in A. unedo after the cold period. The leaf position played an important role in Q. ilex showing a stronger winter effect on sunlit leaves in comparison to shaded leaves. Our results generally agreed with the previous classifications of photoinhibition-tolerant (P. halepensis) and photoinhibition-avoiding (Q. ilex) species on the basis of their susceptibility to dynamic photoinhibition, whereas A. unedo was the least tolerant to photoinhibition, which was chronic in this species. Q. ilex and P. halepensis seem to follow contrasting photoprotective strategies. However, they seemed equally successful under the prevailing conditions exhibiting an adaptive advantage over A. unedo. These results show that our understanding of the dynamics of interspecific competition in Mediterranean ecosystems requires consideration of the physiological behaviour during winter which may have important implications for long-term carbon budgets and growth trends.
Nota: Número d'acord de subvenció MINECO/CGL2011-30590-C02-01
Nota: Número d'acord de subvenció EC/FP7/238366
Drets: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original. Creative Commons
Llengua: Anglès
Document: article ; recerca ; publishedVersion
Matèria: Mediterranean forest ; Carbon metabolism ; Winter
Publicat a: Biogeosciences, Vol. 11 Issue 20 (Oct. 2014) , p. 5657-5674, ISSN 1726-4170

DOI: 10.5194/bg-11-5657-2014


18 p, 721.7 KB

El registre apareix a les col·leccions:
Documents de recerca > Documents dels grups de recerca de la UAB > Centres i grups de recerca (producció científica) > Ciències > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Articles > Articles de recerca
Articles > Articles publicats

 Registre creat el 2015-04-15, darrera modificació el 2016-06-04



   Favorit i Compartir