Aridification determines changes in forest growth in Pinus halepensis forests under semiarid Mediterranean climate conditions.

Vicente-Serrano SM, Lasanta T, Gracia C (2010) Aridification determines changes in forest growth in Pinus halepensis forests under semiarid Mediterranean climate conditions. Agricultural and Forest Meteorology 150: 614-628.

Biocombustibles: Energia o aliment.

Gracia C (2010) Biocombustibles: Energia o aliment. Omniscellula 25: 21-27.

Models for supporting forest management in a changing environment.

Fontes L, Bontemps JD, Bugmann H, Van Oijen M, Gracia C, KramerK, Lindner M, Rötzer T, Skovsgaard JP (2010) Models for supporting forest management in a changing environment. Forest Systems 19: 8-29.

Pilot study on harmonising national forest inventories in Europe.

Requardt A, Siwe R, Riedel T, Köhl M, Tröltzsch K, Varis S, Travaglini D, Corona P, Sanchez A, Vayreda J, Gracia C, Camia A, San Miguel J (2010) Pilot study on harmonising national forest inventories in Europe. European Commission. Joint Research Centre 136 pp.

Intégration des effets du changement climatique sur les forêts méditerranéennes : observation, expérimentation, modélisation et gestion p. 351. Introducing the climate change effects on Mediterranean forest ecosystems: observation, experimentation, simul

Peñuelas J, Gracia C, Filella I, Jump A, Carnicer J, Coll M, Lloret F, Curiel J, Estiarte M, Rutishauser T, Ogaya R, LLusiá J, Sardans J (2010) Intégration des effets du changement climatique sur les forêts méditerranéennes : observation, expérimentation, modélisation et gestion p. 351. Introducing the climate change effects on Mediterranean forest ecosystems: observation, experimentation, simul ation and management . Forêt Méditerranéenne XXXI, nº 4 pp. 357. ISSN 0245-484X.

Soil water stress and coupled photosynthesis-conductance models: Bridging the gap between conflicting reports on the relative roles of stomatal, mesophyll conductance and biochemical limitations to photosynthesis

Keenan T., Sabate S., Gracia C. (2010) Soil water stress and coupled photosynthesis-conductance models: Bridging the gap between conflicting reports on the relative roles of stomatal, mesophyll conductance and biochemical limitations to photosynthesis. Agricultural and Forest Meteorology. 150: 443-453.
Enllaç
Doi: 10.1016/j.agrformet.2010.01.008

Resum:

Various plant responses to water stress have been reported, but conflicting reports as to which limiting process is the most important and ecophysiologicaly relevant during water stressed periods make it difficult to confidently model terrestrial CO2 and water flux responses. It has become increasingly accepted that mesophyll conductance could play a role in regulating photosynthesis during periods of water stress. We adapt the Farquhar-BB-type canopy photosynthesis-conductance model coupling to incorporate mesophyll conductance, embed it in an ecophysiological forest model and use it to simulate the effects of seasonal soil water stress on canopy CO2 and water fluxes at a Mediterranean Quercus ilex forest. Tests of various hypotheses regarding the relative roles of stomatal conductance limitations (SCL), mesophyll conductance limitations (MCL) and biochemical limitations (BL) confirmed that during water stressed periods, applying only BL allows for the accurate simulation of CO2 and water fluxes. Neither SCL nor MCL alone could accurately reproduce the observed CO2 and water fluxes. However, a combination of both MCL and SCL was successful at reproducing water stress induced reductions in CO2 and water fluxes, suggesting that mesophyll conductance could bridge the gap between conflicting reports on the processes behind responses to water stress in the field. © 2010 Elsevier B.V.

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The importance of mesophyll conductance in regulating forest ecosystem productivity during drought periods

Keenan T., Sabate S., Gracia C. (2010) The importance of mesophyll conductance in regulating forest ecosystem productivity during drought periods. Global Change Biology. 16: 1019-1034.
Enllaç
Doi: 10.1111/j.1365-2486.2009.02017.x

Resum:

Water availability is the most limiting factor to global plant productivity, yet photosynthetic responses to seasonal drought cycles are poorly understood, with conflicting reports on which limiting process is the most important during drought. We address the problem using a model-data synthesis approach to look at canopy level fluxes, integrating twenty years of half hour data gathered by the FLUXNET network across six Mediterranean sites. The measured canopy level, water and carbon fluxes were used, together with an inverse canopy ecophysiological model, to estimate the bulk canopy conductance, bulk mesophyll conductance, and the canopy scale carbon pools in both the intercellular spaces and at the site of carboxylation in the chloroplasts. Thus the roles of stomatal and mesophyll conductance in the regulation of internal carbon pools and photosynthesis could be separated. A quantitative limitation analysis allowed for the relative seasonal responses of stomatal, mesophyll, and biochemical limitations to be gauged. The concentration of carbon in the chloroplast was shown to be a potentially more reliable estimator of assimilation rates than the intercellular carbon concentration. Both stomatal conductance limitations and mesophyll conductance limitations were observed to regulate the response of photosynthesis to water stress in each of the six species studied. The results suggest that mesophyll conductance could bridge the gap between conflicting reports on plant responses to soil water stress, and that the inclusion of mesophyll conductance in biosphere-atmosphere transfer models may improve their performance, in particular their ability to accurately capture the response of terrestrial vegetation productivity to drought. © 2009 Blackwell Publishing Ltd.

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