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Universidade de Lisboa (2010)

Effects of Pinus pinaster in the phenological development and ecophysiology performance of Acacia longifolia under different climatic conditions

Fernandes, Patrícia Alexandra Tinoco

Titre : Effects of Pinus pinaster in the phenological development and ecophysiology performance of Acacia longifolia under different climatic conditions

Auteur : Fernandes, Patrícia Alexandra Tinoco

Université de soutenance : Universidade de Lisboa

Grade : Mestrado. Biologia (Biologia da Conservação) 2010

Résumé
The habitat invasions by exotic invasive species have been one of the most important threats to ecosystem biodiversity and may be considered one of the most important effects of global change. These species attain a high density and they change ecosystem composition, structure and function, which lead to a strong environmental impact, such as native species extinction and habitat homogenization. One of the most important challenges is to evaluate the competitive capacity of invasive spp and the use and capture of natural resources. Dune ecosystems are characterized by a high diversity of native plants species. However, the conservation of Portuguese coastal ecosystems is seriously threats by considerable spread of several invasive species, namely Acacia longifolia. Therefore, it is important to understand which environmental conditions enhance A. longifolia invisibility. In the present study, phenological and ecophysiological measurements in Acacia longifolia trees were performed at Osso da baleia (north location) and in the Pinheiro da Cruz (Southern location). In addition were also tested the effect of the Pinus pinaster overstory in A. longofolia physiological performance. Ecophysiological results show that under stressful climatic conditions, namely lower water availability, A. longifolia displayed limited carbon assimilation and inhibition effect on stomatal conductance ; demonstrating that the carbon balance and water fluxes of A. longifolia was affected by water stress. Furthermore, A. longifolia in the presence of P. pinaster overstory is more sensitive to drought, exhibiting lower carbon gain, lower stomatal conductance and lower leaf water potential values. Finally, this study suggests that northern climatic conditions (more mesic conditions) might be more stressful for A. longifolia, displaying higher reproductive cost than in the south, due to an increase in competition with the P. pinaster plantation. In addition, higher air temperatures and irradiance may lead to an earlier display of phenological phases in the Southern than in the Northern plants.

Mots clés : Fisiologia vegetal ; Espécies exóticas ; Acácia ; Pinheiro

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Page publiée le 22 octobre 2013, mise à jour le 22 août 2018