Physiological performance of silver-fir (Abies alba Mill.) populations under contrasting climates near the south-western distribution limit of the species

摘要: Abstract Silver-fir ( Abies alba Mill.) populations located at the south side of main Pyrenean axis and Pre-Pyrenees constitute south-western distribution limit species and, therefore, may be responding more noticeably to climate change than those in centre range. The increasing aridity detected Pyrenees during 20th century should affect negatively physiological performance southernmost silver-fir stand growing under xeric conditions comparison with stands within area mesic conditions. To evaluate climatic influence on silver fir near its limit, we studied several growth variables shoots needles from two nearby but climatically contrasting sites: Paco Ezpela (site E) Gamueta G). Site E showed a stronger Mediterranean site G, i.e. former was characterized by higher temperatures leaf-to-air water vapour pressure difference lower precipitation summer latter site. Silver firs values primary secondary growth, needle length, stomatal conductance, net photosynthesis photosystem II (PSII) efficiency individuals G. reduction could ascribed low CO 2 availability PSII efficiency. We conclude that differences found between both sites were caused as compared environment predicted increase severe droughts southern might cause decrease ecological species.