Nutrient efficiency and resorption in Quercus pyrenaica oak coppices underdifferent rainfall regimes of the Sierra de Gata mountains (central western Spain)

Quercus pyrenaica oak coppices situated in the Sierra de Gata mountains (pr ovince of Salamanca, central-western Spain). The efficiency (NUE) with whic h a given nutrient is used depends on several factors. In the oak coppices studied, availability of P, Ca and Mg in the soil was one of the factors go verning efficiency. On the other hand, there was a certain independence bet ween soil N and K availability and their plant efficiency; in the case of N this occurred possibly because it is a limiting factor. There was a plant nutritional Ca-Mg imbalance due to soil acidity. Leaf absorption and/or lea ching at canopy level would also influence the N and K efficiency. The stan d with the most dystrophic soil was the least efficient regarding Mg, and t he plot with the most eutrophic soil regarding Ca. All the oak coppices had low N efficiency. Bioelement resorption did not affect the NUE decisively but it seemed to be influenced by leaf absorption and leaching occurring at the canopy level. Higher aboveground production suggested that the stands on granite absorbed greater yearly amounts of N, K and P than those on schi st. ((C) Inra/Elsevier, Paris.).