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

Quercus pyrenaica oak coppices situated in the Sierra de Gata mountains (province of Salamanca, central-western Spain). The efficiency (NUE) with which 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 governing efficiency. On the other hand, there was a certain independence between 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 leaching at canopy level would also influence the N and K efficiency. The stand with the most dystrophic soil was the least efficient regarding Mg, and the 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 schist. ((C) Inra/Elsevier, Paris.).