Variation in tissue element concentrations in Quercus ilex L. over a range of different soils

Abstract

In order to study the variability in nutrient concentrations in fourtissues of Q. ilex in relation to soil properties, we selected fifteenstands in both Quercus ilex forests and Q. ilex-Pinus halepensismixed forests. These stands had developed on soils derived from eightdifferent parent materials. Three soil groups were differentiatedaccording to their chemical properties: calcareous soils, siliceoussoils, and volcanic soils. Across sites, nutrient concentrationswere generally less variable in current-year tissues than in oldertissues. Nitrogen and potassium showed the lowest variability amongsites, their concentrations in current-year leaves ranging from 1.17%to 1.39% for N and from 0.53% to 0.68% for K. There were few statisticallysignificant correlations between tissue element concentrations, themost frequent being the antagonistic relationship between calciumand magnesium. Nitrogen concentration in current-year leaves wasnegatively correlated with soil chemical fertility (nitrogen, phosphorusand potassium). This may reflect a nutritional imbalance betweennitrogen and other nutrients, some of which may be more limitingthan nitrogen to Q. ilex growth in Catalonia forests. Negative correlationswere also found between plant magnesium and soil calcium, and positivecorrelations between plant calcium and soil calcium.