NUTRITIONAL-STATUS AND DEFICIENCY DIAGNOSIS OF PINUS-RADIATA PLANTATIONS IN SPAIN

Twenty-one plots of Pinus radiata D. Don were selected for nutritional diagnosis on the basis of parent material (nine different substrates) and climate (Atlantic and Mediterranean). After foliar analysis, nutr itional diagnoses were conducted, using the critical level method and the DRIS system. The nutrient content in fresh litter (L horizon) was also measured, and nutrient levels of green pine needles were compared with leaves of three native hardwood species (Quercus ilex L., Q. rob ur L. and Fagus sylvatica L.) growing near each pine plot. In most cas es, deciduous trees showed higher nutritional levels than evergreen tr ees. Foliar levels of Ca were always higher in hardwood trees, irrespe ctive of leaf longevity. Phosphorus (P) deficiency was the most common among pines (eight plots showed severe P deficiency). Nitrogen and ma gnesium deficiencies were also detected in a few cases. The DRIS syste m diagnosed a larger number of deficiencies than the critical level me thod, but after intercalibration both methods gave the same diagnosis. In the plots studied, litter analysis appeared to be an alternative t o foliar analysis for P, S, Ca, and Mg diagnosis but not for N or K.