VARIATION IN FOLIAR ELEMENTAL COMPOSITION IN MATURE WILD TREES AND AMONG FAMILIES AND PROVENANCES OF VOCHYSIA-GUATEMALENSIS IN COSTA-RICA

Variation in foliage elemental composition provides insights into the adaptive mechanisms of species to a particular site and provides the b ases for selection for greater nutrient use efficiency. Studies of thi s variation in tropical trees have been limited to a small number of s pecies, mainly pines and eucalypts. This study compared the foliage el emental composition of mature trees of Vochysia guatemalensis D. SMITH from 3 sites in Costa Rica. At each site foliar and soil samples were collected individually per tree and analyzed for elemental compositio n. Differences in foliar P, Mg, Fe, Cu, Zn and Mn were found among sit es. No significant nor consistent correlations were found between soil chemical properties and tissue elemental composition. Even though the re were large differences in pH and cation exchange capacity among sit es, tissue Ca (mean 12.4 g kg(-1)) and Al (20,100 mg kg(-1)) content d id not vary significantly. In order to assess the variation in foliage composition among provenances and families within provenances, a prog eny test planted on an acidic, infertile Inceptisol was studied. For t he 6 provenances planted, 3 families and 2 trees per family were rando mly selected and individually sampled for foliage and soils. At 4 year s of age, significant differences among provenances and families were found for P concentration, varying from 0.42 g kg(-1) for the Siquirre s provenance (Costa Rica) to 0.52 g kg(-1) for La Ceiba provenance (Ho nduras). For Ca, Mg, Al, and Zn only differences among families within provenances were detected. Foliar Fe concentration was found to diffe r significantly only among provenances. Even though no final conclusio ns about genetic differences in elemental composition among families a nd provenances of this species can be made due to the small number of provenances and families sampled, these findings indicate that genetic differences in foliage elemental composition occur, suggesting that g enetic differences in response to nutrient availability carl also be e xpected.