ECOTYPIC DIFFERENTIATION AND PLANT GROWTH IN THE LUQUILLO MOUNTAINS OF PUERTO RICO

Abstract

A greenhouse experiment was performed to investigate ecotypic differentiation among tropical trees along an elevation gradient in Puerto  Rico, USA, using  Clibadium erosum  cuttings  and  Prestoea  acuminata var. montana seedlings. Clibadium erosum cuttings (1) grew more after nitrogen (N) addition and after phosphorus (P) addition but there was no N+P  effect,  (2) were larger from El Verde (elevation 350 m) compared with Pico del Este ( 1000 m) , (3) showed increased photosynthesis after N addition, and (4) front Pico del Este were higher in photosynthesis during one sample period but lower in the other. We also found that P. aruminata var. montana seedlings (1) had greater growth after N addition, (2) had different leaf parameters after N addition, and (3) showed an increase in photosynthesis after N addition. We conclude that because only three out of ten plant traits showed differentiation, ecotypes for these two tree species on this neotropic mountain range may not exist.