DELIMITING THE GAP PHASE IN THE GROWTH-CYCLE OF A PANAMANIAN FOREST

Despite the importance of treefall gaps in tropical forest dynamics, f ew studies have followed gap-phase processes for more than 2 y. We mon itored, for five years, the growth and survival of many seedlings of T etragastris panamensis (Engler) O. Kuntze, Protium panamense (Rose) I. M. Johnston, and Desmopsis panamensis (Rob.) Saff. (three common tree species of the Panamanian tropical moist forest) in artificially crea ted treefall gaps and under intact-canopy control plots. On these same plots, we also monitored light levels using hemispherical photographs taken over an 8-y period. Seedling height growth was faster in gaps t han under intact canopies during the first 42 mo of regrowth, then dec lined to rates similar to those under intact canopies. Light levels in gaps similarly rose and fell, returning to pre-gap levels by month 48 . Only Tetragastris panamensis showed higher survival in gaps, contrar y to the general assumption that seedling survival is enhanced by gap creation. Our results document important transition points that mark t he conclusion of the gap phase, suggesting an estimate of dry for the duration of the gap phase in this tropical forest.