Origin and Early Development of Forest Edge Vegetation in Panama

Abstract
An experimental edge was created in a tropical premontane wet forest in Panama to study the origin and early development of edge vegetation. A study of the soil seed bank indicated that seeds of light-demanding species were abundant before edge creation (937/m2). Canopy photographs, germination bioassays, and the germination of many seeds in response to soil disturbance (95/m2) confirmed that lateral light penetration into the forest edge was sufficient to promote germination of light-sensitive seeds. Light-demanding species, however, were rare along this edge and along older edges in the area, in part because soil disturbance normally did not occur during edge creation. Relative growth rate of woody plants <2 m tall over a 10-month period on the experimental edge were twice as rapid as plants in the forest interior (0.029 cm/cm/mo vs 0.014 cm/cm/mo). Changes in seedling density, recruitment, and mortality with time after edge creation were similar on forest edge and in forest interior. Edge plants were derived primarily from seedlings and saplings present before edge creation.