Treefalls and Patterns of Understory Species in a Wet Lowland Tropical Forest

Abstr act. Nested quadrats were used to determine natural clump sizes for three understory species in a mature, wet, tropical forest in Costa Rica. Under a closed canopy, individuals > 60 cm tall of the understory palm Cryosophlila guagara are shown to clump maximally at a size which corresponds to the size of lightgaps created by fallen canopy trees, suggesting that the distribution pattern of this palm is related to the pattern of fallen trees. Two other understory species, Neonichlolsonia watsonii and Car ludovica palmata, clump maximally at sizes which do not correspond to the sizes of average canopy gaps.