ALLOMETRY OF SAPLINGS AND UNDERSTOREY TREES OF A PANAMANIAN FOREST

The dimensional relationships of understorey trees were contrasted with those of saplings of subcanopy-canopy trees in a humid tropical forest on Barro Colorado Island. The 6 selected species were all common, shade-tolerant trees of primary forest and were sampled in shaded understorey. The 2 smallest understorey species had thicker trunks and wider, heavier, leafier crowns than similar height (2.5 m tall) saplings of larger species. The former also showed greater increases in trunk diameter and crown mass per height increment, as inferred from the allometric relationships. Such patterns are consistent with the hypothesis that understorey species have morphologies which increase light interception and persistence in the understorey, while saplings of overstorey species allocate their biomass for efficient height growth, ie they are adapted to efficiently pass through the understorey to reach the high-light environment of the canopy. -from Author