PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Effect of four year teak (Tectona grandis) plantation on understory species composition.
Santana, Mirna*,, Lao, Suzanne2, 2 Smithsonian Tropical Research Institute, Panama
ABSTRACT- The role of non-native tree plantations in facilitating the regeneration of native plant species is controversial. To asses the influences of plantations on the composition and regeneration of native plant comunities, we measured all vascular plants >1.3 m in height in 400 m2 plots in four year-old teak plantations. We include all stems > 20 cm height in three 25 m 2, and all plant species vascular and non-vascular in three 1 m2 sub-plots within the main plots. We measured canopy structure and cover, quantified live and dead ground vegetation cover, as well as the proportion of exposed soil. We determined the distance of each plot to the nearest native forest to test for possible influences on plant species composition. We found 124 native and 5 exotic species. Of these, 33 species were herbaceous angiosperms, 31 trees or shrubs,17 grasses (5 exotics) and 14 climbers. The most abundant species were two tall grasses including Saccharum spontaneum, which formerly dominated the area. The dominance of S. spontaneum suggest that teak is not limiting light availability to understory species. Piper marginatum was the most common forest species. Canopy cover ranged between 70-100% and groundcover vegetation from 15-85%. Groundcover was 40% live material and 60% dead (of which teak leaf litter was 62.5 %). The dominance of dead groundcover suggests poor plant species colonization. Soil exposure varied from 5-25%, mean 12.4%. Average species diversity was 12 in the 400m2 plots, 5 in the 25m2, and 9 at the 1m2 subplots (including non vascular). There was no correlation between species abundance or diversity of the understory with size of teak, ground cover, slope, canopy cover, distance or size of the adjacent forest. Teak plantations supported greater diversity of woody species (31) than S. spontaneus grassland (2,Jones et al. 2004). The diversity of woody species in the understory of teak plantations (31) was lower than under native tree plantations of same age (119 total species). Although teak plantations facilitated regeneration, grasses and non-woody species account for most of their diversity suggesting that silvicultural practices or changes in understory environment of plantations may be limiting species colonization.
Key words: Plant diversity, plantations, teak, tropical forest