Throughfall at an Abandoned Skid Trail in a Tropical Rain Forest in Peninsular Malaysia

Knowledge of throughfall at abandoned skid trails in tropical forests is extremely scarce. Thus, throughfall was measured using 120 storage rain gauges set on a skid trail left abandoned 41 years after forest harvesting in the Bukit Tarek Experimental Watershed (BTEW) in Peninsular Malaysia. All trees of >= 1 m height in the plot were identified to the species level, and their diameter at breast height (DBH) and height were measured. Vegetation along the skid trail comprises trees with smaller DBH (0.2-31.0 cm, with a mean of 2.0 cm) and shorter height (1.0-20.0 m, with a mean of 2.8 m) than those in the regenerated secondary forests of BTEW. The diversity (i.e. 43 families, 131 species) at the skid trail was similar to that in an old tropical forest at BTEW. The ratio of throughfall to gross rainfall (Th/Rg) for 84 rain events ranged from 27.4% to 204.7% with a mean and standard deviation of 98.1% and 33.2%, respectively. We found that a considerable amount of rainwater dropped under bertam (i.e. Eugeissona tristis) and rattan (i.e. Daemonorops callicarpa, Calamus insignis) vegetation. The Th/Rg ratio weakly correlated with canopy openness. The mean Th/Rg ratio is the largest mean ratio ever reported for forests in Malaysia.