LITTER DECOMPOSITION ON FOREST ROADS VERSUS INSIDE TROPICAL RAINFORESTS IN SABAH, MALAYSIA

Forest roads constructed by bulldozers change the physical environment within the forests. A litter-bag experiment using three substrates (wood blocks, and Shorea and Macaranga leaf litter) was performed to clarify the effects of forest roads on initial litter decomposition in tropical rainforests. The results showed that the wood blocks and leaf litter had different decomposition rates between locations (on the path vs. inside the forest). The wood blocks decomposed more slowly on the path than inside the forest, whereas Shorea leaf litter decomposed more quickly on the path than inside the forest. The lower moisture content of both Shorea and Macaranga leaf litter indicated a more pronounced drought condition on the path. The surface area of leaf litter decreased more in Macaranga than in Shorea, whereas the leaf mass per area showed the opposite trend. This findings suggested that Macaranga leaf litter mainly decomposed by fragmentation, whereas Shorea leaf litter mainly decomposed by microbial degradation and leaching, in addition to fragmentation. The results indicated that road disturbance changed the balance between fragmentation and other degradation processes. The findings also highlighted that assessing the loss of surface area and leaf mass per area is appropriate for evaluating the influence of different types of leaf litter decomposition.