Leaf Litter Decomposition Rates in the Mixed Deciduous Forest at Maeklong Watershed Research Station, Kanchanaburi Province
Dokrad Marod, Uthatiwan Sangwanit, Noppakun Danrad, and Samroeng Panuthai
Soil properties, such as fertility, are very important for plant establishment, and is mainly facilitated by organic material. This study investigated the decomposition rates of dominant tree species in a mixed deciduous forest (MDF) and the environmental factors that may affect it. The study site was located at the Maeklong Watershed Research Station in Kanchanaburi Province. Five dominant species in MDF were selected which included Pterocarpus macrocarpus, Xylia xylocarpa, Vitex peduncularis, Canarium subulatum, and Schleichera oleosa. Additional species that were investigated were Shorea siamensis, Dipterocarpus alatus, and a bamboo species (Gigantochloa albociliata). Leaf litter bags weighing 50 g/bag were prepared and 36 such bags were collected for each species and were placed on the forest floor. A randomized complete block design with 3 replications was utilized as the design experiment. The litter bags were randomly collected every month from May 2015 to May 2016. These samples were brought back to laboratory and oven-dried at 60oC for 48 hours, after which they were brushed to remove any soil debris. The residual litter in each bag was weighed to ascertain the reduction in weight of the leaves to determine the decomposition rate (k). The results indicate that the litter decomposition rate varied among species. Many dominant species had a high k-value (k > 3), while D. alatus and G. albociliata returned a medium (k = 2.43) and the lowest (k = 1.88) decomposition rate, respectively. The nutrient content of dominant tree species has the highest Ca in leaf litter. Rainfall had a highly significant (p <0.01) effect on the litter decomposition rate. Soil conservation, particular the soil fertility, can be undertaken through nutrient turnover from leaf litter decomposition.