Hermansah1), Tsugiyuki MASUNAGA1), Toshiyuki WAKATSUKI1), and Aflizar2)
1) Faculty of Life and Environmental Science, Shimane University, Matsue 690-08504, Japan
2) Faculty of Agriculture, Andalas University, Padang, Indonesia
Published: TROPICS vol. 12 No.2 March 2003. The Japan Society of tropical Ecology. ISSN 0917-415X
ABSTRACT In order to clarify the detailed dynamic of litter production and its nutrient characteristics in a super wet tropical rainforest, a study was conducted using twelve litter traps installed in a one ha study plot at Pinang-Pinang, in West Sumatra, Indonesia. The trapped litter was collected monthly in two different years (December 1997 to November 1998 and December 1999 to November 2000). The annual mean litter production in 1997/98 was 12.2 Mg ha-1 and in 1999/2000 was 11.8 Mg ha-1. The contribution of leaf litter to the total litterfall was significantly greater (64.8%) than that of the other component i.e., twigs, branches and fruits. The total litterfall and leaf litter production ranged from 0.16 to 1.98 and from 0.10 to 1.30 Mg ha-1 month-1, respectively, during the two observation periods. The seasonal pattern of leaf litter production showed a strong positive correlation with mean monthly temperature. Since the mean monthly temperature showed a negative correlation to monthly precipitation, the monthly leaf litter production also showed a negative correlation to the monthly precipitation. The negative correlation between leaf litter production and monthly precipitation was, however, less significant than the positive correlation of leaf litter production to temperature. This finding suggest that, although the mechanism is unknown, leaf litter production is strongly regulated by slight fluctuation in monthly mean temperature, within the range of 25-28oC in this super wet tropical rainforest. A positive correlation between temperature and litter production was also observed for the total litter and for the other litter components. However, the correlation was less significant for these other litter categories than for leaf litter. Among the litter components (leaf, twigs, branches and fruit), leaf litter showed the highest concentration of nitrogen (N), magnesium (Mg) and sulfur (S). The reproductive structure (fruit) had a significantly higher concentration of p and K than leaf litter, but the fruits concentration of Ca was lower than those of the other component of the litter. The concentrations of Ca in leaf litter was somewhat similar to Ca. These trends might be due to the effect of dilution on Ca and N, remobilitization on N, and the leaching by rainfall on K.
Key words: Litterfall dynamics, leaf litter production, rainfall effect, super wet tropical rain forest, temperature.
ACKNOWLEDGMENT This work was supported by Grant-in Aid for Scientific Research from the Minister of Education, Science, Sport and Culture of Japan (No.08041150). I thank Darmawan and Mardian Alwis for their help during the contruction of litter traps and data collection. And I am very thangful to Prof. Mitsuru Hotta, Kagoshima University, Prof. K. Ogino, Shiga Prefecture University for establishing the study plot in Gunung Gadut, West Sumatra, Indonesia. Finally I am thankful to Prof. T. Yoneda who coordinated various ecological studies in this study plot.
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