Micro spatial distribution pattern of litterfall and nutrient flux in relation to soil chemical properties in a super wet tropical rain forest, West S

Micro spatial distribution pattern of litterfall and nutrient flux in relation to soil chemical properties in a super wet tropical rain forest, West Sumatra, Indonesia

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 and National Polytechnics of agriculture Payakumbuh

Published: TROPICS vol. 12 No.2 March 2003. The Japan Society of Tropical Ecology. ISSN 0917-415X

ABSTRACT The micro spatial distribution of the litterfall and nutrient flux in relation to tree composition and soil chemical properties was investigated within a one-hectare study plot with 115 subplot (10m x 10m) in a upper wet tropical rain forest in West Sumatra, Indonesia. Litterfall production and its nutrient flux throughout a one-year period were determinated using 63 circular litter traps installed in 63 subplot among the 115 subplots. The aim of this study was to qualify the micro spatial distribution of the litterfall production and nutrient flux in relation to tree composition and soil chemical properties among the 63 subplot within the study plot. To characterize the relationship among the micro spatial distribution of the litterfall, nutrient flux and tree composition and/or soil chemical properties, the correlation coefficients and omega index of Iwao (1997) were determined. The mean litterfall was 11.4 Mg ha-1 y-1 and the litterfall varied among the 63 subplots within the range of 7.4 – 16.3 Mg ha-1 y-1. The variations in litterfall were positively correlated (P=0.01) to tree density and the number of tree species in the subplots. Based on the nutrient contents and the production of leaf litter, the nutrient fluxes in the 63 subplot were calculated, and were found to vary significantly within the subplots as follows: N, 54-140; P, 1.4-4.5; K, 8.8-27.5; Ca, 71-207; Mg, 6.2-17.7; Al, 3.2-26.4; Fe, 0.7-3.5; and S, 6.2-16.4 (kg ha-1 y-1). The amount of each nutrient flux was strongly affected by the amount of litterfall production, and was, in turn, positively correlated with tree density and the number of tree species in each subplot. The micro spatial distributions of nutrient flux showed significant positive correlation with the soil chemical properties of total N and 0.1 M HCl extractable K at the surface (0-5 cm) soil each subplot. However, for the other major element such as Ca and Mg, no correlation was shown. The micro spatial tree species diversity, i.e., the number of species per subplot, showed a significant positive correlation to tree density, litterfall production and N and Ca flux. However, as Kubota et al.(2000) and result in this paper, show, the micro spatial distribution of soil fertility parameters, except for the 0.1 M HCl extractable Fe in top soil, had a negative correlation to the number of tree species. These results suggest that in this super wet tropical rain forest, tree species diversity with diverse tree nutritional characteristics may contribute to create the diversity of an edaphic niche, rather than increase the soil fertility level through nutrient cycling via litterfall.
Key words: micro spatial litterfall distribution, nutrient fluxes of N, P, K and Ca, soil chemical property, super wet tropical rain forest, West Sumatra.

ACKNOWLEDGEMENTS We greatly appreciate Prof. K. Ogino, Shiga Prefecture Universiy and Prof. M. Hotta, Kagoshima University, for the establishment of the study plot. The authors thank also go to the staff members of the the Soil Department, Faculty of Agriculture, Ansity, Padang for its help and support during fieldwork and data collection. Finally my great appreciation goes to the Ministry of Education and Culture of Japan who gave partial finantial support (No.11691084) of our studies in Japan.