Leaf Litter Decomposition in Exotic Tree Plantations at the Royal Agricultural Station Angkhang, Chiang Mai Province

Abstract

Leaf litter decomposition rates in exotic tree plantations at the Royal Agricultural Station Angkhang, Chiang Mai province were studied in Acacia confusa, Fraxinus griffithii, Liquidambar formosana, Cinnamomum camphora and Cunninghamia lanceolata. The study was undertaken from November 2004 to October 2005 by placing litter in nylon screen bags close to the soil surface. Samples were collected every month to determine the litter weight change and nutrient release during the experimental period.

The annual litter decomposition was fastest in C. camphora (72.43%) followed by F. griffithii (61.78%), L. formosana (57.39%), A. confusa (48.36%) and C. lanceolata (23.99%), with annual decay constant (k) values of 1.2886, 0.9620, 0.8530, 0.6609 and 0.2743 per year, respectively. The mean dry weight loss of all five species in each month was related to temperature, relative humidity and rainfall. The carbon concentration varied during the entire experimental period, while the nitrogen, phosphorus and calcium concentrations decreased initially and increased slightly in the later part of the measurement period. Initially, the potassium concentration decreased dramatically, but then increased subsequently. The magnesium concentration decreased as the measurement period progressed.

Keywords: decay constant (k), exotic tree plantation, litter decomposition, plant nutrient