Hydrological Processes in Different Types of Teak (Tectona grandis L.) Plantation

Abstract

Improved knowledge of canopy processes is allowing better estimation of the influence of forests in hydrology for forest function. The societal demand for timber wood has increased rapidly in the last two decades. The best genetic selection of teak (Tectona grandis L.) has been found and produced with shoot cuttings or tissue cultures and planted in Central Java, Indonesia. Understanding the hydrological processes in a teak plantation is helpful to develop a strategy for sustainable forest management system. The aim of this study was to measure the hydrological processes of canopy interception and direct runoff to estimate the forest interception in two types of the teak plantation. Two paired catchment experiments were established to monitor the canopy interception and direct runoff during the rainy season. Catchment T1 was planted with 10-year-old superior teak, and catchment T2 was planted with 10-year-old conventional teak. Superior teak is the result of tree improvement from prospective clonals of teak. Superior teak is propagated by shoot cutting or tissue cultures, while the conventional teak is from seed production in seed orchards. Canopy interception was investigated using 15 units of throughfall and eight units of stemflow in both catchments. The two catchment experiments were equipped with sharp-crested 90⁰ V-notch weirs and automatic water level recorders. The percentage ratio between stemflow and throughfall in the T1 and T2 catchments were 0.08:54.7 and 0.15:70.4 of rainfall. The canopy interceptions in the T1 and T2 catchments were 45.2% and 29.4% of rainfall. Direct runoff in the T1 and T2 catchments were 32.2% and 47.2% of rainfall. Forest interceptions as a function of canopy interception and forest floor interception in the T1 and T2 catchments were 58.2% and 33.1% of rainfall. The difference in forest canopy cover of 13% has led to changes in the canopy interception. This change has affected an increase in the direct runoff and forest interception in the catchment. Characteristics of superior teak with fast growth and uniform physical appearance of diameter, height, and canopy structure showed higher forest interception than that of the conventional teak.