Abu Farah Md. Anisur Rahman
The United Graduate School of Agricultural Sciences, Ehime University, Matsuyama 790-8566, Japan
Hiromasa Hiura
Faculty of Agriculture, Kochi University, Kochi 783-8502, Japan
Kazuo Shino
Faculty of Agriculture, Kochi University, Kochi 783-8502, Japan
Keiji Takase
Faculty of Agriculture, Ehime University, Matsuyama 790-8566, Japan
ABSTRACT
Single catchment experiment was used to assess the effects of thinning on direct runoff and peak runoff properties in a small mountainous watershed of Kochi prefecture, Japan. The watershed is covered with commercial plantations of Japanese cedar (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa), red pine (Pinus densiflora) and oak (Quercus spp.). Following an initial pre-thinning period (1996-1999), stream flow measurements were continued over a comparable post-thinning period (2000-2003) and linear regression models were developed for the two periods to assess the effects of a thinning operation conducted during December 1999 to January 2000. We hypothesized that the regression model for the pre-thinning period is still valid for the post-thinning period and tested this utilizing the Chow`s F Test. A 95% prediction interval was calculated for the pre-thinning regression models to evaluate changes in individual observations of the post-thinning period. The results suggest that the thinning, carried out on 19.25% of the watershed area removing only 6.35% of total timber volume, did not cause noticeable effects on direct runoff and peak runoff. Concentration time was found to be decreased after thinning for some storm events. The study revealed that hydrometric method is not enough for detecting noticeable effects of a small thinning operation on direct runoff and peak runoff properties.
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How to cite this article
Abu Farah Md. Anisur Rahman, Hiromasa Hiura, Kazuo Shino and Keiji Takase, 2005. Effects of Forest Thinning on Direct Runoff and Peak Runoff Properties in a Small Mountainous Watershed in Kochi Prefecture, Japan. Pakistan Journal of Biological Sciences, 8: 259-266.
DOI: 10.3923/pjbs.2005.259.266
URL: https://scialert.net/abstract/?doi=pjbs.2005.259.266
DOI: 10.3923/pjbs.2005.259.266
URL: https://scialert.net/abstract/?doi=pjbs.2005.259.266