Author : Monton Jamroenprucksa

Summary : The role of thinning in Thailand's forest village plantations was assessed. Specifically, the study sought to investigate the post-thinning situation in four and seven-year-old Eucalyptus camaldulensis plantations, particularly the response of tree stands and upland rice. Tree stands, with an initial spacing of 2m x 8m, were thinned to three spacing levels: 4m x 8m, 2m x 16m, and 8m x 8m. Thinning affected tree growth and micro-climate, particularly in relation to light intensity, and would like affect the productivity of intercropped rice. However, thinning did not affect the growth of coppices in the same way that the age of the plantations did not affect coppice growths. Based on the growth parameters: relative growth rate (RGR), leaf weight ratio (LWR), leaf area ratio (LAR), leaf area index (LAI), and crop growth rate (CGR), thinning of stands with an original spacing of 2m x 8m (S (subscript O)) to 4m x 8m (S (subscript 1)), 2m x 16m (S (subscript 2)), and 8m x 8m (S (subscript 3)) showed better growth in both the four and seven-year-old plantations. However, trees in the seven-year-old plantation were more sensitive to thinning than those in the four-year-old plantation. Trees in the four-year-old plantation showed significant difference only between the highly thinned stand (S (subscript 3)) and the unthinned (S (subscript O)), but trees in the seven-year-old plantation showed significant differences between the thinned group (S (subscript 1), S (subscript 2), and S (subscript 3)) and the unthinned stand (S (subscript O)). The performance of the coppices with regards to thinning had no marked difference either between those from four-year-old stumps or those from different stands. Under the 2m x 8m spacing, the maximum productivity of stands in the four-year-old plantation was 25-28 ton/ha, while that of stands in the seven-year-old plantation was 57.5-67.5 ton/ha. Thinning increased light transmission to the stands through leaf area index (LAI) modification.