EFFECTS OF PLANTING DENSITY ON PRODUCTION OF EUCALYPTUS CAMALDULENSIS DEHNH. PLANTATIONS FOR THE AGROFORESTRY SYSTEM APPLICATION

Abstract

This study was carried out at the Agroforestry Research and Demonstration Plots in Kantrarom, Srisaket. The stands were planted with four different grades of; 1,250 (2x4 m spacing), 625 (4x4 m spacing), 417 (4x6 m spacing) and 278 (6x6 m spacing) trees per hectare. There were three 20x20 m plots for each grade of density. All trees of every plot (except border trees) for each stand density were enumerated and their stem diameter at 1.30 m aboveground was measured in April 1981 (2-year old), May 1982 (3-year old) and May 1983 (4-year old). Twelve sample trees from various diameter size classes at 4-year old of four different grades. of density were cut down at the ground level. The relationships between various dimensions of sample trees and dry matter of stem, branch, leaf, wood (stem + branch), total aboveground. (stem + branch + leaf) and stem volume were calculated by using allometric relation. The best one of the relationships of each tree part were selected to estimate the biomass of various parts and stem volume of 2-3-and 4-year old Eucalyptus camaldulensis plantations planted with four different grades of density. Competition-Density effect and Yield-Density effect were investigated. The results revealed that biomass of various parts and stem volume of 2-3-and 4 year old Eucalyptus camadulensis plantations planted with four different grades of density could be estimated appropriately by using the square of diameter at 1.30 m aboveground multiplied by total height of tree (D²H) as the independent variable of the allometric relation. Mean biomass of each part and mean stem volume per tree of Eucalyptus camaldulensis plantations were inversely correlated to stand density, following the C-D effect and varying to stand age. Dry matter yield of each part and stem volume yield of Eucalyptus camaldulensis plantations were directly correlated to stand density, following the Y-D effect and varying to stand age. Four-year old Eucalyptus camaldulensis planted with the density of 1,250, 625, 417 and 278 trees/ha produced the mean total aboveground biomass of 63.04, 96.17, 126.63 and 152.87 kg/tree and mean stem volume of 0.09, 0.14, 0.19 and 0.22 m³/tree respectively and the total aboveground biomass yielded 75.52, 57.89, 49.89 and 42.50 ton/ha and total stem volume of 109.02, 84.28, 72.89 and 62.27 m³/ha respectively.