Silviculture and wood properties research: the third project forest soil and tree nutrition research [in Thailand] [Primary production and nutrient return of Acacia auriculaeformis stand planted on the tailing tin-mine soil: Biomass production of 8-years old Acacia auriculaeformis stand planted on the tailing tin-mine soil]

Study on biomass production of 8-year old Acacia auriculaeformis stand planted on the tailing tin-mine soil was aimed at an estimation of the amount of organic production of this kind of man-made forest. Moreover, the objectives of this study were to evaluate yield and growth of stand gained by the photosythetic process, to obtain a measure of an achievement of soil amelioration. Results of the study were summarized as follows: 1. Biomass of tree could be precisely estimated by using the allometric relationships between biomass of each component and the products of DBH2 and total height of tree (D2H) in forms: log Ws = 0.855 log DH -0.978 for stem biomass (Ws, kg), log Wb = 1.003 log D2H-2.208 for D2H-0.984 for stem biomas (Ws, kg); lob Wl = 1.020 log D2H -2.670 for leaf biomass (Wl, dg); and log Wc = 0.876 log D2H -0.978 for wood biomass (Wc, kg). 2. leaf area of the Acacia auriculaeformis tree species might be obtained from the linear relationships between leaf dry weight (El, g) and leaf area (A, cm2) in form: A = 1.928 + 236.434 Wl, and leaf area index from total leaf biomass in stand by using the same equation. 3. Biomass production of 8-year old Acacia auriculaeformis stand planted on the tailing tin-mine soil with 5 x 5 m spacing were 41.94 ton/ha for the above ground beiomass with 32.64 ton/ha for stem; 6.64 ton/ha for branch; 2.66 ton/ha for leaf; and 39.28 ton/ha for wood. 4. Leaf area index of this tree species was 6.28 ha/ha. 5. A comparison between biomass of 8-year old Acacia auriculaeformis stand and teak (Tectona grandis), 3-needle pine (Pinuskesiya), Gmelina arborea, and Rhizophora apiculata stands of almost the same age was also made. It was found the above ground biomass of Acacia Auriculaeformis stand would be closely comparable to that of tead, but stem biomass was however, more than teak and 3-needle pine while wood biomass was slightly less than 3-needle pine, gmenlina, and Rhizophora stands. 6. The results of the study suggest that Acacia auriculaeformis may well be established on the tailing tin-mine soil and gives a comparatively high biomass production which indicates a suitability for planting as an energy plantation and for soil amelioration