Primary production of pine plantations, 1: net primary production of various age plantations of Pinus kesiya Royle ex Gordon at Hod, Chiengmai [province in the north of of Thailand]
Pongsak Sahunalu | Pricha Dhanmanonda | Wisut Suwannapinant (Kasetsart Univ., Bangkok (Thailand). Faculty of Forestry. Dept. of Silviculture)
Biomass and net primary production of 4, 6, 8, 10, 12 and 14-year-old Pinus kesiya Royle ex Gordon plantations at Hod, Chiengmai were determined by the harvest and summation methods in the 20x20 m2 plots during 1977. Some results of the previous studies on cone and root production were also taken into account. Allometric relations for the estimation of the biomass and stem volume were found by the destructive sampling method using 5 sample trees in each stand feeled from the respective plantations. Total biomass, stem, branch and leaf biomass are found to be related to stand age and stand density, being maximum at age 10 with 2,400 stems/ha and with 268.37 ton/ha of total biomass. Maximum stem biomass and stem volume were also found in this stand with 145.17 ton/ha and 245.23 m3/ha, respectively. Branch biomass attained its largest amount at age 14 with 1,275 stems/ha and 49.31 ton/ha. Leaf biomass was estimated at 11.12 ton/ha in the 12-year-old plantation with 2,025 stems/ha. Leaf area index changed coincidently with leaf biomass and being maximum at age 12 with 19.28 ha/ha. Mean height of each stand was also found to be closely related to the standing crop, stem volume and leaf area index. Net primary production of these age series of Pinus kesiya plantation were estimated to be maximum at age 12 with 69.00 ton/ha. yr and related to stand age or total aboveground biomass and stand density. Stem volume increment was found to be largest in the 10-year-old plantation with 27.45 m3/ha. yr and depended on stand age and density. Efficiency of leaves to produce dry matter and stem production tended to be age dependent but efficiency of leaf to stem volume increment was likely to be determined by stand density and survival of trees in each plantation
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