| The biomass, productivity and nutrient cycle of Larch plantation and Korean pine plantations in Boli of Heilongjiang Province were studied by selecting the similar stands in stand age, stand structure, site and management practices. Results indicated that the two stands were significantly different in biomass allocation, nutrient absorption and accumulation, productivity allocation, nutrient cycle, and nutrient return. The biomass allocations of tree stratum and understory plants, and the nutrient accumulation of understory plants, were similar for the two stands.The community biomass of larch plantation were 82.13t· hm-2, of which 96.31% of the community biomass was allocated to tree stratum(79.10t ·m-2). The allocation pattern of biomass in tree stratum were 48.55t·hm-2 in stem (approach to 60% of tree stratum biomass), 16.18t ·hm-2 in underground (include root crown), 6.82t·hm-2 in branch, and 1.7t·hm-2 in leaf. The community biomass of Korean pine plantatoin was 70.321 · hm-2, 68.89t ·hm-2 in tree stratum, 29.65t ·hm-2 in stem (approach to 50% of tree stratum biomass), 14.61t · hm-2 in underground (include root crown), 12.68t·hm-2 in branch, 7.10t ·hm-2 in leaf, 4.91t ·hm-2 in bark. The comparison of the larch and Korean pine plantations showed that the stem proportion in larch plantation was higher than that in Korean pine plantation, but the leaf and branch proportion in larch were lower than that of Korean pine plantation. The productivities of tree stratum in larch and Korean pine plantations were similar, 8.59t · hm-2 · a-1 and 8.41t · hm-2 · a-1, respectively. The allocations of productivity and biomass were similar.The nutrient accumulation of the five macronutrients in tree stratum of larch plantation were 152.88kg ·hm-2 in stem, 96.62kg · hm-2 in branch, 104.34kg ·hm-2 in bark, 108.62 kg ·hm-2 in root, and 53.54kg · hm-2 in leaf. In larch plantation, the accumulation of calcium, nitrogen, potassium and magnesium elements were 173.65 kg · hm-2, 150.61kg · hm-2, 103.95kg · hm-2, and 36.03kg · hm-2, respectively. The total nutrient accumulation in tree stratum of Korean pine plantation was 656.97 kg ·hm-2, of which 246.16 kg ·hm-2 nitrogen, 40.50kg ·hm-2 phosphorous, 113.99kg · hm-2 potassium, 205.08 kg · hm-2 calcium and 51.23kg · hm-2 magnesium. Compared with larch plantation, the nutrient accumulation in leaf, root, bark and branch of Korean pine plantation were higher, especially in nitrogen.The return amount of nitrogen and phosphor in leaves of larch plantation were 61% and 58%, higher than those of Korean pine plantation, with 30% and 51%, respectively. The nitrogen amount of absorbing by root and losing by abscising leaves in larch plantation was lower than those in Korean pine. The nigrogen utilization efficiency of larch plantation were higher than that of Korean pine.
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