| In this paper, a fast-growing stage Michelia hedyosperma plantation was researched by the methods of quadrat harvesting, litter collection and decomposition of litter bag technique, in Nanning, southern of China. Studies focus on the biomass and productivity, distribution pattern of forest litter nutrient and the characteristics of artificial forest ecosystem nutrient circulation and litter decomposition of Michelia hedyosperma plantation.in order to scientificly fertilization fast-growing stage Michelia hedyosperma plantation, provide a scientific basis to maintain a high productivity of precious tree plantation. The results as follows:(1) The total biomass of11a Michelia hedyosperma plantation was81.678t·hm-2, the tree layer was78.159t·hm-2, which was95.68%of the total biomass. Distribution pattern of biomass in different organs was:trunk> root stump> branch>bark>leaf>big root>middle root>small root. Besides, the biomass of those with a size above the average of DBH was58.427t·hm-2, which was74.76%of the tree layer. Total stand productivity of11a Michelia hedyosperma plantation was7.212t·m-2·a-1, and7.104t·hm-2·a-1of tree layer.(2) The cumulative amount of Michelia hedyosperma arbor layer in N, P, K, Ca and Mg elements as741.437kg·hm-2in total, allocation size was:N(303.306)>K(254.669)>Ca(124.977)>P(30.858)>M(27.900kg·hm-2); distribution pattern of total accumulated in the different organs was:trunk (228.334)>leaf(176.008)>root stump (100.655)>branch (100.283)>bark (92.445)>big root (28.371)>middle root (8.560)> small root(6.701kg·hm-2).(3) There were differences in the enrichment coefficients of Michelia hedyosperma both in different organs and different elements. The size relations of5nutrient elements enrichment coefficient in forest level was:N (4.678)>P (1.423)>K (0.193)>Mg (0.065)>Ca (0.055). N3.881kg, P0.391kg, K3.258kg, Ca1.599kg and Mg0.357kg were needed to produce It dry matter respectively, the total amount was9.486kg·t-1, which was a low nutrient use efficiency.(4) Annual amount of litterfall was6.498～9.21t·hm-2·a-1, amount of litterfall in different months (seasonals) was not uniform, monthly litterfall curve was2peaks and even3peaks, Peaks appeared mainly in5～7months and10-11months, the amount of litterfall between twelfth months to March in the following year was little and volatility quite small. Distribution of littrtfall between seasons:summer>winter>autumn>spring. There were extremely significant positive correlation between the amount of litterfall and monthly temperature, monthly precipitation.(5) The annual returns of N, P, K, Ca and Mg was197.084kg·hm-2, in the order as fallow:N, Ca, Mg, K, P. The plants can adjust the nutrient content in the litter by there own physiological activity, but its effects were limited, and it cannot affect the distribution pattern of litter fall in nutrient return, distribution patterns of nutrient return and litterfall were basically consistent.(6) The annual absorptions, accumulations and returns of five nutrient elements of Michelia hedyosperma plantation was283.333,86.249and197.084kg·hm-2·a-1, respectively. The nutrient utilization coefficient was0.382, the cycling coefficient was0.696, the recycling period was3.762a. There was a great benefit of the recovery and maintenance of forestland fertilization because of the large amount of forest nutrient return and the shorter period of recycling, Michelia hedyosperma plantation shows a good forestland self fertilization. |
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