| The phosphorus element is one of main limit factors of the forest growth and forest ecosystem primary productive forces. As a result of complexity and the research technique limitation of the phosphorus biogeochemistry circulation, the former nutrient cycle concentrates much on the nitrogen cycle. Nearly twenty many years, the phosphorus element circulation obtained more understanding in the control land ecosystem ecology process importance and the more and more widespread attention. Because the phosphorus may the use factor be low in the soil, and the 19th century middles later, the nitrogen subsidence quantity increases unceasingly, the carbon phosphorizes in the soil, the disharmony ratio in nitrogen and phosphorus, changes of the soil nature, in the soil phosphorus element validity is insufficient the balanced nitrogen validity, enables the phosphorus to become many forest ecosystem forest growth and the important ecology process limit factor, therefore, the research forest ecosystem phosphorus circulation appears more and more is important. This dissertation studied on three vegetations to restore the pattern the locates in the observation station in low-mountain and rainstorm section of northern Sichuan, Tested through in the open country investigation and the room-analyzes, to input of phosphorus element in atmospheric precipitation and the surface runoff output, the phosphorus element in Judeich accumulation and the distribution, the restore and the decomposition of withered and fell where the Pinus eliottii Engelm, Robinia pseudoacacia and mixed stands of Pinus elliottii and Robinia pseudoacacia.ecosystem, three kind of different ecosystem biological cycle and the biogeochemistry circulation has made the determination and the analysis, provided the theory basis for this local forest land phosphorus element sustainable development. The research indicated that,1 three kind of different vegetation type Judeich biomass size order is that pinus elliottii＞the mixed forest＞Robinia pseudoacacia. In the biomass composition, is bigger than the bush level and the level for the tree level biomass plant's biomass, in the Pinus eliottii Engelm various components biomass size order in turn is that the bole＞the root＞the leaf＞the branch＞the skin, but in the mixed forest the pinus elliottii various components order for does＞the root＞＞the skin＞the leaf; In the locust tree pure crop and the mixed forest the locust tree various components biomass size order for does＞the root＞＞the skin＞the leaf＞the fruit.the leaves and the barks of the pinus elliottii and Robinia pseudoacacia and Robinia pseudoacacia fruit's phosphorus element content The mixed forestsis bigger than in the pure crop separately the corresponding organ phosphorus element content. The Judeich total phosphorus element biomass in the mixed forest is bigger than the pinus elliottii Judeich phosphorus element content but is smaller than the Robinia pseudoacacia Judeich phosphorus element content. In the tree level and the bush level phosphorus element biomass size order is consistent with the Judeich phosphorus element total content.2 In Robinia pseudoacacia forest and the mixed forest, Robinia pseudoacacia leaves's. phosphorus element content change dynamic all is the autumn＞the summer＞the winter＞the spring, each season all is bigger than the mixed forest for the pure crop. No matter is in the mixed forest or the pure crop the locust tree bough and the bark phosphorus element content all is bigger than the pinus elliottii bough in each season the phosphorus element content, also they change the rhythm to be consistent.Soil structure of Mixed forest obvious is better than pinus elliottii and 1 Robinia pseudoacacia's. The soil entire phosphorus and the effective phosphorus content size order basic is: the Robinia pseudoacacia＞the mixed forest＞the pinus elliottii. The pH value of the soil and the soil effective phosphorus has the remarkable inverse correlation relations. The soil moisture and the soil effective phosphorus has the extremely remarkable inverse correlation relations. The soil organism and the soil effective phosphorus has the extremely remarkable correlational dependence.The soil effective phosphorus content and the soil entire phosphorus quantity does not have the relevance.3 Three kind of Judeich's years wither and fall the quantity order for the pinus elliotti＞the mixed forest＞Robinia pseudoacacia, Robinia pseudoacacia's wither and fall the quantity that are only 3.64 t·hm-2 is smallest. The Judeich phosphorus element year restore quantity is that the Robinia pseudoacacia＞the mixed forest＞the pinus elliotti. In the pinus elliotti, the fallen leaf is withers and falls the phosphorus element restore main component. In the Robinia pseudoacacia and the mixed forest withers and falls the component in the phosphorus element restore size order is in turn the sundry goods＞the fruit＞the leaf＞the branch.4 The Robinia pseudoacacia and the mixed forest wither and fall year weightlessness rate to be bigger than the pinus elliotti's, and leaves and branch's decompose coefficient is the Robinia pseudoacacia＞the mixed forest＞the pinus elliotti. In three Judeich withers and falls the phosphorus element release to tally concentrates - the release pattern, and withers and falls the component other than the mixed forest's fall branch and the Robinia pseudoacacia's fruit has not entered the release condition mostly in the experimental stage.5 In three forest types, the atmospheric precipitation phosphorus element input value the Robinia pseudoacacia is been biggest, and the mixed forest is smallest. Nutrient input by forest internal breaks water percolation primarily. Three kind of Judeich system phosphorus element year preserves the quantity for the Robinia pseudoacacia＞the mixed forest＞the pinus elliotti, that is consistent with the phosphorus element year absorbing capacity size order. The phosphorus element year restore coefficient and absorption coefficient for biggest In mixed forest, In the pinus elliotti, the Robinia pseudoacacia and the mixed forest wither and fall the restore phosphorus element respectively be the plant absorbing capacity 24.04%, 35.33% and 40.30%. The precipitation phosphorus element input only accounts for 6.94%, 3.70% and 3.42%. Three Judeich's phosphorus element year input values are smaller than the year output, the forest land soil soil year only lose money in a big way, in which locust tree forest land phosphorus loss is biggest. Obviously must maintain these three Judeich's phosphorus element to be balanced, forest land nutrient condition depending on extraneous source military supplies.
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