| With the rapid growth of the world’s population, energy crisis, food shortages, environmental degradation and other global issues had become increasingly prominent, human surging demand for agriculture and forestry products, more and more damage to the environment and natural. Rice is one of the major food crops in the world, more than a third of the population around the world as a main source of food. In China, rice is the most important food crop, China also is the largest rice producer and consumer in the world, so rice growing environment has a significant impact for the development of China’s social and economic sustainable development. The paper study the slash pine-paddy ecosystems and conifer-Paddy agroforestry system of the Dong-ting Lake, the main results showed that:(1) Two types of complex ecological systems had COD reduction effect, there existed differences in different types of subduction complex ecosystem. The average water content of COD in pine-paddy, conifer-Paddy and control-Paddy were 23.05mg /L, 11.01mg/L,18.00mg/L. Conifer-Paddy in transplanting and tillering COD were decreased by 41% and 33%, there were 1.9 times higher than the control-Paddy and reduced by 11% in the tillering stage; Rice of conifer-Paddy in transplanting and tillering were reduced by 80% and 25% respectively, conifer subduction of water is better than COD wetland pine.(2) The average content of water-soluble carbon on Pine-rice, mixed-rice and control-rice were 1.17mg/L,12.82mg/L; 10.14mg/L. Mixed-rice in transplanting andtillering were 10% and 51% higher than control-rice, respectively, Pine-rice in transplanting and tillering stage were 161% and 88% lower than the control-rice, we knew that the pine-trees on the wetland paddy field water-soluble organic carbon abatement significant role, and increase the paddy mixed water-soluble carbon.(3) The average total nitrogen content of Pine-rice, mixed-rice and control-rice land were 2.24mg/L,2.98mg/L,7.91mg/L. Compared with the control-rice, mixed-rice in transplanting and tillering stage were decreased by 87% and 7%, pine-rice in transplanting and tillering stage were decreased by 84% and 43% compared with the control-rice. Pine-rice, mixed-rice and control-rice the average content of total phosphorus were 0.22mg/L,0.46mg/L,0.18mg/L. Mixed -rice in tillering stage was 22% higher than the control, pine rice at tillering stage was 156% higher than the control, therefore, two types of complex ecosystems TN has abatement effect on total phosphorus have enrichment.(4) Pine rice, mixed rice and control’s average content of heavy metals in soil total Pb were 25.64mg/kg,18.83mg/kg and 23.05mg/kg, mixed-early rice transplanting, tillering and maturity than controls were reduced by 32%,13% and 12%, pine-transplanting rice in the early was 60% higher than the control,in the tillering stage and mature than the control were reduced by 2% and 20%; pine rice, mixed rice and control of heavy metals in soils average total Cd contents were 3.93mg/kg,3.31mg/kg and 4.56mg/kg, mixed-early rice transplanting, tillering and mature than the control decreased by 16% 20% and 5%, pine-early rice transplanting, tillering and mature than the control were reduced by 40%,26% and 17%. Pine-early rice transplanting, tillering and maturity than mixed-rice were reduced by 28%,8% and 13%,two types of complex ecosystem of the total soil heavy metals Pb, Cd has a total subduction, mixed on subduction of Pb in soil better than wetland forest, pine forest and wetland mitigation effect of Cd on soil heavily than the total mixed.(5) Pine rice, mixed rice and control’s average content of heavy metals in soil total Pb were 25.64mg/kg,18.83mg/kg and 23.05mg/kg, mixed-early rice transplanting, tillering and maturity than controls were reduced by 32%,13% and 12%, pine-transplanting rice in the early 60% higher than the control in the tillering stage and mature than the control were reduced by 2% and 20%; loose-rice, mixed-rice and control of heavy metals in soils average total Cd contents were 3.93mg/kg, 3.31mg/kg and 4.56mg/kg, mixed-early rice transplanting, tillering and mature than the control decreased by 16% 20% and 5%, pine-early rice transplanting, tillering and mature than the control were reduced by 40%,26% and 17%. Pine-early rice transplanting, tillering and maturity than mixed-rice were reduced by 28%,8% and 13%, two types of complex ecosystems to the total soil heavy metals Pb, Cd has a total subduction, mixed pairs subduction of Pb in soil better than wetland forest, pine forest and wetland mitigation effect of Cd on soil heavily than the total mixed.(6)Pine rice, mixed rice the average content of rice and control rice plants total Pb body of heavy metals were 3.98mg/kg,4.76mg/kg and 5.74mg/kg, pine-early rice transplanting, tillering and maturity than controls were reduced by 59%,9% and 27%, mixed-transplanting rice in the early stage of tillering and mature than the control were reduced by 39%,2% and 11%. Pine-early rice transplanting, tillering and maturity than mixed rice were reduced by 32%,7% and 18%, pine-rice, mixed rice- and the average content of heavy metals in the body control the total rice plants were 1.19 Cd mg/kg,1.22mg/kg and 1.32mg/kg, pine-early rice transplanting, tillering and mature than the control were reduced by 12%,7% and 11%, mixed-transplanting rice in early, tillering stage and mature than the control were reduced by 10%,5% and 6%, pine-early rice transplanting, tillering and maturing hybrid rice were lower than 1.7%,1.5% and 5%. Thus, the two types of forests for water and soil purification significantly reduce the Pb, Cd accumulation in rice, wetland pine subduction than mixed. |
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