Study On Interactions Neighborhood Interference And Time Dynamic Of Nutrient Elements Among Three Forest And Grassland

Forest and grass ecosystem plays a very important role in converting agricultural lands to trees. This paper makes a preliminary study on biomass and its distribution and neighborhood interference between forest and grassland and dynamics of nutrient elements about three different forest-grassland Pattern(Pattern I Cunninghamia lanceolatta with Lolium multiflorum Lam. Pattern II Ttiploid populus tomentosa with Lolium multiflorum Lam. Pattern. Pattern III Bambusa pervariabilis xDendrocal amopsis validus with Hemarthria)aiound the Sichuan Basin. In order to know about essence of forest and grassland ecosystem and provided theory for forest mixed with grassland. The result shows that:(1)Proportion of forest and grass biomass is on the ground > under ground; Trunk > twig and leaf. Pattern III be longs to artificially management precisely, and Hemarthria yield attains to 7.281.km"2. In the other patters grass biomass is very low, and especially in the Pattern II .the grass biomass is the lowest. C. Lanceolatta remained content is by the most in the high forest. The second is T. tomentosa. The third is B. pervariabilis xD. validus. The distribution of trunk remained content is higher in every pattern.(5. Pervariabilis xD. validus> C. lanceolatta> T. tomentosa); The rate of the bark remained content is above ten per cent in the high forest. The rate of T. tomentosa root is 23 per cent. And the rate of C. Lanceolatta is the lowest; To B. PervariabilisxD. validus, the ration between trunk and crown is the biggest. This is relating to bamboo s grown features. T. tomentosa crown is the biggest but the ratio is the lowest. About the ratio of branch and leaf, B. Pervariabilis xD. validus is the highest but. C. Lanceolatta is the lowest. The ration of trunk and leaf is B. PervariabilisxD. validus > T. tomentosa> C. lanceolatta. The biggest ration of photosynthetic system and non-photosynthetic system is B. pervariabilis XD. validus. In the pattern III everything is the biggest . It can be seen that Pattern III is very important model.(2)There is relationship between forest and grass neighborhood interference index with tree grown velocity in Pattern I and II pattern. Biomass increase with coverage quickly when the multiplication of coverage squares with grass height is less than the regular data. And after that alternation is smooth. L. multiflorum biomass variation and C. lanceolatta T.populus tomentosa grown interference model indicated the dynamic which the grass interferes the tree growth. L. multiflorum increased the growth rate of C. lanceolatta and T.populus tomentosa (positive effect). But it is different that C. lanceolatta and T.populus tomentosa, and the former have been affected by biomass seriously. Because of L.multiflorum itself biology features, it does not compete resources with others. It can increase soil organic substance content and accelerate tree grown. Hemarthria coverage in Pattern III is 100 per cent, and it can not calculate through model of neighborhood interference. There are many works must be done in order to further study it. Two patterns are all positive effect between tree and grass. The herb accelerates tree grown. From study we can conclude that these patterns are rightful and attain to the desired goals of tree mixed with grass.(3)m Pattern I ,me soil nutrient content is much higher in the upper soil than that in the below; The soil available N and C. lanceolatta N shows the negative relative. The N dynamic of C. lanceolatta with L multiflorum reaches unanimity and shows very clearly positive relativity. In the Pattern II, the function of plant absorption influences severely the soil available N. The variety of N content of T. tomentosa and L. multiflorum is the same. The N content increases when their growth is flourishing. The soil N can almost supply them in mis time. In the Pattern III, the soil available N increase from begin to end.(4)In Pattern I, hydrolysable N have not accumulation and fluctuation, and absorbing and depositing is equal. The hydrolysable N and the C.