Study On The Afforestation Model And Short-term Effects Of Pruning For Poplar On Wan-River Breach

Beach is micro-topography which is seasonally flooded river plains. Forest beach plays important role in the manufacture, which effectively relieves the contradiction between people of densely populated. Therefore, it has a important role in national economy. However, unscientific beach use beach use inefficient, which not only destroys the beach but also causes serious environmental problems and ecological disasters. Those ecological environmental problems affect the sustainable development. Beach resources′effective development becomes a pressing problem which need to be solved, forestation model beach of WAN river and short-term effects of pruning poplar are premise and basis of solving this problem.In the course of the study, this paper fully refers study of Chinese forest ecosystem network system"line"and research of demonstration project, absorbs succeed experience of"priority to forests"in Yangtze river and"forestation, snail disease prevention". The main content of this paper includes three fields: 1) growth pattern and comparative study for different strains of poplar seedlings,2) comparative study of forestation model beach,3) comparative study of different pruning intensity. Have made a preliminary conclusion:1) The growth of seedling height and diameter of four strains of poplar increase linearly with time; the different growth of diameter and height is conspicuous in different strains, south forest 95 and Xianglin 80 are optimal.2) The mode of forest-sesame is the best mode, its density is 4m×4m. Its economic benefits is the biggest, is 5417.3yuan. The intercropping of agriculture and forestry is three years, the tree species (strain) is poplar 80 Xianglin. The age of felling is ten years.3) Through the growth of investigation and analysis show that: the strength of pruning inhibits the grown rate of tree DBH in pruning year (2008), but the strength of pruning promotes the grown rate of tree DBH in next pruning year. The inhibition and advancement due to the strength of tree DBH grown rate shows that: in the weakest strength of pruning the grown rate is the biggest; secondly, it is the treatment of pruning intensity.The investigation and analysis of influence of the understory plants diversity for three pruning intensity shows that: the maximum of species richness index (S) is 14 in P1. The order is P1>P2>P3; The maximum of community evenness index (J) is 0.77 in P1, The order is P1>P3>P2; The maximum of ecology dominance index (D) is 0.44 in P2, The order is P2>P3>P1; Compared with the maximum of species diversity index which is 2.04 in P1, the community evenness index (J) has the same trend. The maximum of species richness index is 14 during the species richness index,simpson index,Shannon-wiene index,pielou uniformity index in the normal land of three pruning intensity. The order is P1>P2>P3; The maximum of community evenness index (J) is 0.77 in P1, The order is P1>P3>P2; The maximum of ecology dominance index (D) is 0.44 in P2, The order is P2>P3>P1; Compared with the maximum of species diversity index which is 2.04 in P1, the community evenness index (J) has the same trend. Only the existence of herb layer has the ecology dominance index in P1, it shows that P1 is obviously controlled by a species of herb layer. We found that it is xanthium through the important value in the front part; P2,P3 is similar with P1, only the existence of herb layer has the ecology dominance index, P2 is obviously controlled by xanthium of herb layer, P3 is obviously controlled by xanthium and phytolacca of herb layer.Through the study of poplar growth and nutrient we can find that total N content is between 1.23~1.39g/kg in poplar forest soil, Nitrogen decreased after pruning in woodland soil. But excessive pruning intensity could reduce the influence; the content of total phosphorus,available phosphorus,potassium,calcium,magnesium has not significant difference before and after pruning(p>0.05). The content of total nitrogen,total phosphorus and available phosphorus in different soil of soil depth is the biggest in 0-10cm layer, decreased with soil depth get deeper, especially, total nitrogen and total phosphorus decreased faster after pruning. Under the same intensity of pruning all kinds of content of nutrient has little difference in different directions, basically flat, only the content of calcium is the biggest by light pruning in every direction.The root contains the largest nitrogen in the plant organ. But under three kinds of pruning strength, the content of total nitrogen get lower along with the growing age and the content of total nitrogen get higher in the root. At the same time, the content of total nitrogen which is in upper branch is obviously affected by pruning (p<0.05); the content of total nitrogen which is in central branch and more than 5 mm length is obviously affected by pruning (p<0.05). The content of total phosphorus which is in every plant components is not obviously affected by pruning (p>0.05); besides the content of total calcium which is in central branch is obviously affected by light pruning and strong pruning (p<0.05), the content of potassium,calcium and magnesium is not obviously affected by pruning (p>0.05), but along with the growing of the branch, the content of potassium,calcium and magnesium tend to decrease; Along with the growing of the root, the content of potassium,calcium and magnesium does not change significantly.