Soil Nutrient Of Pinus Elliottii Forest In Poyang Lake District Research

Due to historical reasons, natural factors and human disturbance,the problem of land desertification in Poyang Lake district has become one of the prominent problems of the ecological environment in the south.To reveal the soil nutrient effects of Pinus elliottii in the restoration of sand vegetation,set desertification comprehensive treatment demonstration area in Gangshang town,Nanchang County and Duobao town,Duchang county in Jiangxi Province as the test area,study the nutrient in the soil of pure forest of Pinus elliottii which are in different ages and forest of Pinus elliottii which are in different structures, and then take a comprehensive analysis by using the grey relational. The results showed that:(1)The water content of different ages showed decreased with increasing ages and the water content of forests in the middle age was significantly lower than those in other ages.In the vertical section of soil, forests of different ages increased with the increasing depth of soil layers; the changes of age has no significant effect on soil bulk density;soil organic matter and total nitrogen increased with the increasing forest age.Comparing to the bare sand,the content of soil organic matter of near-maturation forest, mid-maturation plantation and young-maturation forest increased by 235.71%,133.33% and 130.56%;while the total nitrogen increased by 168.87%,143.71% and 78.06%.The content of total phosphorus^ total potassium^ available phosphorus and available potassium showed increased in the progress to mid-maturation plantation,while significan-tly reduced when it became the near-maturation forest.The content of alkali hydrolyzable nitrogen decreased with the increasing age,but there were no significant differences between the ages(P>0.05). By the using of the grey correlation degree towards the analysis of soil nutrient, near-maturation forest(0.754)>mid-maturation plantation(0.747)> young-maturation forest (0.656)> bare sandy land(0.642).(2)The soil water content had no significant changes between different structures of Pinus elliotttii(Pinus elliottii+shrub+grass、Pinus elliottii+frass、pure forest of Pinus elliottii).Soil bulk density of pure forest of Pinus elliottii structure is less than the others and there was significant difference between them (P<0.05).The content of soil organic matter, total nitrogen,total phosphorus and total potassium all showed that:Pinus elliottii+shrub+grass>Pinus elliottii+grass> pure forest of Pinus elliottii> bare sand forest. Comparing to the soil organic matter content in the forest of bare sand,Pinus elliottii+shrub+grass structure increased by 275.08%,and Pinus elliottii+grass is increased by 189.23%, pure forest increased by 204.31%.The total nitrogen content of Pinus elliottii+shrub+grass structure is 11.8 times of bare sandy land. Pinus elliottii+grass is 5.5 times of the bare sandy land.Pure forest is 2.1 times of the bare sandy land.Comparing to the content of total phosphorus,Pinus elliottii+shrub+grass increased by 40.83%,andPinus elliottii+grass increased by 36.67%,and the pure forest decreased by 4.17%.Comparing to the total potassium content of bare sandy land, Pinus elliottii+shrub+grass structure increased by 46.27%,Pinus elliottii+grass structure increased by 2.25%,pure forest increased by 0.36%.The content of soil alkali hydrolyzable nitrogen and available phosphorus showed that:Pinus elliottii+shrub+grass>Pinus elliottii+grass> pure forest of Pinus elliottii> bare sand forest,and the content of available potassium showed that:Pinus elliottii+ shrub+grass>Pinus elliottii+grass>bare sand forest> pure forest of Pinus elliottii. Comparing to the content of alkali hydrolysable nitrogen in bare sand,pinus elliottii+shrub+grss structure increased by 289.24%,Pinus elliottii+grass increased by 112.47%,pure forest increased by 20.82%. The content of available phosphorus in Pinus elliottii+shrub+grass structure increased by 46.27%,Pinus elliottii+ grassincreased by 2.25%, the pure forest increased by 0.36%. The content of available potassium in Pinus elliottii+shrub+grass structure increased by 28.92%, the Pinus elliottii+grass structure increased by 8.43%, while the pure forest decreased by 41.25%;(3)The different structure of Pinus elliottii forest humus bound mainly to the tightly combined humus,the amount was more than 70%.By the analysis of grey correlation, Pinus elliottii+shrub+grass (0.951)>Pinus elliottii+grass structure(0.711)> the pure forest of Pinus elliottii (0.571)>bare sandy land (0.548).The most effective restoration of soil fertility was the structure of forest shrub grassrestore.