The Research On The Litter Decomposition Of Pinus Hwangshanensis On Wuyi Mountains In Jiangxi

The litter in the product of plant metabolism in the plant growth and development,including plant leaves,dead branches,dead roots and so on.Litter decomposition is an intermediate link of the material cycling of plant and soil and the dynamics balance of nutrient,which is also one of the key links in the material cycling of forest ecosystem,especially in the alpine forest ecosystems.Therefore,the research of alpine litter decomposition has been paid more and more attention.At present,there are few studies on the effects of elevation on litter decomposition of coniferous plants in alpine forest ecosystems.Wuyishan National Nature Reserve in Jiangxi,locates at 27 ° 48'11 "-28 °00'35"N,117 ° 39'30 "-117 ° 55'47"E,with a total area of 1,6007 hectares,and the highest peak is Huanggangshan(elevation 2157.8m).In the Wuyishan National Nature Reserve there is the most complete,the most typical and the largest tropical subtropical forest ecosystempreserved in the same latitude,with obvious vegetation vertical band spectrum.Pinus hwangshanensis W.Y.Hsia is the special species in China,which is the main contructive species in the subtropical zone.It is widely distributed in the Wuyi Mountain at an altitude of 700m-2015m.In this paper,the nutrient reabsorption efficiency and the decomposition rate of of P.hwangshanensis were studied in the Wuyishan National Nature Reserve,and the factors affecting the decomposition rate of the leaves of Huangshan pine were discussed.The results are as follows:(1)The nitrogen and phosphorus ratio of mature coniferous in P.hwangshanensis has a negative correlation with altitude.The nitrogen and phosphorus ratio of litter coniferous in P.hwangshanensis increases with increasing altitude exponentially increasing.The contents of nitrogen and phosphorus of leaves in P.hwangshanensis were significantly by elevation.The minimum reabsorption efficiency of nitrogen and phosphorus of leaves in P.hwangshanensis at each elevation was 58%and 71%respectively.The resorption efficiency of Phosphorus is higher than tha of Nitrogen.Phosphorus played an important role in litter decomposition and nutrient cycling at different elevations of Wuyi Mountains.(2)After 450 days of field experiments of P.hwangshanensis litter decomposition,the decomposition rates were:38.76%,53.44%,47.78%,34.91%and 35.37%at different altitudes respectively.The residual rates of the leaves were decreasing and the decomposition rates were increasing with time.The residual rate had a significant linear correlation with the decomposition time.Basing on Olson's exponential model,the k values are 0.321,0.648,0.441,0.2487 and 0.4,respectively.The time required to decompose 50%is 2.16a,1.1a,1.57a,4.32a and 1.73a respectively.The time required to decompose 95%is:9.33a,4.38a,6.77a,12.88a and 7.4a,respectively.(3)There was a significant positive correlation between the content of nitrogen and the decomposition time and it is the enrichment model.There was a significant positive correlation between the phosphorus and time,and it was the enrichment model.The ratio of C/N firstly decreased,then increased with time.There was a significant negative correlation between the ratio of C/P and time.The trend of ratio of nitrogen and phosphorus was more complicated.Compared with ratio of N/P,ratio of C/N and ratio of C/P were better predictors of decomposition rate of litter.(4)The litter from 2000m the slowliest decomposed;Elevation affected the litter decomposition in P.hwangshanensis,and the effect of the soil fauna on the deconmpositon in P.hwangshanensis was significantly.