The Study Of Soil Chemical Properties And Plant Diversity In Different Forest Types Of Xinjiashan Qinling Mountains

The forest is the important constituent of global ecosystem which has the functions of adjusting the climate, keeping waterhead, purify air, wind-breaking and sand-fixation. It plays an important role in keeping the ecological balance of the earth. It has the vital significance on survival and development of mankind.Qinling Mountain, the watershed of two major river systems: Yangtze River and Yellow River, is north-south clime boundary of China. The complicated features and varied weather bless this region with advantageous conditions of unique and rich vegetation.Xinjiashan is located in the south slope of western Qinling and upstream of Jialing river. Next to Qinling major ridge, it has both complicated and regular features, which is helpful to understand forest structure characteristics, biodiversity formation and soil nutrient status. The research investigated 9 different typical forest communities and soil under them in Xinjiashan from June 2008 to September 2010. On this basis, quantitative analysis was done to study the relations between soil fertility and community type, soil depth, diversity of species. The results show that:(1)The soil nutrient and pH among different forest types were significant different in Xinjiashan. The soil organic matter content had a certain vertical variation, but the maximal value occurs in the surface soil laye(r0~20cm)in most cases. Among 9 different typical forest communities, the organic matter content under Picea asperata and Quercus aliena were higher than others. The soil under Picea asperata had the most total nitrogen and alkali-hydro nitrogen. The total phosphorus content of Pinus tabulaeformis was highest, while the available phosphorus content of Fraxinus mandshurica was the most. Differently, the various indices of soil under Pinus armandii were relatively low.(2) Soil nutrient was significantly different in three soil layer (0 ~ 20cm, 20 ~ 40cm, 40 ~ 60cm) under different forest types. For instance, the organic matter content of surface soil under Pinus tabulaeformis and Fraxiinus mandshurica mixed forest was 1.39 times higher than the lower. The total nitrogen content of surface soil under Quercus aliena was 44% higher than the lower. The Pinus tabulaeformis and Carpinus cordata mixed forest reduced 24% with depth.(3)The soil pH of nine forest types was between 6.22 and 4.75. And soil pH in the surface layer was higher than the sublayer. The content of soil organic matter in the surface layer was higher than the sublayer. The soil total nutrient under Pinus armandii was the lowest in 9 forest types.(4)Correlation analysis showed that total nitrogen, the contents of organic matter, alkali-hydro nitrogen and total phosphorus in different types of forests were very significant positive correlated; alkali-hydro nitrogen, the contents of organic matter and total phosphorus were significant positive correlated; soil pH and total nitrogen were very significant negative correlated; the correlation between available phosphorus and total nitrogen was not significant.(5) Pielou index ranking for: Picea asperata Mast.-Quercus aliena var. > Pinus tabulaeformis Carr. -Fraxinus mandshurica Rupr.> Quercus aliena var. acuteserrata.> Betula platyphylla Suk.> Pinus tabulaeformis Carr.> Picea asperata Mast. > Pinus tabulaeformis Carr. - Carpinus cordata Bl. > Fraxinus mandschurica Rupr. > Pinus armandii Franch. ;Simpson index (D) of this order: Picea asperata Mast. -Quercus aliena var. acuteserrata> Pinus tabulaeformis Carr. -Fraxinus mandshurica Rupr.> Quercus aliena var. acuteserrata.> Betula platyphylla Suk.> Pinus tabulaeformis Carr.> Picea asperata Mast. > Fraxinus mandschurica Rupr. > Pinus tabulaeformis Carr. - Carpinus cordata Bl. > Pinus armandii Franch.Shannon - Wiener index (H) of this order: Picea asperata Mast. -Quercus aliena var. acuteserrata.> Betula platyphylla Suk. > Picea asperata Mast. > Quercus aliena var. acuteserrata > Pinus tabulaeformis Carr. -Fraxinus mandshurica Rupr. > Fraxinus mandschurica Rupr. > Pinus tabulaeformis Carr. - Carpinus cordata Bl. > Pinus tabulaeformis Carr. > Pinus armandii Franch..(6) Most of soil factors studied were significantly correlated with species diversity except pH.