Characteristics Of Soil Organic Carbon And Nitrogen Fractions In Top Soil Of Different Bamboo Forests Of South Of Sichuan Area

Soil carbon and nitrogen pool of bamboo forest is one of the important components of the global carbon sink. Exploring the change of soil organic carbon and nitrogen components can provide the basis for the explanation of the response of soil C and N for reference of climatic change. Therefore, this study was designed to examine topsoil organic carbon and nitrogen fractions along with its controlling factors in nine kinds of bamboo forest types (Dendrocalamus affnnis. Bamdusa pervariabilis. Dendrocalamopsis daii. Phyllostachys pubescences. Bambusa rigida. Bambusa intermedia. Dendrocalamus latiflorus. Bambusa multiplex. Pleioblastus amarus. Chimonobambusa quadrangularis) in Luzhou of southern Sichuan in order to assess the regional carbon and nigtrogen budget.The objectives of this study were to:(1) compare topsoil organic carbon and nitrogen and their fractions under different bamboo forest types. (2) explore the important factors influencing topsoil organic carbon and nitrogen fractions and their relationship of different bamboo forests, and (3) provide useful suggestions related to bamboo forests management and administration with the goal of increasing soil carbon and nitrogen sequestration under the future condition of climate change. The results indicate that:(1) The mean content of topsoil organic carbon is 11.56g/kg in different bamboo forests, the amplitude of variation is 91.72%. The study finds that the differences of topsoil organic carbon components all reach significant level in different bamboo forests. Easily oxidized organic carbon, light fraction organic carbon and heavy fraction organic carbon of Pleioblastus amarus are much higher than that other bamboos; Dissolved organic carbon exhibits rule of Chimonobambusa quadrangularis (CQ)> Pleioblastus amarus (PA)> Bambusa intermedia (BI)> Phyllostachys pubescences (PP)> Bambusa rigida (BR)>Bamdusa pervariabilis Dendrocalamopsis daii (BP)> Bambusa multiplex (BM)> Dendrocalamus latiflorus (DL)> Dendrocalamus affinnis (DA); The content of Participate organic carbon ranges from 0.89-18.39g/kg, the amplitude of variation is 95.16%, in which, BI is the highest, DA is the lowest; The content of soil microbial carbon in PA is the highest 147.73mg/kg, which is 3.24 times the size of DA.(2) The average of topsoil total nitrogen is 1.15g/kg in the study area, the amplitude ofvariation is 67.92%. The coefficient of variation is 9.25?40.59% in different bamboo forests, Among which, DL is the lowest, and the others reach medium level. The content of topsoil alkali hydrolyzable nitrogenin ranges from 49.38-173.30mg/kg in different bamboo forests, and PA>PP>CQ>BI>DL>BP>BR>BM>DA; The content of topsoil dissolved organic nitrogen ranges from 7.31-16.08mg/kg, and PP, BI, PA, CQ are much higher than that DA, BP, BR, DL,5M(P<0.01); The content of ammonium nitrogen changes from 2.24-7.66 mg/kg, the amplitude of variation is 70.76%; The content of nitrate nitrogen in PA is the highest, follows by CQ, both are higher than the other bamboos significantly; The content of microbial biomass nitrogen ranges from 11.11?21.39mg/kg, PP is the highest, DA is the lowest.(3) In this research, the correlation of soil pH and organic carbon components reach extremely significant levels(P<0.01), indicating that the small change in soil pH would have a significant impacts on the carbon components in different bamboo forests. Soil total phosphorus are positively correlated with easy oxidation organic carbon, light fraction organic carbon and heavy fraction organic carbon, available phosphorus and heavy fraction organic carbon present significantly positive correlation(P<0.05), it is clear that soil phosphorus is the important factor that lead to change of soil organic carbon contents. Meanwhile, soil carbon components is affected by soil moisture content. In addition, the coverage and heavy fraction organic carbon are significantly negative correlation, the correlation coefficient is-0.434.(4) Soil pH presents extremely significant negative correlation with alkali hydrolysable nitrogen, microbial biomass nitrogen and dissolved organic nitrogen(P<0.01); Soil total phosphorus is extremely significant positive correlated with alkali hydrolysable nitrogen, nitrate nitrogen, inorganic nitrogen(P<0.01), and significantly correlated with microbial biomass nitrogen(P<0.05). The correlation of soil available phosphorus and nitrate nitrogen, inorganic nitrogen reach significant levels(P<0.01). In addition to ammonium nitrogen, the other nitrogen components are affected by soil moisture content(P<0.01). There is a significant positive correlation between bamboo height and ammonium nitrogen(P<0.05), the correlation coefficient is 0.396; Bamboo cverage presents significantly negative correlation with total nitrogen and alkali hydrolysable nitrogen(P<0.05), the correlation coefficient are:0.358,0.391, indicating that bamboo coverage can reflect the variation characteristics of some nitrogen components.