Study On Plant-Soil Eco-stoichiometry Characteristics Of Larix Gmelinii In Daxing’an Mountains Inner Mongolia

The element balance of ecosystem is a current research hotspot of global change ecology and biogeochemical cycle.In order to understand the distribution pattern of organ and soil C,N,P contents and their eco-stoichiometric ratios of Larix gmelinii forest at different forest age stages in Daxing’ an mountains of Inner Mongolia.This paper selected the Larix gmelinii and soil in Daxing’ an mountains of Inner Mongolia.Study on the distribution pattern of total organic carbon(TOC),total nitrogen(TN),and total phosphorus(TP)content in needles,branches,bark,trunk,fine roots,and soil of different ages of Larix gmelinii forest,as well as the stoichiometric characteristics of C:N,C:P and N:P.In order to understand the nutrient distribution pattern of plant-soil interaction and reveal the interaction between carbon,nitrogen and phosphorus and its balance and restriction in Larix gmelinii.The results are as follows:1.The contents of TOC,TN,TP and their eco-stoichiometric characteristics of Larix gmelinii have different fluctuation ranges.The contents of TOC,TN and TP ranged from 409.86 to 565.26 g·kg-1,1.61 to 19.85g·kg-1 and 0.12 to 2.17g·kg-1.The eco-stoichiometric characteristics of C:N,C:P and N:P ranged from 22.64 to 317.14,217.63 to 4257.13,and 2.53 to 19.96.2.TOC content in various organs of Larix gmelinii has little change with the increase of forest age.The content of TN fluctuated greatly among organs,with the highest content of TN in needles and the lowest in trunk.The content of TN in all organs except the branches increased after maturation.The order of TP content in different organs is needles,branches,bark,fine roots and trunk,and the content of TP in needles,branches and fine roots decreased first and then increased during the whole growth and development stage.Due to the different contents of TOC,TN and TP in each organ,the stoichiometric characteristics are also different.3.The change of soil nutrient TP content showed a trend of decreasing first and then increasing at each forest age,and the lowest content in middle forest age.The contents of TOC,TN and C:N,C:P,N:P all increased and then decreased,with the highest in the near mature forest stage.The contents of ammonium nitrogen(NH4+-N)and nitrate nitrogen(NO3--N)in soil did not change significantly with the growth of forest age.The content of different nutrients decreased with the deepening of soil layer.4.Use of curvature regression to establish the relationship between soil TOC,TN,TP,ecological stoichiometry and soil physical and chemical properties.Different indexes have different correlation.The effect of soil physical properties on soil TOC content is:soil bulk density＞ soil pH.The effect on soil TN and TP content is:soil pH>soil bulk density.The optimal regression equation between soil pH and C:N is a linear function,and the optimal regression equation between soil pH and C:P and N:P is a quadratic function.The optimal regression equation between soil bulk density and C:N is a quadratic function,and the optimal regression equation between C:P and N:P is a linear function.5.Through correlation analysis of TOC,TN,TP contents and eco-st oichiometric ratio in various organs and soil of Larix gmelinii in Daxin g’ an mountains.It is found that apart from the bark,There are differe nt degrees of correlation between the other organs and the soil.The TP content in the soil largely determines the absorption of TP by plants,while the TOC and TN content in the soil have little direct influence o n plants,which indicates that the ecological stoichiometry characteristics of Larix gmelinii organs are not directly determined by the soil nutrie nt content characteristics,but are more influenced by the genetic charac teristics of plants themselves.