Soil Carbon, Nitrogen, Phosphorus Ecological Stoichiometry Of Different Trees In Mixed Broad-leaved Forest In The Hill Region Of Northern Hunan

Ecological stoichiometry is the study of biological systems energy balance and balance of multiple chemical elements science. Ecological stoichiometry is mainly emphasized the relationship between carbon (C), nitrogen (N), phosphorus (P) and other important elements of living organisms. Soil C, N, P is an important nutrient limiting plant growth and development, but also the material basis and important environmental conditions for the survival of plants. Subtropical is the main distribution area of broadleaf forests, as a result of the artificial interference, the natural forest severely degraded.It has been some recovery after afforestation. Therefore, this paper takes the different species of the mixed broadleaf plantation forest in the North Hills area as the research object. Comparative study on the soil C、N and P content and its stoichiometry of different tree species. We revealed the influence of different tree species on the nutrient supply capacity of soil in the same environment, in order to provide a scientific basis for the configuration and management of the artificial forest tree species. The results are shown below:(1) In the study area, the range of the soil C content in the 0-20cm soil layer of 20 tree species was from3.07 toll.51g·kg-1; the range of 20-40cm soil layer was from 2.59-9.65g·kg-1;the range ofthe range of 40-60cm soil layer was from 7.85 to 2.23 g·kg-1.The distribution of soil C content was performed decrement with the soil depth increased. The range of soil N content in the 0-20cm soil layer of 20 tree species was from0.42 tol.Olg·kg-1;the range of 20-40cm soil layer was from0.34 to 1.00g·kg-1;the range ofthe range of 40-60cm soil layer was from0.30 to 0.87g·kg-1And the range of soil P content in the 0-20cm soil layer of 20 tree species was from 0.42 to 0.93g·kg-1;the range of 20-40cm soil layer was from0.35 to 0.94g·kg-1;the range ofthe range of 40-60cm soil layer was from0.27 to 0.84g·kg-1.(2) In the study area, the range of the soil C/N in the 0-20cm soil layer of 20 tree species was from 4.32 to 16.73; the range of 20-40cm soil layer was from3.66 to 15.56; the range of the range of 40-60cm soil layer was from 4.54 to 17.79. And the average of soil C/N in the 0-20cm、20-40cm and 40-60cm soil layer was 11.42、10.70、9.72, respectively. The results above showed that the surface soil C/N is higher, thus the surface soil nitrogen mineralization rate is low, the microbial activity is restricted certainly. The range of the soil N/P in the 0-20cm soil layer of 20 tree species was from 0.56 to 2.17; the range of 20-40cm soil layer was from0.36 to 2.29; the range ofthe range of 40-60cm soil layer was from 0.47 to 1.81. And the average of soil C/N in the 0-20cm、20-40cm and 40-60cm soil layer was 1.16、1.10、0.94, respectively. The range of the soil C/P in the 0-20cm soil layer of 20 tree species was from 5.36 to 23.89; the range of 20-40cm soil layer was from 3.48 to 19.79; the range ofthe range of 40-60cm soil layer was from 2.65 to 25.83. And the average of soil C/N in the 0-20cm、20-40cm and 40-60cm soil layer was 12.62、11.37、9.00, respectively. It is suggested that the absorption efficiency of C, N, P of different species is different, and its the main factors causing differences in chemical characteristics of the soil measurement of CNP.(3) In the study area, the range of the soil pH was from 3.92 to 5.01,the soil is acid. The range of soil moisture was from 10.23% to 11.54%. And the volume weight of soil is 1.38. The relationship among soil physical properties soil C, N, P and chemometrics for the performance of:There was significant correlation between the soil pH and soil C content of Mallotus japonicas Elaeocarpus decipiens、Michelia platypetala% Keteleeria pubescens、Querces variabilis and Lithocarpus henryi,in addition to these 6 tree species above, the other 15 tree species’soil pH value had no significant correlation with soil C. There was significant correlation between the soil pH and soil N content of Liriodendron chinense、Lithocarpus henryi% Keteleeria pubescens and Elaeocarpus decipiens, in addition to these 4 tree species above, the other 16 tree species’soil pH value had no significant correlation with soil N. The soil pH values were not significantly correlated with soil P and soil C/N, respectively, of all species. In addition to the soil moisture of Quercus variabilis was significantly correlated with its soil N/P, there were no significantly correlated in the other species. There was significant correlation between the soil pH and soil N/P of Elaeocarpus decipiens、Liriodendron chinense and Keteleeria pubescens, in addition to these 3 tree species above, the other 17 tree species’ soil pH value had no significant correlation with soil N/P. There was significant correlation between the soil pH and soil C/P of Quercus variabilis、Mallotus japonicas、Keteleeria pubescens and Elaeocarpus decipiens, in addition to these 4 tree species above, the other 16 tree species’soil pH value had no significant correlation with soil C/P.There was significant correlation between the soil moisture and soil C content of Mallotus japonicas、Nyssa sinensis、Cyclobalanopsis gilva and Zelkova schneideriana, in addition to these 4 tree species above, the other 16 tree species’ soil moisture had no significant correlation with soil C. There was significant correlation between the soil moisture and soil N content of Zelkova schneideriana、Quercus variabilis and Magnolia denudate, in addition to these 3 tree species above, the other 17 tree species’ soil moisture had no significant correlation with soil N. The soil moisture were not significantly correlated with soil P of all species. In addition to the soil moisture of Liriodendron chinense was significantly correlated with its soil C/N, there were no significantly correlated in the other species. In addition to the soil moisture of Quercus variabilis was significantly correlated with its soil N/P, there were no significantly correlated in the other species. There was significant correlation between the soil moisture and soil N content of Nyssa sinensis、Quercus variabilis and Mallotus japonicas, in addition to these 3 tree species above, the other 17 tree species’soil moisture had no significant correlation with soil C/P.In addition to the soil bulk density of Ailanthus altissima and Lithocarpus henryi were significantly correlated with theirs soil C content, there were no significantly correlated in the other species. There was significant correlation between the soil bulk density and soil N content of Lithocarpus henryi and Keteleeria pubescens, in addition to these 2 tree species above, the other 18 tree species’soil moisture had no significant correlation with soil C/P. The soil bulk density were not significantly correlated with soil P and soil C/N of all species. In addition to the soil bulk density of Cyclobalanopsis jenseniana and Lithocarpus henryi were significantly correlated with its soil N/P, there were no significantly correlated in the other species. In addition to the soil bulk density of Lithocarpus henryi was significantly correlated with its soil C/P, there were no significantly correlated in the other species.It further indicated that,20 tree species growing in the same environment, hydrothermal conditions and pedogenesis has not become the factor that control the influence of soil chemical characteristics, thus the nutrient uptake efficiency of tree species and litter nutrient return has become a major factor in controlling soil chemical characteristics.