Soil Carbon, Nitrogen and Phosphorus Content and Storage Distribution Characteristics of Three Forest Types in Guizhou Fragile Ecological Area

In order to explore the soil nutrient storage capacity of different forest types, soil carbon（C）, nitrogen（N） and phosphorus（P） contents and storage distribution characteristics of soil of three forest types（cryptomeria conifer forest, maple broadleaf forest and needle and broad mixed forest composed of the two forest types） were analyzed in Kast Fragile Ecological Region of Guizhou Province. The coupling relationship between soil C, N, P content and storage with leaf, litter, humus C, N, P were also discussed. The results showed that,（1） the soil C, N and P contents of the three forest types were as follows: organic carbon content of coniferous forest was 26.51 g·kg^-1, total nitrogen content was 1.18 g·kg^-1 and total phosphorus content was 0.44 g·kg^-1; Broad-leaved forest: organic carbon content was 22.95 g·kg^-1, total nitrogen content was 1.06 g·kg^-1, total phosphorus content was 0.39 g·kg^-1;needle and broad mixed forest: 30.02 g·kg^-1, total nitrogen content was 1.17 g·kg^-1, total phosphorus content was 0.40 g·kg^-1. C, N and P reserves were as follws: organic carbon, total nitrogen and total phosphorus reserves of coniferous forest were 48.62, 2.16 and 0.81 t·ha^-1, respectively. The organic carbon, total nitrogen and total phosphorus reserves of broad-leaved forest were 48.13, 2.21 and 0.84 t·ha^-1respectively. The organic carbon, total nitrogen and total phosphorus reserves of needle and broad mixed forest were 60.43, 2.37 and 0.80 t·ha^-1 respectively;（2） Forest type changes had significant effects on soil C and P contents and C reserves. The C content and C reserves of coniferous and broad-leaved mixed forests were significantly higher than those of coniferous and broad-leaved forests, while the P content of coniferous forests was significantly higher than that of broad-leaved forests.（3） Forest type changes had no significant effects on N content, N reserves and P reserves.（4） Correlation results showed that the contents of C, N and P in leaves, litter and humus were correlated with the contents and reserves of C, N and P in soil to varying degrees. To sum up, in the study area, there were obvious advantages in C content and storage in the mixed needle-wide forest, and obvious advantages in P content in the coniferous forest, and there were different degrees of correlation between leaf, litter and humus nutrients and soil nutrients.