ObjectiveAnalyzing the carbon, nitrogen and phosphorus characteristics in forest soil and their relationship with litter quality can provide references for the accurate improvement of forest quality.

MethodThis paper takes natural Pinus massoniana forest in southern Jiangxi Province, eastern China as the research object and obtains data based on the investigation of standard plots and sample measurement, it extracted the variables which reflect the litter quality characteristics by principal component analysis and set up a regression model with the litter quality and the soil organic carbon (C), total nitrogen (N), total phosphorus (P), respectively to analyze the relationship between the content of C, N and P in soil and litter quality.

Result(1) With the increase of soil depth, soil C, N, P gradually decreased, and C and N contents in 0−10 cm soil layer were significantly higher than that in other layers (P < 0.05), while P content in each soil layer had no significant difference (P > 0.05). In general, the contents of C, N, P in soil changed from the state of moderate to extremely low. With the increase of forest age, the contents of C, N and P in all soil layers showed an upward trend, among which the content of C in 0−10 cm soil layer was significantly different in varied age groups (P < 0.05). (2) The existing amount of semi-decomposed layer and undecomposed layer of litter increased first and then decreased and the maximum value of each age group achieved in near-mature forest; the contents of C, N and P in each decomposition layer did not show significant changes in different age groups, but the contents of C and C/N in the semi-decomposition layer were significantly lower than those in the undecomposed layer (P < 0.05), while the contents of N and P in the semi-decomposed layer were higher than those in the undecomposed layer, and the differences were not significant (P > 0.05). (3) The principal components reflecting the quality characteristics of semi-decomposed layer and the undecomposed layer of litter were significantly correlated with soil C and N contents, but were not significantly correlated with soil P contents, showing that the contents of C, N and P in soil were positively correlated with the contents of C, N and P in the semi-decomposed layer of litter, and negatively correlated with the contents of C, N and P in the undecomposed layer of litter.

ConclusionIn natural Pinus massoniana forest, the soil nutrient contents totally were low. When the contents of C, N and P of litter decreased in undecomposed layer and increased in semi-decomposed layer, the contents of soil nutrients increased. Therefore, promoting the decomposition of litter in the management can improve the soil nutrient content, which is conducive to the growth of trees.