Effects of Building Plantations of Different Species on Cutover Land of Chinese Fir in Subtropical Region on the Accumulation of Soil Carbon, Nitrogen and Phosphorus

By comparing the contents, reserves and stoichiometric ratios of carbon (C), nitrogen (N) and phosphorus (P) elements in the soil layer of 0-100 cm between the 26-year-old Mytilaria laosensis plantation planted on the cutover land of Chinese fir and Chinese fir plantation in the subtropical region of China, the effects of different afforestation species on the vertical distribution of soil carbon, nitrogen and phosphorus were studied. The results showed that:(1) The contents of carbon and nitrogen in the soil of the two stands decreased significantly with the increase of soil depth, and the contents of carbon and nitrogen in the soil layer of 0-10 cm of Mytilaria laosensis plantation were 28.72% and 19.49% higher than those of Chinese fir plantation. (2) There was no significant difference in the content of P among each soil layer of Chinese fir plantation, while the content of P in Mytilaria laosensis plantation decreased with the increase of soil depth. Compared with Chinese fir plantation, the content of P in the soil layer of 0-10 cm in Mytilaria laosensis plantation increased by 11.22%, while the content of P in the soil layer of 60-80 cm and 80-100 cm decreased by 17.40% and 17.92%, respectively. (3) The soil carbon pools of 0-100 cm in Mytilaria laosensis plantation and Chinese fir plantation were respectively 157.49 t·hm^-2 and 132.60 t·hm^-2, and the soil carbon pool in the cultivated Mytilaria laosensis plantation was significantly increased (18.72%) compared with that of Chinese fir plantation, in which the carbon pool in the soil layer of 40-100 cm was significantly increased by 25.34%. However, there was no significant increase of nitrogen pool in each soil layer, and However, the phosphorus pool in the soil layer of 40-100 cm in the cultivated Mytilaria laosensis plantation was significantly reduced, which was 14.40% lower than that of Chinese fir plantation. Therefore, the basement soil was a very important nutrient pool and the conversion of afforestation species also had a significant effect on the basement soil. Compared with Chinese fir plantation, the broad-leaved Mytilaria laosensis plantation had stronger carbon storage capacity, which could improve soil fertility and increase the enrichment of phosphorus in the soil surface.