Ecological Stoichiometry of Soil C, N and P in 4 Different Types of Qiongzhuea tumidinoda Forests in Northeast Yunnan

This paper takes the soil of 4 different types of Qiongzhuea tumidinoda forests in northeastern Yunnan as the research object, and compares and analyzes the soil C, N, and P contents in the soil depths of 0–20, 20–40 cm, and 40–60 cm for each type of Q. tumidinoda forest and its stoichiometric ratio. The vertical variation of soil C, N, P content and stoichiometric ratio in different types of Q. tumidinoda forest was clarified, and the cycle and feedback mechanism of C, N and P elements in Q. tumidinoda forest ecosystem were explored. The results showed that there were no significant difference in soil C content among the 4 types of Q. tumidinoda forests, but significant differences in N and P content. The soil C, N and P contents of different types of Q. tumidinoda forests in each soil layer were 21.8–75.64, 1.56–5.90 g/kg and 0.45–1.35 g/kg, respectively. And soil C, N, and P contents all showed the mixed forest of Q. tumidinoda and broad-leaved tree ˃ the pure forest of Q. tumidinoda. The stoichiometric ratios of soil C, N, and P in the 4 different types of Q. tumidinoda forests were also significantly different, and the variation ranges of soil C/N, C/P, N/P values were 6.22–18.06, 19.46–109.26 and 1.97–6.05, respectively. The soil C/N, C/P, and N/P ratios of the pure forest of Q. tumidinoda were higher than those of the other 3 mixed forests of Q. tumidinoda and broad-leaved trees. There were extremely significant positive correlations between soil C and C/P and between soil N and P in the 4 different types of Q. tumidinoda forests. There were significant positive correlations between soil C and N, N/P and between soil N and N/P. There was a very significant positive correlation between soil C, C/P, soil N, and N/P in mixed Q. tumidinoda and broad-leaved forest, and there was a significant correlation between soil N and C/P in pure Q. tumidinoda forest. Therefore, the soil C, N, and P fertility of the mixed forest of Q. tumidinoda and broad-leaved tree were higher than those of the pure forest of Q. tumidinoda, indicating that the mixed forest of Q. tumidinoda and broad-leaved tree could effectively improve the soil fertility of the woodland, and could be used as an excellent model for vegetation restoration in northeastern Yunnan. This study is beneficial to reveal the soil nutrient status of the Q. tumidinoda forest ecosystem in northeastern Yunnan, and has a guiding role in the management, nutrient regulation and productivity improvement of the Q. tumidinoda forest.