Effects of different management approaches on the stoichiometric characteristics of soil C, N, and P in a mature Chinese fir plantation.

Carbon (C), nitrogen (N), and phosphorus (P) are commonly used to evaluate soil quality. However, still little is known about the effects of human activities on soil C, N, and P. In this study, we compared the stoichiometric characters of soil C, N, and P in a mature Chinese fir (C. lanceolata) plantation under four forest management approaches: uncut as a control (NC), clear-cutting (CC), controlled burning after clear-cutting (CCB) and conversion into a tea garden (TG). We measured the total C (TC), total N (TN), and total P (TP) contents and evaluated the ratios of C:N, C:P, N:P, and C:N:P in each treatment. The results showed that: (1) the contents of TC and TN in all management approaches decreased with increasing soil depth, while the TP content in NC, CC, and CCB decreased at first, then increased. More importantly, there was no significant difference in TP content under the four management approaches. (2) The ratios of C:N, C:P, N:P, and C:N:P decreased with increasing soil depth. Interestingly, the ratio of C:N was lower than that of C:P in every management approach. (3) Despite the different management approaches (NC, CC, CCB, and TG), the ratios of soil C:N:P were relatively stable, which were 24:4:1, 26:4:1, 21:3:1, and 21:3:1, respectively. CCB showed the greatest negative effect on soil TC, TN, and TP contents, suggesting it might be beneficial to avoid this approach for Chinese fir management.