Effects of Three Forest Types on Soil Carbon and Nitrogen Storage and Enzyme Activity in Subtropical China

Abstract

[Objective] The effects of forest types on soil carbon and nitrogen contents and enzyme activity were analyzed in order to provide a scientific basis for the selection of tree species and forest management methods in the transformation of subtropical coniferous forests. [Methods] The study evaluated data from a subtropical evergreen broad-leaved forest (Castanopsis carlesii forest), an evergreen deciduous broad-leaved mixed forest (Betula fujianensis and Phoebe bournei mixed forest), and a coniferous forest (Pinus massoniana forest) at the same altitude and similar environmental conditions. [Results] ① The total soil organic carbon content in the P. massoniana forest was significantly greater than in the other two forest types, and the total soil nitrogen content was not significantly different from that in the B. fujianensis and P. bournei mixed forest. However, both carbon and nitrogen contents were significantly greater than in the C. carlesii forest. The soil nitrogen and carbon reserves of the P. massoniana forest and the B. fujianensis and P. bournei mixed forest were significantly greater than the nitrogen and carbon reserves of the C. carlesii forest. The soil soluble organic carbon contents in the P. massoniana forest and the B. fujianensis and P. bournei mixed forest were significantly greater than in the C. carlesii forest. The soil soluble organic nitrogen content in the P. massoniana forest was significantly less than in the C. carlesii forest and the B. fujianensis and P. bournei mixed forest. The soil microbial biomass carbon and nitrogen contents in the C. carlesii forest and the P. massoniana forest were significantly greater than in the B. fujianensis and P. bournei mixed forest. There were no significant differences in the soil ammonium nitrogen contents among the three forest stands. However, the soil nitrate nitrogen content in the B. fujianensis and P. bournei mixed forest was significantly greater than in the other two forest types. ② The soil urease activity in the C. carlesii forest was significantly greater than in the B. fujianensis and P. bournei mixed forest. There were significant differences in soil invertase activities among the three stands, and the differences in activity followed the order of P. massoniana forest > C. carlesii forest > B. fujianensis and P. bournei mixed forest. The soil catalase activities in the P. massoniana forest and the C. carlesii forest were significantly greater than in the B. fujianensis and P. bournei mixed forest. There was no significant difference in soil phosphatase activity among the three forest stands. Soil β-glucosidase activity in the P. massoniana forest was significantly greater than in the C. carlesii forest and the B. fujianensis and P. bournei mixed forest. RDA analysis showed that the main factors affecting the change of soil enzyme activity in the three forests were total soil carbon (explanation rate of 59.5%), total nitrogen (explanation rate of 11.0%), and nitrate nitrogen (explanation rate of 14.6%). [Conclusion] The P. massoniana forest and the B. fujianensis and P. bournei mixed forest had greater soil carbon and nitrogen storage values than observed for the C. carlesii forest under the same disturbance background. The increased soil organic matter was conducive to increase soil enzyme activity.

Keywords

• forest type
• disturbance
• soil carbon and nitrogen content
• soluble organic matter
• enzymatic activity