Correlation between Changes in Soil Properties and Microbial Diversity Driven by Different Management in Artificial Chinese Fir (Cunninghamia lanceolata (Lamb.) Hook.) Plantations

Abstract

Successive planting is the main pattern for cultivating Chinese fir (Cunninghamia. lanceolata (Lamb.) Hook.). However, the influence of this management has not been totally investigated, especially with respect to the changes in the soil microbial community and the relationship to soil properties. This study investigated the physical and chemical properties of the soil, its enzyme activities, and its microbial diversity in three adjoining plantations managed with different successive planting models (long-term continuous growth without harvest, M1; single harvest cutting followed by the construction of a pure plantation, M2; and double harvest cutting followed by the construction of a mixed plantation, M3) to evaluate the impact of these forest management practices. In most soil layers, M1 was observed to have significantly higher content of Na and Al ions, as well as more polyphenol oxidase (PPO) activity, and M2 had a significantly higher field moisture capacity (FMC) and content of Mg ions, while M3 had significantly higher urease (URE) activity. Changes in the totals of N (TN) and C (TC), alongside the availability of P (AP), C/P, N/P, URE, sucrose (SUC), and PPO values, correlated significantly with bacterial diversity, whereas the dynamics of total K (TK), Na, C/P, N/P, and PPO levels were significantly related to fungal diversity. Among the models, soil bacterial genera, including Burkholderia–Caballeronia–Paraburkholderia, Acidothermus, and Paenibacillus, were mostly affected by TN, TC, AP, organic matter (OM), C/N, C/P, N/P, SUC, and the performance of URE. The distribution of fungal genera in different models showed significant differences. Talaromyces, Trichoderma, and Aspergillus were relatively abundant in M1, while Umbelopsis and Saitozyma exhibited more adaptation in M3. These results illustrated better soil properties and higher abundance of microbial diversity in M1 and M3, and furthermore, demonstrated the strategic benefit of both prolonging the rotation period and of creating mixed artificial plantations to maintain diversity. This study improves the understanding of the impact of a successive planting strategy in C. lanceolata plantation sustainability.