Mountain Tai Forest Ecosystem Research Station of State Forestry and Grassland Administration, Forestry College, Shandong Agricultural University, Tai'an, Shandong 271018, China.
Shandong Academy of Forestry, Ji'nan, Shandong 250014, China.
Sci Total Environ. 2023 Jul 10;881:163492. doi: 10.1016/j.scitotenv.2023.163492. Epub 2023 Apr 14.
Thinning is a common forest management measure that can effectively maintain the ecological service function of protected forests. However, the effect of thinning on the soil carbon (C) pool remains uncertain. In particular, we lack an understanding of the complete link between thinning and microbial communities, microbial necromass C, and consequently, soil C pools in coastal zone protected forests. In this study, three thinning intensities, i.e., a control treatment (CT, i.e., no thinning), light thinning (LT) and heavy thinning (HT), were established in three types of forests (Quercus acutissima Carruth, Pinus thunbergii Parl and mixed Quercus acutissima Carruth and Pinus thunbergii Parl, i.e., QAC, PTP and QP, respectively). Two years after the completion of thinning, we investigated the changes in the soil organic carbon (SOC) fractions, soil microbial community and soil microbial necromass C in the surface layer (0-20 cm) and thoroughly evaluated the relationship between the potential change in SOC and the microbial community. Compared with CT, there was no change in the SOC content under LT and HT, but thinning conducted in QAC increased the proportion of mineral-associated organic C (MAOC) in SOC. Moreover, both LT and HT reduced the soil carbon lability (CL) in the QAC and QP forests. Different thinning intensities changed the soil microbial community structure, and most of the variation was explained by thinning and the soil physicochemical properties. The proportion of soil bacterial and fungal necromass C to SOC increased with increasing thinning intensity. The content of soil bacterial and fungal necromass C was mainly controlled by the relative abundance of the core phylum (relative abundance>10 %). Thinning affected the soil C pool by affecting the content of soil bacterial and fungal necromass C, but their accumulation pathways was different. The results showed that thinning was beneficial to the stability of SOC. The microbial C pool, total organic C pool and even bacterial and fungal C pools should be distinguished when studying the soil C pool, which can effectively deepen our understanding of the mechanism by which soil microorganisms affect the soil C pool.
林分疏伐是维持保护林生态服务功能的常用森林管理措施。然而，疏伐对土壤碳（C）库的影响仍不确定。特别是，我们缺乏对疏伐与微生物群落、微生物残体 C 以及进而对沿海保护林土壤 C 库之间完整联系的认识。本研究在三种林分（麻栎、日本黑松和麻栎-日本黑松混交林）中设置了三种疏伐强度，即对照处理（CT，即不疏伐）、轻度疏伐（LT）和重度疏伐（HT）。疏伐完成两年后，我们调查了表层（0-20cm）土壤有机碳（SOC）各组分、土壤微生物群落和土壤微生物残体 C 的变化，并深入评估了 SOC 潜在变化与微生物群落之间的关系。与 CT 相比，LT 和 HT 下 SOC 含量没有变化，但在麻栎林中进行疏伐增加了 SOC 中矿物结合有机碳（MAOC）的比例。此外，LT 和 HT 降低了麻栎-日本黑松和日本黑松林中的土壤碳易变度（CL）。不同的疏伐强度改变了土壤微生物群落结构，大部分变异可由疏伐和土壤理化性质来解释。土壤细菌和真菌残体 C 占 SOC 的比例随疏伐强度的增加而增加。土壤细菌和真菌残体 C 的含量主要受核心门（相对丰度>10%）的相对丰度控制。疏伐通过影响土壤细菌和真菌残体 C 的含量来影响土壤 C 库，但它们的积累途径不同。研究结果表明，疏伐有利于 SOC 的稳定性。在研究土壤 C 库时，应区分微生物 C 库、总有机 C 库，甚至细菌和真菌 C 库，这可以有效地深化我们对土壤微生物影响土壤 C 库机制的理解。
