Supplementary file 1_Succession characteristics and assembly process of soil microbiome at reclaimed farmlands in coal mining area.doc

Clarifying the succession patterns and assembly mechanisms of soil bacterial and fungal communities across reclamation chronosequences is essential for restoring soil health and ensuring ecological stability in mining areas. We analyzed soil microbial diversity, composition, co-occurrence network structure, and assembly processes using 16S rDNA/ITS sequencing and null models at 0 (R0), 1 (R1), 6 (R6), and 10 (R10) years of post-reclamation. Results showed that (1) Compared to R0, the R10 treatment resulted in significant increases in soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) by 2.1-fold, 1.3-fold, 1.5-fold, and 0.4-fold, and also in activities of β-glucosidase (BG), N-acetyl-β-glucosaminidase (NAG), and leucine aminopeptidase (LAP), by 17-fold, 8.7-fold, and 1.8-fold, respectively (p < 0.05). (2) Rising bacterial diversity (Shannon, Chao1) over time, contrasting with fungal diversity that declined initially before recovering. (3) As the reclamation progressed, the network complexity was increased for both bacteria and fungi, improving stability. The number of bacterial keystone taxa was first increased and then decreased, with Bacillota (formerly Firmicutes) being the dominant keystone phylum. Bacteroidetes, Proteobacteria, and Acidobacteria exhibited rapid temporal responses. The fungal keystone taxa increased progressively, with Ascomycota as the dominant keystone phylum, while Basidiomycota and Mortierellomycota responded rapidly. (4) Enhanced bacterial functional potential (chemoheterotrophy, aerobic chemoheterotrophy, nitrification) and fungal saprotrophic capacity (undefined, wood saprotrophs) (5) Community assembly involved both deterministic (bacteria: dominated by heterogeneous selection) and stochastic processes (fungi: dispersal limitation/undominated). The partial least squares path modeling (PLS-PM) analysis showed that both the reclaimed coal mining and undisturbed normal farmland (NL) soils directly influenced microbial diversity and indirectly shaped microbial communities by influencing their assembly processes. These results underscore the critical role of reclamation in rebuilding soil microbial communities and restoring ecological functions in coal-mining areas.

明确不同复垦年限序列下土壤细菌与真菌群落的演替模式及组装机制，对于矿区土壤健康修复与生态稳定性维持至关重要。本研究以复垦后0年（R0）、1年（R1）、6年（R6）及10年（R10）的矿区土壤为研究对象，采用16S rDNA/ITS测序与零模型（null models）分析了土壤微生物多样性、群落组成、共现网络结构及群落组装过程。结果表明：（1）与R0相比，R10组土壤有机质（SOM）、全氮（TN）、有效磷（AP）和速效钾（AK）含量分别显著提升2.1倍、1.3倍、1.5倍和0.4倍；β-葡萄糖苷酶（BG）、N-乙酰-β-氨基葡萄糖苷酶（NAG）和亮氨酸氨基肽酶（LAP）活性分别显著提升17倍、8.7倍和1.8倍（p < 0.05）。（2）细菌多样性（Shannon指数、Chao1指数）随复垦年限增加而上升，而真菌多样性则呈现先下降后恢复的动态变化。（3）随着复垦进程推进，细菌与真菌的共现网络复杂度均有所提升，群落稳定性增强。细菌关键类群（keystone taxa）数量先升后降，以厚壁菌门（Bacillota，原Firmicutes）为优势关键类群门；拟杆菌门（Bacteroidetes）、变形菌门（Proteobacteria）及酸杆菌门（Acidobacteria）呈现出快速的时间响应特征。真菌关键类群数量持续增加，以子囊菌门（Ascomycota）为优势关键类群门；担子菌门（Basidiomycota）与被孢霉门（Mortierellomycota）响应速率较快。（4）细菌功能潜势（化能异养、好氧化能异养、硝化作用）以及真菌腐生能力（未定义腐生菌、木材腐生菌）均得到增强。（5）群落组装同时存在确定性过程（细菌群落以异质选择为主）与随机性过程（真菌群落以扩散限制/无主导过程为主）。偏最小二乘路径模型（PLS-PM）分析结果显示，复垦采煤区土壤与未受干扰的常规农田（NL）均能直接影响微生物多样性，并通过调控群落组装过程间接塑造微生物群落结构。本研究结果凸显了复垦措施在重构采煤区土壤微生物群落与恢复生态功能中的关键作用。