Table1_Heavy metal pollution decreases the stability of microbial co-occurrence networks in the rhizosphere of native plants.DOCX

Soil microorganisms play an important role in maintaining soil quality and function, although the response of soil microbial biodiversity to heavy metals has been extensively investigated, the microbe-microbe associations under the influence of both native plant species and extremely high heavy metal contamination are not well documented. We examined the diversity and composition of microbial communities and the physicochemical properties in the rhizosphere of three native plant species, Carex breviculmis, Buddleja davidii, and Artemisia annua growing on and around a Pb-Zn waste heap with a nearly 100-year history of natural recovery. Both plant species and heavy metals influence soil microbial diversity and composition. C. breviculmis and A. annua showed a prominent advantage in increasing rhizosphere microbial diversity and richness as well as network complexity compared with plant Buddleja davidii at severely contaminated soil, which was mainly related to the accumulation of soil nutrients such as soil organic carbon (SOC), total nitrogen ammonium nitrogen and nitrate nitrogen rather than a reduction in heavy metal concentrations. Moreover, the heavy metal concentration and soil nutrient levels significantly affected the microbial groups affiliated with Proteobacteria, Chloroflexi, Ascomycota, and Basidiomycota, in which those affiliated with Chloroflexi and Ascomycota were positively associated with heavy metals. Soil microbial network on the Pb-Zn waste heap exhibited higher average degree and a higher proportion of positive links than those around the waste heap, and thus soil microbial structure became more complexity and unstable with increasing heavy metal pollution.

土壤微生物在维持土壤质量与生态功能中发挥关键作用。尽管学界已针对土壤微生物多样性对重金属的响应开展了大量研究，但针对本土植物物种与高浓度重金属污染共同影响下的微生物间关联，目前仍缺乏充分的研究记录。本研究针对生长于具有近百年自然恢复历史的铅锌（Pb-Zn）尾矿堆及其周边区域的3种本土植物——短鳞薹草（Carex breviculmis）、大叶醉鱼草（Buddleja davidii）和黄花蒿（Artemisia annua）的根际微生物群落多样性、组成及土壤理化性质展开了调查分析。植物物种与重金属均可显著影响土壤微生物多样性与群落组成。相较于大叶醉鱼草，在重度污染土壤中，短鳞薹草与黄花蒿在提升根际微生物多样性、群落丰富度及网络复杂度方面表现出显著优势，这一现象主要与土壤有机碳（SOC）、总氮、铵态氮及硝态氮等土壤养分的积累相关，而非重金属浓度的降低。此外，重金属浓度与土壤养分水平显著影响隶属于变形菌门（Proteobacteria）、绿弯菌门（Chloroflexi）、子囊菌门（Ascomycota）及担子菌门（Basidiomycota）的微生物类群，其中绿弯菌门与子囊菌门的类群与重金属呈显著正相关。铅锌尾矿堆上的土壤微生物网络相较于尾矿堆周边区域，展现出更高的平均连接度与正关联边占比，因此随着重金属污染程度加剧，土壤微生物群落结构会愈发复杂且稳定性下降。