Soil viral and microbial interactions facilitate microbial necromass carbon accumulation in the semiarid typical steppe under altered precipitation_Research data

Viruses are regarded as indispensable biotic components of soil ecosystems, where they play critical roles in microbial community succession and soil carbon cycling. However, the formation mechanisms of microbial necromass carbon (MNC), a major stable source of soil organic carbon (SOC), remain unclear under altered precipitation, particularly regarding the regulatory effects of virus–microbe interactions. Based on a multi–year precipitation manipulation experiment in a typical temperate steppe on the Loess Plateau, this study systematically examined the influence of soil viral and microbial community structures, as well as their interactions, on microbial necromass carbon accumulation. The results showed that decreased precipitation significantly reduced microbial necromass carbon (BNC, MNC, and BNC/MNC) and their relative contributions to SOC (BNC/SOC and MNC/SOC), whereas increased precipitation had relatively weaker effects. Altered precipitation changed soil viral and microbial community composition, and their co–occurrence networks were dominated by positive within–trophic and cross–trophic associations. Pearson correlation analysis revealed that microbial necromass carbon and its contribution to SOC were positively correlated with network complexity (e.g., node number, edge number, average degree, network density), as well as with positive WTAs and CTAs. Structural equation modeling further indicated that altered precipitation affected virus–microbe interactions by changing soil moisture, thereby jointly regulating the formation and accumulation of microbial necromass carbon. Collectively, these findings highlight the pivotal role of virus–microbe interactions in shaping microbial necromass carbon dynamics under altered precipitation, offering new insights into the mechanisms underlying soil carbon stabilization.

病毒被视为土壤生态系统不可或缺的生物组成部分，在微生物群落演替与土壤碳循环中发挥关键作用。然而，作为土壤有机碳（soil organic carbon, SOC）的主要稳定来源，微生物残体碳（microbial necromass carbon, MNC）的形成机制在降水变化背景下仍不明确，尤其是病毒-微生物互作的调控效应尚未得到清晰阐释。基于黄土高原典型温带草原的多年降水控制实验，本研究系统解析了土壤病毒与微生物群落结构及其互作对微生物残体碳积累的影响。研究结果显示，降水减少显著降低了微生物残体碳（含细菌残体碳BNC、MNC及二者比值BNC/MNC）及其对SOC的相对贡献（BNC/SOC与MNC/SOC），而降水增加的影响相对较弱。降水变化改变了土壤病毒与微生物的群落组成，且二者的共现网络以营养级内和跨营养级的正关联为主导。皮尔逊相关分析显示，微生物残体碳及其对SOC的贡献与网络复杂度（如节点数、边数、平均度、网络密度）以及营养级内正关联（WTAs）和跨营养级正关联（CTAs）均呈显著正相关。结构方程模型进一步表明，降水变化通过改变土壤湿度影响病毒-微生物互作，进而共同调控微生物残体碳的形成与积累。综上，本研究结果凸显了病毒-微生物互作在降水变化背景下调控微生物残体碳动态的关键作用，为阐明土壤碳稳定的潜在机制提供了全新视角。