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Land use change is a key driver of biodiversity change and plays out over extended spatiotemporal scales. Historical land-use changes may shape present-day microbial communities through legacy effects, but the duration and mechanisms underpinning these legacies are poorly understood. We used historical land use maps detailing land use changes between low-intensive arable land and grassland, and grassland and forest, respectively, in two Swedish landscapes across three centuries to examine legacy responses among soil microbial communities, especially on plant pathogenic taxa. Compared to fungi, the community structure of bacteria showed stronger legacy effects, which, however, largely disappeared within a century. Yet, the diversity and composition of soil-borne plant pathogenic taxa, especially among fungi, showed a persisting influence of arable land use that did not disappear until 150 years after land-use change, suggesting that a dilution occurs over time. This may be related to changes in microbial interactions driven by responses to disturbances, as suggested by species co-occurrence patterns over time. Our findings provide crucial information on the duration of microbial legacy effects in connection with land use and single out soil-borne plant pathogens as a key group to study to understand site history effects on long-term microbial community dynamics.

土地利用变化（Land use change）是驱动生物多样性（biodiversity）改变的核心因子，其作用过程横跨广阔的时空尺度。历史土地利用变化可通过遗留效应（legacy effects）塑造当代土壤微生物群落（microbial communities），但这类遗留效应的持续时长与作用机制仍未得到充分阐释。本研究依托历史土地利用图谱，解析了瑞典两处景观中三个世纪尺度下，分别发生于低强度耕地与草地、草地与森林之间的土地利用转变事件，以此探究土壤微生物群落（尤其是植物致病类群（plant pathogenic taxa））的遗留响应特征。相较于真菌（fungi），细菌（bacteria）的群落结构展现出更强的遗留效应，但这类效应在一个世纪内便基本消散。然而，土传植物致病类群的多样性与组成（尤其是真菌类群）仍受耕地利用的持续影响，直至土地利用变化发生150年后才逐渐消退，这表明该效应随时间推移会发生稀释。这一关联或许源于扰动响应所驱动的微生物相互作用（microbial interactions）变化，该结论可通过随时间演变的物种共现模式（species co-occurrence patterns）得到佐证。本研究结果明确了与土地利用相关的微生物遗留效应的持续时长，并将土传植物病原菌列为核心研究类群，以助力解析样点历史对长期微生物群落动态（long-term microbial community dynamics）的影响。