Soil microorganisms play crucial roles in nutrient cycling and provisioning ecosystem services. However, little is known about how soil microbial communities are affected by soil management and landscape position in silvopastures. The current study aimed to understand effects of forage species [non-native, cool season orchardgrass (Dactylis glomerata L.) and a warm-season native grass mix (Andropogon gerardii L. and Schizachyrium scoparium L.) planted in strips between hedgerows], soil fertility (poultry litter and a control), and soil moisture regimes (aquic and udic) on soil bacterial communities to evaluate linkages between terrain attributes and soil bacterial assemblages. Thirteen terrain attributes representing topographic variability were clustered into four topographic functional units (TFUs) using the k-means method, and their impact on soil microbial diversity was evaluated. Illumina sequencing results identified a soil moisture regime × forage species interaction, with native grass species under wet (aquic) conditions resulting in the most diverse microbial assemblages relative to dry (udic) and wet soil conditions for the non-native forage (orchardgrass). These results suggest an enhanced soil microbial diversity under native grasses with greater available soil water. Overall, microbial diversity was negatively correlated with elevation, suggesting niche differentiation and microbial preference for lower elevations. Overall, TFUs and selected terrain attributes may be useful for predicting microbiota dynamics in integrated tree-livestock systems.

土壤微生物在养分循环和生态系统服务中起着至关重要的作用。然而，人们对于土壤微生物群落结构中土壤管理和景观位置对土壤微生物群落的影响知之甚少。当前的研究旨在了解牧草种类的影响[非天然，凉季果园（Dactylis glomerata L.）和暖季本地草混合物（Andropogon gerardii L.和Schizachyrium scoparium L.），种植在树篱之间的带中]，土壤肥力（家禽粪便和控制）和土壤湿度制度（潮以及城投），以评估地形属性与土壤细菌群落之间的联系。使用k均值方法，将代表地形变异性的13个地形属性聚集成四个地形功能单元（TFU），并评估它们对土壤微生物多样性的影响。Illumina测序结果所识别的土壤水分状况×饲料种类相互作用，用湿（下天然草种潮导致相对于干燥最多样的微生物组合）的条件下（UDIC）和非本地草料（果园）的湿润土壤条件。这些结果表明，在具有更多可用土壤水的天然草下，土壤微生物多样性得到增强。总体而言，微生物多样性与海拔呈负相关，表明生态位分化和微生物对较低海拔的偏好。总体而言，TFU和选定的地形属性对于预测集成树木-牲畜系统中的微生物群落动态可能很有用。