Abstract The diversification of tropical pastures with legumes (trees) for increased forage and animal productivity has been advocated. Nevertheless, effects on soil quality and belowground biodiversity, and the implications for sustainable intensification remain poorly documented, particularly when cattle grazing is included in the study. We evaluated the impact of forage system diversification with herbaceous and woody legumes on soil properties and soil macrofauna communities and their spatial heterogeneity in a three-year-old field trial in Cauca Valley, Colombia. Three forage-based systems were compared: (i) a conventional monoculture-species grass pasture system of Brachiaria hybrid cv. Cayman (CP); (ii) a mixed pasture system consisting of Brachiaria grass with the leguminous herb Canavalia brasiliensis (LP); and (iii) a silvopastoral system with rows of the legume tree Leucaena diversifolia planted within LP pastures (SPS). The experiment was arranged in a complete randomized block design with three replicates and grazing cattle rotating across blocks. Plots were grazed by three (treatments CP and LP) or four bulls (SPS) aiming to reflect the expected cattle intensification in SPS systems. Physico-chemical soil properties and macrofauna abundance and their spatial heterogeneity as affected by the distance from the tree rows in SPS, were assessed. Herbaceous legumes positively affected the abundance and diversity of soil macrofauna and soil physical properties in LP and the alleys between tree rows in SPS, as compared to CP. In the SPS, the highest soil quality and macrofauna abundance occurred at the edge of the tree lines, while the highest soil compaction and the lowest abundance of soil macrofauna occurred in the tree rows, probably due to the behavioral change of the grazing cattle in combination with the higher stocking rate in SPS. Soil properties in LP and in the alleys between the tree rows of SPS were comparable despite higher stocking rate in SPS. Overall, the SPS and LP systems, proved to be suitable alternatives to CP allowing for sustainable intensification of pastures although careful evaluation of possible trade-offs associated with increased spatial heterogeneity in SPS is recommended to avoid localized soil compaction. Soil macrofauna, particularly functional groups (classified by feeding habits) proved to be a sensitive soil quality indicator in response to contrasting pasture systems.

中文翻译：

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牧场多样化影响热带（林）牧区系统中的土壤大型动物群和土壤生物物理特性

摘要 提倡种植豆科植物（树木）的热带牧场多样化，以提高牧草和动物生产力。然而，对土壤质量和地下生物多样性的影响以及对可持续集约化的影响仍然缺乏记录，特别是当研究包括放牧时。我们在哥伦比亚考卡河谷的一项为期三年的田间试验中评估了草本和木本豆类牧草系统多样化对土壤特性和土壤大型动物群落及其空间异质性的影响。比较了三种基于牧草的系统：(i) Brachiaria 杂交品种的传统单一栽培种草牧场系统。开曼 (CP); (ii) 由臂形草和豆科植物 Canavalia brasiliensis (LP) 组成的混合牧场系统；(iii) 林牧系统，其中种植了多排豆科植物银合欢（Leucaena diversifolia）在LP牧场（SPS）内。实验安排在一个完整的随机区组设计中，三个重复，放牧牛在区组之间旋转。地块由三头（处理 CP 和 LP）或四头公牛 (SPS) 放牧，旨在反映 SPS 系统中预期的牛集约化。评估了理化土壤特性和大型动物群的丰度及其空间异质性，这些异质性受与 SPS 中树行距离的影响。与 CP 相比，草本豆科植物对 LP 和 SPS 中树行之间的小巷的土壤大型动物群的丰度和多样性以及土壤物理性质有积极影响。在 SPS 中，最高的土壤质量和大型动物群丰度出现在树木线的边缘，而最高的土壤压实度和最低的土壤大型动物丰度发生在树行，可能是由于放牧牛的行为变化以及 SPS 中较高的放养率。尽管 SPS 的放养率较高，但 LP 和 SPS 树行之间的小巷的土壤特性相当。总的来说，SPS 和 LP 系统被证明是 CP 的合适替代品，允许牧场的可持续集约化，尽管建议仔细评估与 SPS 空间异质性增加相关的可能权衡，以避免局部土壤压实。土壤大型动物群，特别是功能群（按摄食习惯分类）被证明是响应不同牧场系统的敏感土壤质量指标。