Multi-scale effects of habitat structure and landscape context on a vertebrate with limited dispersal ability (the brown-throated sloth, Bradypus variegatus)​

As human population, food consumption, and demand for forest products continue to rise over the next century, the pressures of land use change on biodiversity are projected to intensify. In tropical regions, countryside habitats that retain abundant tree cover and structurally complex canopies may complement protected areas by providing suitable habitats and landscape connectivity for a significant portion of the native biota. Species with low dispersal capabilities are among the most at risk of extinction as a consequence of land use change. We assessed how the spatial distribution of the brown-throated sloth (Bradypus variegatus), a model species for a vertebrate with limited dispersal ability, is shaped by differences in habitat structure and landscape patterns of countryside habitats in north-central Costa Rica using a multi-scale framework. We quantified the influence of local habitat characteristics and landscape context on sloth occurrence using mixed-effects logistic regression models. We recorded 27 sloths within countryside habitats and found that both local and landscape factors significantly influenced their spatial distribution. Locally, sloths favored structurally complex habitats, with greater canopy cover and variation in tree height and basal area. At the landscape scale, sloths demonstrated a preference for habitats with high proportions of forest and nearly large tracts of forest. Although mixed-use areas and tree plantations are not substitutes for protected forests, our results suggest they provide important supplemental habitats for sloths. To promote the conservation and long-term viability of sloth populations in the tropical countryside, we recommend for land managers to retain structurally complex vegetation and large patches of native habitat.

未来一个世纪，随着全球人口、食品消费及林产品需求持续增长，土地利用变化对生物多样性施加的压力预计将进一步加剧。在热带地区，保留充足林木覆盖且林冠结构复杂的乡村生境，可通过为大量本土生物类群提供适宜栖息地与景观连通性，成为保护地的有效补充。受土地利用变化影响，扩散能力较弱的物种是最易濒临灭绝的类群之一。本研究以扩散能力有限的脊椎动物模式物种——褐喉树懒（Bradypus variegatus）为研究对象，采用多尺度分析框架，评估了哥斯达黎加中北部乡村生境的结构差异与景观格局如何塑造其空间分布。本研究通过混合效应逻辑回归模型，量化了局域生境特征与景观背景对树懒出现概率的影响。研究团队在乡村生境中共记录到27只褐喉树懒，结果显示局域与景观因子均对其空间分布存在显著影响。局域尺度上，树懒偏好结构复杂的生境，即林冠覆盖度更高、树高与胸高断面积变异程度更大的生境。景观尺度下，树懒则表现出对高森林占比、连片大面积森林生境的偏好。尽管混合利用区域与人工林无法替代保护林，但本研究结果表明，它们可为树懒提供重要的辅助栖息地。为推动热带乡村区域树懒种群的保护与长期存续，我们建议土地管理者保留结构复杂的植被与大面积原生栖息地斑块。