Table_4_Biodiversity and Ecosystem Functions Across an Afro-Tropical Forest Biodiversity Hotspot.XLSX

Ecosystem functions are important for the resilience of ecosystems and for human livelihood quality. Intact habitats and heterogeneous environments are known to provide a large variety of ecosystem functions. Natural and near natural ecosystems surrounding agroecosystems may positively support crop growing conditions and thus facilitate crop yields. In contrast, monocultures of crops and trees as well as degraded landscapes are known to provide less ecosystem functions. The Taita Hills in southern Kenya are part of the Eastern Afromontane biodiversity hotspot, and represent a habitat mosaic consisting of largely intact cloud forests, agroecosystems and plantations of exotic trees. In this region, subsistence farmers rely on ecosystem functions provided by natural ecosystems. In this study, we analyze three proxies of biodiversity and ecosystem functions, namely pollination activity, predation rates, and arthropod diversity in tree canopies. We set study plots along forest-agroecosystem-gradients, covering cloud forest, forest edge and agricultural fields, as well as plantations of exotic trees. We assessed environmental conditions, to evaluate the extent to which local environmental factors influence ecosystem functions. Based on these data we investigate potential spill over of ecosystem functions from forest into adjoining agroecosystems. For predation rates we found trends of spill over effects from forest interior into the agroecosystem. The expression of ecosystem functions differed among habitat types, with comparatively high predation rates in the forest, high pollinator activity in the open agricultural areas, and highest arthropod diversity along the forest edge. Eucalyptus plantations showed reduced ecosystem functions and lowest arthropod diversity. Local factors such as vegetation cover and flower supply positively influence pollinator activity. Our study show that natural ecosystems may positively contribute ecosystem functions such as predation, while the homogenization of biota through planting of invasive exotic tree species significantly reduce biodiversity and ecosystem functions. Transition habitats such as forest margins, and small-scale ecological enhancement positively influences biodiversity and ecosystem functions.

生态系统功能对于生态系统的弹性和人类生计质量至关重要。完整栖息地和异质环境众所周知能够提供丰富的生态系统功能。环绕农业生态系统的自然和近自然生态系统可能有助于改善作物生长条件，从而促进作物产量。相反，单一作物和树木的种植以及退化景观通常提供的生态系统功能较少。塔伊塔丘陵位于肯尼亚南部，是东非山地生物多样性热点地区的一部分，代表着由大体上完整的云雾林、农业生态系统和外来树种种植园构成的栖息地镶嵌体。在该地区，自给自足的农民依赖自然生态系统所提供的生态系统功能。在本研究中，我们分析了生物多样性和生态系统功能的三个替代指标，即树冠层的授粉活动、捕食率和节肢动物多样性。我们在森林-农业生态系统梯度上设置了研究样地，覆盖云雾林、森林边缘和农田，以及外来树种种植园。我们评估了环境条件，以评估当地环境因素对生态系统功能影响的程度。基于这些数据，我们探讨了生态系统功能从森林向相邻农业生态系统的潜在溢出效应。对于捕食率，我们发现森林内部向农业生态系统的溢出效应趋势。生态系统功能的表达在不同栖息地类型之间存在差异，森林中的捕食率相对较高，开阔的农业区域中授粉活动频繁，而森林边缘的节肢动物多样性最高。桉树种植园显示生态系统功能降低和节肢动物多样性最低。植被覆盖和花源等当地因素对授粉活动有积极影响。我们的研究表明，自然生态系统可能对捕食等生态系统功能做出积极贡献，而通过种植入侵的外来树种导致的生物群落的同质化显著降低了生物多样性和生态系统功能。过渡栖息地，如森林边缘和小规模的生态增强，对生物多样性和生态系统功能有积极影响。