Data from: Biodiversity extinction thresholds are modulated by matrix type

Biodiversity extinction thresholds are abrupt declines in biological diversity that occur with habitat loss, associated with a decline in habitat connectivity. Matrix quality should influence the location of thresholds along habitat loss gradients through its effects on connectivity; however these relationships have seldom been explored empirically. Using field data from 23 independent 1,254 ha landscapes in the Brazilian Atlantic Forest, we evaluated how tropical avian biodiversity responds to native forest loss within habitat patches embedded either in homogeneous pasture matrix context (with a high proportion of cattle pastures), and heterogeneous coffee matrix context (with high abundance of sun coffee plantations). We considered taxonomic, functional, and phylogenetic diversity, and tested if matrix type and choice of diversity metric influenced the location of biodiversity thresholds along the forest cover gradient. We found that matrix type postponed the abrupt loss of taxonomic diversity, from a threshold of 35% of forest cover in homogeneous pasture matrix to 19% in heterogeneous coffee matrix. Phylogenetic diversity responded similarly, with thresholds at 30% and 24% in homogeneous-pasture and heterogeneous-coffee matrices, respectively, but no relationship with forest cover was detected when corrected for richness correlation. Despite the absence of a threshold for functional diversity in either matrix types, a strong decline below 20% of habitat amount was detected. Finally, below 20% native habitat loss, all diversity indices demonstrated abrupt declines, indicating that even higher-quality matrices cannot postpone diversity loss below this critical threshold. These results highlight that taxonomic diversity is a more sensitive index of biodiversity loss in fragmented landscapes, which may be used as a benchmark to prevent subsequent functional and phylogenetic losses. Furthermore, increasing matrix quality appears an efficient conservation strategy to maintain higher biodiversity levels in fragmented landscapes over a larger range of habitat loss.生物多样性灭绝阈值（biodiversity extinction thresholds）是指伴随生境丧失发生的生物多样性骤降现象，其与生境连通性（habitat connectivity）下降密切相关。基质（matrix）质量可通过影响连通性，进而调控生境丧失梯度上阈值的位置，但此类关联尚未得到充分的实证探索。本研究依托巴西大西洋森林中23处独立的1254公顷样区的野外调查数据，针对两类嵌入不同基质的生境斑块开展分析：一类为均质牧场基质（以高强度牛牧场为主），另一类为异质咖啡基质（以大面积露天咖啡种植园为主），以此探究热带鸟类生物多样性对原生林丧失的响应规律；研究涵盖分类多样性、功能多样性与系统发育多样性三类指标，旨在检验基质类型与多样性指标的选取是否会改变林冠覆盖梯度上的生物多样性阈值位置。结果显示，基质类型可延缓分类多样性的骤降：均质牧场基质下的阈值为林冠覆盖占比35%，而异质咖啡基质下的阈值则降至19%；系统发育多样性呈现相似的响应规律，均质牧场与异质咖啡基质下的阈值分别为30%与24%，但在校正物种丰富度相关性后，未检测到其与林冠覆盖的关联。尽管两类基质下均未检测到功能多样性的阈值，但当生境占比低于20%时，功能多样性出现显著下降；最终，当原生生境覆盖占比低于20%（即原生生境丧失比例达80%）时，所有多样性指标均出现骤降，表明即便是高质量基质，也无法将多样性丧失延缓至该临界阈值以下。本研究结果表明，分类多样性是破碎化景观中生物多样性丧失的更为敏感的指标，可作为预防后续功能与系统发育多样性丧失的基准参考；此外，提升基质质量可作为一项高效的保护策略，在更广的生境丧失范围内维持破碎化景观中的较高生物多样性水平。