Data from: Mapping extinction debt highlights conservation opportunities for birds and mammals in the South American Chaco

1. Habitat loss is the primary cause of local extinctions. Yet, there is considerable uncertainty regarding how fast species respond to habitat loss, and how time-delayed responses vary in space. 2. We focused on the Argentine Dry Chaco (ca. 32 million ha), a global deforestation hotspot, and tested for time-delayed response of bird and mammal communities to landscape transformation. We quantified the magnitude of extinction debt by modelling contemporary species richness as a function of either contemporary or past (2000 and 1985) landscape patterns. We then used these models to map communities’ extinction debt. 3. We found strong evidence for an extinction debt: landscape structure from 2000 explained contemporary species richness of birds and mammals better than contemporary and 1985 landscapes. This suggests time-delayed responses between 10 and 25 years. Extinction debt was especially strong for forest specialists. 4. Projecting our models across the Chaco highlighted areas where future local extinctions due to unpaid extinction debt are likely. Areas recently converted to agriculture had highest extinction debt, regardless of the post-conversion land use. Few local extinctions were predicted in areas with remaining larger forest patches. 5. Synthesis and applications. The evidence for an unpaid extinction debt in the Argentine Dry Chaco provides a substantial window of opportunity for averting local biodiversity losses. However this window may close rapidly if conservation activities such as habitat restoration are not implemented swiftly. Our extinction debt maps highlights areas where such conservation activities should be implemented.

1. 生境丧失是引发物种种群局部灭绝的首要诱因。然而，学界对于物种响应生境丧失的速率，以及空间尺度下时间延迟响应的变异规律，仍存在显著认知不确定性。
2. 本研究聚焦于全球森林砍伐热点区域——阿根廷干旱查科（Argentine Dry Chaco，面积约3200万公顷），针对鸟类与哺乳动物群落对景观转化的时间延迟响应展开检验。我们以当代物种丰富度为因变量，分别以当代、2000年及1985年的景观格局作为自变量构建模型，以此量化灭绝债务（extinction debt）的规模；随后借助上述模型绘制群落灭绝债务的空间分布图。
3. 本研究发现了强有力的灭绝债务证据：相较于当代及1985年的景观格局，2000年的景观结构对鸟类与哺乳动物当代物种丰富度的解释度更高，这表明物种响应存在10至25年的时间延迟。其中，森林特化物种的灭绝债务效应尤为显著。
4. 将本研究模型空间外推至整个查科区域后，我们识别出了未来极有可能因未清偿灭绝债务而发生局部物种灭绝的区域。新近被开垦为农业用地的区域灭绝债务水平最高，且不受后续土地利用类型的影响；而保留有较大面积森林斑块的区域，预测发生局部灭绝的概率极低。
5. 研究总结与应用启示：阿根廷干旱查科区域存在未清偿灭绝债务的证据，为规避当地生物多样性丧失提供了宝贵的时间窗口。但若未能快速推进生境修复等保护举措，该窗口将快速关闭。本研究绘制的灭绝债务空间分布图，可为上述保护行动的实施选址提供科学指引。