Abstract：
The practice of space-for-time substitution assumes that the responses of species or communities to land-use change over space represents how they will respond to that same change over time. Space-for-time substitution is commonly used in both ecology and conservation, but whether the assumption produces reliable insights remains inconclusive. Here, we tested space-for-time substitution using data from the North American Breeding Bird Survey (BBS) and Global Forest Change (GFC) to compare the effects of landscape-scale forest cover on bird richness and abundance over time and space, for 25 space-time comparisons. Each comparison consisted of a landscape that experienced at least 20% forest loss over 19 years (temporal site) and a set of 15-19 landscapes (spatial sites) that represented the same forest cover gradient over space in 2019 as experienced over time in their corresponding temporal site. Across the 25 comparisons, the observed responses of forest and open-habitat birds to forest cover over time generally aligned with their responses to forest cover over space, but with comparatively higher variability in the magnitude and direction of effect across the 25 temporal slopes than across the 25 spatial slopes. On average, the mean differences between the spatial and temporal slopes across the 25 space-time comparisons frequently overlapped with zero, suggesting that the spatial slopes are generally informative of the temporal slopes. However, we observed high variability around these mean differences, indicating that a single spatial slope is not strongly predictive of its corresponding temporal slope. We suggest that our results may be explained by annual variability in other relevant environmental factors that combine to produce complex effects on population abundances over time that are not easily captured by snapshots in space. While not being a 1:1 proxy, measuring bird responses to changes in habitat amount in space provides an idea on how birds might be expected to eventually equilibrate to similar changes in habitat amount over time. Further, analyses such as this could be potentially used to screen for cases of regional space-time mismatches where population-limiting factors other than habitat could be playing a more important role in the population trends observed there.
摘要：
时空替代的实践假设，物种或社区对土地利用变化的反应在空间上代表了它们将如何应对相同的变化。时空替代在生态和保护中都常用，但是该假设是否产生可靠的见解仍然没有定论。这里,我们使用北美繁殖鸟类调查（BBS）和全球森林变化（GFC）的数据测试了时空替代，以比较景观尺度森林覆盖对鸟类丰富度和丰度随时间和空间的影响，进行25次时空比较。每个比较包括一个景观，经历了至少20％的森林损失超过19年（临时地点），以及一组15-19种景观（空间站点），它们代表了2019年空间上的森林覆盖梯度，与相应的时间站点随时间的变化相同。在25个比较中，随着时间的推移，观察到的森林和开放栖息地鸟类对森林覆盖的反应通常与它们对空间森林覆盖的反应一致，但是在25个时间斜坡上的影响幅度和方向的变异性要高于25个空间斜坡。平均而言,在25个时空比较中，时空斜率之间的平均差经常与零重叠，这表明空间斜率通常是时间斜率的信息。然而,我们观察到围绕这些平均差异的高度变异性，表明单个空间斜率不能强烈预测其相应的时间斜率。我们建议，我们的结果可以通过其他相关环境因素的年度变化来解释，这些因素会随着时间的推移对人口丰度产生复杂的影响，而这些影响不易被空间快照捕获。虽然不是1:1代理，测量鸟类对空间栖息地数量变化的反应提供了一个想法，说明随着时间的推移，鸟类如何最终平衡到类似的栖息地数量变化。Further,这样的分析有可能用于筛选区域时空错配的情况，在这些情况下，栖息地以外的人口限制因素可能在那里观察到的人口趋势中发挥更重要的作用。本文受版权保护。保留所有权利。
