Department of Biology, Carleton University, Ottawa, Ontario, Canada.
National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada.
Ecol Appl. 2024 Mar;34(2):e2919. doi: 10.1002/eap.2919. Epub 2023 Oct 6.
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.
空间代替时间的做法假设，物种或群落对土地利用变化的空间响应代表了它们对同一变化的时间响应。空间代替时间的做法在生态学和保护学中都很常见，但这种假设是否能产生可靠的见解仍不确定。在这里，我们使用来自北美繁殖鸟类调查（BBS）和全球森林变化（GFC）的数据来测试空间代替时间的做法，以比较景观尺度的森林覆盖对鸟类丰富度和数量随时间和空间的影响，共进行了 25 次时空比较。每次比较都由一个经历了至少 20%森林损失的景观组成（时间点）和一组 15-19 个景观（空间点），这些景观在 2019 年代表了与时间点上相同的森林覆盖梯度，与时间点上的森林覆盖梯度相对应。在 25 次比较中，森林和开阔地鸟类对森林覆盖的观察到的时间响应总体上与它们对空间森林覆盖的响应一致，但在 25 个时间斜率上的效应幅度和方向的变异性相对较高。平均而言，25 个时空比较中空间和时间斜率之间的平均差异经常与零重叠，这表明空间斜率通常可以提供时间斜率的信息。然而，我们观察到这些平均差异周围的高度变异性，这表明单个空间斜率不能很好地预测其对应的时间斜率。我们认为，我们的结果可能可以用其他相关环境因素的年度变化来解释，这些因素结合起来，对随时间变化的种群数量产生复杂的影响，而这些影响很难通过空间中的快照来捕捉。虽然不是 1:1 的代理，但测量鸟类对空间中栖息地数量变化的响应提供了一个关于鸟类如何最终适应随时间变化的栖息地数量的想法。此外，这种分析可以潜在地用于筛选出区域时空不匹配的情况，在这些情况下，除了栖息地之外的其他限制因素可能在观察到的种群趋势中发挥更重要的作用。
