Habitat selection theory enables inferences about species habitat choice across a range of observed population densities. However, it is relatively uncommon to use habitat selection theory in studies of habitat restoration efficacy to understand the effect of restoration on habitat competition. We combined observational density data and resource selection functions to analyze habitat correlations with both habitat selection theory and a mark–recapture experiment to show how habitat restoration can mitigate competition between species with similar habitat preferences. To restore degraded and channelized riverine habitat for juvenile Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss) engineered log jams (ELJs) have been installed to create pools to enhance growth and rearing. Application of habitat selection theory first showed that both species share a preference for ELJ‐treated habitat over unrestored habitat. Linear models showed that steelhead are generalists with respect to depth in unrestored habitat, whereas both species' abundance varies along a depth gradient in ELJ‐treated habitat. Selective versus opportunistic use of deep and shallow ELJ pools was density‐dependent. We found a range of densities at which a “ghost of competition” exists, where Chinook are selective on deep ELJ‐treated pools and steelhead are selective on shallow pools. A mark–recapture experiment confirmed that steelhead limit Chinook movement into unrestored habitat, but this competitive effect vanished in ELJ‐treated habitat where selection occurred with respect to pool depth. The experiment, combined with theory, enabled (1) the identification of a mechanism allowing for shared preference of restored habitat and (2) the description of how restoration can mitigate competition.

中文翻译：

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通过结合理论、观察和实验，了解恢复如何减少对栖息地的竞争


栖息地选择理论能够推断出在一系列观察到的种群密度下物种栖息地的选择。然而，在栖息地恢复效果研究中，使用栖息地选择理论来了解恢复对栖息地竞争的影响相对较少。我们将观测密度数据和资源选择函数相结合，通过栖息地选择理论和标记-重新捕获实验来分析栖息地相关性，以展示栖息地恢复如何减轻具有相似栖息地偏好的物种之间的竞争。为了恢复奇努克鲑鱼幼鱼 （Oncorhynchus tshawytscha） 和虹鳟鱼 （Oncorhynchus mykiss） 退化和渠道化的河流栖息地，已经安装了工程原木堵塞 （ELJ） 以形成水池以促进生长和饲养。栖息地选择理论的应用首先表明，这两个物种都偏爱 ELJ 处理的栖息地，而不是未恢复的栖息地。线性模型表明，在未恢复的栖息地中，虹鳟在深度方面是多面手，而在 ELJ 处理的栖息地中，这两个物种的丰度都沿深度梯度变化。深浅 ELJ 池的选择性使用与机会性使用是密度依赖性的。我们发现了存在“竞争幽灵”的一系列密度，其中奇努克鱼对 ELJ 处理的深水池有选择性，而虹鳟对浅水池有选择性。标记再捕获实验证实，虹鳟限制奇努克进入未恢复的栖息地，但这种竞争效应在 ELJ 处理的栖息地中消失了，因为选择发生在池深度方面。 该实验与理论相结合，使 （1） 确定了一种允许对恢复的栖息地的共同偏好的机制，以及 （2） 描述了恢复如何减轻竞争。