Pacific salmon spawning and rearing habitats result from dynamic interactions among geomorphic processes, natural disturbances, and hydro‐climatological factors acting across a range of spatial and temporal scales. We used a 21‐year record of redd locations in a wilderness river network in central Idaho, USA, to examine which covariates best predict the spawning occurrence of Chinook Salmon Oncorhynchus tshawytscha and how shifts under a changing climate might affect habitat availability. We quantified geomorphic characteristics (substrate size, channel slope, and valley confinement), climatic factors (stream temperature and summer discharge), wildfire, and conspecific abundance (as inferred by the number of redds) throughout the network. We then built and compared logistic regression models that estimated redd occurrence probability as a function of these covariates in 1‐km reaches throughout the network under current and projected climate change scenarios. Redd occurrence was strongly affected by nearly all of the covariates examined. The best models indicated that climate‐driven changes in redd occurrence probabilities will be relatively small but spatially heterogeneous, with warmer temperatures increasing occurrence probabilities in cold, high‐elevation reaches and decreasing probabilities in warm, low‐elevation reaches. Furthermore, positive effects of wildfire on redd occurrence may be more important than climate‐driven effects on stream temperature and summer discharge, although climate‐related changes in temperature and scour regime during the egg incubation period may influence survival to emergence. Our results identify where favorable spawning habitats are likely to exist under climate change, how future habitat distributions may differ from contemporary conditions, and where habitat conservation might be prioritized. Furthermore, the positive occurrence–abundance relationship we observed indicates that the study site is underseeded, and effective management actions are needed for increasing the recruitment of spawning adults to take advantage of available habitat.

中文翻译：

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气候，火种，地貌和种属影响奇努克鲑鱼的空间分布

太平洋鲑鱼的产卵和饲养栖息地是由地貌过程，自然扰动和跨各种时空尺度作用的水文气候因素之间的动态相互作用产生的。我们使用了21年美国爱达荷州中部荒野河网中变红位置的记录，以检查哪些协变量可以最好地预测奇努克鲑鱼Oncorhynchus tshawytscha的产卵情况以及气候变化下的变化如何影响栖息地的可用性。我们量化了整个网络的地貌特征（基质尺寸，河道坡度和谷底限制），气候因素（溪流温度和夏季排放量），野火和特定物种的丰度（由冲数确定）。然后，我们建立并比较了逻辑回归模型，该模型估计了在当前和预期的气候变化情景下，整个网络中1 km范围内红变发生概率与这些协变量的关系。几乎所有协变量均强烈影响了Redd的发生。最好的模型表明，气候驱动的变冲发生概率变化将相对较小，但在空间上是不均匀的，随着温度升高，寒冷，高海拔范围和温暖，低海拔范围的概率降低。此外，野火对变红的积极影响可能比气候驱动的对溪流温度和夏季排泄的影响更为重要，尽管在卵孵化期间与温度有关的温度变化和冲刷状态可能会影响成活率。我们的结果确定了在气候变化下可能存在有利的产卵栖息地的地方，未来栖息地的分布可能与当代条件有何不同，以及优先考虑栖息地保护的地方。此外，我们观察到的正发生-丰度关系表明该研究地点未播种，并且需要有效的管理措施来增加对产卵成虫的募集，以利用可用的栖息地。