Research dating back to the 1950 s has documented negative effects from harvesting of primeval forests on stream ecosystems of the Pacific Northwest. By the early 1990 s, state and federal forest practice rules governing timber harvest were modified throughout North America to better protect aquatic habitats and biotic resources, principally salmonids. These rules inspired a generation of studies using a before-after-control-impact (BACI) design to document the capacity of contemporary timber harvest rules to protect salmonids in headwater streams of second-growth forests. One important unanswered question concerns the potential effects of successive clearcuts in second growth forests. Consequently, we used a paired watershed approach to evaluate the effects of two successive clearcut harvests in the Alsea Watershed, site of the seminal Alsea Watershed Study that was conducted from 1958 to 1973, on relative biomass, movement, survival, and distribution of coastal cutthroat trout (Oncorhynchus clarkii clarkii) and three physical habitat characteristics (pool area and depth, and water temperature). Although the total clearcut harvest encompassed 87% of the treatment catchment in six years, no negative effects of logging were detected for either age-1 + coastal cutthroat trout or habitat variables. Comparisons between the harvested and reference catchments suggested the survival of coastal cutthroat trout (>94 mm fork length) and total catchment relative biomass of age-1+ (i.e., > 80 mm) exhibited similar patterns, increasing from the pre-logging period (2006–2009) through the Phase I post-logging period (2009–2014), and decreasing to levels observed in the pre-logging period during the Phase II post-logging period (2014–2017). Additionally, there was no evidence for differences in movement of coastal cutthroat trout related to the harvesting treatment. In terms of habitat variables, there was a relative increase in annual total pool area in the harvested catchment during the Phase II post-logging period, but there was no evidence the 7-day moving mean maximum stream temperature changed after the Phase I and Phase II harvests. Moreover, stream water temperatures never exceeded the criterion designed to protect core coldwater habitat for salmonids (16 °C). As such, it is unlikely that cutthroat trout experienced thermal stress following either harvest. More generally, results from this and other recent studies suggest that forest practice rules developed in conjunction with current best management practices for logging in headwater catchments have substantially improved outcomes for stream biota relative to unregulated forest harvest, at least for short periods of time after logging (i.e., ≤ 8 years).

研究可以追溯到20世纪50年代记录了从太平洋西北地区的河流生态系统原始森林采伐负面影响。通过管理木材采伐与世纪90年代初，州和联邦森林实践规则在北美进行了修改，以更好地保护水生生物栖息地和生物资源，主要是鲑鱼。这些规则启发了一代使用前，后控制的影响（BACI）设计的水源流的次生林记录的当代采伐规则来保护鲑鱼的能力的研究。一个重要的悬而未决的问题涉及在第二生林皆伐连续的潜在影响。因此，我们使用了配对流域的方法来评价两个连续皆伐收获在阿尔西厄流域的影响，银钩虾虾）和三个物理栖息地特性（池面积和深度，以及水温度）。虽然总皆伐收获在六年内所包含的处理流域的87％，共进行任何年龄-1 +沿海山鳟或栖息地变量检测记录的没有负面影响。收获和参考集水区之间的比较表明沿海山鳟（>94毫米叉长度）和与年龄1总集水相对生物量+（即> 80mm）中表现出类似的模式，从预记录期间增加（生存2006-2009）通过I期后记录期间（2009-2014），并降低到在第二阶段后的记录期间（2014 - 2017年）在预记录期间观察到的水平。此外，有在相关收获治疗沿海山鳟的运动差异的证据。在栖息地变量方面，有在第二阶段后的记录时间，在年度总公摊面积相对增加在收获流域，但没有证据的7天移动平均最高气流温度的I期和之后改变二收成。此外，流水温从未超过旨在保护对鲑科鱼类芯冷水栖息地（16°C）的标准。因此，这是不可能的山鳟经历了热应力，无论是收获以下。更普遍，