We investigated population responses of Microtus longicaudus to cumulative clear-cutting of coniferous forests and to enhanced understory vegetation in young, fertilized pine stands near Summerland, British Columbia, Canada. We explored if there was a threshold level of habitat quality arising from a given forest disturbance for M. longicaudus to increase to high population levels and potentially fluctuate in abundance over time. Secondly, we asked if these outbreaks were site-specific or part of a long-term pattern. We tested three hypotheses (H) that populations of M. longicaudus would increase in abundance and potentially fluctuate owing to (H1) the availability of early seral postharvest habitats associated with cumulative clear-cut harvesting; (H2) woody debris piles on clear-cuts; and (H3) have higher mean abundance, reproduction, and survival in fertilized forest sites with enhanced understory vegetation. Mean annual and peak abundances of M. longicaudus were significantly different across the four Periods of cumulative forest harvesting with numbers being highest in the first two Periods. Thus, H1, that long-tailed voles would increase in abundance on new clear-cuts, was partially supported for the first two Periods but not in the later Periods. Constant cattle (Bos taurus) grazing during summer periods over the four decades may have reduced vegetative productivity for voles and damped out population responses on these clear-cut sites, at least in the last two Periods. Woody debris piles on clear-cuts may have increased abundance and generated a population fluctuation, thereby supporting H2. Enhanced abundance of understory vegetation had no effect on mean abundance, reproduction, or survival of M. longicaudus, and hence did not support H3. We conclude that it is site-specific disturbances, particularly in forest management, that generate occasional outbreaks of M. longicaudus, and there does not appear to be any long-term pattern to these discordant fluctuations.

中文翻译：

---

管理森林中长尾田鼠（Microtus longicaudus）的种群波动：特定地点的干扰还是长期模式？

我们调查了 Microtus longicaudus 对针叶林的累积清除以及加拿大不列颠哥伦比亚省萨默兰附近受精的年轻松树林下植被增强的种群反应。我们探讨了是否存在由给定森林干扰引起的栖息地质量阈值水平，以使 M. longicaudus 增加到高种群水平并可能随着时间的推移而波动。其次，我们询问这些爆发是特定地点还是长期模式的一部分。我们测试了三个假设 (H)，即 M. longicaudus 的种群数量会增加，并且可能会由于 (H1) 与累积的明确收获相关的早期收获后栖息地的可用性而波动；(H2) 空地上的木质杂物堆；(H3) 具有更高的平均丰度、繁殖率、并在林下植被增强的施肥林地生存。M. longicaudus 的年平均丰度和峰值丰度在四个累积森林采伐时期存在显着差异，前两个时期的数量最高。因此，H1，即长尾田鼠将在新的砍伐区增加丰度，在前两个时期得到部分支持，但在后期没有得到支持。至少在过去两个时期，在过去 40 年的夏季期间，持续放牧的牛（Bos taurus）可能降低了田鼠的营养生产力，并抑制了这些明确地点的种群反应。空地上的木本杂物堆可能增加了丰度并产生了人口波动，从而支持了 H2。增加的林下植被丰度对平均丰度没有影响，M. longicaudus 的繁殖或存活，因此不支持 H3。我们得出的结论是，特定地点的干扰，特别是在森林管理中，偶尔会产生 M. longicaudus 的爆发，并且这些不协调的波动似乎没有任何长期模式。