阿拉斯加东南部温带雨林加氏和肯氏鹿鼠密度与微生境利用的相关性(英文)

Correlates of microhabitat use and density of Clethrionomys gapperi and Peromyscus keeni in temperate rain forests of Southeast Alaska

为了验证对阿拉斯加东南部温带雨林中有关栖息地关系的预测,我们于1999年和2000年8-9月以及1999年和2000年4-5月研究了亚历山大群岛加氏(Clethrionomys gapperi)和肯氏鹿鼠(Peromyscus keeni)种群。我们测量了26个植被和结构特征以检验林隙老龄生长林、多时代老龄生长林、采伐前壮龄(23岁)生长林和泥炭混交针叶林的丰富度与微栖息地利用的相关性。微栖息地利用随季节和栖息地而变化,但加氏与林下落叶灌木覆盖度的正相关最显著。肯氏鹿鼠利用的微环境的林地有较少的苔藓,但是林隙与抓获加氏的概率有直接关系。两种鼠在两个季节的密度与林下腐朽的倒木直接相关。春季的肯氏鹿鼠密度说明加氏密度变化的62%,说明肯氏鹿鼠密度变化的89%。我们的结果印证了早期对阿拉斯加东南部肯氏鹿鼠在各种栖息地尤其早期的演替林中兴旺时的研究;但偏离了西部地貌中肯氏鹿鼠种群在晚期演替针叶林中达到最高密度的普遍结论。与北美西北部其它地区的种群不同,加氏能持久生活在上层被砍伐的雨林板块中。泥炭针叶混交林对两种鼠的繁殖种群几乎没有贡献,因而不可能减轻对多产的老龄生长雨林大规模皆伐所造成的影响。

We studied red-backed vole Clethrionomys gapperi and Keen＇s mouse Peromyscus keeni populations in the Alexander Archipelago to test predictions regarding habitat relations in temperate rain forest of southeastern Alaska during August- September 1998 and 2000 and April- May 1999 and 2000. We measured 26 vegetative and structural features to correlate abundance among and microhabitat use within gap-phase old growth, multi-cohort old growth, pre-commercially thinned young （23-yr-old） growth, and peatland mixed-conifer forests. Populations of both species were higher in 1998 than 1999 and 2000. Both species used microhabitats randomly in 1998, but were highly selective in 1999 -2000. Correlates of microhabitat use varied between seasons and among habitats, but C. gapperi captures were most often positively correlated with the percent cover of deciduous shrubs in the understory. Microhabitats used by P. keeni had less moss cover on the forest floor, but in gap-phase were directly related to the probability of capturing a C. gapperi. Density of both species during both seasons was directly correlated with decayed downed wood in the understory. Density of P. keeni in spring explained 62% of the variation in C. gapperi density, which in turn explained 89% of the variation in P. keeni density. Our results corroborate the findings of earlier studies that P. keeni in southeastern Alaska flourishes in a variety of habitats, especially early seral forests; but, departed from the general conclusion that C. gapperi populations in western landscapes achieve their highest densities in late-seral coniferous forests. Unlike populations elsewhere in northwestern North America, C. gapperi may be able to persist in rain forest patches where the overstory has been removed. Peatland mixed-conifer forest contributed little to breeding populations of C. gapperi or P. keeni and thus is unlikely to mitigate any impacts of broad-scale clearcut logging of productive old-growth rainforests [ Acta Zoologica Sinica 51 （6） ： 973-988, 2005].