Department of Botany, University of Wyoming, Laramie, Wyoming 82071, USA.
Ecology. 2010 Nov;91(11):3177-88. doi: 10.1890/09-1216.1.
We explored the interacting effects of marine-derived nutrient fertilization and physical disturbance introduced by coastal river otters (Lontra canadensis) on the production and nutrient status of pristine shrub and tree communities in Prince William Sound, Alaska, USA. We compared production of trees and shrubs between latrines and non-latrines, while accounting for otter site selection, by sampling areas on and off sites. Nitrogen stable isotope analysis (delta15N) indicated that dominant tree and shrub species assimilated the marine-derived N excreted by otters. In association with this uptake, tree production increased, but shrub density and nonwoody aboveground shrub production decreased. The reduced shrub production was caused by destruction of ramets, especially blueberry (Vaccinium spp.), through physical disturbance by river otters. False azalea (Menziesia ferruginea) ramets were less sensitive to otter disturbance. Although surviving individual blueberry ramets showed a tendency for increased production per plant, false azalea allocated excess N to storage in leaves rather than growth. We found that plant responses to animal activity vary among species and levels of biological organization (leaf, plant, ecosystem). Such differences should be accounted for when assessing the influence of river otters on the carbon budget of Alaskan coastal forests at the landscape scale.
我们探讨了海洋营养物质施肥与沿海海獭（Lontra canadensis）所带来的物理干扰的相互作用，对美国阿拉斯加威廉王子湾原始灌木和树木群落的生产力和养分状况的影响。我们通过在海獭栖息地和非栖息地取样，考虑到海獭的选址，比较了树木和灌木在便坑和非便坑之间的生产力。氮稳定同位素分析（δ15N）表明，主要的树木和灌木物种吸收了海獭排泄的海洋来源的氮。随着这种吸收，树木的生产力增加了，但灌木的密度和非木质地上灌木的生产力下降了。灌木生产力的降低是由于河流獭通过物理干扰破坏了小枝，特别是蓝莓（Vaccinium spp.）。假杜鹃（Menziesia ferruginea）小枝对海獭的干扰不太敏感。尽管幸存下来的单个蓝莓小枝表现出每株植物产量增加的趋势，但假杜鹃将过多的氮分配到叶片中储存，而不是生长。我们发现，动物活动对植物的影响因物种和生物组织（叶片、植物、生态系统）的层次而异。在评估海獭对阿拉斯加沿海森林景观尺度碳预算的影响时，应该考虑到这些差异。
