Multi-trophic resilience of boreal lake ecosystems to forest fires.
Multi-trophic resilience of boreal lake ecosystems to forest fires.
复制标题
北方湖泊生态系统对森林火灾的多营养恢复能力。
作者：
T. L. Lewis;M. Lindberg;J. Schmutz;Mark Bertram
火灾是北方森林的主要自然干扰，随着气候变暖，火灾的频率和强度可能会增加。火灾释放的陆地养分可能被输送到北方湖泊，刺激初级生产力的增加，这可能会辐射到多个营养级。使用前后控制影响（BACI）设计，火灾前和火灾后的数据从燃烧和未燃烧的地区，我们研究了自然火灾的影响，在几个营养水平的北方湖泊，从营养和叶绿素水平，大型无脊椎动物，水鸟。总氮和磷的浓度没有受到火灾的影响。叶绿素a水平也未受影响，可能反映了稳定的营养浓度。对于水生无脊椎动物，我们发现，密度的三个功能喂养组没有响应火灾（过滤器，采集器，刮刀），而两组增加（碎纸机，掠食者）。端足类占98%的碎纸机数量，我们假设，火介导的栖息地变化可能有利于他们的通才喂养和栖息地生态。片脚类动物的增加反过来又可能导致捕食者密度的增加，因为片脚类动物是我们湖泊中数量最多的无脊椎动物，通常被当作猎物。最后，主要以水生无脊椎动物为食的大量水鸟幼鸟没有受到火灾的影响。总的来说，我们研究的湖泊生态系统在很大程度上对森林火灾具有弹性，这可能是由于其初始营养浓度高和集水面积小。此外，这种复原力跨越了多个营养层次，这对生态相似的北方地区来说是一个重要的结果，特别是考虑到未来气候变化很有可能增加火灾。
Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll a levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.