CESAM and Departmento de Biologia, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal.
CESAM and Departmento de Biologia, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal.
Sci Total Environ. 2019 Feb 15;651(Pt 2):3117-3126. doi: 10.1016/j.scitotenv.2018.10.176. Epub 2018 Oct 15.
Catchment wildfire can decimate freshwater benthos when burnt material washes through river channels. We conducted detailed seasonal surveys over the course of one-year at N = 9 sites following summer-time wildfire in 2009 and N = 3 sites following summer-time wildfire in 2010 (constituting one-year time-series of 9 ∗ 5 and 3 ∗ 5 samples, respectively). Basic one-year-on surveys were conducted at an additional 12 sites following 2009 wildfires (Sum:Sum; N = 12 ∗ 2). Burnt sites were compared with 6 reference sites surveyed seasonally between autumn and summer, 2009-2010 (N = 6 ∗ 4), supplemented by 6 additional sites surveyed in summer 2004 (total reference samples: N = 6 ∗ 5). While benthic macroinvertebrates were largely unaffected by the fire event, richness and abundance were decimated during the winter, yet recovered to initial survey levels by the following summer. The differential response of assemblages in the exceptionally wet winter of 2009-10 versus 2010-11 highlighted the catalytic role of rainfall as a driver of benthic disturbance. Ecological disturbance was proportionally greater for less abundant taxa with community evenness peaking at the time of maximum disturbance. Seasonal dynamics in fire-impacted and reference sites followed a similar pattern, implying that despite the major reduction in macroinvertebrate standing crop the general character of benthic processes was sustained. One year after the wildfire event community structure was similar to the immediate post-fire assemblages and generally indistinguishable from reference samples. The statistical importance of habitat parameters at the landscape and local scale (catchment size, landuse, slope, bank management and benthic substrate) were indicative of mechanistic processes underlying wildfire disturbance-recovery and define the scope for mitigation management. The remarkable resilience of community structure in these Mediterranean streams marks an emphatic contrast to the response of benthic macroinvertebrates to comparable disturbance processes in temperate regions. Given the increasing geographic scale and frequency of fires accompanying global warming wildfire-risk may become a leading issue for river management.
集水区野火在燃烧物质冲刷河道时会摧毁淡水底栖生物。我们在 2009 年夏季野火和 2010 年夏季野火后，分别在 9 个地点进行了为期一年的详细季节性调查（分别构成了 95 和 35 个样本的一年时间序列），并在 2009 年野火后在另外 12 个地点进行了基本的一年后调查（总计：Sum；N=122）。与 2009-2010 年秋季至夏季季节性调查的 6 个参考点相比，对燃烧点进行了调查（N=64），并补充了 2004 年夏季调查的 6 个额外参考点（总参考样本：N=6*5）。虽然底栖大型无脊椎动物基本上不受火灾事件的影响，但在冬季其丰富度和丰度受到严重破坏，但到下一个夏季又恢复到最初的调查水平。2009-10 年异常湿润的冬季与 2010-11 年冬季群落的差异反应突出了降雨作为底栖干扰驱动因素的催化作用。在生态干扰方面，较少丰富的分类群比例较大，群落均匀度在最大干扰时达到峰值。受火灾影响和参考点的季节性动态遵循相似的模式，这意味着尽管大型无脊椎动物现存量大幅减少，但底栖过程的总体特征得以维持。野火事件发生一年后，群落结构与火灾后立即形成的群落相似，通常与参考样本无法区分。景观和局部尺度（集水区大小、土地利用、坡度、河岸管理和底质）的生境参数的统计重要性表明了野火干扰-恢复背后的机制过程，并确定了缓解管理的范围。在这些地中海溪流中，群落结构的显著恢复与温带地区类似干扰过程对底栖大型无脊椎动物的反应形成鲜明对比。考虑到全球变暖带来的地理范围和频率不断增加的火灾，野火风险可能成为河流管理的一个主要问题。
