A before-and-after assessment of patch-burn grazing and riparian fencing along headwater streams

Fire and grazing are common in grasslands world-wide to maintain grass cover and cattle production. The effects of fire, cattle grazing and riparian fencing efficacy on prairie stream ecology are not well characterized at catchment scales. We examined alterations to stream water quality and biology from patch-burn grazing (PBG) in tallgrass prairie during a five-year, replicated, catchment scale experiment that used a Before-After/Control-Impact (BACI) design and was analysed by mixed-effects models. Treatments included two patch-burned control catchments (fire but no grazers) and PBG in two riparian-fenced and two unfenced catchments. We assessed the effectiveness of riparian fencing for mitigating potential water quality impacts by monitoring water quality and riparian usage by cattle via Global Positioning System. Riparian fences effectively excluded cattle; however, in unfenced pastures, cattle aggregated along streams 10–20% of the grazing season. After initiation of PBG, we det...火与放牧是全球草原中维持草本覆盖与肉牛生产的常用管理手段。目前，针对火、肉牛放牧及河岸围栏效能对草原溪流生态的影响，在集水区尺度上尚未得到充分的量化与表征。 本研究依托一项为期五年、设置重复的集水区尺度野外实验，采用前后对照/控制影响（Before-After/Control-Impact, BACI）设计，并通过混合效应模型开展分析，探究了高草草原中斑块焚烧放牧（Patch-burn Grazing, PBG）对溪流水质与水生生物的改变效应。实验处理组设置为：2个仅实施焚烧的对照集水区（有火无放牧），以及2个布设河岸围栏、2个未布设河岸围栏的斑块焚烧放牧集水区。本研究通过全球定位系统（Global Positioning System, GPS）监测肉牛的河岸活动频次，以此评估河岸围栏对缓解潜在水质负面影响的实际效能。 河岸围栏可有效阻挡肉牛进入溪流周边区域；但在未布设围栏的牧场中，肉牛会在放牧季的10%~20%时段聚集于溪流沿岸。 在启动斑块焚烧放牧干预后，我们[原文内容截断]