Synergistic fire and floodplain solutions

野火已经是各大洲的一个主要问题，预计其频率和强度将增加，影响世界上以前未受影响的地区（包括未来气候变化下的英国）。事实上，2020年是全球野火创纪录的一年，据估计，仅在美国，野火就造成了130亿美元的损失（路透社2020年12月15日）。糟糕的河流管理措施导致洪泛平原干涸，造成火药箱效应，从而增加了野火的威胁。几个世纪以来，人类对河流进行了改造，通常是将多河道的河流改造成单一的、更深的河道。这会使洪泛区排水和断流，降低地下水位，增加下游洪水风险，并通过减少河流环境的多样性来减少生物多样性。因此，改变我们的河流管理方式可以带来多重好处：减少火灾、减少洪水、增加生物多样性和生态系统服务。自2010年以来，洪泛区恢复理论开始转向恢复多个河道和增加湿润面积，以减缓水流速度，促进地下水补给。这被称为“0阶段”修复，因为它旨在使河流恢复到自然状态（人类干预前）。已经建立了几个地点来测试该方法的有效性，特别是2017年开始的美国俄勒冈州的南福克麦肯齐河恢复项目。到目前为止，河漫滩的三分之一已经恢复。建立了一项价值120万美元的数据收集方案，迄今已运行3年，其中包括监测陆地和水中的野生动物和植被，以评估修复工作相对于洪泛区未修复部分的有效性。该项目的成功最近在英国引发了类似的洪泛区恢复试验，特别是在萨默塞特郡波尔洛克谷的国民信托土地上。第0阶段恢复有许多潜在的好处，但直到现在还没有考虑到野火。然而，这在2020年9月至11月发生了巨大变化，当时一场大火（“假日农场大火”）席卷了南福克麦肯齐地区，在36小时内燃烧了60000公顷。大火直到2020年11月下旬才停止，但项目团队最近获准进入现场。最初的观察结果强烈表明，虽然其他地区遭受了严重的、均匀的烧伤，但洪泛区恢复后的地区却形成了多种多样的火灾马赛克，许多地区几乎没有受到火灾的损害。根据最近野火生态学的假设，除了降低整体烧伤严重程度外，恢复地区更多样化的火灾强度实际上可能对生物多样性有益，并进一步建立生态弹性。因此，假日农场火灾为研究野火和0阶段洪泛平原恢复之间相互作用的生态和环境影响提供了一个独特而有限的机会。项目现场，33%的洪泛区已经恢复，其余部分尚未改善，结合详细的基线数据和最近的大型火灾事件，有效地向我们展示了一个自然景观规模的实验。我们打算利用这个绝佳的机会来检验这两个假设，并对洪泛区的淡水和陆地生物多样性产生重要的新认识，以及在气候变化和野火风险增加的情况下管理洪泛区的实际解决方案。

Wildfires, already a major concern in all continents, are forecast to increase in frequency and intensity, impacting parts of the world not previously affected (including the UK under future climate change). Indeed, 2020 was a record year for wildfires globally, and they are estimated to have cost $13 billion in the USA alone (Reuters December 15, 2020). Poor river management practices have contributed to the increased threat of wildfires by drying floodplains, creating a tinderbox effect. For centuries, humans have modified rivers, typically converting multi-channelled rivers into single, deeper channels. This drains and disconnects floodplains, lowers water tables, increases downstream flood risk, and reduces biodiversity by reducing the variety of riverine environments. Changing our approach to river management can therefore have multiple benefits: reduce fires, reduce flooding and increase biodiversity and ecosystem services.Since 2010, floodplain restoration theory has begun to move towards reinstating multiple river channels and increasing wetted area to slow flow velocities and encourage groundwater recharge. This has become known as 'Stage 0' restoration because it aims to return rivers to their natural (pre-human intervention) state. Several sites have been set up to test the effectiveness of the approach, notably the South Fork McKenzie River restoration project in Oregon, USA, which started in 2017. One third of the floodplain has been restored to date. A $1.2 million data collection programme was established, running for 3 years so far, which includes monitoring of wildlife and vegetation, on the land and in the water, to assess the effectiveness of the restoration, relative to unrestored parts of the floodplain. The project's success has recently led to similar floodplain restoration trials in the UK, notably on National Trust land in Porlock Vale, Somerset.Stage 0 restoration has many potential benefits, but until now it has not even been considered in terms of wildfire. However, this changed dramatically in Sept-Nov 2020, when a major wildfire (the 'Holiday Farm Fire') swept through the South Fork McKenzie area, at its peak burning >60,000 ha in 36 hours. The fire only ceased in late Nov 2020, but limited access to the site has recently been granted to the project team. Initial observations strongly suggest that while other parts of the landscape suffered a severe, uniform burn, the restored areas of the floodplain resulted in a diverse fire mosaic, with many parts suffering little or no fire damage. As well as reduced overall burn severity, the more diverse fire intensity in the restored area may actually have biodiversity benefits and build further ecological resilience, according to recent hypotheses in wildfire ecology. The Holiday Farm Fire therefore provides a unique and time-limited opportunity to investigate the ecological and environmental effects of the interaction between wildfire and Stage 0 floodplain restoration. The project site, with 33% of the floodplain restored and the rest as yet unimproved, combined with the detailed baseline data available and a large, very recent fire event, effectively presents us with a natural landscape-scale experiment. We intend to use this amazing opportunity to test the two hypotheses, and to develop both important new understanding of freshwater and terrestrial biodiversity on floodplains, and practical solutions for managing floodplains under both climate change and increasing wildfire risk.