School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.
Biodiversity, Ecology and Conservation Group, International Institute for Applied Systems Analysis, Vienna, Austria.
Sci Rep. 2024 Feb 27;14(1):4815. doi: 10.1038/s41598-024-55322-z.
The increasing frequency and severity of UK wildfires, attributed in part to the effects of climate change, highlights the critical role of fuel moisture content (FMC) of live and dead vegetation in shaping wildfire behaviour. However, current models used to assess wildfire danger do not perform well in shrub-type fuels such as Calluna vulgaris, requiring in part an improved understanding of fuel moisture dynamics on diurnal and seasonal scales. To this end, 554 samples of upper live Calluna canopy, live Calluna stems, upper dead Calluna canopy, dead Calluna stems, moss, litter and organic layer (top 5 cm of organic material above mineral soil) were sampled hourly between 10:00 and 18:00 on seven days from March-August. Using a novel statistical method for investigating diurnal patterns, we found distinctive diurnal and seasonal trends in FMC for all fuel layers. Notably, significant diurnal patterns were evident in dead Calluna across nearly all sampled months, while diurnal trends in live Calluna canopy were pronounced in March, June, and August, coinciding with the peak occurrence of UK wildfires. In addition, the moisture content of moss and litter was found to fluctuate above and below their relative ignition thresholds throughout the day on some sampling days. These findings underscore the impact of diurnal FMC variations on wildfire danger during early spring and late summer in Calluna dominated peatlands and the need to consider such fluctuations in management and fire suppression strategies.
英国野火的发生频率和严重程度不断增加，部分原因是气候变化的影响，这凸显了可燃物水分含量（FMC）对塑造野火行为的关键作用。然而，目前用于评估野火危险的模型在诸如石南属灌木等灌木型燃料中的表现并不理想，这部分需要更好地了解日变化和季节变化尺度上的燃料水分动态。为此，在 3 月至 8 月的 7 天内，每天从 10:00 到 18:00 每小时对 554 个上层活体石南冠层、活体石南茎、上层死石南冠层、死石南茎、苔藓、凋落物和有机层（矿质土壤上方 5 厘米的有机物质）进行采样。使用一种新的统计方法来研究日变化模式，我们发现所有燃料层的 FMC 都存在明显的日变化和季节变化趋势。值得注意的是，在几乎所有采样月份，死石南都存在显著的日变化模式，而活体石南冠层的日变化趋势在 3 月、6 月和 8 月较为明显，这与英国野火的高发期相吻合。此外，在某些采样日，苔藓和凋落物的水分含量全天都在其相对点火阈值上下波动。这些发现强调了日变化 FMC 变化对石南主导泥炭地早春和夏末野火危险的影响，需要在管理和火灾抑制策略中考虑到这种波动。
