60%. Though our cores were by necessity taken from areas without smouldering, and after the flaming surface fire had been extinguished, smouldering was still underway when these samples were collected. In further lab experiments Benscoter et al. (2011) achieved successful peat combustion at moisture contents as high as 295% and observed smouldering continuing at higher moisture contents than those required for ignition. Both our and Benscoter et al.’s (2011) results therefore have implications for forecasting the selleck chemical potential maximum spread of smouldering wildfires. It is important that ignition and combustion limits are explored in greater detail
as they appear to be highly sensitive to fuel structure, fuel moisture and ignition mechanisms. Smouldering appeared to have occurred preferentially around the bases of trees and to have followed the root network, meeting those from the adjacent plants, thus propagating along the line of trees. Whether this was a result of peat being drier due to mounding from ploughing or due to the presence of the trees themselves was unclear as there was little peat left around tree bases leaving no Tyrosine Kinase Inhibitor Library or little evidence of the original micro-topography. However, a number of isolated trees on the
moorland area outside the forest had significant peat consumption around their bases matching the observations of Miyanishi and Johnson (2002). Our results suggest that it is important to investigate the extent to which plantation forestry on peat
soils, and associated ploughing, draining and ridging prior to planting, leads to peat desiccation Cediranib (AZD2171) and increased peat fire hazard. Smouldering was still occurring in isolated locations at the perimeter of the fire 33 days after the initial surface fire despite a number of days with rain. The fire spread was primarily through the peat and the propagation front formed a cavity beneath the damp moss/duff layer undercutting it by up to a metre. The heat produced by smouldering dried out the overlying material which subsequently ignited and burnt via smouldering or flaming combustion. This produced a pattern of fire spread characterised by gradual extension of the smouldering front below the duff, moss and litter followed by sudden ignitions and collapses of this surface material. This observed spread pattern compares favourably with changes in fuel moisture indices during and after the fire (Fig. 2). An initial period of high fire risk with conditions suitable for the spread of both surface flaming and subsurface smouldering combustion (high FFMC and high DC, Fig. 2) gave way to low FFMC (low fire danger) at the time of our visit. The DC however remained high, suggesting smouldering could continue, due to the long lag-time of this moisture code and the need for more substantial amounts of precipitation to re-wet subsurface fuel layers.