Victoria Tall Eucalypt Forest Plot Network: Victorian Central highlands fire refuges project: Fire severity predictions and maps for the O’shannassy and Maroonndah Water Catchments, Victoria, Australia, 2002-2009

We used a case study in an Australian wet montane forest to establish how predictive fire simulation models can be interpreted as management tools to identify potential fire refuges. We tested the ability of a topographically based fire prediction model developed by Mackey et al (2002) in the O’Shannassy and Maroondah water catchments, NE north-east of Melbourne, Australia, with fire severity data collected following a large wildfire in 2009 in the same area. We derived our fire severity data from a larger map created by the Department of Sustainability and Environment (2009), using SPOT satellite imagery and the normalised-burnt ratio. We examined the relationship between the probability of fire refuge occurrence as predicted by an existing fire refuge model and fire severity experienced during a large wildfire. We also examined the extent to which local fire severity was influenced by fire severity in the surrounding landscape. We used a combination of statistical approaches including generalised linear modelling, variogram analysis and receiver operating characteristics and area under the curve analysis (ROC AUC). We found that the amount of unburnt habitat and the factors influencing the retention and location of fire refuges varied with fire conditions. Under extreme fire conditions, the distribution of fire refuges was limited to only extremely sheltered, fire-resistant regions of the landscape. During extreme fire conditions, fire severity patterns were largely determined by stochastic factors that could not be predicted by the model. When fire conditions were moderate, physical landscape properties appeared to mediate fire severity distribution. Our study demonstrates that land managers can employ predictive landscape fire models to identify the broader climatic and spatial domain within which fire refuges are likely to be present. It is essential that within these envelopes, forest is protected from logging, roads and other developments so that the ecological processes related to the establishment and subsequent use of fire refuges are maintained. Department of Sustainability and Environment (2009) Remote sensing guideline for assessing landscape-scale fire severity in Victoria’s forest estate. Unpublished technical manual., Department of Sustainability and Environment, Melbourne. Mackey, B., D. Lindenmayer, M. Gill, M. McCarthy, and J. Lindesay. 2002. Wildlife, Fire and Future Climate: A Forest Ecosystem Analysis. CSIRO publishing, Collingwood.

本研究以澳大利亚湿润山地森林为案例，旨在明确火灾预测模拟模型可作为管理工具，用于识别潜在火灾避难所（fire refuge）。

本研究选取澳大利亚墨尔本东北部的奥沙纳西（O’Shannassy）与马隆达（Maroondah）集水区为研究区域，采用2009年该区域大型野火后采集的火灾烈度数据，测试了Mackey等人（2002）开发的基于地形的火灾预测模型的性能。

本研究的火灾烈度数据源自可持续发展与环境部（2009）制作的全域地图，该地图基于SPOT卫星影像（SPOT satellite imagery）与归一化燃烧比（normalised-burnt ratio）生成。

本研究探究了现有火灾避难所模型预测的火灾避难所出现概率，与大型野火期间实际火灾烈度之间的关联；同时分析了周边景观火灾烈度对局地火灾烈度的影响程度。

本研究采用了多种统计分析方法，包括广义线性模型（generalised linear modelling）、变异函数分析（variogram analysis）以及受试者工作特征曲线下面积分析（ROC AUC）。

研究结果表明，未燃生境面积以及影响火灾避难所留存与分布的相关因子，均随火灾情境的变化而存在差异。极端火灾情境下，火灾避难所的分布仅局限于景观中极隐蔽且耐火的区域；此时火灾烈度的空间格局主要由模型无法预测的随机因子决定。当火灾情境为中等强度时，景观物理属性似乎可调节火灾烈度的空间分布。

本研究证明，土地管理者可借助景观火灾预测模型，确定火灾避难所大概率存在的宽泛气候与空间范围。在此范围内，必须对森林实施保护，避免伐木、道路建设及其他开发活动，以维持与火灾避难所的建立及后续利用相关的生态过程。

参考文献：
1. 可持续发展与环境部. 2009. 评估维多利亚州森林景观尺度火灾烈度的遥感指南. 未公开技术手册. 墨尔本：可持续发展与环境部.
2. Mackey B, Lindenmayer D, Gill M, McCarthy M, Lindesay J. 2002. 野生动物、火灾与未来气候：森林生态系统分析. 科林伍德：CSIRO出版社.