Abstract Severe fires in tropical savanna systems are recognised as incurring significant impacts on a variety of ecological attributes, including woody vegetation structure and greenhouse gas emissions. However, knowledge of the frequency and extent of severe fires is restricted given challenges associated with the development of reliable remotely sensed mapping procedures. This study takes advantage of three wildfires, 900–5300 km2 in extent, containing very severely affected areas, occurring in semi-evergreen, eucalypt-dominated, tropical Australian savanna, which resulted in significant areas of complete canopy scorch, very significant tree stem mortality (24–55%), and associated loss of living above ground biomass (47–69%) at respective sites. Although increased map scale is generally considered to improve the reliability of fire severity mapping, our analysis found > 90% agreement between Landsat and MODIS-derived burnt area mapping, and > 80% for binary (severe vs. non-severe) fire severity mapping. Mapping of internal fire (unburnt) patchiness was enhanced with finer resolution Landsat imagery, but the much longer orbital return cycle precluded its use at two of the three sites given extended cloudy conditions. Application of an automated MODIS-derived fire severity mapping algorithm (overall reliability in 2015 = 75%) calibrated for generalised north Australian savanna conditions, suggests that 15% and 12% of Australia's 1.3 M km2 tropical savannas region were burnt by severe fires in 2015 and 2016, respectively. The study illustrates the potential for MODIS-derived fire severity mapping, the impacts of very severe fires on stand structure, and ongoing challenges associated with deriving reliable fire severity mapping products in Australian savanna systems.

中文翻译：

---

澳大利亚北部热带稀树草原中卫星衍生的火灾严重程度绘图技术的比较和验证：极端火灾和树干死亡率

摘要 热带稀树草原系统中的严重火灾被认为会对各种生态属性产生重大影响，包括木本植被结构和温室气体排放。然而，鉴于与开发可靠的遥感测绘程序相关的挑战，对严重火灾的频率和范围的了解是有限的。本研究利用了三场野火，范围为 900-5300 平方公里，包含受灾非常严重的地区，发生在半常绿、桉树为主的热带澳大利亚热带稀树草原，导致大面积的冠层完全烧焦，非常显着的树干死亡(24–55%)，以及相关地点的地上生物量损失 (47–69%)。尽管通常认为增加地图比例可以提高火灾严重程度制图的可靠性，但我们的分析发现，Landsat 和 MODIS 衍生的燃烧面积制图之间的一致性 > 90%，而二元（严重与非严重）火灾严重性映射之间的一致性 > 80% . 更高分辨率的 Landsat 图像增强了内部火灾（未燃烧）斑块的映射，但由于长期多云条件，更长的轨道返回周期使其无法在三个站点中的两个站点使用。应用自动 MODIS 衍生的火灾严重性映射算法（2015 年的总体可靠性 = 75%）针对广义的澳大利亚北部稀树草原条件进行校准，表明 2015 年澳大利亚 130 万平方公里的热带稀树草原地区有 15% 和 12% 被严重火灾烧毁和 2016 年，分别。