Instituto Dom Luiz, Universidade de Lisboa, 1749-016, Lisboa, Portugal.
Institut für Landschaftsökologie, Westfälische Wilhelms (WWU) - Universität Münster, 48149, Münster, Germany.
J Environ Manage. 2021 Oct 15;296:113098. doi: 10.1016/j.jenvman.2021.113098. Epub 2021 Jul 2.
The Brazilian savanna (Cerrado) is considered the most floristically diverse savanna in the world, home to more than seven thousand species. The region is a mosaic of savannas, grasslands and forests whose unique biophysical and landscape attributes are on the basis of a recent ecoregional map, paving the way to improved region-based strategies for land management actions. However, as a fire-prone ecosystem, Cerrado owes much of its distribution and ecological properties to the fire regime and contributes to an important parcel of South America burned area. Accordingly, any attempt to use ecoregion geography as a guide for management strategies should take fire into account, as an essential variable. The main aim of this study is to complement the ecoregional map of the Cerrado with information related to the fire component. Using remotely sensed information, we identify patterns and trends of fire frequency, intensity, seasonality, extent and scar size, and combine this information for each ecoregion, relying on a simple classification that summarizes the main fire characteristics over the last two decades. Results show a marked north-south fire activity gradient, with increased contributions from MATOPIBA, the latest agricultural frontier. Five ecoregions alone account for two thirds of yearly burned area. More intense fires are found in the Arc of Deforestation and eastern ecoregions, while ecoregions in MATOPIBA display decreasing fire intensity. An innovative analysis of fire scars stratified by size class shows that infrequent large fires are responsible for the majority of burned area. These large fires display positive trends over many ecoregions, whereas smaller fires, albeit more frequent, have been decreasing in number. The final fire classification scheme shows well defined spatially-aggregated groups, where trends are found to be the key factor to evaluate fire within their regional contexts. Results presented here provide new insights to improve fire management strategies under a changing climate.
巴西稀树草原（Cerrado）被认为是世界上植物种类最多样化的稀树草原，拥有超过 7000 种物种。该地区是稀树草原、草原和森林的马赛克，其独特的生物物理和景观特征是基于最近的生态区域地图，为基于区域的土地管理行动策略提供了依据。然而，作为一个容易发生火灾的生态系统，Cerrado 的分布和生态特性在很大程度上归因于火灾发生的频率和强度，它是南美洲燃烧面积的重要组成部分。因此，任何试图将生态区域地理作为管理策略的指南的尝试都应该考虑到火灾，将其作为一个重要的变量。本研究的主要目的是用与火灾相关的信息来补充 Cerrado 的生态区域地图。我们使用遥感信息来识别火灾发生频率、强度、季节性、范围和疤痕大小的模式和趋势，并结合每个生态区域的信息，依靠一个简单的分类来概括过去二十年的主要火灾特征。结果显示，火灾活动呈现出明显的南北梯度，MATOPIBA（最新的农业前沿）的贡献越来越大。仅五个生态区域就占每年燃烧面积的三分之二。Arc of Deforestation 和东部生态区域的火灾更为剧烈，而 MATOPIBA 的生态区域的火灾强度则在下降。对大小分类的火灾疤痕进行的创新分析表明，不频繁的大火是造成大部分燃烧面积的原因。在许多生态区域，这些大火呈现出积极的趋势，而尽管更频繁的小火灾数量却在减少。最终的火灾分类方案显示出空间上聚集的明确分组，其中趋势是在其区域背景下评估火灾的关键因素。这里呈现的结果为在气候变化下改善火灾管理策略提供了新的思路。
