Forest fires have increased in extent and intensity in the Mediterranean area in recent years, threatening forest ecosystems through loss of vegetation, changes in soil properties, and increased soil erosion rates, particularly in severely burned areas. However, establishing the relationships between burn severity and soil properties that determine infiltration remain challenging. Determining where soil burn severity evaluation should be carried out is critical for planning urgent measures to mitigate post-fire soil erosion. Although previous research has indicated that spectral indices are suitable for assessing fire severity, most of the classifications used consider combined effects in vegetation and soil. Moreover, the relationship between spectral indices and soil burn severity has scarcely been explored until now. We selected three pine stands in Spain for study immediately after being burned by wildfires. We analyzed various soil properties (soil saturated hydraulic conductivity, mean weight diameter of soil aggregates, and soil organic carbon) in relation to six levels of soil burn severity in all three stands. In addition, we established 25 field plots in the burned areas. We computed ten spectral indices for each plot by using Sentinel-2 satellite data. The soil burn severity categories indicated the degree of degradation of important soil properties related to soil erosion susceptibility. Of the spectral indices considered, the relativized burn ratio (RBR) was the best predictor of cumulative infiltration and mean weight diameter of soil aggregates. The differenced mid-infrared bispectral index (dMIRBI) was most closely correlated with soil organic carbon content. The findings demonstrate the potential applicability of remote sensing to determining changes in soil properties after fire.

中文翻译：

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探索使用光谱指数评估西班牙冠火影响的松林土壤性质的变化

近年来，地中海地区的森林大火程度和强度不断增加，特别是在严重烧毁的地区，由于植被丧失，土壤特性变化和土壤侵蚀率上升，威胁着森林生态系统。然而，在烧伤严重程度与决定渗透的土壤性质之间建立关系仍然具有挑战性。确定应在何处进行土壤燃烧严重性评估，对于规划缓解火灾后土壤侵蚀的紧急措施至关重要。尽管先前的研究表明光谱指数适合评估火灾的严重性，但大多数使用的分类方法都考虑了对植被和土壤的综合影响。此外，到目前为止，几乎没有探索光谱指数与土壤燃烧严重性之间的关系。在野火烧毁后，我们立即在西班牙选择了三个松林进行研究。我们分析了所有三个林分中与土壤烧伤严重程度的六个级别相关的各种土壤特性（土壤饱和导水率，土壤团聚体的平均重量直径和土壤有机碳）。此外，我们在烧毁地区建立了25个田地。我们使用Sentinel-2卫星数据为每个图计算了十个光谱指数。土壤烧伤严重性类别表明与土壤侵蚀敏感性相关的重要土壤特性的退化程度。在考虑的光谱指数中，相对燃烧率（RBR）是累积渗透和土壤团聚体平均直径的最佳预测指标。差异的中红外双光谱指数（dMIRBI）与土壤有机碳含量关系最密切。这些发现证明了遥感在确定火灾后土壤性质变化方面的潜在适用性。