Soil Burn Severities Evaluation Using Micromorphology and Morphometry Traits After a Prescribed Burn in a Managed Forest

Prescribed burn is a tool that must imply low soil burn severity (SBS) levels; however, a wide range of soil impacts have been demonstrated because of the influence of very variable factors. The effects on biological, physical, and chemical soil properties are well reported in numerous studies; nonetheless, there are still questions about the effect of prescribed burns on soils at the micro-scale. As a result, an analysis of the link between micromorphological features and SBS does not currently exist. Thus, the main aim of the present study is to perform a micro-scale evaluation for complementing the SBS visual examination after prescribed burning in a managed pine forest in western Mexico. Morphometry and micromorphology analyses of mineral soil revealed that at low SBS levels, only the soil structure in the first centimeter is affected by prescribed burns. While at high SBS, the prescribed burn affected the first 2 cm, showing soil structure disturbance, ash filling porous, and soil aggregates getting reddish. Therefore, immediate actions have to be made by land managers after applying prescribed burns before the first rain to prevent post-fire surface soil erosion, particularly in bare soil patches where the burned aggregates are more susceptible to rain splash and runoff.