How Does Fire Affect Forest And Tundra Soil?
Changes in soil nutrients and temperature are among the first environmental changes triggered by fire. When plants and dead vegetation are burned, the minerals trapped in their leaves, stems, and wood are released and returned to the environment in the form of gases and ash. The ashes left by fire are rich in calcium, phosphorus, potassium, and other minerals. These minerals, previously trapped in organic material, enrich the soil. Fire also helps enrich the soil indirectly by affecting the depths of the permafrost and active layers. Few fires directly thaw the permafrost layer. It is usually insulated from the heat of fire by the active layer, a thick mat of organic material and soil. But fire indirectly thaws the permafrost by burning some of the organic mat, blackening the soil surface, and reducing the insulating qualities of the active layer. These changes cause the soil to absorb more of the sun’s heat. The depth of the active layer increases as the permafrost layer shrinks. In i
