Prescribed burning reshapes the relationship between soil chemical properties and understory plant biodiversity

Fire can influence plant diversity directly by damaging or killing individuals or indirectly by changing soil properties. However, the impacts of prescribed burning on biodiversity and the relationship between soil and biodiversity in northeast China remain poorly understood. In this study, we explored the impact of low-intensity prescribed burning on temperate forest ecosystems in northeast China by investigating changes in post-fire plant biodiversity and soil properties and characterising the relationship between these variables. Contrary to previous studies, the results showed that prescribed burning in Pinus koraiensis plantations did not increase understory biodiversity. In contrast, it resulted in a significant decrease in biodiversity over the three-year period. Legumes (especially Lespedeza bicolor) were the understory species that benefitted the most from the fire. Burning changed the connection between soil and plant diversity. After burning, soil organic C overtook nitrate as the main driver of plant biodiversity. Our findings showed that prescribed burning alters soil chemical properties, particularly soil organic C, thus affecting the understory plant composition and biodiversity.