Fire-driven disruptions of global soil biochemical relationships.

Fires alter the stability of organic matter and promote soil erosion which threatens the fundamental coupling of soil biogeochemical cycles. Yet, how soil biogeochemistry and its environmental drivers respond to fire remain virtually unknown globally. Here, we integrate experimental observations and random forest model, and reveal significant divergence in the responses of soil biogeochemical attributes to fire, including soil carbon (C), nitrogen (N), and phosphorus (P) contents worldwide. Fire generally decreases soil C, has non-significant impacts on total N, while it increases the contents of inorganic N and P, with some effects persisting for decades. The impacts of fire are most strongly negative in cold climates, conifer forests, and under wildfires with high intensity and frequency. Our work provides evidence that fire decouples soil biogeochemistry globally and helps to identify high-priority ecosystems where critical components of soil biogeochemistry are especially unbalanced by fire, which is fundamental for the management of ecosystems in a world subjected to more severe, recurrent, and further-reaching wildfires.