Does a wildfire destroy an ecosystem?

Yes, a wildfire can destroy an ecosystem but generally only when the fire was highly intense and/or slow-moving. This is because soil sterilization occurs which means all soil fungi and bacteria are destroyed along with the amount of available nitrogen, impacting the nutrients needed for plants to survive.

What can typically happen is that these conditions prevent the return (or slow the return) of the original native species and robust non-native invasive species can take over. One example, specific to the northwest United States, is Scotch broom, a noxious weed whose seeds can live in soil for up to 60 years.