Think about it. What things are necessary to create fire? It's three things actually... fuel, oxygen and heat. The fuel part is interesting, as it occurs to me that all fuel for fire on Earth comes from the bodies of living things. All of it. Wood in the stove or fireplace, trees and grassland with wildfires. Even the gasoline burning in your car's engine is refined from crude oil, which is made up of the bodies of ancient zooplankton. Without life, there is no fire. Rain yes, wind yes, fire... not without life.
What about the oxygen? Again it's LIFE that brought it forth. The planet did not come with a ready supply. In fact up until about 2.5 billion years ago there was almost no oxygen in the early atmosphere of Earth. Until, a simple bacteria called 'cyanobacteria' showed up.
Cyanobacteria (above: NASA photo) is believed to be the first life form to make oxygen through the process of photosynthesis. So successful were they, that they filled the atmosphere with oxygen. That oxygen, mixed with fuel and a heat source like lightning, creates the chemical reaction known as fire. Flames are a bi-product of this chemical reaction.
You can still find this early bacteria today. These mounds in the shallows of oceans are piles and piles and piles of cyanobacteria bodies, piled up in mounds that form these structures called 'stromatolites.' (below: NASA photo)
For the forest, although it can be destructive at first, many species of plants, grasses and trees, require the heat of wildfire to germinate and release new seeds. Wildfire also clears dense forest and undergrowth. Clearing the way for sunshine to reach the new growth. Continuing the process of photosynthesis, new plant life, more fuel, and eventually the return of life's cycle of fire.