How is wildfire automatically a bigger threat with more trees? Is it because with more trees given the same quantity of water, the drier wood helps the fire spr

How is wildfire automatically a bigger threat with more trees? Is it because with more trees given the same quantity of water, the drier wood helps the fire spreads more quickly? Or perhaps the forest is more densely populated? But that doesn't increase the vulnerable area. Pardon my ignorance, I'd like to know more.