Maybe not "depend on", but "adapted to" ...

"Coast redwood are adapted to fire and other disturbance. Seeds germinate best on mineral soil as is exposed by flooding, fire, or wind throw for seed germination and establishment."

"The fire return interval in coast redwood forests varies drastically with latitude, microclimate and distance from the coast. In general, forests that are further north, closer to the coast, or located on mesic sites tend to burn less frequently."

From https://www.nps.gov/pore/learn/management/firemanagement_fir...

Sempervirens can reproduce without fire, but are healthier with a good fire now and again. My guess is that's one of the reasons the trees in big basin look sickly compared to the ones up north.

https://fireecology.springeropen.com/articles/10.1186/s42408...

Well I grew up in the redwoods up in Humboldt, it is generally far to wet up there for a forest fire even occur, and if they do it doesn't spread much.

I think flooding is a far more realistic, as that happens every winter.

It has gotten much warmer and sunnier in recent years because of climate change, so perhaps forest fires will start to be a thing.

Also they don't even drop seeds until they are like 200 years old-- with all the logging that has been done most redwoods aren't growing from seeds these days, but from cuttings & off of existing stumps/roots.