How do you change Landscape Material with volumes?

So I am making a landscape material which textures based on slope angles but one thing I want to do is be able to set up biomes quickly and my idea is to use triggers / volumes that change the material.

So if the landscape has no volume it is normal grassland, if the landscape has a bubble / volume on it called forest it changes the textures in the material to forest textures, if the volume is called swamp it changes the materials to swampy textures etc etc.

I hope I am explaining this correctly.

You can use Material Parameter Collection and several sphere mask or box mask material expressions for that.