As the title says, how do I decrease density of trees? After playing a bit on a server with "OpenTerrainGenerator + BiomeBundle", I find BOPs tree density too much. I saw a wiki page on biome overriding, but was unable to find anything on how to edit the trees in a biome. Any help on this would be appreciated. Thanks!

The Github issue tracker is not really for support questions.
You can try using Biome O' Plenty's Discord channel instead!
Discord BoP channel invite: https://discord.gg/0loJvLMgvZi0q596