This actually is a bunch of hardcore staff that changing biome behavior to encourage player building multi base on more biome for different purpose and exploration of bigger area to find a better place to live. To let the player don't just live in a plain or a high Mountain with his high security base.
Hardcore mining:
Increase ore occur in hill biome and decrease in other to encourage building mining base in hill.
Hardcore farming:
Increase crop grow rate in plains and decrease in others to encourage farming on plains. (or different crop type with different biome?)
Hardcore animal:
Increase animal baby grow rate in plains.
Hardcore tree:
Increase tree Saplings grow rate in forest to let building lumberjack base.
Spruce Tree wood should burn longer then oak to encourage logging in Taiga and more like the one in real life.
Hardcore Swamp fishing:
Just increase fishing rate in swampland.
Hardcore Hunting:
Increase hostile mobs spawn rate on Desert to encourage hunting(or mob farming?) on desert.
This is not meaning you must mining in hill biome and farming in plains, but you work it on a suitable area will increase your production rate 10 times.
Rail material should also change to iron nuggets for building railway system connecting all bases. (As currently, you dig out whole chunk that is not enough iron to make rail pass through that chunk).