http://pastebin.com/09kkKAyr

Agricraft doesn't do any biome decorating.

so, the problem is from another mod that conflict with agri but it's not agri..mhm.. I'm sorry to have posted the issue here then :c
but, since I'm here, could you kindly help to tell me what mod seems to give problems with biome decorating/tesselation?

It's not tessellation,

first does it happen every time you make a new world? Second if you remove agricraft then it doesn't happen anymore?
If this is the case, there must be a mod that adds world gen if agricraft is enabled.
Also you could try to disable the agricraft greenhouses, but I don't think that will fix it.

I made some test, if I disable the greenhouses in the config file the crash still occur; if I remove the world tryng to recreating it, the crash still occur, even with the greenhouses disabled in the config file. If I don't add agricraft the crash doesn't occur :l I'm not sayng is your mod fault, I really would like to figure out which mod is that create problems to yours, I would even contact other author if I would be aware of which one could be the responsable