Every time I load a new world with Natura/Mantle, I get this error. I don't know if this is some captabilty glitch with another mod, but I know its Natura. Someone else on Minecraftfroums was having the same issue.
https://www.dropbox.com/s/dgd5dc1d3j44qxp/crash-2014-09-30_20.12.46-server.txt?dl=0

Yea, doesn't work. SOmething about a block or something.

this looks like an issue w/ plantmegapack