Since its not in the manual......

[Corentor]

maybe someone can help me with this.

How big a penalty to bioharvesting is "Barren".

[doradus]

Good question. That info's not in the "Strategy Guide" either

[Tuberski]

Try the Galactic Encyclopedia, I haven't started a game yet, but that would be my guess.

ACK!

[Goncyn]

"Barren" means that the average fertility of regions on the planet is Barren. That is, if it's a size 6 planet, you might have 2 Fertile regions, 2 Barren regions, and 2 Hostile regions. So you can grow a decent amount of food in those two Fertile regions, but on average the planet is bad for food.

In case you didn't understand the above, it's not a penalty, it's a summary of the quality of the planet's regions for the purpose of Bioharvesting DEAs.