Tree Farm (SMAC)

is a base facility in Sid Meier's Alpha Centauri.
==Strategy==
Coming two techs after Gene Splicing and the Research Hospital comes the Tree Farm, and the lifting of the energy restrictions. Just one tech before, your mineral restriction was removed, and all your 2-mineral crawlers moved off the forests and onto the mine/road/rocky tiles you cunningly had just prepared with this tech in mind, and doubled their production to 4 minerals/turn. As a result, you suddenly hear *pop* and you know its time to start with the Tree Farms.
The main reason to build these facilities is not for the extra Econ or Psych. What we are after is the extra nutrient from our forests, (they should be everywhere by now) which will give us the +2 nutrients/turn we need for a popboom. If we're playing a faction that needs a Golden Age to popboom, then view the +50% Psych as the game telling you to get into the Social Engineering screen and push that central slider to the right.
Like Research Hospitals, they boost income by 50%, in this case for Psych and Econ, the other two of the three energy categories, and in the same way they cover their own costs, as long as the base is producing a base 12 energy after inefficiency, with anything else being profit. Tree Farms, however, are the one facility where I'm inclined to ignore the maths. The extra nutrients translate into extra growth, which is always good - see my comments on Children's Creches. If you want to count every last ec though, then I'd say that the only bases that are really too small to build a Tree Farm are any bases undersize 4 which are not directly working either at least 2 forested rivers, or at least two forests under Free Market.
The "hidden" effects of Tree Farms are also worth considering. Each Tree Farm built increases the number of "clean minerals" for all your bases by one, as long as it was built after the first fungal *pop* and also reduces the Ecodamage at that base caused by terraforming within the base radius.
There's only two instances where I would consider not building Tree Farms as soon as they became available. Either if I was still pumping units for an expansion or a war, or if I was running towards a future "All Specialists" strategy, which was using only advanced terraforming instead of any forests.