That reminded me (for some reason, not really sure why) of a reading about an interesting finding about the mycorrhizal fungi living in symbiosis with the roots of many plants. These help the plant by improving its water/mineral uptake, etc, and get their energy from leeching off the plant. I remember reading a couple of years ago though that some green plants actually take more nutrients of all kinds from the fungus. Many plants use the fungus (one fungus may be linked with several plants) as a way to steal nutrients from their neighboring plants. In temperate zones it isn't uncommon for a plant to take slightly more from the fungus than it gives, sometimes only durring certain phases of its growth cycle. In tropical rainforests it is rather common for some green plants (which are still fully capable of photosynthesis and could produce enough energy for themselves if they had to) to instead get over 90% of their energy from the fungi around their roots (which in turn steal from other plants). This is probably due in large part to the dense canopy reducing the amount of light availible.
(Of course, if the sun actually didn't rise for too long, the plants that have been mooching off of their neighbors would still suffer indirectly. I guess plants being fed by nature mana may make more sense)
I would usually think of farms in the forests as being more like orchards. (hmm...why isn't there an Orchard improvement?) (There is actually a theory that much of the Amazon rainforest were actually orchards. Most of the Amazon has some of the worlds worst soil, but a few places that have the most "wild" fruit and nut trees have some of the richest soil in the world, with lots of charcoal, pottery shards, and rare bacteria present. Planting trees is much more productive than later slash and burn agriculture, especially for a people that know nothing of metalworking. See 1491) However, there are also plenty of other crops (lots of native American crops, many of which are far more nutricious than crops more commonly grown now, but typically with lower yields) that would grow well in the shade of larger trees. The only thing that doesn't make sense about elvish farms in the forest is that they use wheat, corn, or rice.
