Clumps of gas producing fungus, bits of rock and soil. Farmed / mined by Haflings. Most forests are smaller than a square mile and support a few halfling families.
The mined gas is lighter than air and provides most of the gas used in zeppelins. The forests also produce various edible plants, fungus and farmers often raise animals as well. Some fungi can be dried and used for construction and as fuel. Others can be fermented into AEther.