Mabye not trees, but what about mines? Think about it plz, like say there would a 3 diffrent types of mines: small, med., large - and each of the had unlimited resources, but say only 2 people can gather ore in a small mine, 4 in medium and 6 in large. It would provide endless resources but will still make large mines a desirable location to be controlled by your forces - more income per minute. Large mines would be locations to be fought over and would provide the controlling side with more resource. Because I remember WarCraft straight away - those fields full of tree trunks, makes you feel sad... I dunno guys, just think about it. - some examples with endless resources: Cossaks, Empire Earth 2, Caesar, Stronghold. Or maybe you would like to consider adding building that generate endless income like hmm.....market, special sort of plantation, fishing etc. By the way a good game too look at for regenerating trees "Knights and Merchants" the game isn't too good, but the aspect of regenerating trees is interesting.