well there was a lot of acacia and oaks, but I chopped them down and left only the pine trees since those are the only ones that I could not grow. I reforested in Acacia, and had just started to grow oak trees after getting the acorns from the trader.
The whole center portions of the oasis was filled with trees, and a zillion (well a lot) of cactus flowers and silkweed. These picture skews the perceived ratio of pine to the others.