Would you believe that the Sahara desert was a tree infested savana at one time, long ago. And then man came and cut down all the trees (and never re-planted). And the Spanish almost did the same thing to Spain as they cut down the trees to build ships! Again, with no re-planting. Without trees to cover the land and capture the water then the land dries out and becomes arid or even desert! Sad! But your oasis is phenomenal!