If you do want to make a forest of those its possible but I suggest you use some sort of adaptive degradation, to do this you simply find some way to reduce the number of polygons and make multiple models staring with your best one and ending with the most poly reduced one, then make it choose a model to draw depending on the distance from the camera, so when you look at one close to you it looks good but one off in the distance is a chopped up mess but hope the player cant tell from said distance

i've been able to make a pine tree model with 12 polys, you just have to learn to be creative with your alpha textures and polygons. as for the type of tree you're trying to make, it could be done with about 400-800 polys porbably, i just don't see how you got 6396... try to optimize the cylinders a bit more i guess. another trick is to make the branches out of 1-3 planes with a well thoughtout/placed branch texture and use that for your branches. the techniques for you to use kind of vary with the models use and viewing angle.

edit: damn server lag....