Tall Fir Trees For Cycles
I can't see the fir needles?
This is done as viewport optimization method. The needle meshes are quite dense and slow everything down once you start duplicating the trees, so they're turned off in the viewport. Once you start rendering, they'll show up just fine.
Why targa and EXR textures?
There's currently a bug (T79836) that slows down rendering when using large textures in jpg, png and tif formats. The way to get around this is by using targas and EXR's.
How do I know these models are for me?
Check out a free sample version with lower resolution textures here to get a feel for the quality of the trees and decide for yourself. :)