Nate

So, I took a few remote sensing courses in college, loved it, and then didn't get to use it. I'm pretty rusty and am getting back into remote sensing with an ArcGIS student licence I have leftover from school. My question is can I, and if so HOW, calculate the number of trees in a plot using ArcGIS? Could I calculate volume based on canopy size? Would this be better tackled in ENVI? I'd like to try to use what I have though, especially since it's free and I can't afford ENVI. :-P