As a farmer, filing a schedule F, you are probably pushing the limits of usual and ordinary farm expenses but if the trees are off your own farm land and you can show proof of major farm building construction and repairs, and perhaps lumber sales, you are probably just fine. I personally know a rancher/farmer that sells ruff cut corral lumber (2X8's) off his farm as extra income that he cuts with his own mill. He also builds and sells cattle feeders. So, the bottom line is if it produces taxable income, yes.