Trails most likely would not add any value to the property and the cost of creating such trails would probably not be a depreciable expense. I can't say if it would actually add to the cost basis or not though. However, it's possible (though I can't say for sure) that if you built and install things such as a bridge over a ravine or something of that nature, that would probably qualify as a land improvement that's depreciable over 15 years. But again, that's not something I'd commit to, when it comes to depreciable assets.
