That's an interesting concept. But most native species don't do well indoors. Each race you're competing in though can have varying surrounding flora and this can contribute to varying performance in my opinion. I don't think varying fauna will have any impact though. Unless they get in the way of your bike... :-)

Quite frankly... I don't think the various pollens and toxins of the varying surrounding flora will have as much impact as one's normal training emphasis on aerobic functional threshold power... so it's probably not worth the effort to mimic this environment in training.