My suspicion is that the non-flying landowner will likely prevail in a court challenge in this case. It's his property, and his right to grow trees on it if he so chooses. Unless there's some easement or deed restriction in place already, I can't see how he could be prohibited from using his property as he sees fit. Why would anyone be required to let others use their property as an airstrip? Does that suck for the pilots using this strip? Yeah, it sure does, and I can entirely appreciate the problems that might cause. I just can't (personally) see many ways to prevent his actions legally.
However, I do wonder if an "adverse possession" type of law (if existing in that state) might allow for continued use of this portion of property. Although I'm not well versed in the specifics of this law, I know Colorado has an adverse possession statute that has resulted in some newsworthy court cases in the past few years. In essence, it appears that a property can be claimed by someone who has used it without contest by its legal owner under certain circumstances over a specific period of time (again, I'm not totally familiar with this issue, but there was a case making the media rounds here a couple of years ago... in that instance I believe an owner of an adjacent property had been utilizing a portion of the neighbor's property for some number of years, and this use had not been contested by the property's owner. As a result of this action, the neighbor was able to claim possession of this portion of the property in court when they wanted to use it later). You'll need a real estate attorney to sort out that kind of stuff though, and I'm clearly not qualified to give advice on this subject!
Alternatively, you could use this tool:
http://youtu.be/OW2UvW6xLP8