I am a township clerk and have had to deal with some fence disputes. There is some gray area that only lawyers and a judge can settle but here are some certain things. Two Supreme Court rulings, the most recent in 2001, upheld that Iowa is a shared fence state. This means that you are responsible for your half of a fence,EVEN IF YOU HAVE NO LIVESTOCK.That's as far as the court ruled. The right hand rule USUALLY applies. There are many left hand fences made for conveniences of one sort or another. These usually go way back when everyone in the country was a farmer. If you buy some land, you should always talk to your neighbors and determine whose fence is whose and if it ISN'T right hand, get it recorded at the courthouse. Township trustees only determine if a proper fence is built,NOT whose fence is whose, or if a fence is in the right place. That is a court matter. I am not aware of any law which permits your neighbor to cut trees on your side of the fence in order to repair his fence. In the same vein, if a tree on your property falls on the neighbor's fence, I believe you are responsible for fixing that fence. That's just common sense and being a good neighbor.Also, you can't do anything on your property that adversely affects your neighbor's land. An example would be a tile line coming out in the fence line which creates a wet spot on your neighbor's land.I believe this also includes trees on your property growing over a fence and shading your neighbor's crops. Keep your tree plantings a few feet away from your property line and save problems later. Just common sense. A fence built a few feet off the line is common, and you will have to decide if it's worth fighting over. A judge would decide if cost of a survey would be shared. I wouldn't pay for a survey and assume the cost will be split. Some of the problems in this thread can only be settled in court. But don't think that because you have no livestock, you don't have to maintain your fence. If your neighbors cattle get out thru your fence, you can be held liable for damages. That's also why farmers carry huge liability insurance policies. If their cattle get out and cause a car accident, they won't lose the farm in a lawsuit. If you own propery in the country, and cattle could conceivably get on a road thru your fence, you would be wise to have such a policy too.