While a fence built of “modern” materials such as barbed wire, chain link or lumber is fast to put up for the long haul you might want to consider a traditional hedgerow. This involves living material that can be as secure as any other fence that you could build with the advantage of lasting forever if maintained as well as providing habitat for small wildlife.
Too start you need small diameter growth saplings already growing in the line you want the hedgerow. Some plants that work well at least in the mid-west are hazel and osage orange. Something like willow you can do with cuttings that will root.
If you start while the plants are young you can weave them together into a nice looking fence, this works particularly well with willow. Generally you can just cut willow branches and stick them in the ground and weave them into the shape you want.
In the case of a European style hedgerow you cut the small trees almost all the way through and lay it over. A strip of bark is left that keeps it growing which makes the hedgerow thicker over time with the new growth. I’ve planted a row of hazels along the road and hope to do this in the future.
In the case of Osage Orange if you plant them thick enough you can have a fence that is “horse-high, bull-strong, and hog-tight” in 4-5 years. You can plant seedlings 1′ apart or gather up a bunch of the fruit in the fall. To plant the fruit you need to mash it up into a slurry in the spring and dig a small trench where you want the fence a few inches deep and pour the Osage Orange slurry into this trench and cover it up. This will give you a very dense planting for nothing if you can find a mature tree to gather fruit from.
A living fence or hedgerow does take some advanced planting, but it can be in service for hundreds of years and be done for very little money outlay. Give it some thought before you clear your land of bushy growth, you might find the problem is the solution. Check out the videos below to see it being done.