Here’s an idea I had recently: a “hybrid living fence.” The problem with dead fences is largely the fence post, not the wire product. Thoroughly galvanized (Class III) wire products last for a half-century and probably longer, and when they wear out, they are easily replaced. There are thousands of old wire fences where I live in humid Indiana and some probably hail from the 1930s or perhaps earlier. And this old wire certainly has inferior galvanizing compared to quality fence of today. The problem is the posts!
It doesn’t matter if posts are treated wood or steel; they rot/rust off at the ground and then need to be replaced, sometimes in only 15 years. Experimental people, like Andre Voisin, used concrete fence posts back in the 1940s and 1950s. They never really caught on, mostly because they were probably very expensive and labor intensive to build. I am sure they were long lasting, however. And there are of course posts made out of super rot-resistant Osage Orange or Black Locust that have lasted for more than a half-century, but in the present time there is nowhere near enough of these trees to meet the need for fence posts. And furthermore, when the fence post fails, sometimes only one of them in a long run, the fence more or less fails. Sort of like the foundation of a building. The post supports all the other components, and the offending post is not easily worked around. I suspect there are far more people that have put in wood fence posts than have removed them. I’ve done both, and the latter is a far more difficult job. If this was commonly appreciated, I think people would think twice before putting up miles and miles of wood posts!
I only had this idea because of a peculiar obstacle I have on my farm. There is a major interstate gas pipeline running right through the middle of my main field. It is perfectly acceptable to grow field crops and pastures over the pipeline (sometimes it is difficult, because the soil is more or less ruined). It is not permissible to grow trees; even short hedges are impermissible. So, the problem with my farm is that I cannot have a hedge completely around my farm since there are two ends where for a minimum of 50 feet I cannot plant hedge trees. Hedges are also difficult to abut to a gate end. There will always be a gap between the gatepost and the hedge, which is venerable to penetration. And their thorny nature makes them hard to trim and otherwise manage. So it came to me the idea of using both living fence posts and dead fence posts with wire fencing material together in a living hybrid fence.
Pollarding is the practice of allowing a tree to grow to a certain height, usually above browsing height (if you are raising giraffes this would not work), which for cattle is around 5-6 feet, and then cutting the trunk. Certain species of trees will re-generate from the stump by sending out “suckers” and eventually form a knob. The suckers are periodically harvested (every 2-7 years I’ve read) and usually fed to livestock. They may be fed directly or dried to make “tree hay” and fed later. It is best to cut in late summer or early fall while the leaves are green and before the sap has run back into the trunk and roots, and so the nutrients are retained. Many species of tree have nutritious, palatable leaves. The 5-6’ tall pollarded tree trunk is pretty much the perfect living fence post. If grown in a row and the trunk is kept clean of side growth, stringing barb or eclectic wire will not be a problem at all. Because the tree is kept more or less in a juvenile state, and is defoliated periodically, it grows very slowly and will live a very long time. There are pollarded trees in Europe and probably elsewhere that are hundreds of years old. And if it should come to pass that there is a place where a pollarded tree doesn’t grow, or dies, or is run over by a drunk driver, or you have a pipeline to cross over, then you simply used a dead fence post (either steel or treated wood) to fill the occasional gap. Also, dead fence posts (which do not grow or move) could be used for gatepost, etc. Since the wire product is strung continuously, the butt-end-of-a-hedge problem is averted.
Some general ideas I have about this fence are that one, two, or maybe three strands of barb wire should be used at the bottom of the fence: one strand laying on the ground and one or two going up to about one foot. Going up from the barbwire is regular steel (not high-tensile) galvanized electric fence wire—14 or 14.5 gauge would work fine. I suppose very long lasting stainless steel or aluminum could be used, too. Since you can afford to put a pollarded tree pretty much spaced as close as you want, there is no need for difficult to work with high tensile wire. The barbwire is there to prevent digging critters from entering and helps to get the fence up above most weeds that ground short the electric wire. The electric wire keeps the animals off, and keeps out all sorts of predators, and is very difficult to climb. It is also much more pleasant to work with than barb wire, which could be omitted if digging critters are not a concern.
There are several species of trees that are recommended for this treatment. Many of them aren’t adapted to North America, unfortunately. The North American trees I’ve read that take pollarding well are Beech, Oaks, Cherry, Mulberry, Osage Orange, Willows, Black and Honey Locust, Hawthorn, and Hazel. Unfortunately, many have thorns (Osage Orange, Honey Locust, Hawthorn) or are toxic to livestock (Black Locust and Cherry) or are slow growing (Beech and Oaks) or don’t really like to grow like trees (Hazel). This leaves Mulberry and Willow. I have confirmed that both Mulberry and Willow have palatable leaves, and Mulberry rivals the best of hay for nutritive quality. Both Willow and Mulberry are very fast growing and tolerant of a wide range of conditions. Willow, of course, is more tolerant of wet soil. Mulberry has the added benefit of Mullberries, which are actually okay to eat if you add some sugar and acid to them. If nothing else, they attract birds AWAY from your better berries. My neighbor, who provided the Hedgeapples has also an impressive Mulberry tree and an impressive Black Willow (nice neighbor, huh?). Mulberry grows very well from seed, and unlike its relative Osage Orange, Mullberry doesn’t require the half-year-long weathering process to make its seeds plant-able. In fact, it is such a weedy tree that they randomly pop up in my fields and garden. So does Willow (and Cottonwood). I am going to implement this experiment in the coming year. I plan on using hedges now for interior fencing only. I should have thought of this two weeks ago!
Unfortunately, this will take even longer to establish than a hedge (since the tree needs to get larger), and it might be more vulnerable to herbicide over-spray from your neighbors. It will be necessary to protect it with internal fencing from the animals for a longer time, but since I control where my animals graze very carefully with portable, temporary electric fence, it should be possible. Ideally, by the time the portable fence wears out (about a decade), the pollards should be ready to be strung with barb and electric wire.
Though it doesn’t pollard well and produces no practical edible, the Eastern Red Cedar could possibly be allowed to simply grow normally as a tree and then be strung with wires. They certainly grow from seed well and would have the benefit of not needing to be protected from animals since their foliage is unpalatable. In fact, on a very large farm, where the labor of pollarding would be overwhelming, or on a farm where set-stocking is practiced, Eastern Red Cedar may be the ideal tree for this scheme.