There are many effective anti-predator tools available at lower or higher cost (fladry, electric fencing, regular fences, range-riding etc.).
These tools are implemented successfully where the area of livestock holding and grazing is rather fixed and relatively limited and where the community can afford the materials and labour / maintenance costs.
However, there are places where:
- The livestock grazing areas are too large (in extensive, rotational grazing systems) to perhaps become fenced properly;
- The distinction between predator range and human / livestock range is less apparent and more difficult to draw (e.g., grassland, steppe, prairie ecosystems);
- The local communities are living very close to large predators but they cannot afford an investment in an artificial territory boundary system because the proximity rather blends the two environments (anthropogenic and wild) and a fence would be too long to be economically viable etc.
Historically, hedgerows have been used since at least Neolithic times (Fichtner, A. & Wissemann, V., 2021) to either keep animals (mainly livestock or large wild ungulates) inside a predetermined space or outside of it.
In some cultures hedgerows have become understood as simplistic systems of a monoculture variety in single stratum, well-pruned formations.
However, ancient hedgerows and biodiversity hedgerows consist of several strata and multiple layers and native plants are used successfully delivering many wildlife benefits (floral and faunal species biodiversity, carbon sequestration, erosion prevention, water retention, water filtration etc.) as well as possible benefits to the community if the hedgerow community is planned to yield nuts, fruit, berries, edible leaves, livestock feed, medicinal plants etc.
An excellent article listing most of the hedgerow benefits has been published by Katarina Zimmer on BBC Future Planet.
I believe hedgerows might be used in the same manner as they once were – to mark land boundaries.
However, on this occasion, they would serve to mark land boundaries between the wilderness and the space that humans wish to allocate to themselves keeping out large predators.
If designed properly, such hedgerows could deter many species from ‘trespassing’ and thus conflicts with humans would be limited around settlements.
Predator species might even learn to recognize hedgerows as the boundaries beyond which they can meet with hostility if they still have managed to find a way through, beneath or over.
It might be easier for wild animals to identify land boundaries in semi-wild elements (hedgerows) than in artificial elements (fences).
In their eyes, it might become a type of habitat that has its own risks and benefits.
We tend to view fences manufactured from artificial materials as more secure while, to animals, the fence might be an element of unclear message.
If the wild species learned that beyond the hedge, a human community lives that is not welcoming of the species’ presence, they might rather perceive the hedge as an habitat indicator than the more abstract fence is perceived.
Hedgerows could be planned with such considerations in mind that make them more impenetrable for large or medium sized predators (although some medium sized predators, e.g., foxes might use hedgerows as den sites).
Several strata (trees and shrubs) could be combined to provide the necessary height (above 1.5 – 2 m).
Thorny and prickly woody species might be used to make in uncomfortable for animals to climb if some of the predators are tree-climbing.
However, in regions with tree-climbing predators such higher level species should be selected that disallow using the branches (thinner branches or very tangled structures).
The hedge might be thickened in years through the application of traditional hedge-laying methods (instead of coppicing).
Hedge-laying has the advantage of rejuvenating the hedge without creating a gap in it that takes a long time to regrow (a risk factor).
The base layer might be planted with bramble-type entangled, dense structures that preferably also contain prickly, thorny species making the base difficult to penetrate and limiting the animals’ willingness to dig under.
Digging could also be prevented through the selection of tree and shrub species with deep and intensive root systems (instead of shallow roots that are torn apart easily).
In vulnerable communities these species could be combined to provide additional benefits (the aforementioned food, medicinal and other resources).
The use of native plants and local propagation methods would alleviate the cost of establishing the boundary hedge (when implemented successfully, the hedge might cost nothing while yielding some profit through food production or carbon credits etc.).
Hedgerows might create a barrier between the wilderness and the settled area that is not only physical and clearer for predators to perceive as a new type of habitat with its rules (on the other side – hazing awaits), but that additionally limit the amount of predator-enticing scents and sounds passing through (for example, in places where waste management is an issue that is difficult to resolve due to poor infrastructure).
As stated before, I believe this would be especially beneficial in regions where the boundary between the wilderness and the human space is very vague such as in grasslands or in settlements very close to forests (e.g., jungle).
Hedges have been proven to limit spread of bovine tuberculosis (airborne infection) between cattle herds (i.a., Winkler, B. & Mathews, F., 2015).
Infection transmission between human and wildlife communities might be thus reduced also with respect to other pathogens/parasites.
Hedgerows have wildlife benefits beyond count, e.g., the reduction of human pollution (above-ground flows or groundwater contamination) reaching the wild areas etc.
Therefore, both human communities and wildlife communities would profit from the established bound.
Notes by Ieva 