Disadvantages of Living Fences
Some living fences can have serious disadvantages as follows:
Tree growth may be excessive and pruning may require excess work.
Trees through shade or superficial roots can compete for water and fertilizers with other crops.
Because of these reasons, living fences have to be controlled. Whether or not living fences are used on the farm will depend on the weighing of the advantages versus the disadvantages.
Establishment and Care of Living Fences
The tradition of living fences varies from place to place in the tropics, as does the suitability of the various species used to make them. There may be many other species of trees that are well suited that have not come to the attention of the author. In any area it would be desirable to investigate the trees that are already being used as living fences. It might also be appropriate to select for suitable species for living fences in the wild.
If new species are selected, they should have the following characteristics:
Resistance to cattle (can be observed in pastures).
Can be grown rapidly from stakes or seeds.
Have other useful properties.
If suitable materials are not locally available, then importation of seed might be desirable. The species most recommended would be:
Bursera simarouba- for dry regions.
Gliricidia sepium- for areas of alternating wet and dry.
Erythrina bertervana, or other Erythrina species- for wetter areas.
Trees and other plants are used as living fences in three principal ways: posts, hedges, and palisades (a fence of closely set stakes). While any tree can be used as a living post, many trees would not normally be so used because of their size, propagation difficulty, slow growth, adverse characteristics, or inadequate lifetime. A few large trees used as occasional posts are retained for other values (teak as valuable wood, mango for fruits and shade). The majority of the species used as living fence posts can be propagated from large woody cuttings, generally the size of the fence pole required. There are, however, exceptionally fast growing trees that are planted from seeds.
Posts are used with conventional barbed wire or wire screen. Plants that are used in hedges tend to be spreading so that they fill in the spaces between them rapidly. They may or may not be strung with wire. Plants used as palisades are planted very carefully as close together as necessary in order to achieve an animal proof cage-like fence immediately. Such plants may be propagated from stakes or offshoots.
Living fences are seldom fertilized. They are often pruned, however, to form them, to obtain new planting material or other products, and to eliminate excess foliage. In some cases, pruning is an annual task, usually done during the dry season. Fences can be carefully formed by weaving and tying branches, if so desired. Insects and disease are seldom a problem.
Species for Living Fences
Gliricidia sepium, Mother-of-cacao (madre-de-cacao, madera negra, mata raton). This small leguminous tree is so well known to farmers in some countries and so useful that it has been given a medal in Honduras. Common from low to medium elevations, the tree prefers a medium rainfall, and is well adjusted to a periodic dry season. The tree can be propagated from branches. An old living fence post will tend to produce a large number of long, narrow branches, perfect for planting. The branches root readily but the rate of growth is moderate. Gliricidia can also be propagated from seed.
Moringa oleifera, Horseradish tree (malunggay). This “vegetable tree” is one of the most successful plants in ECHO’s seedbank. It handles dry seasons well and grows especially quickly the first year. The Asian Vegetable Research and Development Center in Taiwan has developed a gardening plan which starts with palisade of moringa grown from closely spaced seed. Trees are pruned at about head height, and the leaves used as a nutritious cooked vegetable or for animal feed.
Ipil-Ipil, Small plant up to 8 m high; leaves alternate, twice compound, 15-25 cm, base of petiole enlarged; leaflets 9 to 18 pairs, 7 to 12 mm long, linear-oblong, unequilateral; flowering stalks axillary, 3.5 to 5 cm long; flowers in dense globule heads 2 to 3 cm in diameter, white; fruit a pod, strap-shaped, falttened, 12 to 18 cm long, 1 to 2 cm wide, papery, green turning brown and splits open along two edges when mature, several fruits develop from each flower head; seeds obovate, 5 to 8 mm long, 3 to 5 mm wide, shiny, brown.
Mahogany. In the natural rainforest, Mahogany is a very large canopy tree, sometimes reaching over 150 feet in height, with trunks sometimes more than 6 feet in diameter above a large basal buttress. It is a generally open-crowned tree, with gray to brownish-red fissured bark. It is regarded by many as the world’s premier wood for fine cabinetry, high-class furniture, trimming fine boats, pianos and other musical instruments, sculpture, joinery, turnery, figured and decorative veneer, interior trim, and carving.
If you’re not familiar with the tree species , you can always ask advice and guidance from plant nursery owners and suppliers.
author: Dr. Franklin Martin, www.practicalaction.org