LIVING TUNNELS WITH LOCAL TREES
by Prof. Dr. Willem VAN COTTHEM (Ghent University, Belgiuym)
Today I read the interesting article “Fresh water, the reward of land restoration, flows in Ethiopia’s dry zone” at the Agrofirestry World’s blog
Here are some of the important paragraphs:
- Land restoration has brought back water and vibrant colour to a previously bleak and desolate landscape just south of the Sahara.
- …it was hard to imagine that 15 years ago this land was bare and unproductive, the people relying on food aid for sustenance.
- …how the sophisticated soil and water conservation structures built on the hillsides control the every-present threat of soil erosion. “These structures, together with our regenerated trees and shrubs, ensure that we can make use of every raindrop that falls during the two-month rainy season.”
- …farming community has moved from barely surviving to having surplus produce to sell. New economic activities, such as beekeeping and growing fruit trees for sale, have also sprung up in the restored landscape.
- …referring to Faidherbia albidas reverse phenology—the tree sheds its leaves in the wet season (when the crop is in the field) and it regains them in the dry season, when fodder is scarece. And its flowers are excellent bee forage for the community’s 50-odd beehives.
- Over a thousand hectares of land have been restored here, and naturally regenerated native tree species such as podo (Podocarpus falcatus); African juniper Juniperus procera and Cordia africana are to be found alongside planted exotic species like the nutritionally and economically important avocado.
The restoration of Geregera catchment focused on soil and water conservation measures. Thanks to the improved ground water recharge, Geregera’s water is today servicing communities living up to 30 km downstream.
- …landscape regeneration has brought back numerous natural grasses and native tree species that had disappeared from Mossa. Trees like the sand olive, Dodonaea angustifolia, and bush guarri, Euclea schimperi, are back on the landscape.
- Bench terraces with stone stabilization and deep trenches, along with regulated grazing, were used to control land degradation and surface runoff of water in Mossa. These measures helped improve ground water recharge. Today, the native pastoralists have fodder and water for their livestock, thanks to the grasses, shrubs, waterfall and numerous natural springs found in their restored landscape. And the farmers living on the shoulders of the valley have irrigation water.
- Lessons learnt: The main ingredients that enabled land restoration in Tigray were political support, community ownership and collective action, the use of by-laws, and partnership.
- “We are also supporting farmers with choosing tree species to diversify their farms with and training them in rainwater harvesting,”
Focus on some tree species mentioned above
(1) Faidherbia albida (Fabaceae)
Faidherbia is a genus of leguminous plants containing one species, Faidherbia albida, native to Africa and the Middle East. It has also been introduced to Pakistan and India. Common names for it include apple-ring acacia (their circular, indehiscent seed pods resemble apple rings),ana tree, balanzan tree and winter thorn. It is a thorny tree growing up 6–30 m (20–98 ft) tall and 2 m (6.6 ft) in trunk diameter.The bark is grey, and fissured when old. There are 11,000 seeds/kg. Its deep-penetrating tap root makes it highly resistant to drought. It grows in areas with 250–600 mm (9.8–23.6 in) of rain per year.
The northernmost natural populations are found in relict groves in Israel (in the Shimron nature reserve, near the communal settlement of Timrat). All of the trees in a given grove are genetically identical and seem to have multiplied by vegetative reproduction only, for thousands of years.
The seed pods are important for raising livestock, are used as camel fodder in Nigeria, and are relished by elephant, antelope, buffalo, baboons and various browsers and grazers, though strangely ignored by warthog and zebra.
The wood is used for canoes, mortars, and pestles and the bark is pounded in Nigeria and used as a packing material on pack animals.
Ashes of the wood are used in making soap and as a depilatory and tanning agent for hides. The wood is used for carving; the thorny branches useful for a natural barbed fence. Pods and foliage are highly regarded as livestock fodder. Some 90% of Senegalese farmers interviewed by Felker (1981) collected, stored, and rationed Acacia alba pods to livestock. Zimbabweans use the pods to stupefy fish. Humans eat the boiled seeds in times of scarcity in Zimbabwe.
It is also used for nitrogen fixation, erosion control for crops, for food, drink and medicine. Unlike most other trees, it sheds its leaves in the rainy season; for this reason, it is highly valued in agroforestry as it can grow among field crops without shading them. The leaves from this legume tree are high in nitrogen, and can double yields in maize crops when added to the soil.
The extract is used to treat ocular infections in farm animals.
(2) Juniperus procera (Cupressaceae)
Juniperus procera (known by the common English names African juniper, African pencil-cedar, East African juniper, East African-cedar, and Kenya-cedar) is a coniferous tree native to mountainous areas in Africa and the Arabian Peninsula. It is a characteristic tree of the Afromontane flora.
Juniperus procera is a medium-sized tree reaching 20–25 m (rarely 40 m) tall, with a trunk up to 1.5–2 m diameter and a broadly conical to rounded or irregular crown. The leaves are of two forms, juvenile needle-like leaves 8–15 mm long on seedlings, and adult scale-leaves 0.5–3 mm long on older plants, arranged in decussate pairs or whorls of three. It is largely dioecious with separate male and female plants, but some individual plants produce both sexes. The cones are berry-like, 4–8 mm in diameter, blue-black with a whitish waxy bloom, and contain 2-5 seeds; they are mature in 12–18 months. The male cones are 3–5 mm long, and shed their pollen in early spring.
Juniperus procera is native to the Arabian Peninsula (in Saudi Arabia and Yemen), and northeastern, eastern, west-central, and south tropical Africa (in the Democratic Republic of the Congo; the Republic of the Congo; Djibouti; Eritrea; Ethiopia; Kenya; Malawi; Mozambique; Somalia; Sudan; Tanzania; Uganda; Zambia; and Zimbabwe)
It is the only juniper to occur south of the equator, and is thought to be a relatively recent colonist of Africa; the species shows very little of the variability associated with a long period of evolution. It is closely related to Juniperus excelsa from southwestern Asia, probably deriving from a common ancestor with that species in southwestern Asia.
It is an important timber tree, used for building houses, for poles, for furniture; bark used for beehives.
(3) Cordia africana (Boraginaceae)
Cordia africana has been used in the manufacture of drums. … It is also sometime called Sudan Teak and has been used for cabinet making, high-quality furniture, veneers and general construction. The wood can be used to manufacture beehives which can be kept in this tree where the bees can live off the plentiful supply of nectar which comes from the flowers. In addition the tree supplies leaves for forage and an edible fruit.
(4) Dodonaea angustifolia (Sapindaceae)
Dodonaea angustifolia, the sand olive, is a slender shrub or small tree that occurs naturally from southern Africa to Arabia, as well as in Australia and New Zealand. The seed capsules are three-winged and are dispersed by wind. Although naturally occurring in rocky areas it is also cultivated to stabilise moving sand and to prevent erosion. Extracts are used as medicine.
(5) Euclea schimperi (Ebenaceae)
We found a Wikipedia description for Euclea racemosa:
Euclea racemosa (the Sea Guarrie or Dune Guarrie) is a small to medium-sized evergreen tree that is indigenous to the Indian Ocean coast of Africa from Egypt to South Africa, as well as in Comoros, Oman and Yemen.
Euclea racemosa has leathery foliage that can be exceptionally even and dense – making it an ideal plant for hedges. A dioecious tree (male and female flowers on separate trees), it produces small white flowers, which are followed by red, purple and black fruits that attract birds. The berries are used locally to make “Guarrie vinegar”.
MY RECOMMENDATIONS TO FORM A LIVING TUNNEL
- To produce a sufficient number of each of these drought-tolerant tree species
- To plant these species in 2 rows over a certain distance, e.g. 50 meter.
- To plant the 2 rows at a distance of e.g. 5-7 meter.
- To let the trees grow vertically for a certain number of years, until they reach a sufficient height to bend them over towards the opposite row.
- To prune the trees so that only the lateral branches in the plane of the 2 rows are left growing.
- When the trees are high enough, to bend them over to the opposite row and to bind them to one another in order to form a “living tunnel”.
- To continue pruning the living tunnel to densify the covering walls of the tunnel.
- To use such living tunnels for growing fresh food in containers (buckets, pots, bottles, drums, sacks, bags, …) inside the shady tunnel.