If you set out to design a shrub for the desert you wouldn’t be amiss in choosing ratam as a model. The desert environment has selected for plant characteristics that are ideally suited to meet the challenge of the driest lands.
Water
To make the most of rare rain events ratam can grow quickly when water is available. Shrubs can reach 3 meters in height and 6 m in spread. Roots can grow to considerable depth to reach soil moisture or groundwater. Roots have to grow fast to keep up with the drying front as the soil dries down after a heavy rain or flood event. Researchers have found roots at 20 m, and perhaps, like the similar shrub mesquite of SW North America, they may reach 50 m. The roots can also extend a long horizontal distance following moisture in dunes.
Nutrients
Ratam fertilizes itself. The deep roots form symbioses with bacteria to fix atmospheric nitrogen in root nodules. This can happen at considerable depth where the soil is damp. Roots benefit from the partnerships with mycorrhizal fungi in (endo) and on (ecto) the roots that help the plant gain water and nutrients. The fine hyphae (filaments) of the fungi can reach into the smallest spaces. They reach out from the plant at the lowest possible energy cost and can include 10 to 100 meters of hyphae per gram of soil.
A single plant is likely to have hundreds of meters of fungal filaments with potential mineral binding sites exceeding the root surfaces. In one study the most diverse fungal species, with 35 virtual taxa, were found in the Negev desert. The plant leaves and twigs help fertilize the soil. In North America the Tohono O’Odham collected and used similar materials to fertilize the soils for their crops.
Photosynthesis
During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds. The photosynthesis needed for energy is carried out by both leaves and stems. When times are tough the leaves drop off and the stem keeps the plant alive. To reduce water use even more the ratam pores (stomata) are hidden within the longitudinal grooves of the stem to conserve water.
Defense
To defend against grazing animals and insects ratam deploys a range of phytochemicals. Studies have shown that these species are very rich in flavonoids (isoflavones) and alkaloids (quinolizidine and bipiperidyl). These chemical compounds evolved to make the seedlings, seeds and shrubs less edible. Camels eat the flowers and pods. The pods are also eaten by rabbits, other animals and insects. Goats and camels will eat the stems if there is no other forage, but may be poisoned if they eat too much. Like honey mesquite, the pods may develop aflatoxins from mold after they are on the ground.
Reproduction
To increase the chance of fostering future generations in such a harsh environment ratam produces many flowers and up to 3,000 seeds per square meter. Ratam blooms between January and April and is an important food for bees and other insects.
The fruit is a short single-seed pod. The seed is yellow, with a very hard coat. When the pods are eaten the seeds are not digested and are excreted in the droppings. The hard seed coat that can otherwise protect the seed for years or decades is thinned by the stomach acid, making it easier to germinate. Flood events also chip and erode the hard seed coat and leave the seed ready to germinate and grow roots quickly after the flood. The roots are likely to grow much faster than the shoots.
Medicine
Ratam’s complex chemicals were used in many traditional medicines and treatments. Various parts of the plant were (and perhaps still are) used by desert Bedouin for treatment of backache, diabetes, stomach ache, worms, infertility, temporary paralysis of the limbs, joint pain, infected skin lesions, syphilis, toothache, sprains and fractures. An eyewash gave relief to sore eyes and throat. Small quantities have been used as a purgative.
Tests have shown the plant phytochemicals are antibacterial, antiseptic and were effective against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Although used as medicine the pods are considered toxic and may provoke hallucinations. Ingesting large amounts of the plant to produce abortions has sometimes led to poisoning and even death. Further studies are warranted to more fully understand the medical applications of ratam.
Sequestering Carbon
Ratam is a good candidate for carbon sequestration. Deep roots last for many years even after a plant dies. The root partner arbuscular mycorrhizal fungi produce glomalin to coat the hyphae to keep water and nutrients from being lost. Glomalin is resistant to microbial decay (lasting at least 10 to 50 years) and does not dissolve easily in water. Sequestration of carbon up to 6.6 Mg/ha at 25% canopy cover was suggested for a comparable plant in the desert of North America.
Ratam can be planted in rows with alley inter-cropping or coppice blocks for fuelwood, honey, and perhaps flowers and pods. Ratam is well suited for use in windbreaks for dust management. Geesing et al. (2000) estimated that with effective planting programs tree planting for semi-arid lands could sequester 6.2 billion metric tons of carbon per year. Much of this could be in agroforestry applications. This is about two-thirds of the world annual emissions.
The Biggest Risk
The biggest threat to ratam was (and is) human use for fuel. The shrub wood has been burned as a firewood and as charcoal. The roots have also been used. A household relying on ratam branches might use 10 kg of shrubs from 1 ha a month. Over more than a thousand years this pressure has reduced the range and availability of ratam. Ratam can be pruned and will regrow with support from the extensive root system. Ratam shrubs could provide 2-15 kg each. With 7 x 7 m spacing 200 ratam per hectare could yield 1-2 tons of wood. Camel and goat grazing continue to diminish rata as well.
The Future
Ratam would be a good choice for restoration and revegetation in Jordan and similar arid land where it once grew. The availability of seeds and the toughness of seedlings will help. The value for the future in bioenergy, biodiversity, erosion reduction, wind control, and carbon sequestration would make it worthwhile.
Test plots of 100-200 ha with Vallerani plows and ratam seedlings would be a good start. The first step would be to collect, process and store seeds and to grow up seedlings in tall containers to protect tap roots (Stuewe and Sons https://stuewe.com/product-category/treepots-trays/). Deep pipe irrigation could be added for more rapid growth. Ratam harvest could be by hand or, on a large scale, mechanized. A mobile charcoal kiln could turn cuttings into charcoal and minimize transport cost. Or a series of kilns could be built, of stone or earth. The Cottonwood kilns of 1873 were built of earth to supply charcoal to the mines in eastern California. Low cost charcoal briquette making machines might be tested and refined as well.
Ratam – an under-appreciated resource
It could help reduce the demand for costly imported fossil fuels and reduce the vulnerability of families to energy shortages and high costs. Ratam can also provide protection and nutrients for crops. If developed on a large scale it could sequester significant amounts of climate changing carbon, while reducing erosion, suppressing dust, and lowering the risk of floods, all while helping to preserve and restore biodiversity.
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