Shade as a Drylands Strategy

The mostly rock and dust soil of the Greening The Desert Project, Jordan had to be rehabilitated. That started with hard-working elements that got the site ready for sophistication and diversity. These original pioneer species were hardy nitrogen-fixers, like Jerusalem Thorn, that could withstand harsh conditions and provide organic material to build fertility pathways for new species. These types of trees were normally a bit thorny.

Prosopis was great pioneer species. Many people hate them because they volunteer on damaged ground, acting like “weeds”. They put out a canopy that swoops right to the earth and shades the tree’s root system. The canopy also helps to catch debris and organic matter, and animals use them for shade. Prosopis can also be easily manipulated by pruning, including coppicing and pollarding for chop-and-drop mulch, making these trees great for starting the sequence of recovery.

Of course, these spiky pioneers had to get large and then be cut to add organic matter to the soil to build soil. They also had to be slowly sequenced out. They were cut when more friendly legumes can be put into place. Once cut, the base kept sending up shoots, which is good for organic material but still thorny. The thorny pioneers, however, can be phased out by cutting all sprouts and leaf growth as low to the stump as possible until the tree finally dies.

Dealing with prunings from these difficult (thorny) trees was a challenge as well. The chop-and-drop mulch had to be cut up into small material before being put on the ground so that it could decompose more quickly. For the larger stuff like logs and tree trunks, GTD dug huge pits, two meters wide and two meters deep. They layered this with manure as they filled the pits, which consumed some 200 pioneering trees. Within a year, the area—one of the most damaged spots on the property – developed strong fungal networks between the pits and plants began to thrive.

The harsh trees, like Prosopis, were then replaced with more agreeable support species, such as Leucaena. These are pruned at the beginning of winter for chop-and-drop each year, but the prunings are no longer covered in spikes, so they can go right to the ground. There are also larger legume trees that can live long-term (Albizzia lebbeck and Poinciana), and they let light in during the winter and provide shade in the summer. Smaller trees like cassia, acacia, neem, casuarina, and hibiscus tilaceus (Rose of Sharon) have added other layers of controlled shade to the mix. Even the southern wall creates shade and makes the area near it more fertile.

By manipulating (pruning) the shade through height, layers, and timing, the growing system can flex with the change of season and what’s happening with the climate. This is how we work with nature rather than opposing it, and the consequence is incredibly rich soil to go along with a hospitable space to grow.

Key Takeaways

- Dryland strategies use hard-working and difficult plants to set the groundwork for soil recovery, which hinges on both the creation of shade and organic matter.
- The original pioneering species for the Greening the Desert Project, trees like Jerusalem thorn and prosopis, were thorny and tough, perfect for surviving in the harsh climate and poor soil.
- Because these thorny species were difficult to use as mulch, they were cut down and buried in pits when the soil had recovered enough to cultivated other support species.
- After the super hardy and rugged pioneers, support species like leucaena, Albizzia lebbeck, Poinciana, cassia, acacia, neem, casuarina, and hibiscus tilaceus helped to further pave the way for productive species.
- In the desert, the game is to manipulate the shade through height, layers, and timing, and with chop-and-drop trees, it’s building soil all the while. This is working with nature.

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Permaculture integrates land, resources, people, and the environment through mutually beneficial synergies – imitating the no waste, closed-loop systems seen in diverse natural systems. Permaculture applies holistic solutions that are applicable in rural and urban contexts and at any scale. It is a multidisciplinary toolbox including agriculture, water harvesting and hydrology, energy, natural building, forestry, waste management, animal systems, aquaculture, appropriate technology, economics, and community development.

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