Because of climate change, more and more land that was once used to grow crops or provide food for animals is turning to dry, unusable desert land. There are many proposals about how to stop this process, known as desertification. A number of proposals involve growing trees, because trees can help protect soil and provide many other benefits to fight against desertification. Some scientists have proposed that the best way to grow trees in dry areas in danger of desertification is by using a box-shaped device surrounding the young tree. The device collects water that condenses from vapor in the atmosphere and helps the tree to grow. However, other scientists believe that this device will not be successful in fighting against desertification for the following reasons.
First, at a cost of 25 U.S. dollars each, the device would make growing trees a prohibitively expensive process. Meaningful efforts to fight desertification involve growing millions of trees. Some countries most affected by desertification cannot afford to buy devices for millions of trees.
Second, plans for fighting desertification involve asking local people to install and maintain the devices. People living in some of the areas most affected by desertification work long days in harsh conditions: sometimes barely managing to provide food for their families. It would be difficult to motivate these people to look after trees that cannot serve as a source of food for them.
Third, the device’s ability to collect and conserve water is limited. Each one provides only enough water to keep a small tree alive. Trees that have outgrown the device have to deal with unforgiving environmental conditions on their own. In some places where the devices are being tried, six months can pass without a drop of rain. Once the trees become too big for the device, they may not be able to survive in such a harsh environment.
The reasons against using the box-like devices to grow trees are not very convincing. It is worthwhile to use these devices to help grow trees in the fight against desertification.
First, the cost. You have to take into account that once a young tree growing inside the device gets bigger, the device can be removed and used to start growing a new tree. In other words, the devices can be reused. Each can be used 20 times or more. If you divide the cost of one device by the number of trees you can use it for, the cost becomes much more reasonable.
Second, about installing and maintaining the devices. It’s true that people are being asked to maintain trees that they cannot use for food. But still, there are possible rewards for the local people who help with this project. For one thing, the devices can be used to collect water for other plants, not just trees. If the locals are allowed to use some of the devices for their vegetables, for example, that should help them grow more food. Another benefit to the locals is that once the trees become larger, the trees’ branches can be used for firewood. Having access to more food and more firewood should provide motivation for the local people to take part in the project.
Third, a tree can survive very harsh conditions once it outgrows the box-like device. That’s because the devices help young trees grow long roots. Those long roots are able to reach down to the moist soil that lies beneath the dry desert surface. Once the tree roots reach the sources of water underground, the trees can survive without the devices. In a recent effort to grow trees in the Sahara desert using the devices, 90% of the trees were still thriving two years after the devices had been removed.