Deserts currently make up about 33 percent of the Earth’s land surface area, with more being co-opted every day. When one thinks of deserts, they usually picture arid places with little to no vegetation. However that’s not always the case anymore.
“Desert Greening” is the term used to describe the phenomenon of taking over existing deserts and reclaiming them for ecological purposes (afforestation, farming, biodiversity, etc.). These processes are now taking place on large scales all over the world, with a leading example being the Yatir Forest in Israel. The largest forest in that country, it was originally created in 1966 with the intent of using trees to roll back the desert. But after years of growth, the forest turned out to have a larger benefit than first thought possible by reducing carbon dioxide emissions in the area by a large amount. Through photosynthesis, the trees exchanged the polluted carbon dioxide in the air with breathable oxygen. Over 70 to 100 years (the estimated life span of deciduous trees), each tree in the Yatir Forest takes in and synthesizes about 500-800 kg of carbon.
Like me, you may be wondering whether planting a bunch of trees in the middle of the desert will have a negative impact on the water shortage issue in the area. Interestingly, the trees in the Yatir Forest have learned to adapt to the arid climate, and use a lot less water. According to Professor Dan Yakir, a researcher from the Weizmann Institute of Science, because of the rise in the level of carbon dioxide in the air, the trees absorb all the carbon dioxide they require without needing to fully open all the stomas (apertures) in their leaf membranes. Partial opening of the stomas reduces the evaporation rate and a tree uses less water without any damage to its development. The Yatir has served as a living laboratory testing the impact of process since 2000, when this was first discovered.
In addition to Israel, other countries such as China are practicing desert greening at large scales. Could the science related to desert plants and water conservation impact the way we approach landscape architecture in arid climates? Do you have any experience with this phenomenon? We’d love to hear about it.
Image is courtesy of Google Earth: 31°20’47.55″N and 35° 3’3.59″E
Posted by Brooke Storey in Ecology, Landscape Infrastructure, News, Performance Planning on
Bruce Gradek
In cases such as reclaiming desert areas, I wonder if biochar has been looked at for it’s capacity to increase the water holding capacity (along with retaining more nutrients within the root zone) of the resident soil? A good ‘green’ solution as well.
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Chris
Check out topos issue 82 from 2013 – great article on China’s desert afforestation program.