Chapters 5.60
5.60 -planting desert poplar trees (Populus euphratica) would affect smallholder farmers in arid regions of Africa and counteract desertification
Audrey Shi, University of Guelph, Canada
Suggested citation for this chapter.
Shi,A. (2022) planting desert poplar trees (Populus euphratica) would affect smallholder farmers in arid regions of Africa and counteract desertification, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Desertification
In arid regions of Africa, a major problem faced by smallholder farmers is desertification caused by extreme periods without rainfall. Desertification has more effects than just soil degradation: it also causes loss of ecosystems. As soil is eroded, there is also loss of vegetation and wildlife (Darkoh, 1998). Desertification prevents smallholder farmers from having sustainable farms. Climate change is a factor that is causing desertification in drier regions of Africa because rainfall patterns are changing (Meadows & Hoffman, 2003). Dust storms are also a frequent issue in arid regions of Africa and are damaging and dangerous to many farmers (Nasa, 2005). Human activities such as over cultivation also contribute to the land degradation (Darkoh, 1998). With poor soil quality and lack of vegetation, it would be hard for smallholder farmers to get good crop yields which affects their livelihoods and causes food shortages (Khogali, 1991). Desert poplar trees represent one promising option to combat desertification.
Characteristics of desert poplar trees (combating desertification)
The desert poplar tree (Populus euphratica) is a medium sized, deciduous tree (Orwa et al., 2009). It is mostly found in arid regions of central Asia and is able to grow in arid, barren lands. This is because the roots are able to reach deep water tables. The tree’s drought tolerance is related to its roots rather than being able to live without water per se (Tang, 2013). Furthermore, this tree has a high tolerance to saline soil. The conditions for germination are bright sunlight, and a temperature between 25 and 30 degrees Celsius (Rajput et al., 2016).
Planting desert poplar trees
The main method of propagation for desert poplar trees is from seedlings but it can be propagated by cuttings as well (Jiang et al., 2003). The seedlings should be pre-soaked in a 2 molar solution of sucrose for 30 minutes in order to allow for germination, and the temperature for germination should be 29-32 degrees Celsius. It is important to sow the seeds as soon as possible because they do not store well (University of Florida, 2013). This tree can withstand very harsh climates and poor soil. It grows to 7.5-15 metres in height and achieves a diameter of 30-70 centimeters under good conditions. It grows very fast as the diameter increases around 4.0-5.3 centimeters every year (The University of Waikato, 1983). The tree needs a lot of sunshine and warmth to grow. The seedlings or cuttings should be planted at a spacing of 2 m x 3 m (The University of Waikato, 1983). The preferred soil types for Populus euphratica are rocky and hilly soils, and the best pH range is 5.0-6.5 (Orwa et al., 2009). The tree can tolerate annual rainfall as low as 75-200 mm, making it highly drought tolerant (Orwa, et al., 2009).
Costs of planting
The costs of planting many desert poplar trees could total a large sum of money for smallholder farmer. A lot of funds and work are required to purchase and distribute seeds, teach farmers how to plant and grow them, to ensure the trees are able to grow and thrive. The Great Green Wall Project is/was a project in 2007, where the African Union and other organizations tried to plant many trees across the African continent to prevent land degradation and stop desertification. However, this project has been struggling because of the amount of funds needed. It has been estimated that 33 US billion dollars would be needed to complete the Great Green Wall (UNCCD, 2021). Planting trees on a mass scale is costly, but introducing Populus euphratica to smallholder farmers on a smaller scale could be beneficial. In general, the cost to plant a single tree, is about $0.85 USD. This includes the cost of the seeds, tools to plant the tree and maintaining the tree (Chaplin, 2017).
How this affects smallholder farmers
Having many trees planted around a village or field site creates a barrier to dust storms which are caused by soil and sand erosion (National Commission of the People’s Republic of China for UNESCO, 2010). In China, after 1999, the government made efforts to stop soil erosion by banning tree cutting, unrestricted grazing, etc. (Buckingham, 2016). This allowed vegetation to develop. These actions had a significant impact in terms of decreasing the frequency and intensity of sand storms. This could be implemented in Africa to help protect smallholder crops from dust storms. Furthermore, this tree species could be used for fire wood if needed and as a fodder for livestock (The University of Waikato, 1983).
Competing tree species and limitations
Planting desert poplar trees offers many benefits to smallholder farmers, but there are still limitations to it. In Korea, they were able to restore areas affected by deforestation, but there was a lack of species diversity that resulted, causing the trees to be susceptible to pests and disease (Buckingham, 2016). Therefore, Populus euphratica could promote disease and pests if it is the only species planted. Populus euphratica has had issues with being attacked by beetles and other insect borers (Hu et al., 2009). This tree is mainly found in Asia currently and has faced issues with Asian long horned beetle infestation (Hu et al., 2009). It is considered slightly resistant to the insect but can still be infected (Hu et al., 2009). Furthermore, a study in south-western Iran found a leaf spot disease on Populus euphratica trees (Osdaghi & Rahimi Kakavandi, 2015).
Another issue that comes with planting trees is people cutting trees down too quickly, or cutting down immature trees. Many people cut trees down too soon because of the need for fuelwood (Fleshman, 2008). A solution to people cutting down trees would be to have the government place regulations against tree cutting (Fleshman, 2008). Animals can also damage trees because they eat leaves and can erode the soil around them (Department of Primary Industries and Regional Development, 2017). A solution to this could be putting fencing around the trees. More solutions to animals eating leaves are providing the animals with mineral licks instead and applying manure to the tree trunk (Department of Primary Industries and Regional Development, 2017).
Other trees that could be more beneficial include Acacia and date palms. Acacia is a good tree to plant because it provides the soil with nitrogen and is drought tolerant. It has the similar benefits as Populus euphratica, such as crop shelter. The FAO and Senegalese forestry service had a project from 2004 to 2007 that provided Acacia seedlings and taught women how to sow and plant the trees (FAO, 2011). In the future, Acacia could be used more widely with more research and development. Date palms are another alternative tree. It can adapt to drought and bears fruit, but it takes a long time to grow, around 4 to 6 years to start producing fruit and 15 to 20 years to reach full production (Chao & Kreuger, 2007).
Conclusion
In conclusion, desert poplar trees could be a simple solution to help combat desertification in Africa. It can shelter crops, provide firewood and it an easy to grow tree. There are limitations such as costs to plant many trees and teach farmers how to plant them.
Practical resources for smallholder farms
Video on how to plant poplar trees from cuttings: https://youtu.be/7Li8ice09qk
Video on hybrid poplar growth (not Populus euphratica but still a hybrid poplar): https://youtu.be/dSXhs8i5oHM
General instructions for tree planting from seeds: https://www.treehelp.com/how-to-grow-a-tree-or-shrub-from-seed/
Information from the World Agroforestry Center on Populus euphratica http://apps.worldagroforestry.org/treedb/AFTPDFS/Populus_euphratica.PDF
Website with a lot of details about Populus euphratica https://pfaf.org/user/Plant.aspx?LatinName=Populus+euphratica
References
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