BUJUMBURA January 28th (ABP) – Water scarcity is a thorny problem that is increasing more and more in developing countries, with many countries in East Africa already facing increased water scarcity, according to a study conducted in 2009 by FAO.
Some trees that are integrated into farming systems can increase efficiency in water use, while planting fast-growing trees can exacerbate water shortage problems. The most controversial water issue and related to eucalyptus plantations is their effect on soil water content.
Eucalyptus is said to absorb more soil water than any other tree species. The results of more than twenty years of research on the consequences of water use and balancing in East African countries like Kenya show that eucalyptus consumes much water, especially during the period corresponding to its start of growth, if one compares it to Pinus species for example.
The conclusion of that study has implications for water management, forestry and agroforestry in areas where water is scarce, in semi-arid and arid regions.
The absorption of soil water depends mainly on the architecture of the root structure and the depth of root penetration as well as the density of plantations, soil and environmental conditions.
As in most natural forests and forestry plantations, the roots of most eucalyptus plantations are concentrated in the upper layers of the soil.
Since eucalyptus species are quite different in terms of their root systems, their water absorption capacity also differs according to the type of root structure.
The growth of the root structure of eucalyptus depends on environmental factors such as soil compaction. This has been verified by reviewing and commissioning studies on certain species such as Eucalyptus citiodora, grandis, pellita, cloeziana, of which only citiodora and pellita have been able to develop sufficiently fine roots to penetrate in a compacted layer of soil, according to FAO.
The area of eucalyptus foliage is also an important factor influencing the rate of water consumption. This FAO study concluded that there is a significant linear relationship between tree foliage area and average water consumption for a diverse range of eucalyptus species planted under similar climatic conditions.