Photo credit: Elquiglobalenergy
Opuntia spp: an efficient tool to combat desertification
Reasons for the increased importance of cacti in arid zones
The increased importance of cacti, such as Opuntia species, in arid zones is because of their ability to (i) grow in “deserts” and their drought tolerance; (ii) produce forage, fruit, and other useful products; and (iii) mitigate long-term degradation of ecologically fragile environments.
In central and south Tunisia, cactus plantations provide a large amount of fodder for livestock and play a key role in natural resources conservation. Land terraces are easily damaged by water runoff, but use of cactus helps to stabilize them, with its deep and strong rooting system. Two rows of cactus pads are planted on the inner side of the terraces (Figure 1).
The various Opuntia species have developed phenological, physiological and structural adaptations favouring survival in arid environments, in which water is the main factor limiting the development of most plant species. Pre-eminent among these adaptations are asynchronous reproduction and its crassulacean acid metabolism (CAM), which combine with structural adaptations, such as succulence, to allow this plant to continue the assimilation of carbon dioxide during long periods of drought. In this way, acceptable productivity levels are attained even in years of severe drought.
Cactus can be used in combination with cement barriers or cut palm leaves to stop wind erosion and sand movement. It will fix the soil and enhance the restoration of the vegetative plant cover (Figure 2).
They can develop in severely degraded soils, which are inadequate for other crops. Opuntia spp. have a great capacity for adaptation and are ideal for responding to global environmental changes. Their root characteristics avoid wind and rain erosion, encouraging their growth in degraded areas.
Marginal lands are fragile ecosystems, and when subjected to ploughing and indiscriminate vegetation removal the result has been large-scale degradation and destruction of vegetative cover. The increasing scarcity, if not disappearance, of several plant species indicates the magnitude of genetic and edaphic losses.
Rangeland areas and productivity in WANA countries are decreasing dramatically and can currently provide only a small portion of livestock needs (Figure 3).
Significant achievements in desertification control using cactus
To reverse the desertification trend and restore the vegetative cover in marginal arid and semi-arid areas, appropriate integrated packages can be applied for rangeland monitoring, livestock husbandry, and natural resources conservation. Spineless cactus (Opuntia ficus-indica), a drought- and erosion-tolerant plant, is being used advantageously in Tunisia, Algeria and Morocco to slow and direct sand movement, enhance the restoration of vegetative cover, and avoid the destruction by water of the land terraces built to reduce runoff.
Read the full article: IFAD
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