Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.6, No.8, 2016 11 Cactus Pear (Opuntia ficus-indica L.) a Valuable Crop for Restoration of Degraded Soils in Northern Ethiopia Solomon Abera Bariagabre 1* Isaack K. Asante 2 Christopher Gordon 1 Ted Yemoh Ananng 1 1. Institute for Environment and Sanitation Studies, University of Ghana, Legon, Accra 2. Department of Botany, University of Ghana, Legon, Accra Abstract Opuntia ficus-indica (L.) commonly referred to as cactus pear is a dicotyledonous angiosperm plant. It belongs to the Cactaceae family and is characterized by its remarkable adaptation to arid and semi-arid climates in tropical and subtropical regions of the globe. Opuntia species have developed phenological, physiological and structural adaptations for growth and survival in arid and semi-arid environments where severe water stress hinders the survival of other plant species. Among these adaptations, the asynchronous reproduction and CAM metabolism of cactus stands out, which combined with structural adaptations such as succulence, allow them to continue the assimilation of carbon dioxide during long periods of drought reaching acceptable productivity levels even in years of severe drought. In the present stud soil physical and chemical properties are considerably improved under the canopies of cactus pear compared to adjacent open areas. The generalized linear model showed that soil organic carbon, soil total nitrogen, soil available phosphorus, soil bulk density, soil moisture, and electric conductivity of soil samples were positively and significantly influenced by cactus pear canopy cover compared to adjacent open areas. Keywords: Cactus pear, land degradation, restoration, physical property, chemical property, northern Ethiopia 1. Introduction Drylands cover over 40% of the earth’s land surface, and are home to more than a third of the world’s population–many of whom are the poorest of the poor (IUCN, 2008). Drylands as tropical and temperate landscapes and regions with an aridity index value of less than 0.65 includes: dry sub-humid, semi-arid, arid, and hyper arid (IUCN, 2008b). Land degradation occurs in all continents and affecting livelihoods of millions of people including a large proportion of the poor in the drylands (Nefzaoui et al., 2014). Land degradation triggered by population increase and over exploitation of the natural resources is a major threat to sustainable land use in Ethiopia (Hurni et al., 2005). Regardless of the geographic locations, arid and semi-arid areas are characterized by specific vegetation and climatic conditions. Vegetation in arid and semi-arid lands includes plants with mechanisms of resistance and/or adaptation to water stress, such as cactus, mesquites, bushes etc. (Nobel, 2009). Climatically arid and semi-arid lands are characterized by extreme temperature conditions and torrential precipitation events with short duration and high intensity (Wei et al., 2007). Vegetation plays an important role in regulation of soil erosion and improvement of the physical, chemical and biological properties of soils (Wei et al., 2007). In arid and semi-arid lands, the degradation of plant communities (vegetation structure and species diversity) is concomitant with the degradation of physicochemical and biological properties of soil (Requena et al., 1996). However, the functioning and stability of terrestrial ecosystems are primarily depending on the composition and species diversity of vegetation cover (Tilman et al., 1996). Arid and semi-arid ecosystems are considered as very fragile systems since they are susceptible to various forms of degradation (Ferrol et al. 2004). Ountia ficus-indica (L. Mill.) commonly referred to as cactus pear belongs to the dicotyledonous angiosperm plants. It belongs to the Cactaceae family, a family that includes about 130 genera and 2000 species (Shedbalkar et al., 2010). Opuntia ficus-indica is the most widely known genus of this family. It is characterized by its remarkable adaptation to arid and semi-arid climates in tropical and subtropical regions of the globe (Griffith, 2004: El-Mostafa et al., 2014). Cactus pear plants are remarkable for their diversity of growth forms and their ability not only to grow but also to thrive under environments recognized as stressful for most plant species. They are evolved to grow into water scarce environments (Shedbalkar et al., 2010). Opuntia ficus-indica exhibits Crassulacean Acid Metabolism (CAM), with nocturnal stomata opening and CO 2 uptake occurring typically from dusk to dawn. Many reasons may account for the great interest devoted to cactus pear. The multipurpose use of this plant species and their ability to grow in harsh environments are the main reasons. The establishment of sustainable production systems based on cactus pear may contribute to food security of populations in agriculturally marginalized areas and to soil improvement (Nefzaoui et al., 2014). Opuntia species have developed phenological, physiological and structural adaptations for growth and survival in arid environments where severe water stress hinders the survival of other plant species. Among these adaptations, the asynchronous reproduction and CAM metabolism of cactus stands out, which combined with structural adaptations such as succulence, allow them to continue the assimilation of carbon dioxide during long periods of drought reaching acceptable productivity levels even in years of severe drought (Nefzaoui et al.,