Rangeland evaluation in relation to pastoralists perceptions in the middle Awash valley of Ethiopia

[摘要] Pastoralism is the most dominant land use form in the arid rangelands of Sub-Saharan Africa in which Ethiopia is not an exception. However, in Ethiopia andelsewhere, rangeland-based life-styles are in difficulty with the rangelandenvironment under threat because of both external and internal constraints. Thespatial variability of the annual rainfall in these areas also has an affect on thepastoralists livelihood. Accordingly, four studies were undertaken in twoneighbouring districts occupied by pastoralists of different ethnic groups living in themiddle Awash valley of Ethiopia with the objective of evaluating the condition of therangelands, which was related to the perception of the pastoralists in order to comeup with possible recommendations to minimize further degradation.The pastoralists perceptions of the rangeland resource were studied through groupdiscussions and by using a structured questionnaire where each household was takenas a unit of analysis (90 households from Oromo living in Kereyu-Fantale districtand 55 households from Mar living in Awash-Fantale district). The data wasanalysed using Statistical Package for the Social Sciences (SPSS). The result showedthat the average family size per household was about 6.74, with nearly 80% of thepeople without any kind of education. The main source of income for both pastoralgroups was from the sale of animals. The second source of income to the Oromo andAfar pastoralists was from the sale of crops and milk and milk by-products,respectively. Both pastoral groups reported that woody species like Cryptostegiagrandiflora, Capparis fascicularis, Erythrina abyssinica and Flueggea virosa) andherbaceous species like Tribulus terrestris, Tephrosia subtriflora and Cynodo aresources of poisons which affect their livestock production. Ninety seven and 3% ofthe Oromo respondents use Cymbopogon commutatus and Chrysopogon plumulosusfor house roofing respectively, while 38.1%, 23.0%, 10.6% and 28.3% of the Afarpastoralists use C. commutatus, C. exacavatus, Enterpogon and Sporobolus ioclados,respectively for a similar purpose. Seventy six percent of the Oromo and 77 % of theAfar respondents do not harvest grasses from the rangelands and the primary use ofwoody plants in both pastoral groups was for livestock feeding. It was indicated thatthe grazing lands were bush encroached notably with Acacia senegal, A. nubica andProsopis juliflora (Awash-Fantale district only) and the condition of the rangeland tobe in poor condition. None of the Afars and only 12% of the Oromo pastoralists hadprivate grazing lands. The majority of the respondents chose to continue withcommunal type of ownership in the grazing lands and a shortage of water was acritical constraint to the Oromo pastoralists. There is a critical shortage of livestockfeed during the dry season and the first measure taken to solve feed shortage ismigration. Unfortunately, 90% of the Oromo and 60% of the Afar respondentsreplied that migration is a bad practise. The Afar pastoralists (cattle = 20; sheep = 12;goats = 26; Camels = 15) had a higher number of livestock owned per householdthan the Oromo pastoralis (cattle = 10; sheep = 8; Goats = Il; Camels = 5).Rangeland condition in terms of grass, browse and soil parameter was studied at Ilsites in Awash- Fantale district and 10 sites iri Kereyu -Fantale district usingtechniques and/or methods mostly developed in South Africa. Grazing and browsingcapacities were also calculated for each of the rangeland sites. The most dominantgrass species-in the study districts was Chrysopogon plumulosus followed bydifferent species of Sporobolus. The percentage bare ground as estimated by thepoint method varied from 0.33 to 10.79 with a mean value of 5.27. The basal coverin both districts was low, averaging 3.35%. The DM yield of the grass rangedbetween 168.52 kg ha to 832 kg ha-I. The grazing capacity varied from as low as54.14 ha LSU-I to as high as 7.06 ha LSUI. The results of the evapotranspiration treeequivalent (ETTE ha) showed that the study districts were bush encroached with A.senegal, A. nubica and P. juliflora. In both districts, the browse production (total leafDM) ranged from as low as 194 kg ha to 3 311 kg ha-I, with most of the leaf drymass found above the height of 1.5 m. In both districts, the highest browsing capacity(ha BU-I) was contributed by A. senegal and A. nubica.The condition of the communal grazing lands was also assessed m relation tobenchmark sites. Basal cover and the DM yield of grasses was higher in thebenchmark sites (basal cover= 5.3% and DM yield of grasses = 985.7 kg ha) thanthe sample sites (basal cover = 3.3% and DM yield of grasses = 447.2 kg ha), whichindicated that given proper management, there is ample room to improve the grazingcapacity of the rangelands.With the objective of studying the effects of tree species' on grass speciescomposition, yield and some soil parameters under different grazing gradients (light,medium and heavy) in two sub-habitats (under canopy and open grassland), two treespecies (Acacia tortilis and Balanites aegyptica) were identified. The data wasanalysed using DECORANA and SAS (Statistical Analysis System). The resultsshowed that the grass species found at the heavily grazed sites were mostly annualsand less desirable species. The major difference between the medium and lightlygrazed site in grass species composition was the presence of Panicum maximumunder the canopy of trees in lightly grazed condition. The DM yield of grassimproved substantially as the grazing intensity decreased (heavy = 31l. 9 kg ha,medium = 1 607 kg ha-I and light = 2 737.5 kg ha). At the medium and lightlygrazed sites, the DM yield of grass was higher (P<0.001) under tree canopies thanthe corresponding open grasslands. Soil nutrient status increased as the grazingpressure decreased from heavy to light grazing. Electrical conductance, percentagenitrogen and organic carbon increased (P<0.01) under tree canopies compared to thecorresponding open grasslands whereas they decreased with an increase in the depth.of soil. In conclusion, all studies with different objectives and arguments clearly indicate thatthe condition of the rangelands IS poor, requiring careful and participatoryinterventions. Future studies need to distinguish between climate and man-madedroughts although droughts are a normal phenomenon in these drier areas.Rangelands in poor condition increase the intensity and frequency of climaticdroughts.

[发布机构] University of the Free State