Rangeland condition and feed resources in Metema District, North ...

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Range forage varies in quality from time to time and from place to place. Plants are most nutritious during the growth stages. Once mature, plants are subject to leaching and dilution of nutrients and reduction in nutritive value. Declines in nutrient composition and leaching are especially serious in the case of herbaceous plants (Alemayehu 2006). As plants mature, contents of crude protein, readily digested carbohydrates and phosphorus decrease, while contents of fibre, lignin and cellulose increase (Osuji et al. 1993). Most grasses and tree leaves in arid environments are low in nutritive value because of high contents of lignin and relatively indigestible (compared with starch) cellulose and hemicellulose. The plants require such substances as an adaptation mechanism to protect themselves from high temperatures and evapotranspiration. Unfortunately, these substances reduce their nutritional content and digestibility (Mathur et al. 1991). The stage of growth, maturity of grasses and taste influence their nutritional value. Mathur et al. (1991) reported that cattle kept solely on grazing mature grass exhibited loss in body weight during the dry season. The use of some roughages is also limited by their low contents of protein and digestible energy (Ncube and Mpofu 1994), especially as the season progresses. Further problems are caused by secondary factors such as antinutritive or toxic constituents in the plants, which restrict acceptability of the diet (Osuji et al. 1993; Kumar and D’Mello 1995). Crop residues are roughages that become available as livestock feeds after crops have been harvested. Residues can usually be grouped by crop type such as cereals, grain legumes, roots and tubers. Apart from being a source of animal feed, residues are also used as building, roofing and fencing materials, as fuel, and as fertilizer or surface mulch in cropland. Their value when used as feed depends on the demand from livestock owners, which varies with the overall supply and demand situation for feeds. This in turn depends on the livestock density and the supply of other feed resources, in particular forages and browse from natural vegetation (de Leeuw and Rey 1995). The supply of crop residues is a function of the proportion of land used for cropping and of the edible feed yields per unit of land, where consumable feed from the crop residues exceeds grazing from natural pastures (expressed in tonne of dry matter per hectare, t DM/ha). Depending on the production system, expansion of cropland may have a positive effect on overall feed supply 2.4 Causes of rangeland degradation Rangeland degradation may be defined as the loss of utility or potential utility or the reduction, loss or change of features of rangeland ecosystem, which cannot be replaced (Chrisholm and Dumsday 1987). In general, rangeland degradation implies a reduction in rank or status, which includes a loss of topsoil, a change to a simple floral/ 6
fauna composition or a transition from one organic form to a lower organic form, and continuous reduction of productivity/biomass of the ecosystem. Generally, a lower biological diversity is supposed to occur in a degraded rangeland. 2.4.1 Drought and shortage of rain Prolonged drought including shortage and erratic rainfall can cause serious range degradation. Rainfall during drought is hardly adequate to allow grasses to grow and unable to fill the surface water ponds (Cossins and Upton 1988). 2.4.2 Bush encroachment Overall, woody vegetation reduces grass cover through increasing competition for available water and nutrients and reducing light reaching the grass layer. In addition to competing with grasses, these noxious woody plants are commonly thorny and thicket forming and reduce the grazing capacity of the rangeland (Alemayehu 2004). From rangeland management perspective, understanding the factors that contribute to invasion process of undesirable woody vegetation is important. Many factors may be involved in bush encroachment. Overgrazing, including high stocking rates, is claimed to be the major problem and a high concentration of woody plants are found around water points where stocking densities and grazing intensities are relatively high (Cossins and Upton 1988). As reported by Archer (2003), the characteristics common to many woody species that increase in grazed environments include high seed production, seeds that persist in soil for many years, ability to disperse over long distances, ability to sprout following top removal, tolerance to low levels of water and nutrients and low palatability. A report by Alemayehu (2004) indicates that the ecological succession in the Borana rangelands of Ethiopia indicates that the potential of grassland is threatened by bush encroachment in many areas. 2.4.3 Over population and overstocking Increase in human population necessitates the increase in livestock population in rangelands in order to maintain survival. In pastoral areas of Ethiopia, the animal and human populations are growing at an increasing rate, while the pasture resource on which they depend is limited or diminishing both in terms of grazing area and range productivity (Coppock 1994). These increases in population and over stocking are increasing the imbalances in the Borana range system and have already resulted in over grazing and range degradation (Alemayehu 2004). Gamedo (2004) also reported that overgrazing has been one of the major factors for rangeland degradation in Borana and 7
Page 1 and 2: www.ipms-ethiopia.org www.eap.gov.e
Page 3 and 4: Authors’ affiliations Tesfaye Des
Page 5 and 6: 4.7 Availability of natural pasture
Page 7 and 8: Table 20. Common and dominant grass
Page 9 and 10: Abbreviations ADF ADL AEZ ANOVA ANR
Page 11 and 12: Abstract The study was conducted in
Page 13 and 14: 1 Introduction Ethiopia, with its d
Page 15 and 16: 2 Background 2.1 Livestock resource
Page 17: availability of rainfall. Alemayehu
Page 21 and 22: change. A change in plant compositi
Page 23 and 24: The four classes of range condition
Page 25 and 26: 2.8 Biomass estimation methods Biom
Page 27 and 28: are the Gumuz people. Until recentl
Page 29 and 30: Enclosures used as benchmark was se
Page 31 and 32: the distribution was assessed as fo
Page 33 and 34: samples for herbaceous species and
Page 35 and 36: The overall educational status of t
Page 37 and 38: Table 6. Mean ± SE land holding an
Page 39 and 40: Table 8. Livestock herd structures
Page 41 and 42: espectively, while 93.6, 4.3 2.1% r
Page 43 and 44: 4.7.2 Crop residues production and
Page 45 and 46: Table 13. Percentages of respondent
Page 47 and 48: than in P. spheslatum and C. ciliar
Page 49 and 50: of the respondents (69.3%) water th
Page 51 and 52: Table 20. Common and dominant grass
Page 53 and 54: owsing height of the animals. Accor
Page 55 and 56: Grazing types Herbaceous species Ca
Page 57 and 58: Table 25. Herbaceous species compos
Page 59 and 60: low density a decade ago, but curre
Page 61 and 62: 2004). Based on the results of this
Page 63 and 64: at the landscape scale; short tempo
Page 65 and 66: Soil compaction also directly restr
Page 67 and 68: Dry matter biomass 18000 16000 1400
Page 69 and 70:
i.e. 312,300 ha, about 71% is natur
Page 71 and 72:
• Transhumance production system
Page 73 and 74:
Beruk Yemane and Tafesse Mesifin, 2
Page 75 and 76:
van der Westhuizen, HC van Rensburg
Page 77 and 78:
Appendix Table 2. Criteria for the
Page 79 and 80:
Appendix Table 4. Herbaceous specie
Page 81 and 82:
Appendix Table 5. Correlation matri
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Source: IPMS (2005). Appendix Figur
Page 89 and 90:
Appendix Figure 5. Partial view of
Page 91 and 92:
Appendix Figure 9. Communal grazing
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