Effects of controlled grazing on a degraded dwarf shrub, annual grass semidesert vegetation type of northwestern Kenya
✍ Scribed by G. Oba
- Book ID
- 102927320
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 930 KB
- Volume
- 3
- Category
- Article
- ISSN
- 1085-3278
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✦ Synopsis
A degraded dwarf shrub, annual grass semidesert vegetation type in Turkana, northwestern Kenya, was protected from livestock grazing from October 1985 to December 1990. The effects of controlled grazing on plant cover, litter cover and bare ground were monitored to appraise the trend in range condition using grazed transects (GT) and ungrazed transects (UGT). Despite an initial increase, plant cover on the UGT deteriorated in a similar manner to that on the GT. At the conclusion of six years of protection, the cumulative mortality of Indigofera cliflordiana on the UGT exceeded 60 per cent whereas on the GT it was 6 per cent. Furthermore the density of I . cliflordiana on the protected area decreased whereas that on the GT remained substantially unchanged. Aristida mutabih replaced 1. cliflordiana on the UGT but showed little change on the grazed area. Sedera hirsuta disappeared from the GT. On the UGT the percentage of bare ground, despite an initial decline (39.3 7.3 per cent), increased substantially (68.9 f 15.7 per cent) in parallel with the GT (77.3 4.7 per cent). The results contradict a commonly held view that land degradation only occurs when plants are overused. The findings suggest that degradation can occur in the absence of grazing, especially if the plant species involved are dependent on perturbation. As over-resting eliminates I . cligordiana, it seems judicious to allow a 2-3 year deferral period followed by moderate grazing if it is to be optimally managed.
KEY WORDS Aristida mutabih Degradation Dwarf shrubs Indigofera cliflordiana Range conditions and trends
Semidesert Northwestern Kenya 0898-58 1 2/92/O40199 -15% 1 2.50