Degradation of communal grazing land vegetation is a widespread problem throughout Sub- Saharan Africa and its restoration is a challenge for the management of many semi-arid areas. This study assessed the effectiveness of different age (young versus old) exclosures on species composition and diversity, biomass production and woody structure in northern Ethiopia. The species composition and diversity of herbaceous and woody plants was higher in the exclosures than in the grazed areas. The mean aboveground biomass measured inside the exclosures was more than twice that of the adjacent grazed areas and more biomass was produced from the young than the old exclosures. The study showed that degraded semi-arid vegetation is able to recover in a relatively short time when protected. Extended protection, however, reduces herbaceous species diversity and biomass. Therefore, it is suggested that a slight shift in management where exclosures protected for longer periods may be moderately used by livestock.
International Journal of Water Resources and Arid Environments