The effects of a deferred grazing system on rangeland vegetation in a north-western, semi-arid region of Tanzania
AbstractThe present study assessed the effects of deferred grazing management on rangeland condition using aboveground biomass, vegetation cover and species composition as indicators of range condition. The experiment was based on traditionally conserved exclosures (ngitili). Data were collected in Shinyanga rural and Meatu districts, Tanzania, from October to November 2011. Five grazing strategies were compared: old private ngitili, young private ngitili, old communal ngitili, young communal ngitili and continuously grazed land. Aboveground biomass was significantly higher in old private ngitili than continuously grazed land, but there was no significant difference in amount of biomass between communal ngitili and continuously grazed land. The mean percentage basal cover was significantly higher in ngitili than continuously grazed land. The duration of protection (old ngitili compared with young ngitili) was not found to have any significant influence on both aboveground herbaceous biomass production and basal cover. The Shannon–Wiener index and Simpson index of diversity revealed no significant differences in species diversity among the different strategies. Both the continuously grazed land and communal ngitili were generally in poor condition and a special rehabilitation programme for improvement of these fragile grazing lands should be investigated.
Keywords: biomass, grazing management, ngitili, species diversity, vegetation cover
African Journal of Range & Forage Science 2013, 30(3): 141–148