Changes in soil nutrients, vegetation structure and herbaceous biomass in response to grazing in a semi-arid savanna of Ethiopia

The effect of grazing was studied on vegetation structure, herbaceous biomass, basal and bare ground covers, together with soil nutrient concentrations in two locations in an Ethiopian semi-arid savanna. The lightly grazed sites had significantly higher herbaceous diversity, total abundance, basal c...

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Vydáno v:	Journal of arid environments Ročník 75; číslo 7; s. 662 - 670
Hlavní autoři:	Tessema, Z.K., de Boer, W.F., Baars, R.M.T., Prins, H.H.T.
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	Kidlington Elsevier Ltd 01.07.2011 Elsevier
Témata:	aboveground biomass african savanna Animal and plant ecology Animal, plant and microbial ecology Biological and medical sciences Biomass Carbon Density Dung electrical conductivity Ethiopia feces Fundamental and applied biological sciences. Psychology grasslands Grazing Grazing pressure International trade long-term middle awash valley mineralization nitrogen nutrient content Nutrients Perennial grasses phosphorus Plant abundance rangelands redistribution savannas soil Soil (material) Soil composition soil nutrients south-africa species diversity Species richness Synecology Terrestrial ecosystems Vegetation vegetation structure woody plants Woody species Ethiopia Africa Grazing pressure Soil composition Perennial grasses Woody species Plant abundance Species richness Composition Savannah Arid environment Browsing Soil structure Biomass Woody plant Soils Semi arid zone Nutrient Herbaceous plant Vegetation structure
ISSN:	0140-1963, 1095-922X
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Shrnutí:	The effect of grazing was studied on vegetation structure, herbaceous biomass, basal and bare ground covers, together with soil nutrient concentrations in two locations in an Ethiopian semi-arid savanna. The lightly grazed sites had significantly higher herbaceous diversity, total abundance, basal cover and aboveground biomass, and a lower percentage of bare ground compared with the heavy grazed sites. Grazing pressure had no effect on the density and number of woody species as well as on the proportion of encroaching woody species. The light grazing sites had higher organic carbon, phosphorus and exchangeable bases, and therefore a higher pH and higher electrical conductance, indicating an improved soil nutrient status compared with heavy grazing sites, mainly attributed to the higher basal cover and standing biomass at light grazed sites, and the export of nutrients through grazing and dung collection from the heavily grazed sites. There were significantly higher soil nutrients, species diversity, aboveground biomass and basal cover in the light grazing sites compared with heavy grazing sites. We concluded that changes in herbaceous vegetation, standing biomass and soil compositions are caused by interactions between grazing, soil and vegetation, and these interactions determine the transitions of semi-arid savannas. ► Lightly grazing had a higher herbaceous diversity, abundance, basal cover and biomass, and a lower bare ground than heavy grazing. ► Grazing pressure had no effect on the density and number of woody species, and on the proportion of encroaching woody species. ► Light grazing sites had higher soil nutrients due to higher basal cover and biomass than heavy grazing. ► Changes in herbaceous vegetation, standing biomass and soil compositions are caused by interactions between grazing, soil and vegetation. ► The interactions of vegetation and soil under influence of grazing determine the transitions of semi-arid savannas.
Bibliografie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0140-1963 1095-922X
DOI:	10.1016/j.jaridenv.2011.02.004