How does agro-pastoralism affect forage and soil properties in western Serengeti, Tanzania?

Abstract

The impacts of agro-pastoral activities on soil properties, plus nutritive value and residual standing biomass of herbaceous plants in areas of different land uses in western Serengeti, were evaluated. Vegetation and soil were sampled along 4,000 m transects laid across fallow land, areas grazed only by livestock, mixed grazing (livestock and wildlife) and wildlife grazing only. A total number of 123 plant species were encountered during sampling. Analyses of soil and vegetation samples were conducted at Sokoine University of Agriculture laboratories. The estimated average density of grazing animals encountered was 160 TLU/km2 on transects within livestock-dominated grazing lands, 129 TLU/km2 for mixed grazing and 83 TLU/km2 for wildlife grazing only. Results indicated that ADF, IVDMD, IVOMD, ME and TDN in residual herbaceous forage at flowering were significantly (P<0.05) affected by land use type but CP, NDF and ADL were not affected. Soil pH, OC, CEC, C:N ratio and Ca differed significantly (P<0.05) between land use types. An overall evaluation indicated that regardless of climatic conditions, residual biomass of herbaceous plants in western Serengeti is determined by intensity of grazing, soil C:N ratio and concentrations of Ca and P in the soil. We conclude that agro-pastoral practices conducted in western Serengeti affected residual standing biomass of herbaceous plants and soil properties. We recommend that grazing pressure in communal grazing lands be reduced by either reducing number of grazing animals or duration of grazing in a particular grazing area, and specific studies be conducted to establish stocking rates appropriate for specific communal grazing lands in villages.

Repercussions of Agro-Pastoralism on Soil Condition in Western Serengeti, Tanzania

“…However, variation in soil pH occurred across soil depth with low soil pH occurring in subsurface soils. This indicates that spatial distribution of shallow rooted plants like herbaceous plants in western Serengeti is determined by other factors such as soil texture [31]. Likewise, soil pH was spatially moderately heterogeneous implying that variation of soil pH in the study area was influenced by soil structure and random factors [63].…”

“…Contrary to the increase in soil pH due to high grazing density, our study showed that increase in grazing density caused a decrease in soil pH which agrees with few studies reported by Hiernaux et al [26], Cui et al [12] and Zhang et al [65] who conducted studies in sandy soils in semi-arid lands. The reason for this phenomenon could be our study was conducted in area dominated with sandy clay soils [31]. Furthermore, high grazing animals' density subjected sandy soil to erosion and removal of exchangeable bases by water runoff leaving high concentration of hydrogen ions that increased soil acidity.…”

Interaction of Grassland Ecosystem with Livelihood and Wildlife Sustainability: Tanzanian Perspectives

“…The dominant grass species in the drylands of central Tanzania include Cenchrus, Aristida, and Heteropogon. These grasses normally grow in association, and the establishment pattern of herbaceous plants is generally determined by the environment and soil texture [13]. Hyparrhenia, Hyperthelia, and Pennisetum polystachyon tall grass are common in the miombo woodlands of western Tanzania.…”

“…Population trends in Figure 7 indicate that livestock increased continuously from 1995, possibly due to an increase in demand for livestock products that resulted from the increase in the human population. It has been reported that there is a close relationship between increases in cattle and growth in the human population that result from the need for livestock products to cater to the growing human population [26]. However, livestock in grasslands increases typically at the expense of wildlife [26].…”

“…It has been reported that there is a close relationship between increases in cattle and growth in the human population that result from the need for livestock products to cater to the growing human population [26]. However, livestock in grasslands increases typically at the expense of wildlife [26]. Many studies show that markets, technology, and infrastructure development, the position of a rangeland/grassland on its production possibility frontier (PPF), changes with agricultural production becoming specialized, driving down the possibilities for wildlife production [27][28][29][30][31].…”