PRELIMINARY INVESTIGATION ON PIOSPHERE FORMATION AROUND DIP-TANK AREAS IN THE LOWVELD AND LOWER MIDDLEVELD COMMUNAL GRAZING LANDS OF SWAZILAND: 1) GRASS SPECIES DISTRIBUTION AND SOIL NUTRIENTS

Abstract

In the communal areas of Swaziland, ticks are controlled chemically through a compulsory programme of dipping cattle and livestock movement controls. These dip-tank sites can have significant ecological effects in their surrounding ecosystems. The objectives of this study were to investigate the ecological effect of dip-tanks on the surrounding grass and soil layer in the communal grazing lands of Swaziland. Three and two dip-tank sites were selected from the Lowveld (LV) and lower Middleveld (LMV) ecological zones, respectively. At each dip-tank site, a 1000 m transect was established and divided into five sub-transects at 100 m, 300 m, 500 m, 700 m, and 900 m away from the dip-tank points to record data. A total of 20 grass species were identified in both study areas. In the LV area, notable piosphere formation includes greater frequencies (P<0.05) of Brachiaria deflexa, Bothriochloa radicans and Sporobolus africanus in the further sites, and Cynodon dactylon and Eleusine coracana in the nearest sites to the dip-tank. In the LMV area, B. deflexa, C. dactylon and E. coracana responded significantly (P<0.05) to the piosphere, generally increasing with proximity to dip-tank points, while B. radicans and Urochloa mosambicensis responded conversely. Generally, in both ecological zones, highly and moderately palatable groups formed piosphere with decreasing trend in moving away from the dip-tank. Most soil nutrients did not respond to the piosphere. This study concluded that the grass and soil layer are the most important components that are most sensitive to the impact of livestock around the dip-tank areas. Certainly, not all grass species and soil variables formed piosphere in response to grazing disturbance. Those variables that responded could serve as key indicators of degradation in range monitoring. The current study also recommended that if restoration of the rangelands is intended, this should focus primarily within a radius of 300 m from the dip-tanks.