Get reliable science

This paper set out to analyse time-series and spatial livestock data in the arid west of Namibia over a period of 11 years. These were interpreted in the context of rainfall conditions and access to water points and encompass communally and commercially managed rangelands. The study showed that stock densities maintained by both, communal and commercial farmers, were remarkably lower than estimated national-level carrying capacities for these rangelands. In the arid communal areas (50-100 mm annual rain), these hovered on average around 1 kg ha-1, increasing to 4 kg ha-1 at 100-200 mm rain and to 8 kg ha-1 in the 200-300 mm annual rain bracket in commercial areas. Stock densities showed no statistical correlation to annual rainfall, but grazer-browser ratio did in communal areas. Although the spatial analysis showed shortcomings, some general trends--to be considered hypotheses for further testing--were evident in these arid rangelands: - Available grazing rather than access to water appeared to limit stock densities, particularly in the drier areas, since the number of water points was not statistically correlated with stock density.- Overall, stock densities in commercial areas were less affected by annual rainfall over the observed period than in the communal areas.- A shorter-term response to annual rainfall was indicated in the communal areas, compared to the commercial farming areas. This indicates that communal farmers adopted an opportunistic management strategy and effectively rested rangelands after a below-average rain year by reducing stock densities.- The shorter-term response strategy was also reflected in greater changes in grazer-browser ratio over time in the communal areas.- Equally, shorter-term responses followed a good season in communal areas by an increase in livestock numbers.- This shorter-term response strategy in communal areas could result in high stock densities coinciding with a poor rainy season, if a good season and the parallel increase in stock densities, is immediately followed by a poor season.