Ecological impact of large herbivores on the woody vegetation at selected watering points on the eastern basaltic soils in the Kruger National Park

Abstract

A lack of quantitative data on the impact of large herbivores on woody vegetation around watering points in the Kruger National Park gave rise to an in depth study. This paper reports on trends found at two artificial watering points on the basaltic soils in the Satara Land System. As a result of the almost complete lack of woody individuals in the immediate vicinity of the watering points, this area could be described as a ‘sacrifice area’. Shrub density increased with distance from the watering point, with the impact of large herbivores on shrub density extending up to 2.8 km. The practice of providing artificial water in troughs at windmills in the Kruger National Park causes the formation of a multiple ‘piosphere’ effect, with the existence of a zone of high utilization in woody vegetation extending far beyond the sacrifice area.

Tree cover and biomass increase in a southern African savanna despite growing elephant population

“…Both trends, therefore, suggest that the first 12-year period of water provision has had no measurable effect on vegetation structure dynamics within the immediate influence zones of the AWPs. These findings are in contrast with the general assumption, and our hypothesis, that water provision leads to a decrease of tree density, browse availability, and/or tree height in the influence range of AWPs due to year-round browsing pressure (see, for instance, Brits et al 2002, Chamaille´-Jammes et al 2007, Smit et al 2007a, Holdo et al 2009). …”

“…To the best of our knowledge this is the first study comparing vegetation structure dynamics around seasonal pans and AWPs that included baseline data from soon after the opening of AWPs (sensu Brits et al 2002). After 12 years of providing drinking water to waterdependent animals, we found a clear increase of tree density, cover, and canopy volume.…”

“…Establishment of these AWPs transformed this area from waterlimited to food-limited for water-dependent animals (Andrew 1988, Chamaille´ -Jammes et al 2007). Increased and year-round browsing pressure, particularly from elephants, is expected to reduce tree density and height within the influence zones of these AWPs (Ben-Shahar 1993, Brits et al 2002. No significant changes were found in the vegetation composition or biomass within the first three years after the AWPs were made operational (Winterbach and Kalwij 2000).…”

Risk factors associated with the prevalence of tuberculosis-like lesions in fenced wild boar and red deer in south central Spain

“…Watering sites may also concentrate mating behaviour and brushing at the end of the summer in red deer [4]. In addition, the practice of providing artificial water at these sites may cause the formation of a multiple "piosphere" effect, which consists in the existence of a zone of high ungulate utilisation in woody vegetation extending far beyond the area [2], and subsequently, an increased risk of indirect transmission. Models for each species suggest that interspecific indirect transmission at these sites is probably more likely to occur from the wild boar to red deer.…”

Contrasting responses of two passerine bird species to moose browsing

“…The overall moose density in the municipality varies between 1.1-3.4 moose per km 2 (Gundersen et al 2004;Storaas et al 2005), but in winter the effective moose density may be many times higher in the vicinity of feeding stations. High moose densities at feeding stations may be comparable to concentrations of large herbivores around waterholes or salt-licks (Brits et al 2002;Miller and Litvaitis 1992), or areas with extremely high densities due to population increase (Côté et al 2004;Garrott et al 1993;McShea et al 1997).…”