Degradation of communal rangelands in South Africa: towards an improved understanding to inform policy

In South Africa, the relative extent of range degradation under freehold compared to communal tenure has been strongly debated. We present a perspective on the processes that drive rangeland degradation on land under communal tenure. Our findings are based on literature as well as extensive field work on both old communal lands and ‘released’ areas, where freehold farms have been transferred to communal ownership. We discuss the patterns of degradation that have accompanied communal stewardship and make recommendations on the direction policy should follow to prevent further degradation and mediate rehabilitation of existing degraded land.Keywords: communal rangelands, land degradation, rehabilitation, social systemsAfrican Journal of Range & Forage Science 2013, 30(1&2): 57–6

Determinants of woody encroachment and cover in African savannas

Savanna ecosystems are an integral part of the African landscape and sustain the livelihoods of millions of people. Woody encroachment in savannas is a widespread phenomenon but its causes are widely debated. We review the extensive literature on woody encroachment to help improve understanding of the possible causes and to highlight where and how future scientific efforts to fully understand these causes should be focused. Rainfall is the most important determinant of maximum woody cover across Africa, but fire and herbivory interact to reduce woody cover below the maximum at many locations. We postulate that woody encroachment is most likely driven by CO2 enrichment and propose a two-system conceptual framework, whereby mechanisms of woody encroachment differ depending on whether the savanna is a wet or dry system. In dry savannas, the increased water-use efficiency in plants relaxes precipitation-driven constraints and increases woody growth. In wet savannas, the increase of carbon allocation to tree roots results in faster recovery rates after disturbance and a greater likelihood of reaching sexual maturity. Our proposed framework can be tested using a mixture of experimental and earth observational techniques. At a local level, changes in precipitation, burning regimes or herbivory could be driving woody encroachment, but are unlikely to be the explanation of this continent-wide phenomenon

Wastewater management systems o f tourism establishments in the Okavango Delta

This study was carried out to establish an inventory of wastewater  management systems in the delta and to evaluate their performance in achieving expected effluent quality standards. The study established that the most common method of wastewater treatment and disposal for permanent lodges/camps in the delta was septic tank with soakaway, constituting 77.5 percent of all wastewater management systems. The study also established that the installed septic tank with soakaway systems do not meet the theoretical efluent quality expected from such systems,nor the national efluent quality for disposal into the environmellf. The study recommends criteria for selection of a wastewater management technology that coulll be used in the Okavango Delta to minimize pollution risk.Key words: Wastewater, Okavango, Delta, effluellf, quality, septic ta

Landscape Suitability in Botswana for the Conservation of Its Six Large African Carnivores

<div><p>Wide-ranging large carnivores often range beyond the boundaries of protected areas into human-dominated areas. Mapping out potentially suitable habitats on a country-wide scale and identifying areas with potentially high levels of threats to large carnivore survival is necessary to develop national conservation action plans. We used a novel approach to map and identify these areas in Botswana for its large carnivore guild consisting of lion (<i>Panthera leo</i>), leopard (<i>Panthera pardus</i>), spotted hyaena (<i>Crocuta crocuta</i>), brown hyaena (<i>Hyaena brunnea</i>), cheetah (<i>Acinonyx jubatus</i>) and African wild dog (<i>Lycaon pictus</i>). The habitat suitability for large carnivores depends primarily on prey availability, interspecific competition, and conflict with humans. Prey availability is most likely the strongest natural determinant. We used the distribution of biomass of typical wild ungulate species occurring in Botswana which is preyed upon by the six large carnivores to evaluate the potential suitability of the different management zones in the country to sustain large carnivore populations. In areas where a high biomass of large prey species occurred, we assumed interspecific competition between dominant and subordinated competitors to be high. This reduced the suitability of these areas for conservation of subordinate competitors, and vice versa. We used the percentage of prey biomass of the total prey and livestock biomass to identify areas with potentially high levels of conflict in agricultural areas. High to medium biomass of large prey was mostly confined to conservation zones, while small prey biomass was more evenly spread across large parts of the country. This necessitates different conservation strategies for carnivores with a preference for large prey, and those that can persist in the agricultural areas. To ensure connectivity between populations inside Botswana and also with its neighbours, a number of critical areas for priority management actions exist in the agricultural zones.</p></div

Dung beetle assemblage structure across the aridity and trophic resource gradient of the Botswana Kalahari: patterns and drivers at regional and local scales

Understanding pattern and process at both regional and local scales is important for conservation planning although such knowledge of insects is frequently lacking. To assess patterns along a regional gradient of increasing aridity and diminishing food resources in the Botswana Kalahari, Scarabaeine dung beetles were sampled quantitatively using four dung types at three local sites in six regional areas. At regional scale, factor analysis of species abundance extracted a maximum of six factors, each dominated by a single area. Therefore, the statistical significance of regional spatial variation far outweighed that of dung type association. At local scale, six factor analyses of species abundance extracted from four to six factors. The importance of local dung type associations was relatively high but diminished with increasing local spatial heterogeneity. At regional scale, hierarchical analysis of oblique factors divided assemblages into unique local and shared regional components. Primary extended factors accounted for 40–50 % of unique local faunal composition in five out of six areas. Two secondary extended factors showed either high shared proportional contribution to regional assemblage structure in the northeast with a steep decline to the southwest, or an opposite trend. Their point of intersection was consistent with a boundary zone between mesic northeast and arid southwest faunal components in the central Kalahari. Despite some inconsistencies in rank position between regression methods, rainfall, temperature, and mammal density/diversity were the strongest influences on regional patterns defined by secondary factors. Patterns are discussed according to conservation and changes in land usage around reserves.The GEF-Small Grant Programme and the University of Pretoriahttp://www.springerlink.com/content/100177/hb2013ab201

Termite mounds mitigate against 50 years of herbivore-induced reduction of functional diversity of savanna woody plants

Context: Spatially heterogeneous habitats often promote woody plant species and functional diversity (FD). Ungulate herbivory can have the opposite effect. Across the globe, the type and intensity of herbivory is changing, as domestic livestock replace wild ungulates, which are increasingly confined to protected areas. Despite recognition of the importance of FD for ecosystem functioning, the interactive effect of soil-related fine-scale heterogeneity and larger-scale ungulate herbivory on woody plant FD is little-known.\ud \ud Objectives: In miombo woodland of Zimbabwe, we investigated (1) how bottom-up fine-scale heterogeneity created by Macrotermes termitaria interacts with top-down effects of herbivore foraging-guilds on woody plant FD; and (2) whether browsing combined with grazing impacts FD more than grazing alone.\ud \ud Methods: The three different herbivore treatments (grazing, combined browsing-and-grazing, and exclusion) had been maintained for 50 years. We surveyed 10 termite mound-matrix plots within three sites per treatment. We assessed woody plant traits and FD across treatments (herbivore feeding-guild) and position (mound or woodland-matrix), and interactive effects between these.\ud \ud Results: Woody plant FD was greater on mounds, and lowest overall with browsing-and-grazing. Specific traits were associated with position (e.g. palatability was greater for mounds), and treatment (e.g. spinescence increased with grazing).\ud \ud Conclusions: Long-term enclosure of ungulate herbivores (browsing-and-grazing, and grazing alone) decreased woody FD, but this was mitigated by termitaria. The novel finding is that at regional scales, mounds can enhance woody plant FD despite the impacts of herbivory. At broader scales encompassing the miombo system, potential exists for mounds to stabilise woody plant FD from livestock-induced impacts