LBBE

Pastoralism and agriculture have affected rangeland ecosystems over the past millennia, including many ecosystems that are currently protected as reserves. However, the legacy of these land-use practices on current ecosystem functioning remains unclear. We studied legacy effects of former human land use on soil physical and chemical properties in a South African savanna. We did this by comparing soil properties in grazing lawns (patches of short grass maintained by the positive feedback between grazing intensity and forage quality) with the surrounding less grazed bunch grasslands within three different human land use history contexts: (i) Abandoned bomas: permanent stone enclosures where livestock were kept overnight and dung and urine accumulated for several years or decades. (ii) Old fields: areas where vegetation was cleared, soil tilled and cultivated, but received little or no fertilisation. (iii) Natural grasslands: not cultivated but grazed by livestock before the establishment of the reserve and wildlife thereafter. Former human land-use rather than soil texture was the main determinant of grazing lawn location. Moreover, lawn soil properties also varied among land-use histories. In all grazing lawns, soil nutrient concentrations were higher than in adjacent grasslands but abandoned bomas contained three times more phosphorus, and twice as much nitrogen and carbon than old field and natural grassland lawns. In addition to past land-use, soil texture influenced lawn soil nutrients: Concentrations of phosphorus, potassium, calcium, magnesium, total nitrogen and carbon in lawns were higher on clayey soils than sandy soils, whereas phosphorus, C:N ratio and pH did not change with soil texture. Our study confirms previous findings on the effect of human land-use on savanna heterogeneity, but also highlights how legacy effects may vary among different historic land-use practices.

Newcastle disease (ND) is one of the most important and widespread avian pests. In Africa, backyard poultry production systems are an important source of protein and cash for poor rural livelihoods. ND mortality in these production systems is important and seriously disrupts benefits derived from it. This study undertook an African continental approach of ND epidemiology in backyard poultry. After a systematic literature review of studies published from 1980 to 2009, a meta-analysis of spatio-temporal patterns of serological prevalence and outbreak occurrence was performed. Average ND serological prevalence was estimated at 0 . 67 [95 % confidence interval (CI) 0 . 58-0 . 75] in regions characterized by humid ecosystems, high human and poultry densities and low altitudes; 0 . 36 (95 % CI 0 . 30-0 . 41) in dry ecosystems at intermediate altitude where human and poultry densities are low and 0 . 27 (95 % CI 0 . 19-0 . 38) in mountain ecosystems where human and poultry densities are intermediate. In terms of seasonality, ND outbreaks occur mostly during the dry seasons in Africa, when environmental conditions are likely to be harshest for backyard poultry. In addition, a phylogeographical analysis revealed the regionalization of ND virus strains, their potential to evolve towards a higher pathogenicity from the local viral pool and suggests a risk for vaccine strains to provide new wild strains. These results present for the first time a continent-wide approach to ND epidemiology in Africa. More emphasis is needed for ND management and control in rural African poultry production systems.

In this study we describe and calibrate a quantitative index method to estimate leaf biomass and forage availability for browsers at different feeding heights. The method is based on an index relating leaf biomass to a number of leaf contacts with a vertical, three-dimensional (25·25·165 cm) metallic quadrat with a central rod and takes into account the characteristics of leaves (shape, size, and thickness) to define plant categories and then produce general allometric equations per category. We then discuss the use of this biomass index to evaluate the quality of habitats for browsers in terms of food resources.

Pastoralism and agriculture have affected range- land ecosystems over the past millennia, including many ecosystems that are currently protected as reserves. However, the legacy of these land-use practices on current ecosystem functioning remains unclear. We studied legacy effects of former human land use on soil physical and chemical properties in a South African savanna. We did this by comparing soil properties in grazing lawns (patches of short grass maintained by the positive feedback between grazing intensity and forage quality) with the sur- rounding less grazed bunch grasslands within three different human land-use history contexts: (i) Abandoned bomas: permanent stone enclosures where livestock were kept overnight, and dung and urine accumulated for several years or decades. (ii) Old fields: areas where vegetation was cleared, soiltilled, and cultivated, but received little or no fer- tilization. (iii) Natural grasslands: not cultivated but grazed by livestock before the establishment of the reserve and wildlife thereafter. Former human land use rather than soil texture was the main deter- minant of grazing lawn location. Moreover, lawn soil properties also varied among land-use histories. In all grazing lawns, soil nutrient concentrations were higher than in adjacent grasslands but aban- doned bomas contained three times more phos- phorus, and twice as much nitrogen and carbon than old fields and natural grassland lawns. In ad- dition to past land use, soil texture influenced lawn soil nutrients: Concentrations of phosphorus, potassium, calcium, magnesium, total nitrogen, and carbon in lawns were higher on clayey soils than sandy soils, whereas phosphorus, C:N ratio, and pH did not change with soil texture. Our study confirms previous findings on the effect of human land use on savanna heterogeneity, but also high- lights how legacy effects may vary among different historic land-use practices.

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Body mass is often considered as a good indicator of body condition of individuals in ungulates, hence of their fitness, and thus, may be used as an index to monitor the status of populations subject to harvesting schemes. Here, we report the influence of annual rainfall (a proxy for primary production) and habitat on the body mass of impala in a population cropped for meat in a communal area of Zimbabwe. We analyzed the data from 2 contrasted years for rainfall, in two different habitats. In the good year (i.e. high annual rainfall) impala were heavier than in the poor year, and adult females seemed to be less affected than males by variation in primary production. We show that adult males were suffering from a seasonal decrease in body mass, supposedly linked to the rut, particularly in good habitat Overall, the habitat effect appeared to be dominated by the rainfall effect, and this may be due to the very high animal densities in the good habitat, i.e. fast resource depletion. Our results also suggest that males (juvenile and adult) are more susceptible to changes in food resource abundance and quality than females, which supports previous studies on sexually dimorphic and polygynous species.