Oecologia (2011) 165:1095–1107 (mainly cattle) ranching was practiced from the early 1900s until about 1970. Since then, wildlife has been the domi- nant land-use form. During the livestock era, livestock were kept in enclosures (known as ‘kraals’ in South Africa; ‘bomas’ in East Africa) at night to safeguard the animals against predation and theft. The outcome was that nutrients accumulated in kraals as a result of the high deposition of nutrients (taken up while grazing during the day) in the form of dung and urine (Blackmore et al. 1990; Augustine 2003). After the change in land-use, the former kraal sites remained as nutrient hotspots in the landscape (Blackmore et al. 1990; Augustine 2003). In this paper, we compare the current soil nutrient status and vegetation structure of kraal sites with nearby control sites located in the surrounding landscape. The main objectives were to test (1) whether the effects of nutrient enrichment created by large herbivores (managed livestock) were still detectable in the soil and vegetation decades after abandonment; (2) if this higher nutrient status feeds back to enhanced vegetation produc- tivity, forage quality and herbivore use, which characterize enhanced nutrient cycling in other systems (Bardgett and Wardle 2003); (3) if the clearing of the woody component that obstructs visibility inﬂuences nutrient redistribution by herbivores such as impala, which may explain the main- tenance of high nutrient concentrations in kraals if these prove to remain structurally open over time (Blackmore et al. 1990; Augustine 2004); (4) if woody plants have invaded kraal sites after these were abandoned; and (5) if the competitive effect of grasses on tree seedlings increases under fertile conditions as hypothesized by Sankaran et al. (2008). Lastly, we propose a conceptual diagram on the interplay between nutrient availability, tree–grass compe- tition and herbivores to integrate these results and to explain how the vegetation structure of abandoned kraals may be maintained in savannas. Materials and methods Study area and selection of study sites The study was carried out in the Associated Private Nature Reserve (APNR), consisting of the Timbavati, Klaserie, and Umbabat Private Nature Reserves and the Balule Nature Reserve (24 030–24 330S, 31 020–31 290E), which covers an area of more than 1,700 km2. The APNR is sit- uated in the South African Lowveld, and abuts the Kruger National Park (KNP) in the east. In the APNR, commercial livestock farming (mainly cattle) was widely practiced during the ﬁrst half of the twentieth century, but proved uneconomical due to poor market access, predator prob- lems (mainly lion), and the high prevalence of tick-borne diseases. Around 1970, livestock ranching was ﬁnally 1097 abandoned and wildlife-related enterprises became the dominant land-use form. Game fences separating individ- ual reserves and the KNP were removed by 1993, enabling wildlife to move freely between the conservation areas (Bigalke 2000). Large herbivore species occurring in the APNR includes African elephant Loxodonta africana, gir- affe Giraffa camelopardalis, African buffalo Syncerus caffer, zebra Equus burchelli, blue wildebeest Conno- chaetes taurinus, kudu Tragelaphus strepsiceros, water- buck Kobus ellipsiprymnus and impala Aepyceros melamphus. Predators include lion Panthera leo, leopard Panthera pardus and spotted hyena Crocuta crocuta. Soils in the APNR are mainly derived from weathered granite and gneiss (Venter et al. 2003), and the availability of nutrients such as N and P are generally low (Treydte et al. 2007), but heterogeneously distributed in the landscape (Grant and Scholes 2006; Treydte et al. 2007). In the study area, the mean annual precipitation ranges between 450 and 600 mm. A well-developed woody layer includes species such as Sclerocarya birrea, Acacia nigrescens, Combretum apiculatum and Colophospermum mopane. The herbaceous layer includes grass species such as Uro- chloa mosambicensis, Bothriochloa radicans, Digitaria eriantha, Panicum maximum, Heteropogon contortus and a wide variety of forb species. Fires in the APNR are con- trolled and generally exceed a ﬁre return period of 3 years. Plant nomenclature follows Gibbs Russell et al. (1990) for grasses and Coates Palgrave et al. (2002) for trees. Mam- mal nomenclature follows Kingdon (1997). Nine deserted kraal sites with paired controls were selected in the APNR. Kraal sites (10–30 m diameter) were identiﬁed in the ﬁeld by residents with knowledge of the layout of former farming infrastructures. The presence of old fencing material such as fencing posts and wire con- ﬁrmed the locations of these former kraal sites. The mid- points of control sites were located at a 200-m distance from kraal midpoints, and were chosen at the same topo- graphical position in the landscape as kraal sites to minimize the confounding effect of topography on kraal– control comparisons. The study was conducted during the wet season from November 2006 to March 2007. Soil collection and analyses To contrast the fertility of kraal soils with that of the sur- rounding soils, we analyzed soils sampled in kraal and control sites. At each site, about 30 kg of topsoil (0–15 cm depth) was collected at six random locations per site, pooled, sieved and thoroughly mixed. Sub-samples were chemically analyzed by the Agricultural Research Council in Nelspruit, using standard procedures (Anonymous 1990). For the analyses, cations were extracted with ammonium acetate, aluminium was extracted with KCl and 123