Table 3 A comparison between control (n = 9) and kraal sites (n = 9) of the dung pile deposition rates (dung piles ha-1 day-1) of large herbivore species Species Numbers Dung pile deposition rate (piles ha-1 day-1) Mean dung pile mass (g) % N in dung Dung N deposition rate (g N ha-1 day-1) In addition, the nitrogen deposited in dung is calculated for control and kraal sites from mean dung pile weights and mean dung N concentration per species. Animal census numbers for a total helicopter count in 2006 of the area where six kraal-control site pairs were located are also given. No dung was recorded in control sites for kudu and wildebeest. Means ± SE are given Signiﬁcance levels *** P \ 0.001, ** P \ 0.01, * P \ 0.05, ns P C 0.05 Oecologia (2011) 165:1095–1107 1.73 2.27 2.30 1.84 2.08 1.66 1.17 1.15 1.24 1.16 Control 0.61 0.01 0.04 0.00 0.68 0.05 2.01 0.21 0.00 0.18 3.97 Kraal 12.36 0.14 0.97 0.35 2.66 0.09 9.81 0.67 0.10 4.39 31.54 1102 Impala Steenbok Duiker Kudu Giraffe Warthog Elephant Buffalo Wildebeest Waterbuck Total 7,649 – – 385 320 163 569 1,657 102 95 Control 1.2 ± 1.5 0.1 ± 0.1 0.2 ± 0.1 0.0 0.1 ± 0.1 \0.1 ± 0.1 0.5 ± 0.3 0.1 ± 0.1 0.0 0.1 ± 0.1 Kraal 24.7 ± 20.1 0.9 ± 1.2 4.4 ± 3.2 0.1 ± 0.2 0.4 ± 0.6 \0.1 ± 0.1 2.2 ± 1.9 0.3 ± 0.5 \0.1 ± 0.1 1.9 ± 2.2 P *** * *** – ns ns ns ns – *** 28.8 6.6 9.6 172.9 289.5 116.3 384.0 221.2 186.0 199.8 Fig. 1 The effect of fertilization on Colophospermum mopane tree seedling survival. The proportion of tree seedlings that survived 4 months after transplantation into the ﬁeld in areas fertilized at 0, 1.2, 6.0 and 30.0 g N m-2. Signiﬁcant differences (P \ 0.05) from control survival are indicated with asterisks above fertilizer rate treatments. The seedlings (n = 144) were planted after a 58-mm rain event in December 2006, taking care that the grass layer was minimally disturbed. Mortalities occurred during a mid-season drought in January 2007, when only 28 mm was recorded. Error bars indicate 95% conﬁdence limits competing with grasses (Fig. 2). Likewise, stem diameter RCI increased with increasing inorganic N. The RCI values for seedling height and aboveground biomass showed positive trends (Fig. 2), but these were not sta- tistically signiﬁcant (P [ 0.05). 123 Discussion We assumed that the soil nutrient differences between kraal and control sites were initiated by livestock management and not by other determinants of soil fertility, i.e., geo- logical parent material (e.g., granite vs gabbro in the study area; Venter et al. 2003) and other biotic agents such as termites (Grant and Scholes 2006) or large trees (Ludwig et al. 2004). The boundaries of kraal sites were still clearly visible in terms of plant species composition, structure and herbivore activity, which were conﬁrmed to align with former kraal perimeter structures. This suggests that her- bivores were the primary cause of the observed soil fertility differences: initially by penning livestock at night and evidently thereafter by free-ranging wild herbivores. Our data provide evidence that large herbivores may inﬂuence the structure of savanna vegetation indirectly via control over soil nutrient availability. We propose that the observed patterns reﬂect soil–plant–herbivore feedbacks (Fig. 3). Management of livestock in the study area left behind a legacy of nutrient hotpots after livestock were removed. On average, the availability of elements such as P was 25-fold higher in kraal than in control soils about 40 years after abandonment. This is similar to the 19-fold increase in extractable P found in boma compared to bushland sites in Laikipia, Kenya (Augustine et al. 2003). Our hypothesis is that this resulted in locally enhanced sward productivity and quality, which attracted wild her- bivores. In turn, we suggest that wild herbivores may have maintained, or possibly even increased, local nutrient