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Phosphorus (P) is a key limiting nutrient in tropical and subtropical soils but with unknown responses to climate change. We hypothesized that storage and distribution of P pools differ between reference soil groups, but P availability increases with an increase in precipitation in native sub‐Saharan Africa, an underrepresented region in the global P database. To test these hypotheses, we sampled topsoils (0–10 cm; Arenosols, Lixisols, Acrisols) of uncultivated Savannah woodlands along climate gradients stretching from Mozambique to Zambia. Mean annual precipitation (MAP) ranged from 365 to 1227 mm. We extracted P fractions using Hedley's sequential fractionation, yielding resin‐exchangeable P, P in 0.5 M NaHCO3, 0.1 M NaOH, 1 M HCl and aqua regia. Extracts were analysed for total P using inductively coupled plasma–optical emission spectroscopy and inorganic P using the colorimetric molybdenum blue method. We found that total P contents were highest in Acrisols (235 ± 76 mg kg−1), followed by Lixisols (214 ± 45 mg kg−1) and Arenosols (133 ± 74 mg kg−1). Beside P storage, also P distribution differed between soils. Mean annual temperature (MAT) did not reveal significant correlations with P fractions. However, with increasing MAP, concentrations of almost all P pools increased; available Pi (Resin‐P) increased significantly in Arenosols while potentially bioavailable P (NaHCO3‐Po) increased in all soils, with MAP explaining 43% of data variability in Arenosols, 74% in Lixisols and 85% in Acrisols. Hence, P availability increased with an increase in MAP to different degrees, that is, climatic effects on P dynamics were soil‐group‐specific. Therefore, different regions in the native sub‐Saharan woodlands are likely prone to different soil fertility responses when climate changes. [ABSTRACT FROM AUTHOR]

Nature conservation and restoration in terrestrial ecosystems is often focused on increasing the numbers of megafauna, expecting them to have positive impacts on ecological self‐regulation processes and biodiversity. In sub‐Saharan Africa, conservation efforts also aspire to protect and enhance biodiversity with particular focus on elephants. However, elephant browsing carries the risk of woody biomass losses. In this context, little is known about how increasing elephant numbers affects carbon stocks in soils, including the subsoils. We hypothesized that (1) increasing numbers of elephants reduce tree biomass, and thus the amount of C stored therein, resulting (2) in a loss of soil organic carbon (SOC). If true, a negative carbon footprint could limit the sustainability of elephant conservation from a global carbon perspective. To test these hypotheses, we selected plots of low, medium, and high elephant densities in two national parks and adjacent conservancies in the Namibian component of the Kavango Zambezi Transfrontier Area (KAZA), and quantified carbon storage in both woody vegetation and soils (1 m). Analyses were supplemented by the assessment of soil carbon isotopic composition. We found that increasing elephant densities resulted in a loss of tree carbon storage by 6.4 t ha−1. However, and in contrast to our second hypothesis, SOC stocks increased by 4.7 t ha−1 with increasing elephant densities. These higher SOC stocks were mainly found in the topsoil (0–30 cm) and were largely due to the formation of SOC from woody biomass. A second carbon input source into the soils was megaherbivore dung, which contributed with 0.02–0.323 t C ha−1 year−1 to ecosystem carbon storage in the low and high elephant density plots, respectively. Consequently, increasing elephant density does not necessarily lead to a negative C footprint, as soil carbon sequestration and transient C storage in dung almost compensate for losses in tree biomass. [ABSTRACT FROM AUTHOR]