Dataset on effects of conservation with wildlife and agriculture on plant lignin and n-alkanes components in soils

1. Nature conservation is fostered through the expansion of protected areas. This is particularly evident in Sub-Saharan Africa (SSA), where conservation is intended to simultaneously promote the recovery of megafauna like elephants. Rising numbers of megaherbivores induce woody biomass losses but restore soil organic carbon (SOC). We hypothesized that increases of SOC under conservation with wildlife in SSA go directly along with increases in the preservation of plant residues in soil organic matter (SOM), traceable by plant biomarkers such as lignin and n-alkane. In contrast, intensification with agriculture leads to a reduction of them. To test this, we sampled topsoil (0-10 cm) and corresponding plant samples along different intensities of conservation and intensification in the Zambezi Region of Namibia, comprising a) conservation sites with low, medium and high elephant densities and b) adjacent intensification sites with rangeland and cropland. We found that lignin and n-alkane patterns of the above-ground vegetation were preserved in the soil. Confirming our hypothesis, increasing SOC contents with rising elephant densities went along with increasing accumulation of lignin-derived phenols. Under conservation, lignin concentrations were influenced by the input of woody debris into the soil, traced by carbon isotopes, clay, and total woody biomass. This could not be proved for n-alkanes. Under intensification, lignin derived phenols were lower than under conservation, but again, there was no clear pattern for n-alkanes. We showed that conservation with wildlife leads to an increase of SOC, which was accompanied by an accumulation of lignin-derived phenols in the soil organic matter. Increased input of woody debris, clay content and total biomass were important parameters for this lignin accumulation. In contrast, intensification with agriculture leads to a loss of lignin. Contrary, n- alkanes were not sensitive to detect effects of conservation or intensification. We conclude that increasing incorporation of woody residues into soil is a key mechanism controlling SOC accrual and to offset losses of aboveground biomass on SOC in sites under conservation with wildlife. The dataset contains raw data of lignin and n-alkanes and related soil properties. A third sheet contains a legend with information on abbreviations.