Termites as vectors for the lateral movement of elements in the landscape: Their influence on nutrient cycling and landscape heterogeneity

Common landscape features of the Fynbos and Succulent Karoo biomes in southwest Africa are large, salt-enriched soil mounds ( heuweltjies ) inhabited by Microhodotermes viator termites. The role of termites in mound formation has become evident, but the input of elements by M. viator in mound soils has not been quantified. The aim of our study was to assess whether M. viator is a vector for the lateral movement of elements in heuweltjie landscapes via foraging activities and to calculate rates of associated salt inputs. Plant species targeted by termites for consumption were distinguished by observational studies and stable δ 13 C isotope analysis. Plants targeted by termites contained oxalate salts, the occurrence of which may explain calcite formation in heuweltjie soils via the oxalate‑carbonate pathway, thereby sequestering long-term stores of carbon. Calcium inputs in heuweltjie soils due to termite foraging and frass deposition (9 % and 75 % of net calcium inputs, respectively) were sufficient for the formation of the reported amount of calcium carbonate (112 t) in one heuweltjie of the Succulent Karoo biome within the expected heuweltjie lifespan. This study shows that M. viator is an important vector in the lateral movement of elements in the landscape and concentration of salts in heuweltjies . • Microhodotermes viator termites forage for a variety of plant materials. • Salts from plant tissues and surfaces are deposited in termite mounds ( heuweltjies). • Heuweltjie soils become enriched with ions, especially calcium and sodium. • Plants targeted by M. viator contain substrates for calcite biomineralization. • M. viator is a vector for lateral ion movement in heuweltjie landscapes.