Baert, Geert

Boeckx, Pascal

Erens, Hans

Mees, Phlorias

Mujinya Bazirake, Basile

Van Ranst, Eric

English

Ghent University Academic Bibliography

Geophysical Research AbstractsVol. 16, EGU2014-1954, 2014EGU General Assembly 2014© Author(s) 2014. CC Attribution 3.0 License.Variability of soil properties within large termite mounds in SouthKatanga, DRC – origins and applications.Hans Erens (1), Basile Bazirake Mujinya (1,2), Pascal Boeckx (3), Geert Baert (1,4), Florias Mees (1,5), and EricVan Ranst (1)(1) Laboratory of Soil Science, Ghent University, Belgium, (2) Laboratory of Soil Science, University of Lubumbashi,Democratic Republic of Congo., (3) Isotope Bioscience Laboratory (ISOFYS), Ghent University, Belgium., (4) Department ofPlant Production, University College Ghent, Belgium., (5) Department of Geology and Mineralogy, Royal Museum forCentral Africa,Tervuren, BelgiumThe miombo woodlands of South Katanga (D.R. Congo) are characterized by a high spatial density of large conictermite mounds built by Macrotermes falciger (3 to 5 ha-1). With an average height of 5.05 m and diameter of14.88 m, these are some of the largest biogenic structures in the world. The mound material is known to differconsiderably from the surrounding Ferralsols. Specifically, mound material exhibits a finer texture, higher CECand exchangeable basic cation content, lower organic matter content, and an accumulation of phosphorous, nitrateand secondary carbonates. However, as demonstrated by the present study, these soil properties are far fromuniform within the volume of the mound. The termites’ nesting and foraging activity, combined with pedogenicprocesses over extended periods of time, generates a wide range of physical, chemical, and biological conditionsin different parts of the mound. Analysis of samples taken along a cross-section of a large active mound allowedgenerating contour plots, thus visualizing the variability of soil properties within the mound. The central columnsof three other mounds were sampled to confirm apparent trends.The contour plots show that the mounds comprise four functional zones: (i) the active nest, found at thetop; (ii) an accumulation zone , in more central parts of the mound; (iii) a dense inactive zone, surrounding theaccumulation zone and consisting of accumulated erosion products from former active nests; and (iv) the outermantle, characterized by intense varied biological activity and by a well-developed soil structure. Intermittentleaching plays a key role in explaining these patterns.Using radiocarbon dating, we found that some of these mounds are at least 2000 years old. Their currentsize and shape is likely the result of successive stages of erosion and rebuilding, in the course of alternatingperiods of mound abandonment and recolonization. Over time, termite foraging combined with limited leachingresults in the mounds becoming nutrient sinks. As the mounds contain over 1000 m3 ha-1 of soil, they represent aconsiderable part of the total nutrient budget of the ecosystem. A recent development in the Lubumbashi region isthe advent of large-scale pivot-irrigated agriculture. The termite mounds in new fields are completely leveled, thusdispersing the accumulated nutrients. Our study predicts short- and long-term effects of termite mound spreadingon soil fertility.

Variability of soil properties within large termite mounds in South Katanga, DRC : origins and applications

https://biblio.ugent.be/publication/5807565/file/5912840

Variability of soil properties within large termite mounds in South Katanga, DRC : origins and applications

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