Within the context of ANR COBESOLI and MITI SMEEB, two team members spent a week at the Succulent Karoo Reserve Station (SKRS) in South Africa. Observing the behavior of Karoo rats coupled with geochemistry and isotope analysis of their environment will soon enable us to better understand the impact of their activity on the health of the soil beneath their home, and thus the symbiosis between both.
These two CNRS projects take an interdisciplinary approach, combining data from long-term ecological monitoring, behavioral ecology, chemistry, physics and soil ecology. Thanks to its ECHoMICADAS and IRMS-Orga technical platforms, the GeoTrac team is responding to the need to determine the average and maximum age of Karoo rat huts in the Succulent Karoo biodiversity hotspot, and to understand whether Karoo rat huts enrich the soil in organic matter (C and N).
In November 2024, 16 occupied lodges were sampled. Samples were taken from the top and middle of the habitats. At their bases, several samples will be used to check whether they are recent pieces that have fallen from the top, or old samples that may be associated with the creation of the lodge. In addition, we have collected a piece of wood near each lodge, branches that Karoo rats might use to build their lodge. This will provide us with information on the age of the wood before it is collected for lodge construction. Finally, we chose three shrubs close to the field site in an area not used by Karoo rats to determine the rate of decomposition under the same climatic conditions as at the field site. Here, we systematically collected all plant residues we found in a 15 cm x 15 cm square, visually representative of what lay beneath the shrub. We collected, measured, classified by type (seed, twig, branch, dry leaf, decomposed branch residue, etc.) and weighed all the plant residues we found.