Workpackages of Subproject S02

Workpackage WP02.1

Dr. A. Gröngröft, Institute of Soil Science, University of Hamburg, Germany
A.Groengroeft@ifb.uni-hamburg.de

Pedodiversity of the Observatories and its significance on biodiversity

Short description:This work package focuses on the pedodiversity and its significance for biodiversity on the Observatory level. Central aim is the development of pedodiversity-indices describing the patterns of soil units and properties on the Observatory level. The suitability of these indices will be tested by the comparison of soil data with both, botanical and zoological data of the other subprojects. The already existing soil data of the first phase provides an excellent basis for this work package, as it until now comprises soil properties and vegetation composition for 13 Observatories investigated by the standardised geostatistical approach. The data set will be enlarged by surveys on additional observatories

Workpackage WP02.2

Dr. A. Gröngröft, Institute of Soil Science, University of Hamburg, Germany
A.Groengroeft@ifb.uni-hamburg.de

Up-scaling of soil properties from Observatory to farming systems level as a database for socio-economic issues

Short description: The economic and spatial units for decisions on land use and land use related impacts on soils are the farming system areas, which in the studied region are of 100 - 1500 km2 size. Within the BIOTA-Southern Africa project, the relation between natural properties such as pedodiversity, biodiversity and economic issues will be studied for selected farming systems (see work packages in subproject S11). For this approach, soil data for the entire farm areas are needed. As detailed soil investigations exist for the Observatories within the farm area, up-scaling of soil properties is principally possible. However, the suitability of the up-scaled data depends on how representative the assessed soil properties of the Observatory are for the entire farm area and how these properties can be correlated with remote sensing data. Thus, by the comparison of classical soil survey techniques with up-scaling techniques on the basis of satellite and airborne data the advantages and restrictions of these techniques will be studied.

Workpackage WP02.3

Dr. A. Gröngröft, Institute of Soil Science, University of Hamburg, Germany
A.Groengroeft@ifb.uni-hamburg.de

Evaluation of biodiversity controlling soil properties

Short description: Whereas in the work package 2.1 the relation between soil units and biodiversity is studied by correlation statistics, the investigations of this work package will concentrate on the functional aspects of soil properties and their interrelation with the occurrence of plant species and small mammals in detail. The investigations have the aim to detect those soil parameters from the large array of potentially responsible soil features which are responsible for the occurrence of key species of plant communities or of selected animal taxa, respectively. The knowledge of these dominant soil properties will lead to a strong reduction in the soil investigation effort for comparable studies in future.

Workpackage WP02.4

Dr. A. Mills, Department of Soil Science, University of Stellenbosch, South Africa
Dr. A. Gröngröft, Institute of Soil Science, University of Hamburg, Germany
mills@nbi.ac.za
A.Groengroeft@ifb.uni-hamburg.de

Surface-crusting, top soil properties and human impact as key factors for soil erosion

Short description: In arid and semi-arid ecosystems, the infiltration of water into the soil profile is critical for ecosystem functioning. Dispersion of clay and the growth of algae and lichens (see subproject S05) can result in a crusting/sealing of the soil surface. Physical seals, comprised of a "washed in layer" of silt or clay need only be 0.1 mm thick to potentially reduce infiltration by over a thousand fold. This work package is divided into two tasks, both aiming at a better understanding of the process and the ecological effects of soil crusting on erosion in arid landscapes. With the 1st task the potential of soil properties for sealing is investigated by laboratory analyses. This task will be conducted by A. Mills, F. Ellis & M. Fey (Stellenbosch). Within the 2nd task, conducted by A. Gröngröft & G. Miehlich (Hamburg), the small scale distribution of soil crusts (physical and biological) is assessed in relation to plant and animal distribution

Workpackage WP02.5

Dr. A. Gröngröft, Institute of Soil Science, University of Hamburg, Germany
A.Groengroeft@ifb.uni-hamburg.de

RESTORATION and MANAGEMENT

Short description: Restoration and management experiments act as an important tool for the study of land-use related impacts on biodiversity. Within the main phase different experiments are planned:

• Rehabilitation of 'bare patches' in the Thornbush savannah (together with WP 6.6)
• Rehabilitation and exclosure experiments in the farming-systems on the Observatories 11 Nabaos, 18 Koeroegapvlakte, 22 Quaggasfontein and 24 Leliefontein (WP 6.5, 6.6).
• Replanting of indigene species in the Knersvlakte (WP 6.6).

These experiments need to be supported by soil investigations. The data of the soil survey and additional analyses will be used for the design of the experiments as well as for the interpretation of the experimental results.