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C·I·B postdoctoral research associate, Dr Denise Mager was awarded one of the 2011 Claude Leon Foundation Fellowships to study the spatial structure of biological soil crusts (BSC) in drylands of southern Africa.

Each year the trustees of the Claude Leon Foundation award several fellowships to young researchers in the fields of science, engineering and medical sciences. The Claude Leon Foundation is a South African charitable trust that resulted from a bequest by Claude Leon (1884 - 1972). By supporting young researchers, the Foundation seeks to increase the volume and quality of research output, the transfer of technical skills, and more generally enhance the research culture at South African universities. The fellowships are awarded on a competitive basis, taking the applicants' academic achievements and potential as researchers into account.

Dr Denise Mager intends to determine the spatial distribution of soil microbial communities, quantify the input of microorganisms to soil fertility and produce a regional map of soil microbial communities using ecological niche modelling. Her work with C·I·B core team members Dr Cang Hui and Prof. Karen Esler lead her to conclude that soils are one of the main driving determinants of biodiversity and thus community structure.

Southern Africa contains many dryland ecosystems. Because these ecosystems are temporally variable and dynamic, drylands are inherently vulnerable and susceptible to disturbance and degradation. Multiple factors may drive drylands beyond their resilience potential for restoration. For instance, global climate change with increasing temperatures and rainfall variability can substantially alter fire regimes and soil nutrient cycles. Changes in land use and biological invasions will further intensify the pressure on the capacity of dryland ecosystems to sustain productivity and stability. This poses further threats to the social and food security of these areas, especially those around poor communities. This raises an urgent call for cross-disciplinary solutions to this ecological complexity.

Biological soil crusts (BSC) - the association of soil particles and microorganisms which live in the top few millimetres of the soil - are potential indicators of soil quality. BSC play an important role in arid ecosystems. Because they are concentrated in the top 1 to 4 mm of soil, they primarily affect processes that occur at the land surface or soil-air interface. These include soil stability, carbon sequestration, and atmospheric nitrogen-fixation, nutrient contributions to plants, soil-plant-water relations, seedling germination, and plant growth. Given the low concentration of carbon naturally found in dryland soils, the presence of BSC can significantly increase the amount of organic carbon. Higher soil carbon content can further increase the biotic resistance of plant communities to invasions by alien plant species. In addition, BSC also contribute considerably to the biodiversity of microorganisms in arid ecosystems. Therefore, the conservation of soil microbial communities and careful use of specific soil organisms through biological soil management can be used to maintain and enhance soil fertility, restore systems dominated by invasive plants and ensure productive and sustainable agricultural systems.

The project will provide the first spatially explicit quantification of BSC in a geographical region at both broad- and fine-scale, and offers the potential to provide interesting results both for the scientific and local communities.

Drs Denise Mager and Cang Hui collecting soil samples from different localities to quantify types and functions of soil microbial communities. (Photo: D. Mager)