An integrated approach for assessing environmental changes in soil-covered landscapes: the case of Madagascar.

The role of human activities in past environmental changes, e.g. vegetation shifts and soil degradation, is all too often assumed to be simple and direct but recent research shows that the relationship is far more complex. The island of Madagascar is a textbook example where the role of human disturbance versus natural variations in environmental change is poorly understood. Parts of the island are characterized by extreme erosion features (lavaka), and the grassland-dominated landscape in the central and western region is often assumed to result from human interference, even though several lines of evidence caution against this view. Yet, until present our understanding of this landscape is insufficient to fully disentangle the role of different drivers in its development. Here, we aim to (i) test a novel comprehensive hypothesis explaining the initial phases of lavaka formation using a combination of high-resolution field data and modelling, (ii) use a suite of geochemical proxies to characterise surface and lavaka-derived sediments and associated organic carbon (C), (iii) quantify and characterise sediment and C yields from contrasting catchments in the Lake Alaotra region, and (iv) use geochemical and pollen records in L. Alaotra sediment cores to reconstruct vegetation changes and the role of lavakas in sediment delivery in this landscape. By doing so we aim to clarify how humans and natural drivers have combined to shape the environmental history of Madagascar.

Keywords:Madagascar

Disciplines:Applied mathematics in specific fields, Geophysics, Physical geography and environmental geoscience, Other earth sciences, Aquatic sciences, challenges and pollution, Geomatic engineering