ELephant Engineering of dry woodland and consequences for CArbon SEquestration – ELECASE

Engineering actions of African elephant are diverse, here we select one specific engineering effect, dry savanna woodland
transformation, to measure the consequences for carbon sequestration in sites presenting dry woodlands used by elephants (protected area) and used by elephants and humans (natural forest, classifies forests). Using long-term vegetation monitoring plot and new sampling sites along gradient of elephant densities, in WP1, we will investigate the relationship between elephant use of trees and the changes in woody biomass and carbon stock, accounting for change sin trait composition in the tree assemblage with particular attention in traits involved in C storage (e.g. wood density). In WP2, the focus is on measuring the consequences of elephant engineering of these woodlands on the soil carbon sequestration, by quantifying carbon return to the soil from elephant activities (dungs, wood detritus) and assessing their contribution to C stocks using isotopic techniques. We will assess the root response of trees as they contribute to the below ground carbon stock. We will measure how the influx of C and the root responses will influence the proportion of labile and stable carbon in the soil, a critical attribute of C persistence in the soil and a key driver of sequetration. In the WP3, building on the data and knowledge from WP1 and WP2, we will adjust and parameterize a model based on a generic Soil-Vegetation-Herbivore model. We will the identify the factors and combinations of factors that favour C sequestration or C-release from the vegetation and the soil under a gradient of herbivory pressure by the elephant, and to define the thresholds and key combinations of these factors that promote C-sequestration by dry woodland in presence of elephants. Predicted IPPC scenarios will be used to constrain these models. We will then discuss the mitigation and adaptation aspects to climate change for dry woodland ecosystems (with and without human use) under high elephant engineering.