RG5501/1: Landscape context - landscape-scale restoration dynamics in western Rwanda (SP SP2)

Rwanda is restoring vast areas of land as part of the Bonn Challenge. As patches of restored sites are expanding throughout the country, dynamic landscape change will alter the spatial composition of woody vegetation and through this, influence the context and connectivity, as well as the trajectory of restored sites. Site-level changes, in turn, will influence the ecological functions of their surroundings. To advance the currently limited knowledge on the relative importance of different mechanisms underpinning these changes, this sub-project will identify spatiotemporal dynamics of restoration-related landscape change across the entire study area.

To examine how tree cover in western Rwanda has changed through time, and how this might explain present-day ecosystem processes and biodiversity patterns, we will use satellite remote sensing to quantify landscape change through space and time. Here, four sets of concepts and associated methodologies central to this sub-project will be examined in particular: (1) landscape context that describes the conditions surrounding a particular patch of vegetation, (2) landscape, habitat and functional connectivity, (3) extinction debt (i.e., a location where a species can no longer reproduce sufficiently to maintain its population in the long term) and immigration credit (i.e., a location that will be ultimately occupied by more species than have colonised that location to date), and (4) bright spots of restoration whose diversity and composition of woody species are especially similar to that of historical reference sites. The remote-sensing-based findings will then be used to formulate and test hypotheses about species distribution patterns and ecosystem functioning, using field data collected in sub-project 1 as well as remotely-sensed indices of ecosystem functioning.

Given the global proliferation of large-scale restoration initiatives, it is important to better understand how landscape-wide tree planting influences landscape context, connectivity, biodiversity patterns and ecological functioning at a landscape scale. Because of Rwanda’s ambitious restoration efforts, the country provides an exciting opportunity to advance knowledge about how ongoing changes in land cover and connectivity shape ecosystems. This sub-project thus makes contributions to the fields of landscape ecology and restoration ecology. In addition, this sub-project will benefit the research unit as a whole by generating an important spatiotemporal understanding that is useful for all other sub-projects.