A methodological framework for the use of landscape graphs in land-use planning

Abstract

Landscape graphs are now widely used for representing and analysing ecological networks. Although several studies have provided methodological syntheses of how to use these tools to quantify functional connectivity, it is still unclear how landscape graphs can be used for decision support in land planning. This paper outlines the different types of application that may provide relevant responses to the main questions arising in land planning about ecological networks. Three approaches are distinguished according to their objective: (1) to support prioritisation within an ecological network from a conservationist perspective; (2) to increase connectivity by identifying the best locations for adding new elements to the network, either when starting from the current state of the network or when seeking to mitigate the barrier effect engendered by a development project; (3) to assess the potential impact of a development project in terms of decreased connectivity. The computations based on connectivity metrics are explained for each of these three approaches. Then each approach is illustrated in the context of a pond network near the town of Belfort, in eastern France. The results show how the same connectivity metric used in the different approaches may serve different purposes. This emphasises the potential value of landscape graphs for the land-planning decision-support process and not just for conservation purposes (i.e. prioritisation).