Stepping stones

Abstract

Purpose Large-scale urbanisation has become a significant barrier to the natural migration of tree species, which is being exacerbated by accelerated climate change. Within this context, improving the permeability of urban landscapes is expected to be an effective strategy to facilitate the process of forest migration through cities. The purpose of this paper is to develop a method to assess the permeability of urban green spaces as stepping stones for forest migration, from the perspective of seed dispersal. Design/methodology/approach The proposed method combines a least-cost path (LCP) model and a graph theory-based approach. The LCP model is applied to map the potential pathways of seed dispersal at multiple spatial and temporal scales, based on which graph theory-based indices are used to quantify the accessibility of urban landscapes for seed dispersers. This method is demonstrated by a case study in the Greater Manchester area, UK. Eurasian jay, Eurasian siskin, coal tit and grey squirrel are selected as the main seed dispersers in the study area. Findings The results provide a comparison of the landscape permeability maps generated from different seed dispersers and identify key areas likely to facilitate the process of forest migration. Recommendations regarding landscape management for improving permeability are also discussed. Originality/value This method allows designers to re-visualise highly modified and fragmented urban landscapes as stepping stones for seed dispersal, which in turn allows for a more piecemeal form of landscape design to optimise urban landscapes for climate adaptation.