The impact of increasing tree cover on landscape metrics and connectivity: a cellular automata modelling approach

The United Kingdom has a low percentage cover of woodland, which exists in small, highly fragmented patches. Plans to increase the cover from 14.5% to 17.5% by 2050 will require guidance to help target the planting of new forests to maximise ecological connectivity. This study develops a novel approach to landscape simulation utilising real-world spatial boundary data. The Colne Valley river watershed is chosen as a study site. Three different future woodland creation goals (+10, 30, and 50%) are tested alongside manipulations of the mean new patch size and the mode in which new woodland is created in relation to existing woodland. Scenarios which expanded existing woodland and used riparian planting created larger, more connected patches with more core area. The model outputs are used to assess the impact of the UK woodland increase plans, and past woodland creation efforts are assessed. Increasing the percentage cover generally boosted connectivity, functional connectivity (species dispersals), and increased patch size and core area index. We suggest that proximal growth offers the greatest benefits in terms of biodiversity, but in terms of habitat connectivity smaller isolated woodland patches may also be needed as stepping stones to aid dispersal.