Combining occupancy and dispersal models to predict the conservation benefits of land-use change

Abstract

Context Economic incentives for habitat creation in productive agricultural land are an important tool for halting biodiversity loss. Given inevitable funding constraints, assessing the cost-effectiveness of potential habitat creation strategies should be a priority. Objectives We make model predictions of changes in the populations of ten woodland-affiliated bird species over time across a set of contrasting woodland creation scenarios in a 25 × 25-km square of primarily arable land in England. Methods Using an economic agent-based model of landowners who make economically rational decisions on land use in response to financial incentives for woodland creation, we created a suite of potential landscapes with varying spatial configurations (and amounts) of newly planted woodland. We then parameterised an individual-based model for each of ten woodland bird species, and used these models to simulate dispersal and settlement across the altered landscapes. Results Across all bird species, population increases were greater when woodland creation plots were clumped together than when randomly sited. When woodland plots were adjacent to existing woodland, increases were comparable to those in the clumped arrangements, except at lower planting densities, where wood-adjacent planting was more beneficial for birds. In all cases, benefits were very gradual, typically taking at least thirty years to be fully realised. Conclusions Our study demonstrates that the cost-effectiveness of woodland creation, in terms of subsequent benefits to biodiversity, is strongly determined by its spatial configuration. Short-term biodiversity targets for woodland birds are unlikely to be well served by woodland creation, given the time required for newly planted trees to reach maturity. We recommend the use of interim targets, but emphasise that current rates of woodland creation may only result in modest changes in woodland bird populations.