Habitat functionality: Integrating environmental and geographic space in niche modeling for conservation planning

Abstract

Niche modeling is typically used to assess the effects of anthropogenic landuse and climate change on species distributions and to inform spatial conser-vation planning. These models focus on the suitability of local biotic and abi-otic conditions for a species in environmental space (E-space). Althoughmovements also affect species occurrence, efforts to formally integrate geo-graphic space (G-space) into niche modeling have been hindered by the lackof comprehensive theoretical frameworks. We propose the“functional habitat”framework to define areas that are simultaneously of high quality in E-space,and functionally connected to other suitable habitats in G-space. Originatingin metapopulation ecology, approaches have been developed to assessthe amount of suitable connected habitats, based on the proximity betweenpairs of locations. Using network theory, which operates in topologicalspace (T-space, defined by a network), we extended these metapopulationapproaches to integrate movement constraints in G-space with niche modelingin E-space. We demonstrate the functional habitat framework using empiricaldata (GPS tracking and population monitoring) throughout the European wildmountain reindeer (Rangifer t. tarandus) distribution range. We show thatfunctional habitat outperforms traditional suitability in explaining the species’distribution. This approach integrates effects from habitat loss and fragmenta-tion for spatial conservation planning, and avoids overemphasizing small,inaccessible areas with locally suitable habitats. The functional habitat frame-work formally integrates biotic, abiotic, and movement constraints in nichemodeling using network theory, thus opening a wide range of applications inspatial conservation planning. connectivity, fragmentation, habitat, habitat loss, metapopulation theory, network theory,niche,Rangifer, species distribution