Assessment of land cover trajectories as an indicator of urban habitat temporal continuity

Abstract

The trends of land cover dynamics in cities have major repercussions on urban biodiversity, ultimately impacting the health and well-being of human urbanites. Older habitats, i.e., habitats with higher spatiotemporal continuity, allow ecosystem processes promoting the maintenance of diverse microhabitats and the accommodation of diverse species over time, contributing for a richer biodiversity at the city level and beyond. Thus, we implement the analysis of land cover trajectories proposed as an indicator of habitat continuity, in order to identify priority areas for conservation or restoration that can be integrated in urban planning. The method was applied in the city of Porto, Portugal, and it was used to detect the main habitat patches associated with trends of vegetation persistence, gain and loss, between 1947 and 2019. The most common change was related to urbanization processes, where artificial built elements replaced areas of tree, shrub and herbaceous cover, completely dominating the territory in 2019 (66% cover). Moreover, tree and shrub cover had a relatively balanced dynamics, keeping a constant area (20–25%) while newly created wooded habitats compensated for the lost ones. Finally, areas covered with herbaceous vegetation suffered a drastic loss and fragmentation over the period of 72 years (from 40% in 1947 to 10% in 2019). This analysis of land cover evolution allowed for the identification of areas that have been continuously covered by vegetation, displaying a greater stability and higher probability of habitat continuity. This information, with its spatially explicit character, can help to inform future planning, design and management policies at a local scale and contribute to the conservation, restoration and expansion of urban habitats and their biodiversity.