The urban matrix matters: Quantifying the effects of surrounding urban vegetation on natural habitat remnants in Santiago de Chile

Abstract

Urbanization destroys and fragments natural habitats, resulting in a system of natural remnants embedded in an urban matrix. Urban natural remnants (UNRs) can provide multiple ecosystem services for urban areas. Nevertheless, the long-term provision of ecosystem services by UNRs depends on their capacity to retain the ecosystem processes supporting the services. As vegetation from the urban matrix could play a key role in remnants ecological dynamics, understanding the effect of surrounding urban vegetation on UNRs ecosystem processes is fundamental for sustainable urban planning. In this work, we used a multi-temporal and -spatial scale approach to evaluate the role that vegetation patterns (i.e. composition and configuration) of the urban matrix have played on ecosystem processes (i.e. primary productivity) of 10 UNRs located in the city of Santiago (Chile). Using a set of six remote sensing-derived vegetation indices (years 1985–2010), we analyzed how temporal changes in primary productivity of UNRs were related to changes in vegetation patterns of the surrounding urban matrix, and assessed the potential role of the matrix’s socioeconomic level on these results. Our results show that productivity decreased in all UNRs and that this productivity loss was spatially correlated with the changes in vegetation cover of the surrounding urban matrix. UNR productivity was more strongly correlated with matrix composition than matrix configuration. Correlation strength between matrix composition and UNR productivity increased in time and decreased with distance from the edge of UNRs inward, suggesting that the effects of matrix vegetation on the ecological processes within UNRs are both time- and location-dependent. The socioeconomic level of the matrix showed a positive association with the vegetation cover of the matrix, but did not have a statistically significant correlation with UNR primary productivity. Results from our work demonstrate that the changes in urban matrix vegetation induced by urbanization may have strong impacts on the ecological processes that underpin the provision of ecosystem services by UNRs. If planners ought to increase the provision of ecosystem services by these UNRs, the strategies should not only focus on managing vegetation within UNRs, but also on properly planning vegetation in the surrounding urban matrix.