Characterization of multi-scale urban habitat wildness: Integration of the rewilding theory into novel urban ecosystem restoration and management

Abstract

With the global extension of novel urban ecosystems (NUEs), it is urgent to significantly adjust the restoration and management strategies apart from the traditional focus on historical assemblages. Urban rewilding provides a transformative direction in this context. However, there is a lack of multi-scale rewilding performance indicators and decision-making tools for NUEs, particularly at the urban habitat scale. Here, we proposed a multi-scale wildness conceptual model that nests from the biotope (plant community) to habitat scale and integrates biotope wildness and evenness based on the self-organization theory, where biotope wildness is constructed with naturalness and integrity. Secondly, we conducted an empirical study on 144 biotopes from 12 core habitats in Wuhan by plant survey and soil sampling. With the universal eukaryotic primer pair NF1F/18Sr2bR and high-throughput sequencing, we identified the main soil eukaryotic groups and assessed the above- and below-ground biodiversity. Next, we employed the spontaneous plant richness and a soil multidiversity index to represent biotope naturalness and integrity, respectively. Finally, we used the random forest algorithm, generalized additive model, and piecewise linear regression to further reveal the determinants of biotope wildness and their thresholds. The selected metrics were proved as good proxies for biotope naturalness and integrity, respectively, and have different determinants. There are indeed thresholds of biotope wildness determinants, which are useful tools for NUE management and restoration. This study highlights the necessity of transformative shifts in urban habitat management and restoration practices and reintroduction of natural processes to enhance urban socio-ecological resilience.