Flies, E. J. | Search bioRxiv

bioRxiv2026

Population density is a selective driver of urban soil microbiomes: evidence from bacteria, fungi and protozoan communities in a regional city

Urbanisation is widely recognised as a major driver of environmental change, yet its impacts on soil microbiomes remain poorly understood, particularly outside megacities and beyond bacterial taxa. Population density is frequently used as a proxy for urban intensity, but its relevance across different microbial kingdoms and urban contexts is unclear. Here, we investigated how soil microbial communities vary across population density bands in the regional, temperate city of Hobart, Australia. Using a multi-kingdom metabarcoding approach, we analysed bacterial, fungal, and protozoan communities from soils collected in urban green spaces along a population density gradient. Bacterial alpha-diversity differed significantly across population density bands, exhibiting an inverse U-shaped relationship, with the highest diversity at green spaces in intermediate population density areas. In contrast, fungal and protozoan alpha-diversity did not vary with population density. Community composition (beta-diversity) did not differ consistently across density bands for any microbial group, and variation in soil physicochemical properties explained more community variation than population density alone. These results indicate that population density is a selective, rather than universal, driver of urban soil microbiomes and that responses to urbanisation differ markedly among microbial kingdoms. Our findings highlight important limitations of using population density as a sole indicator of urban impact and challenge the generalisability of conclusions drawn from bacteria-focused studies in large cities. By demonstrating kingdom-specific and context-dependent responses in a regional city, this study underscores the need for multi-kingdom, multi-scale approaches to better understand how urbanisation shapes soil microbiomes and their potential implications for urban ecosystem functioning and human health.

ecology↗

bioRxiv2023

Nature-based solutions in Australia: a systematic quantitative literature review of terms, application and policy relevance

Nature-based Solutions (NbS) are emerging as an approach to sustainable environmental management and addressing environmental and social issues in ways that benefit human well-being and biodiversity. NbS have been applied to social-environmental challenges such as climate change and urbanization, but with diverse conceptualisations and applications that may impact their effectiveness and broader uptake. Much of the literature and implementation of NbS has emerged from Europe and though NbS use is rising in Australia, the context is unclear. This systematic quantitative literature review aims to understand Nature-based Solutions in an Australian context. Here we explore the meaning and practical uses of NbS in Australia, through three research questions: In Australia, 1) what is meant by the term nature-based solutions? 2) what socio-ecological challenges do NbS aim to address and how? 3) are there gaps in NbS research and policy application that are hindering uptake of NbS approaches? We show that in Australia, local governments are using NbS in urban planning to address the compounding challenges brought on by climate change in the human-environment interfaces. However, there is no consensus on NbS definitions and approaches, research is focussed on urban areas and problems, and NbS implementation follows a bottom-up, localised pattern without an integrated policy framework. Based on these findings, we provide recommendations for improving the implementation of NbS in Australia including: 1) a consistency of NbS definition and awareness of NbS approaches; 2) interdisciplinary and interdepartmental collaboration on NbS methods and effectiveness and; 3) an integrated policy framework supporting NbS nationwide.

ecology↗