Role of Plants and Urban Soils in Carbon Stock: Status, Modulators, and Sustainable Management Practices

Abstract

Urban soils are vital components of urban ecosystems, significantly influenced by anthropogenic activities and environmental factors. Despite misconceptions about their quality, urban soils play a pivotal role in carbon (C) cycling and storage, impacting global emissions and sequestration. However, challenges such as soil contamination, land use changes, and urban expansion pose significant threats to soil quality and C storage capacity. Over the last two decades, there has been an increasing interest in the C storage potential of soils as part of climate change mitigation strategies. In this review, a bibliometric analysis covering the last twenty years (2004-2024) was performed to offer insights into global research trends, mainly in urban soils of the Mediterranean region. This paper also identifies research gaps and proposes essential solutions for mitigating the negative impacts of urbanization on soil biodiversity and functions. Key modulators, including plants, microbes, and soil features, are highlighted for their role in C dynamics, emphasizing the importance of effective soil and vegetation management to enhance C sequestration and ecosystem services. Strategies such as reintroducing nature into urban areas and applying organic amendments are promising in improving soil quality and microbial diversity. Further research and awareness are essential to maximize the effectiveness of these strategies, ensuring sustainable urban soil management and climate resilience.

Keywords: biochar; climate change; compost; soil C cycle; urban soils; urban vegetation.

Figure 1

Main pathways of C cycle ((a) reproduced from [54] with permission from the authors) and CH₄ transformations ((b) reprinted from [55] with permission from the authors) in soils.

Figure 1

Main pathways of C cycle ((a) reproduced from [54] with permission from the authors) and CH₄ transformations ((b) reprinted from [55] with permission from the authors) in soils.

Figure 2

Map highlighting the Mediterranean region.

Figure 3

Two divergent routes (a,b) influencing the connection with microbial C use efficiency (CUE), promoting global soil C storage and soil organic C (SOC) storage. Microbial CUE and microbial C uptake (ng C g⁻¹ h⁻¹) can be calculated by the following equation [126]: (CUE = C growth/C growth + C respiration = C growth/C uptake). Reproduced from [127] with permission from the authors.

Figure 4

The terrestrial C cycle with the major processes mediated by soil microorganisms. Reproduced from [133] with permission from the authors.