Existing evidence on the potential of soils constructed from mineral wastes to support biodiversity: a systematic map

Abstract

Background: The development of cities and transport infrastructure produces a large volume of mineral waste (e.g. excavated earth material). At the same time, cities are increasingly trying to develop green infrastructures, given the ecosystem services they provide to people, but this comes with considerable economic and environmental costs associated with the transfer of fertile soil from rural areas to cities. In a circular economy approach, the reuse of mineral waste to build fertile soil is a substantial opportunity to reduce the economic and environmental costs of both mineral waste management and green infrastructure development. Soils constructed from these materials (constructed Technosols) must be able to support vegetation growth and become a suitable living environment for soil organisms. This requires ecological engineering to maximise the potential of constructed soils for biodiversity, both from a taxonomic and functional perspective. In this context, we systematically mapped the evidence related to the ability of soils constructed from mineral wastes to support biodiversity.

Methods: We gathered published and grey literature through searches in two publications databases (Scopus and Web of Science Core Collection), one search engine (Google Scholar), nine organisational websites and through a call for literature. Titles, abstracts, and full-texts were successively screened using eligibility criteria. All included studies were described with coded variables and a database was produced. The extent of evidence was assessed and knowledge clusters and gaps were identified.

Review findings: The searches yielded 9265 articles, and 153 articles were retained after the screening process. More than half of these articles were from European countries, with France leading the field with 40 articles, followed by Spain (15 articles) and Italy (10 articles). Most of the articles (75%) were produced after 2015. The main reasons for constructing soils from mineral waste were for mine rehabilitation (35%), waste recycling (16%) and experimental purpose (15%). The 153 articles were divided into 1962 studies, a study being a combination of a taxon, an intervention (i.e. soil construction) and a measured outcome. Among these studies, the most studied biological group is plants (69% of studies) and especially herbaceous species (32%), followed by microorganisms (17%) and invertebrates (14%). The most used type of mineral waste is mine waste (31% of studies) followed by excavated soil (16%) and demolition waste (14%). Finally, the most frequently measured outcome is plant growth (42% of studies), followed by organism abundance (16%) and diversity (10%).

Conclusions: Three main knowledge clusters were identified which could be addressed in the future for full synthesis of the results: (1) How well do plants grow in soils constructed from mineral wastes? (2) What is the potential of soils constructed from mineral wastes to support biodiversity? and (3) How do microbial communities develop in soils constructed from mineral wastes? There is a lack of studies investigating several biological groups at the same time: only 6 articles out of 153 investigated the response of both plants, invertebrates and microorganisms to soil construction. More research is therefore needed on the ability to support a diversity of organisms.

Keywords: Anthropogenic soil; Anthroposol; Anthrosol; Artificial soil; Circular economy; Constructed Technosols; Construction and Demolition waste; Pedological engineering; Recycling.

Fig. 1

Diagram illustrating how the economic and environmental costs of the present management of mineral waste and topsoils could be reduced through pedological engineering in a circular economy approach (based on Freepik images and credit Le Parisien / Faustine Léo (landfill picture), L’opinion / Grandin de l’Epervier Jade (construction site picture), Pro24.fr (soil scraping picture) and ECT (green space picture)

Fig. 2

ROSES flow diagram [21] of the systematic map

Fig. 3

Chronological distribution of the articles until June 2022, with information on their sources (Databases are Web of Science Core Collection and Scopus)

Fig. 4

Geographical distribution of the articles (a) with information on the reasons for intervention (b) and on the number of biological groups that were studied (c)

Fig. 5

Network of the keywords defined by the authors of articles about the potential of soils constructed from mineral wastes to support biodiversity. From the 153 articles included in the systematic map, only the 138 that had defined keywords were analysed. Only keywords with a minimum of three occurrences are presented here. The bigger the circle, the more frequently the keyword appears in the literature. The lines connect the keywords that appear together

Fig. 6

Distribution of the 1962 studies by taxa and outcome measured

Fig. 7

Distribution of the 1962 studies by type of mineral waste