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Research article - Peer-reviewed, 2020

Alkaline habitat for vegetated roofs? Ecosystem dynamics in a vegetated roof with crushed concrete-based substrate

Jauni, Miia; Kuoppamaki, Kirsi; Hagner, Marleena; Prass, Marju; Suonio, Taina; Fransson, Ann-Mari; Lehvavirta, Susanna;

Abstract

Using local and recycled materials is a sustainable way to establish a vegetated roof. In order to understand how the roof ecosystem functions and returns ecosystem services, it is important to study vegetation, soil organisms and runoff quality. We established a vegetated roof experiment based on a substrate containing lightweight crushed concrete, an alkaline side product from a concrete factory, mixed with compost. This five-year experiment in southern Finland tested how planting method (pre-grown vegetation mats vs. pot planting), compost content (20% vs. 40%, fresh volume), and substrate depth affect the cover and diversity of plants, the abundance of soil animals and the quality of runoff. Although the substrate had a high pH (7.3-11.8), many vascular plants were able to survive and establish viable populations. The planting method had a strong effect on plant diversity and the cover of individual species because the vegetation mats became dominated by the invasive, non-native Phedimus hybridus. Establishment with pot plants in turn provided bare ground that was colonised by spontaneous non-invasive species. This resulted in higher diversity, and a more even distribution of species. The amount of compost had only a weak impact on vegetation, whereas high pH generally reduced plant abundance and diversity. The concentrations of total phosphorus and total nitrogen in runoff were low as compared to values reported from many other vegetated roofs, were not affected by compost content and decreased over time. In summary, the high-pH substrate based on recycled materials is an environmentally responsible choice, suitable for a wide variety of plants, even rare and endangered species.

Keywords

Green roof; Nature-based solutions; growth media; Vegetation dynamics; Runoff quality; Recycled materials

Published in

Ecological Engineering

2020, volume: 157, article number: 105970
Publisher: ELSEVIER

Authors' information

Jauni, Miia
University of Helsinki
Kuoppamaki, Kirsi
University of Helsinki
Hagner, Marleena
University of Helsinki
Prass, Marju
University of Helsinki
Suonio, Taina
University of Helsinki
Fransson, Ann-Mari
Swedish University of Agricultural Sciences, Department of Landscape Architecture, Planning and Management
Lehvävirta, Susanna
Swedish University of Agricultural Sciences, Department of Landscape Architecture, Planning and Management
Lehvävirta, Susanna
University of Helsinki

Sustainable Development Goals

SDG12 Ensure sustainable consumption and production patterns

UKÄ Subject classification

Landscape Architecture
Ecology

Publication Identifiers

DOI: https://doi.org/10.1016/j.ecoleng.2020.105970

URI (permanent link to this page)

https://res.slu.se/id/publ/108180