The research programme "Fifth Dimension - vegetated roofs and walls in urban areas" aims to produce high-level scientific and broadly applicable knowledge on optimal vegetated roof solutions in Finland.

Scientifically, vegetated roofs serve as experimental model ecosystems for research and provide an opportunity for inter- and transdisciplinary research that is societally relevant. The research policy of the programme includes working in close contact with the end users of scientific knowledge, such as municipal and state authorities, companies and citizens. Our main target concerns the potential of vegetated roofs to enhance urban nature and ecosystem services, as part of multifunctional urban green infrastructure. The aim of the programme is to evaluate the various benefits vegetated roofs may offer, and to develop optimal solutions and designs for vegetated roofs that offer the best possible services for urban residents.

Our ongoing and past research themes include:


Contact person Susanna Lehvävirta

Environmental change and habitat loss threaten biodiversity and increase species extinctions. Green roofs may provide opportunities for habitat creation to support plant diversity, and the existence of rare and threatened, indigenous plant species, such as dry meadow plants. We study the survival, diversity and composition of plants on Finnish green roofs, and determine the most important environmental factors (e.g. substrate depth) promoting the success of plant species in the green roofs. Furthermore, green roofs provide opportunities for gardening and food production in kitchen gardens. In order to estimate the most suitable species for harsh, roof conditions, we investigate the survival of multiple garden plants and crops in green roofs and facades.

Related articles:

Moss roofs

Contact person Juhamatti Niemi-Kapee

Green roofs have wide diversity of moss species. Often mosses are the first to colonize empty spaces like roof tops, even in the cities. By understanding how and why this happens we could benefit from the extraordinary characteristics of mosses. Due to climate change we will need a wide range of different adaptation solutions for the cities. Moss roofs offer us novel ultra light solutions for greening our surroundings. Applying mosses on surfaces earlier considered unusable for green infrastructure we can mitigate several consequences of climate change.

Plant symbiontic microbes

Contact person Long Xie

Plant associated soil microbes (mycorrhiza) have co-existed with host plants throughout evolution resulting in mutualistic symbiosis by beneficial microbes in more than 80 % terrestrial plant species. Many plant-growth-promoting microbes (PGPMs) largely depend on the host plants for exchangeable nutrients, especially heterotrophic ones. The symbionts can be in the form of a hyphal web growing in and outside of roots, a layer of microbial biofilms, or root nodules. Nutrient absorption, water uptake, hormone manipulation and pathogen resistance are among the benefits for plants given by these microbes. Commercial PGPMs products have proved to be effective on crop productions, reducing the need of chemicals. The use of PGPMs can be extended to other ecosystems, such as green roofs in order to restore a balanced and interactive microbial community. As a result, better ecosystem services provided by green roofs can be achieved in the form of healthy green roof vegetation, more efficient nutrient cycling and, thus, less nutrient leaching to stormwater. When plants grow well, there will be less need for maintenance like irrigation, pest control or pathogen control.

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Contact person Johan Kotze, Kyrö Kukka

Vegetated roofs can provide supplementary habitat for invertebrate species of, primarily, open habitat. In Nordic environments, meadow-like environments are under threat due to management and abandonment. Vegetated roofs, analogous to habitat islands, can be interesting model systems to investigate the colonization success of invertebrates, and in investigating the role of classic island biogeography theory (roof size and isolation, both horizontally and vertically) in predicting species occupancy. The question is whether these roofs can also serve as habitat for locally threatened species. Our work includes the characterization of vegetated roof invertebrate communities in terms of their response to i) roof characteristics (roof size, age, height, substrate depth, etc.), ii) landscape properties (i.e., the proportion of various habitat types in the immediate surroundings of vegetated roofs), and iii) invertebrate fauna at ground level.

Related articles:

  • Kyrö, Kotze, Müllner, Hakala, Kondorosy, Pajunen, Vilisics & Lehvävirta 2020. Vegetated roofs in boreal climate support mobile open habitat arthropods, with differentiation between meadow and succulent roofs. Urban Ecosystems (2020).
  • Kyrö, Brenneisen, Kotze, Szallies, Gerner & Lehvävirta 2017. Local habitat characteristics have a stronger effect than the surrounding urban landscape on beetle communities on green roofs. Urban Forestry & Urban Greening 29: 122-130. DOI 10.1016/j.ufug.2017.11.009
Stormwater management

Contact person Kirsi Kuoppamäki

Stormwater management is challenged in densely built urban areas and even more so in the future with increasing precipitation due to climate change. Abundant rooftops offer an opportunity to reduce the amount of stormwater by using green roofs. We study the functioning of green roofs in terms of their ability to retain rainwater in the Finnish climate in all four seasons and what factors affect the quality of green roof runoff. Furthermore, we are searching for solutions to prevent the leaching of nutrients from green roofs.

Related articles:

Kuoppamäki, K. 2021. Vegetated roofs for managing stormwater quantity in cold climate. Ecological Engineering 171: 106388.

Kuoppamäki, K., Setälä, H. & Hagner, M. 2021. Nutrient dynamics and development of soil fauna in vegetated roofs with the focus on biochar amendment. 100001


Substrate properties and soil animals

Contact persons Marleena Hagner & Susanna Lehvävirta

All terrestrial ecosystems consist of aboveground and belowground components that interact with each other. Green roof substrate type and depth affect the retention of water and nutrients, diversity of soil organisms and growth of plants on the roofs. Our aim is to build up knowledge for solutions that improve the health of green roof soil ecosystem, effective (closed) nutrient cycling and sustain plant communities on green roofs. This work is carried out in connection to the vegetation and stormwater management research. Long-term studies are being done on a number of experimental and observational setups both in green roofs and walls to see whether and how the systems develop over time. Such long-term research is extremely important as the expected life-span of a green roof is several decades.

  • Jauni Miia, Kuoppamäki Kirsi, Hagner Marleena, Prass Marju, Suonio Taina, Fransson Ann-Mari & Lehvävirta Susanna 2020. Alkaline habitat for vegetated roofs? Ecosystem dynamics in a vegetated roof with crushed concrete-based substrate. Ecological Engineering 157: 105970
Restorative and aesthetic experiences on green roofs

Contact person Susanna Lehvävirta

Key ecosystem services that are expected from green roofs are recreational experiences and well-being for urbanites. Key elements that we measure are how people experience green roofs aesthetically, and whether green roofs provide restoration, escape from the every stressors of urban life. Green roofs are often small in size and located very close to where people live and work. Thus, they have an important role in providing experienced benefits, as compared to other types of recreational benefits, such as physical exercise. As green environments are know to provide aesthetic benefits and restoration from everyday stress, we assume that this applies also to green roofs. We study restorative and aesthetic experiences on different types of green roofs to find out, for example, if even a small amount of vegetation increases experiential and aesthetic values of the roof.

Related articles:

  • Subiza-Pérez, Hauru, Korpela, Haapala, Lehvävirta 2019. Perceived Environmental Aesthetic Qualities Scale (PEAQS) – A self-report tool for the evaluation of green-blue spaces. Urban Forestry & Urban Greening 43: 126383
  • Mesimäki, Hauru & Lehvävirta 2019. Do small green roofs have the possibility to offer recreational and experiential benefits in a dense urban area? A case study in Helsinki, Finland. Urban Forestry & Urban Greening 29: 122-130.
User-centered planning, co-design and conceptual issues

Contact person Marja Mesimäki

In the era of climate change, accelerating urbanization and demographic change (e.g. aging), cities should be resilient in many ways. Urban green areas need to meet various needs of different groups of urbanites, and thus, it is important to gather information on their expectations, not only for present but also for future urban spaces. Building-integrated vegetation may offer an interesting supplementation to traditional green areas, as concerns recreational and experiential benefits. We study the role of this kind of novel green infrastructure in planning- and construction processes, develop user-centered methods for co-design, and implement scientific knowledge of users’ needs in real-life cases.

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Past research themes
Research sites

Experimental green roof posters: