Furthermore, we explore the relevance of artificial greenspaces, such as green roofs and bioinfiltration ponds, in ES provision in heavily-built urban areas. We also aim at providing data that are readily usable for end users, such as city planners and authorities. We recognize urban greenspaces as multifunctional “urban oases” with a high potential to provide many of the same ES that more natural systems do.
Our ongoing and past research themes include:
Contact: Heikki Setälä, Johan Kotze
In this project, funded by the Academy of Finland, we explore plant-soil feedbacks in urban parks and their influence on soil-derived ecosystem services in Lahti (Finland), Singapore and Baltimore (USA). Furthermore, we study the potential impact of biological and functional homegenisation of soil biota in urbanised settings vs. natural habitats.
Contact: Johan Kotze
Urbanisation is associated with the loss, fragmentation, isolation and pollution of greenspace. These impacts affect arthropod and plant communities and their contribution to ecosystem services. We investigate the responses of invertebrates, primarily carabid beetles (Carabidae), and vegetation (such as forest understory and green roof plants) to various factors brought about by urbanisation, such as edge effects, fragmentation, isolation and management. Our current research on carabid beetles include i) the effects of urbanisation on trait distribution, both at the community and individual-species levels, ii) the role of history (in terms of past landscape structure) on contemporary assembly and trait distribution, and iii) intraspecific beetle body size and mass differences across various habitat types in the urban milieu.
Semi-natural grasslands and many of their typical species have become threatened due to the decline in the amount and quality of these habitats. Urban grasslands have the potential to support some of the species that have declined, while they also provide other ecosystem services such as carbon sequestration and aesthetic or recreational values. We study the factors that drive and filter plant biodiversity in urban and/or novel grasslands, as well as practical methods for fostering their biodiversity.
In the Helsinki region, we explore the vascular plant communities in various urban grasslands such as road verges, rocky outcrops, remnant semi-natural grasslands and abandoned fields managed as meadows. We study what kind of vegetation cities have created by sowing native grassland plants, or by reducing management intensity in lawns. We also study the practical actions, motivations and barriers related to biodiversity conservation in urban grasslands.
At the Lammi Biological Station, we set up an experiment that evaluates different methods of turning unused lawns into biodiverse meadow-like habitats. We test different methods of topsoil treatment and the use of a hemiparasitic plant (Rhinanthus minor) to weaken the grasses and legumes that dominate lawn vegetation.
In 2022 the city of Lahti, we established ten 5 x 5 m plots in urban park lawns with reduced management. We plan on following these plots over the next few years, comparing aboveground biodiversity and belowground processes, including carbon sequestration, with the adjacent managed park lawns.
Contact: Marju Prass, Johan Kotze, Heikki Setälä
The non-native large-leaved lupine (Lupinus polyphyllus) aggressively invades Finnish road verges and expands to more natural areas. Thereby, it threatens many local meadow species. The invasion has been especially rapid in urban ecosystems due to disturbance and other human activity. Here we aim at improving understanding of its basic ecology and interactions with other species. For example, we are studying the effects of lupine on soils (fertilisation and allelopathy), and the effects of herbivory on the lupine (natural biocontrol). An improved understanding of why the lupine is invasive helps to develop effective control measures for this alien plant. Albeit we mainly concentrate on mollusc herbivory, we recorded the occurrence of the non-native lupine aphid (Macrosiphum albifrons) for the first time in Finland, during the autumn of 2017 in the city of Lahti.
Contact: John Allen, Heikki Setälä, Johan Kotze
Pets, especially dogs, are an important but understudied source of nutrient inputs to urban areas. The global increase in urbanisation coupled with increasing dog ownership rates means that urban dog populations are rising rapidly in many countries. The urine of dogs is high in nitrogen (N) and can represent a significant portion of the annual urban N load. And while other sources of anthropogenic nitrogen continue to decline due to regulations and technological advancements, the input from dogs in urban areas is increasing due to their increasing numbers. Many urban dog owners visit greenspaces with their pets daily and the dogs are significantly impacting soil biogeochemistry in these areas. This, along with reductions in the overall area of greenspaces due to densification, is placing these areas under mounting pressure even as the benefits and services they provide become more important to more people. In this project, we are examining the magnitude, spatial distribution and the impacts of nitrogen deposition from dog urine on soil chemistry and microbial communities in urban greenspaces.
Contact: Heikki Setälä, Johan Kotze
The increasing demand for land due to urbanisation often takes place at the expense of urban green areas, such as parks. These threatened greenspaces, especially their soils, can provide many of the same important functions or ecosystem services (ES) as the more natural systems, such as the cleaning of water and the purification of contaminants. The loss of urban green spaces can thus result in the weakening or complete loss of life-supporting ES. Here we explore whether different plant types (evergreen trees, broadleaf trees or lawn grass) have a divergent influence on ES provision in urban parks, and whether the ES potential depends on park age (young vs. old). In particular, we aim at exploring the interactions between soil organisms and plant types in ES provision.
Contact: Heikki Setälä
Soil provides a considerable amount of ecosystem services, which are largely sustained and performed by soil microbiota. The study of soil microbiota has mainly focused on non-urban ecosystems. It is now well recognised that different plant functional types can shape diverse soil microbial communities and that these communities evolve over time. Urban soils represent a peculiar ecosystem: high levels of disturbance, such as use, pollution, the raking of organic material (leaves) are specific feature in urban green spaces, while at the same time trees can freely grow an extensive and undisturbed root system. Thus, we aim to shed light on the composition of urban microbiota, how this is related with plant functional type, which temporal dynamics it follows and on the differences, or similarities, between urban and non-urban ecosystems. This should serve as a starting point to understand urban soil ecosystem structure and functioning better. Similarly, we aim to understand how soil nutrient dynamics work in the urban ecosystem, considering that these could be impaired or modified by the high level of disturbance compared to non-urban ecosystems.
Contact: Vesa Yli-Pelkonen, Heikki Setälä
Deteriorated air quality in urban areas is one of the most pressing environmental challenges. Polluted air harms living organisms – human health effects being the most important issue – and built structures as well as adjacent ecosystems (causing e.g. acidification and eutrophication via leaching/washout). Plants have been suggested as an effective means to clean the air, although scientific evidence for this ecosystem service has been rather weak. By studying the role of plants in dispersion and residence times of air pollutants, we gain direct knowledge on the real-world (as opposed to model calculations) effects of plants on local air quality. We have studied air quality in terms of particles (total suspended solids, PM10, PM2.5, ultra-fine particles), nitrogen dioxide, ozone, volatile organic compounds, sulphur dioxide and polycyclic aromatic hydrocarbons.
Contact: Kirsi Kuoppamäki, Marleena Hagner, Heikki Setälä
One of the most dramatic ecological changes caused by urbanisation is the spread of impervious surfaces resulting in increased surface runoff that washes urban-derived pollutants from roads, parking lots and rooftops. Traditional urban drainage collects this stormwater into underground pipeline sewage systems, transporting it directly to nearby water bodies. Climate change is predicted to increase precipitation in northern Europe, which means that stormwater loading and the risk of urban flooding will become an even more serious problem in the future. Natural and constructed ecosystems in the built environment can be utilised to retain and purify runoff. This urban green infrastructure helps to avoid relying only on grey sewer infrastructure that is expensive to build, while nature can provide cheaper and more sustainable solutions. However, densely built city centres typically have very limited amount of space for such nature based solutions. 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 Finnish climate in all four seasons and identify which factors affect the quality of green roof runoff. Ground level examples of green infrastructure measures include various kinds of bioinfiltration basins, which can infiltrate and purify stormwater. We study this green technology experimentally in large-scale lysimeters as well as in pilot sites in the city of Lahti.
Contact: Heikki Setälä, Anna-Lea Rantalainen, Shen Yu
Urbanisation causes the emissions of a wide range of pollutants to aquatic environment from various urban point sources or via scattered loadings. The critical questions under this research theme include: what are these pollutants, what are their routes to surface waters (and sediments), what is the amount of a given pollutant, what are the environmental effects and fate of the pollutants, and how do polluted sites recover from this contamination burden. Here we focus on (i) surface run-off water from urbanized catchments, (ii) deposition of air-borne contaminants and (iii) emissions from waste water treatment (WWTP) or industrial plants. Furthermore, we use sedimentary records to illustrate contamination levels of persistent hydrophobic pollutants; contamination of the water phase is typically analysed using grab sampling or passive samplers. A variety of bioassays are used to test the effects of various contaminant both in the aqueous layer and in the sediment. This research theme (1) uses a source-sink approach (from catchment soils to stream and lake sediments) via composition analysis of contaminant inventory under different types of urbanization processes in Chinese cities (rapid development of urbanization) and in Finland (regular development rate), (2) aims at getting a holistic understanding of emissions of PAH, PCB and oil hydrocarbon from the city of Lahti (a medium-sized city in S-Finland) to an adjacent lake, and (3) explores anthropogenic contaminants in a river receiving effluents from WWTP and emissions from urban and agricultural areas.