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Havainnekuva Katanpäänpuiston luontopohjaisista ratkaisuista. Puisto on osa Turkuun rakenteilla olevaa uutta Pihlajaniemen asuinaluetta.

Biodiversity plays a key role in the development the detailed plan in Pihlajaniemi area, Turku

Published: Oct 5, 2023

The City of Turku aims for carbon neutrality by 2029. This is also reflected in the plans for construction projects: Turku has drawn up a detailed plan amendment for the Pihlajaniemi area, the aim of which is to build a new urban district in a climate-smart manner and taking nature values into account. Sweco is partering in this project with Senate Properties in strengthening the climate goals of the City of Turku.

A new urban and maritime residential area will be planned for approximately 2500 residents. The are in planning is owned by Senate Properties in the northern part of Pihlajaniemi, paying special attention to the City of Turku’s climate goals and sustainable modes of transport. The construction of the area is scheduled to begin in 2024, and the project, divided into four contracts, aims to be completed in 2029 – just in time for the goal of Turku’s carbon neutrality.

“As a landowner in the area, Senate Properties is strongly committed to promoting carbon neutrality and increasing biodiversity in the Pihlajaniemi area. Our goal is to create a new district that is climate-smart and respects nature values, promotes the use of sustainable modes of transport and supports the climate goals of the City of Turku and the whole state,” says Otto Virenius from Senate Properties.

Based on the detailed plan, Sweco has drawn up street and park plans for the area, as well as street and park construction plans, which include the planning of the streets, water supply and stormwater management. Structural designers and architects have drawn up plans for the viewing terrace, pavilion and four bridges, which, together with pedestrian and cycling routes, form a network of recreational, maintenance and rescue routes.

The effects of climate change are mitigated with urban green

Urban green plays a significant role in mitigating climate change and preparing for its effects. Especially when planning new residential areas, attention can be paid from the outset to the quantity and quality of flora and fauna. The aim of Pihlajaniemi’s central green area and street green is to store atmospheric carbon dioxide, increase shaded areas, make the microclimate more pleasant, promote stormwater management and act as a buffer for stormwater floods.

“Urban green has other benefits: it supports the well-being of people and biota and biodiversity, which is in great short supply, especially in urban areas,” says Jenni Tuuli, Sweco’s Landscape Design Project Manager. Tuuli leads biodiversity work in the design project.

At present, the planning area is crossed by an open ditch that collects stormwater from several kilometres away. Planning stormwater parks and wetlands as part of the urban structure is one way to manage heavy rainfall and even large water masses, which have become more common due to the increase in extreme weather phenomena.

“A green stormwater park has been planned around the ditch, where the water flows in the stream, sometimes gathering in ponds and wetlands. At the same time, waters can be delayed, evaporated and lowered by natural means,” Tuuli continues.

The trees in the area have also been rethought from a new perspective. Unilateral and low-species tree plantings have traditionally been favoured by the streets in Finland, but climate change has also intensified the spread of plant pests and diseases. So, single-species plantings are very vulnerable to major damage. Aki Männistö, wood expert at the City of Turku, is involved in the project to expand the selection of tree species in the Pihlajaniemi area:

“In urban environments, one of the cornerstones of biodiversity development is open-minded experimentation with rare or lesser-used species, otherwise new varieties that can withstand the demanding conditions of the city cannot be found. Multi-species and layered plantings have been carried out on the residential roads within the area, as well as on the promenade that cuts through the area and the square,” says Aki Männistö.

Buzzy bugs, decayed trees and diverse vegetation – biodiversity is taken into account in several ways

“Pollinator-friendly habitats are declining globally. Therefore, the role of urban green as a pollinator-friendly environment should be supported. Pollinator-friendly vegetation can be favoured in all landscaping from parks to yards and meadows, not forgetting vegetable roofs,” Jenni Tuuli describes one of the project’s sustainability goals.

In Pihlajaniemi, efforts have been made to take pollinators into account by favouring willows, alder and rowan, as well as other flowering species, such as cherry and ornamental apple trees, on the edges of the stormwater ponds. To make up for the food shortage in the spring, bulbous flowers have been planted and allowed to spread to the area. Pihlajaniemi Square and narrow pedestrian streets will be planted with hay and multi-species abundant perennials with multiple species and layers, inspired by the layers of nature and plant communities. In addition, natural areas with young deciduous stands and plants suitable for damp areas, such as bushy undergrowth and alder, will be preserved in the planning area.

“Compared to bred varieties, wildflowers are more pollinator-friendly because they provide better pollen and nectar patches. They are also adapted to our climate and are durable and easy to maintain. Vegetation is allowed to develop and change and adapt to prevailing conditions over time. Competition, natural life cycles and variation between years shape the visual look of the area,” sums up Jenni Tuuli from Sweco.