The junction of four dominant landscapes creates our unique natural environment (Fig. A1). Lahti’s landscape was formed by the last Ice Age, 12 000 years ago . The Salpausselkä ridge system has numerous kettle holes and is covered by forests. The lake district has many forests and a varying landscape: steep ridges and cliffs, rivers and lakes. Clay and silt plains, south of the ridge, are accented with sparse moraine ridges, granite cliffs and the Porvoo River.
Mapping of the Siberian flying squirrel in 2014-2015, revealed that the species occurs in nearly all of the larger forests. Mapped species data is used in land use planning. All bird species have been mapped. We are monitoring the abundances in co-operation with the Päijät-Häme Ornithology Society. Abundances of black woodpeckers and Eurasian three-toed woodpeckers are increasing and both are protected under the EU Birds Directive Annex I. Bird maps were published in book format (“Bird Atlas of Lahti”) in 1999 and 2012 (freely available online). Otters and rattle grasshoppers are monitored in 5-year cycles that follow populations and habitats. A bird and plant atlas is published every ten years, and bats and the Siberian flying squirrel are monitored in 10-year cycles.
Nature protection targets for 2030, is implemented into the new Environmental Programme of Lahti 2017-2030. We are committed to increase the share of protected sites to 8% of total city area by 2030.
Over 80% of Lahti is covered by water and green spaces (Figs. A3-A5). 995 ha are protected by national legislation (Fig. A2). Two core areas for biodiversity, Pesäkallio and Linnaistensuo, were included in the Natura 2000 network in 2004. Lahti has designated over 400 smaller sites (1 933 ha) representing a variety of habitats (meadows, old-growth forests, cliffs, springs, small rivers, ponds and individual trees). Most of the forests are not protected yet. They generally receive minimal management, and are close to their natural state . Mature street trees and smaller green spaces in the inner city (Fig. A4) function as green corridors (e.g. for flying squirrels).
Compensation to land owners (METSO funding) from the Finnish government has made designating protected areas easier. All protected sites have management plans.
Restoration has involved closing drainage ditches in the Linnaistensuo Bog and grazing sheep and cows along the Luhdanjoki River. The restoration of Lake Vesijärvi is an internationally renowned success story (5B).
Protecting common urban species has not been regarded as being as important compared to more pristine areas. This attitude is changing as ecosystem services and the need for wide ecological connections are being recognized.
The value of biodiversity is emphasized in many of our projects and programmes for residents, especially for children, e.g. in the LUMA projects, where children study natural sciences outdoors. Adults are encouraged to take care of their local nature i.e. by removing invasive species.
Lahti University of Applied Sciences launched the Salpausselkä Geopark project in 2017 with the goal of applying for UNESCO Global Geopark status. Seven municipalities situated along the Salpausselkä formations or around Päijänne National Park, with some 182 500 inhabitants in total, form the area of the aspiring geopark and are the main stakeholders (Fig. A5).
Biodiversity protection started in 1962 (first protected site), but truly gained momentum after the 1990s. Linnaistensuo was partially designated (100 ha) as a Natura 2000 site in 1998, as being representative of a southern Finnish bog. The bog had already been drained, but the value had been preserved. We began restoring the Linnaistensuo Bog in 1995, by closing the ditches. Linnaistensuo is important to black grouse and butterflies (Light Brocade, Freija Fritillary, Streaked Wave). The conservation area has been enlarged (currently 200 ha). Other protected areas, e.g. Pesäkallio, have been enlarged and improved (from 70 hectares to 200 hectares, since 2013). Many of the conservation sites are still small (average 30 ha).
New conservation sites have been added, almoust annually, through METSO funding (Fig. B1). In 2012, the hugely popular Lapakisto site (230 ha) was protected.
Locally protected smaller biodiversity sites (LUMO) were first designated in 1995 and by 2016 covered 1933 ha of Lahti. Nationally protected areas and LUMO sites cover 24% of the total forest area owned by the City of Lahti. Many of the LUMO sites are located in the inner-city, making them important for urban biodiversity and to residents.
All protected sites have management plans (drafted for designation and updated when widened). Due to changes in farming practices, open habitats have started to becoming overgrown. To preserve the valuable habitats, sheep and cows have been re-introduced to the Luhdanjoki conservation site. Additionally, sheep are annually used to maintain the Paakkolanmäki and Ristolanniitty meadow sites.
Information signs are installed to inform visitors of the value and rules of the conservation sites. Many of the protected sites have good quality wooden paths. Fallen trees are used to guide people to recommended paths, to avoid wear and tear from walking.
The 2013-2025 Green Spaces Programme focuses on ecosystem services. Urban ecologists from the University of Helsinki drafted a sound programme for enhancing biodiversity and ecosystem services. Opinions of residents and other interested parties were also considered. Residents desired both higher maintenance levels and ecological management. Thus, important nature areas (e.g. forests on the Salpausselkä Ridge) will receive very little maintenance, while city centre parks will be highly managed. A diverse set of local plant species is recommended for aesthetic purposes.
Biocides are only allowed, by special permit and only if other measures have failed (no biocides were used in 2015-2016). A non-toxic hot foam system has been tested for controlling weeds and invasive plants, although generally, simple weeding is used.
We manage forests according to our Guidelines for Management and Use of Municipal Forests, and the 2013-2025 Green Spaces Programme. Lahti owns 7 000 ha of forest, where nearly 40% is over 80 years old (Fig. B2). Most forests have trees of the same age and species. We are now planting new trees and keeping old-growth trees to increase diversity. Management involves thinning and making small gaps, to allow forest regeneratione. Tree species diversity of trees has increased, recently. This ensures forest sustainability as a habitat, increases pest resistance and resilience to climate change. If possible, dead wood is left in urban forests by girdling trees or by cutting living trees at a height of 2-4 meters. Ditch drainage is only carried out if absolutely necessary. Protected sites are minimally managed. The high share of old-growth trees and dead wood is evident from the city’s species list (see 4A) and population trends (Fig. B3).
In the 1970s, Lake Vesijärvi (Fig. B4) was one of the most polluted lakes in Finland. Restoration started in the mid-1970s, when an urban wastewater treatment plant was built. Later, biomanipulation was used. In 2001, restoration began in co-operation with several municipalities, universities and research organizations. The work is funded by the Lake Vesijärvi Foundation (primarily funded by the Lahti City Group: 250 000 €). The current restoration stage involves such measures as mapping pollution sources, eliminating wastewater sources from private dwellings, constructing retention ponds and wetlands, management fishing (roach, bream, bleak) and planting predatory fish. As a result, oxygen depletion occurs less often, populations of predatory fish and several rare species have increased (e.g. eel, pike perch, sea trout, moor frog, dragonflies). We annually stock 10 000 elvers, since traditional eel populations are endangered.
We have constructed about 20 wetland systems for treating stormwater, before release into water bodies, over the past 10 years. Wetlands and retention ponds are used in new developments or added to old urban areas, whenever possible.
Since 2012, Lahti has participated in the “Jokitalkkari” Project. The project aims to improve river conditions so that salmonid populations will increase or return. The project also improves living conditions for other migrating fish and grayfish. We also stock the rivers with sea trout. Over the past three years, we have helped nearly 1 000 mature eels migrate to the sea.
In 2016 we mapped all the springs. This data was set in the city’s GIS system, where information is available to all experts on WebMap, to assist with managing land use, building sector and environmental services.
Nature protection investments reach approximately 95 000 € yearly, and are mainly used to improve access to protected and other nature areas (paths, resting sites, information signs) and for education (e.g. guided tours, nature trails publications, protected species and habitats information signs, bird watching towers).
Lahti has numerous programmes and projects related to environmental education, including:
• A permanent environmental teacher position to guide and train schoolteachers in organizing outdoor lessons and provides equipment (e.g. trekking bags, loupes, binoculars and simple identification keys).
• A mobile classroom, “Ecovan”, equipped with modern technology for studying nature.
• Environmental grandparents: volunteers who teach children about environmental issues and nature - connecting children and the elderly.
• 50 kindergartens that mapped interesting nature objects and species in nearby green spaces to help find them more easily. The data is stored in the city’s GIS system for use in detailed planning and forest management.
• The project “Mun juttu” (“My Thing”) for improving wellness of young adults and reconnecting them with nature.
Another unique project, taking place in Lahti, is the ADELE research project from the University of Helsinki, which studies the links between biodiversity and the human immune system strength (Fig. B5).
Residents finance or volunteer for nature conservation and restoration. Community work is organized to control invasive species . We provide advice and equipment. In 2016, giant hogweed and its early development stages were demonstrated at exhibitions in the city centre to ensure early control of this species. A clean-up campaign  is organized yearly in schools and residential areas: In 2016, nearly 10 000 children and adults participated in cleaning the city.
The pressure to build houses, industrial areas and roads in green spaces and wider nature areas is increasing. Forecasted population growth is 1% annually. Meanwhile, the ecological network needs to be improved and expanded, to ensure the survival of local populations and increase resilience (Fig. C1). To safeguard the functioning of ecosystem services, the quality of green spaces must be enhanced.
The Lahti City Strategy 2030 states that Lahti will succeed as a bold environmental city. Taking care of the environment is at the heart of the strategy and is to be incorporated into all plans, budgets and actions. The Master Plan emphasizes the need for improved ecological connections and the recreational importance of green spaces within and around the city area.
Actions in the Programme of Green Spaces 2013-2025 and Guidelines for Management and Use of Municipal Forests will continue (5B). Urban forests will be managed as little as possible, a diverse set of local species are recommended and ecosystem services are considered. Implementation of the plan is monitored yearly.
According to our Stormwater Management Plan, stormwater must be managed ecologically in newly built areas (Fig. C2).
A Biodiversity Action Plan is currently in preparation and targets are also incorporated into many other plans, such as the Green Spaces Programme, the Master Plan, Guidelines for Management and Use of Municipal Forests, Controlling of Invasive Alien Species etc. We consider and incorporate the EU Habitats and Birds Directives, e.g. protecting critically endangered eel. The biodiversity area targets are incorporated into the Environmental Programme 2030, which states that 8% of the city’s area should be protected by 2030.
• New protected areas are added and old ones enlarged: Kintterö, Viuha and Lapakisto in 2017.
• To celebrate Finland’s centenary year, we will donate a new area to protect the Sammalsillan suo (bog). A nature path will be built to increase accessibility of all people.
• We have initiated a project to apply for UNESCO Global Geopark status for the Salpausselkä Ridge around Lahti.
• Small and previously fragmented forests are made available for recreation to meet the increasing number of residents. Large and pristine areas are protected from wear and tear.
• More circular hiking routes are planned to complement existing ones, to create a walkable city. We will build a circular trail around Lake Joutjärvi and lengthen the trail from River Porvoonjoki to Okeroinen.
• In the immediate future, wetlands will be built in Ranta-Kartano and Hennala. Stormwater from the city centre will be managed in these areas (Fig. C2).
• Planting 150-250 trees along streets and 200-300 in parks, yearly, to improve connectivity for flying squirrels and bats. The City of Lahti has roughly 10 000 street trees, of which 3 000 are in the city centre.
• 10 000 € yearly to eliminate alien species, such as Persian hogweed, Himalayan balsam and garden lupine (since the 1990s). In 2016-2018, we will invest 24 000 € and concentrate on hogweed in forested areas and finding the best non-toxic solutions.
• In the coming years, we will draft more detailed action plans (for local sites of biodiversity value, build urban parks).
• The drafts for Invasive alien species management plan, and Green networks plan are almost completed.
• Over the next five years, we will update old species maps, e.g. bats (existing 2004), the Siberian flying squirrel (existing 2015), the European otter (existing 2014), birds (existing 2010).
• School students have now mapped their local nature areas, similarly to that done by the kindergartens. The data is to be incorporated into the city GIS systems.
• The environmental teacher and the Ecovan will continue working with children (Fig. C3). Other successful environmental education projects will continue, such as “Environmental Grandparents”.
• “A whole day outside kindergarten” is to be created (Fig. C4).
• Health and wellbeing: Kintterö “healing forest” in 2018 will be created in cooperation with Aalto University, the Natural Resources Institute Finland, Lahti University of Applied Sciences, the Central Hospital of Päijät-Häme Region, the Ministry of Social Affairs and Health and the National Institute for Health and Welfare (Fig. C5).
• Mapping of experience-based information from residents, regarding favourite places in the forests, launched in September 2017.