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Biodiversity is good for the community

The healthier our natural environment, the better we humans feel. Biodiversity is a valuable asset for Lahti and worth protecting.

Lahti lies sprawled along the edges of the ice-age ridge system of Salpausselkä and the fragile groundwater resources underneath. The vast forests of the region are home to many species of plants and animals, and both the wilderness and planted green spaces are also important for the health and well-being of the area’s human inhabitants.

That is why it matters how the city is built and developed.

‘It is only in the last few years that the science of how dependent we are on nature and how important biodiversity is has really hit home both globally and locally. We in Lahti also get a lot from nature and rely on the well-being of our natural environment’, says the City of Lahti’s Environmental Coordinator Aino Kulonen.

‘This is just like climate change, which the scientific community have been talking about for decades. All it takes to get people’s attention is to show that there is an economic dimension, that the entire global economy depends on natural resources.’

Growing up close to nature

The Lahti Regional Health and Environment Programme 2022–2032, subtitled ‘Nature Step to Health’, reminds us that we, too, are part of nature and that staying connected to nature is like recharging our batteries.

‘When we look after nature, it looks after us. Spending time in the great outdoors affects both our physical and mental well-being. An old-growth forest in a nature reserve, for example, produces a different impact on our health than managed commercial woodland’, Kulonen explains.

The relationship between humans and nature has also been studied in children’s nurseries in Lahti. The outdoor space at nursery plays a significant role in strengthening children’s immune system. Nurseries with microbe-rich natural woodland on their doorstep work completely differently on the immune system than nurseries with a purpose-built concrete playground.

Children are also the future when it comes to protecting our natural environment. The city can mould the relationship that children form with nature through the environmental education provided in schools.

‘Environmental educators visit schools to talk about the importance of respecting and cherishing nature. They take groups of schoolchildren to the woods and teach them to identify different species of plants and about biodiversity’, explains the City of Lahti’s Nature Conservation Specialist Mia Honkanen.

More nature conservation areas

Honkanen is working with an external consultant to draw up a new nature conservation plan for the City of Lahti and to identify the areas of public land that need to be protected.

‘We want the network of nature reserves to also include habitats that are currently underrepresented, such as small streams and riverbanks, traditional landscapes and areas that are home to endangered species.’

Among the ecosystems that are close to Honkanen’s own heart are Lahti’s old, spruce-dominated forests that are rich in coarse woody debris.

‘The City of Lahti understands the importance of woodland, which is evidenced, for example, by our robust flying squirrel population.’

The City owns approximately 7,000 hectares of forest. These woods are not exploited commercially, and instead the primary aim is to secure the provision of ecosystem services. The City of Lahti’s forest management programme also factors in the use of the woods for recreation and outdoor leisure purposes.

Significant habitats in the Salpausselkä area include sunny ridges where the lack of vegetation provides a home for many vulnerable insect species. Simply preserving these and other habitats is not enough, however; to promote biodiversity, active restoration efforts are also needed.

‘We are currently working on woods that are home to, for example, the white-backed woodpecker. The aim there is to remove young spruce trees to give deciduous trees a better chance to succeed. Local waters are being stocked with predatory fish species. The critically endangered eel population, for example, has been successfully revived thanks to an annual stocking rate of 10,000 and by ensuring that the fish can get past dams on their migration to the sea’, Honkanen explains.

Non-native species represent the wrong kind of diversity

Not all diversity is good. Non-native species that are being introduced to Lahti and elsewhere in Finland cause havoc in the environment and destroy local ecosystems. The large and greedy Spanish slug, for example, has become a frequent and unwelcome guest in Finnish gardens. Local residents are being engaged to fight the pest by throwing garden work parties and supplying special bins in areas where slugs have been spotted.

Another species that is causing concern in Lahti at the moment is the European spruce bark beetle, whose larvae have already destroyed vast areas of forest. Although not an invasive species per se, outbreaks of the larvae are yet another consequence of global warning.

The best known non-native plant species in the area are the Himalayan balsam and Persian hogweed.

‘In terms of Persian hogweed, the situation is largely under control. However, it has taken years to get to this point and we cannot afford to take our eye off the sites where the plant is known to have grown in the past. Managing invasive species is a long-term effort’, Honkanen says.

The Himalayan balsam, on the other hand, is currently spreading like wildfire and has become a real problem. This invasion is being fought off battle by battle.

‘The City of Lahti has got the community involved by, for example, providing crates in the areas where the plant thrives and inviting local residents to uproot the weeds and place them in the crates. The City takes care of the destruction of the plants.’

Ecological compensation for the disadvantages of urban development

Urban development is always a threat to the natural environment – wherever there is construction, nature has to give way. However, the adverse effects of development can be mitigated by means of ecological compensation. Ecological compensation means making up for the loss of natural habitats in one place by investing in a natural green space somewhere else.

‘The first rule is always to avoid building in areas that are ecologically valuable altogether. If no suitable alternative location for the construction project can be found, steps must be taken to minimise the impacts on biodiversity on site and only if this, too, is not possible, can the effects of the project be mitigated by means of ecological compensation in another location’, explains the City of Lahti’s Landscape Architect Maria Silvast.

The City is currently piloting ecological compensation by restoring old woodland on the shores of Lake Alvojärvi to make up for the adverse effects of a residential development in Kytölä.

Lahti is a pioneer in ecological compensation.

‘The concept was experimented with in a project called No Net Loss City in Jyväskylä and the City of Espoo has similar projects in the pipeline, but we in Lahti have made the most progress so far. Work on the compensation model continues in the form of, for example, a project called BOOST (, which follows in the footsteps of No Net Loss City and in which the City of Lahti is also involved.’

According to Silvast, consulting all the interested parties is critical to the success of ecological compensation initiatives.

‘Land-use planning has far-reaching effects. That is why it is so important that all those who could potentially be affected are kept in the loop and given an opportunity to express their views.’

Towards a nature-tolerant society

The City of Lahti fights biodiversity loss through a number of large projects and ambitious plans. Grassroots action is also needed, and everyone can do their part.

‘It all starts with our own habits as consumers and focusing on the long term. We all need to think about how we live, what we buy and how we move around’, Mia Honkanen says.

Local residents can literally make a difference in their own back garden. This applies not just to people who own their own houses but also to those living in flats, who can influence the look of their building’s communal garden through the residents’ association.

‘Every garden should have an unkempt corner where biodiversity can thrive. Pollinators can be attracted by the choice of plants and by providing them with suitable nests in, for example, insect hotels.’

People who have grown up in the city are used to seeing pristine lawns and carefully pruned hedges and bushes.

‘Letting lawns turn into meadows and hedgerows into thickets in city parks would actually be better from the perspective of biodiversity’, says Environmental Coordinator Aino Kulonen.

Not everyone likes this, however, and the City of Lahti is used to receiving feedback such as ‘looks untidy’ and ‘there could be ticks’.

‘The eye can be trained to also enjoy wilder forms of natural beauty.’

Modern society expects tolerance in all areas of life. Perhaps we also need to learn a little nature tolerance!


Text: Sami Turunen
Photo: Hannes Paananen