Biodiversity as part of land use planning

The planning of a growing city is a combination of many different perspectives and development objectives. One important objective is to promote biodiversity. To promote biodiversity, cooperation between experts is needed at all stages of city planning. In addition to biodiversity, city planning needs to take into account the values related to the quality of green areas as well as recreation and other ecosystem services, i.e. the benefits that nature provides to humans.

In Espoo, the aim was to identify existing or piloted tools for measuring biodiversity, ecosystem services or green elements as part of the Nature-wise Espoo project. Examples of tools were also sought from other cities in Finland and other countries. The goal was to compare tools for assessing the quantity and quality of natural values and ecosystem services, to compare the current state of natural values with the planned situation or planning options, and to measure and illustrate the positive and negative effects of land use planning on biodiversity and ecosystem services.

The no net loss of biodiversity principle safeguards biodiversity and ecosystem services in the face of land use change. The concept of no net loss of biodiversity refers to a state in which the overall impact of human activities does not lead to the loss of biodiversity. A mitigation hierarchy can be applied to pursue the goal of no net loss. According to the mitigation hierarchy, negative environmental impacts of land use changes are firstly avoided by directing development to areas less damaging to nature, secondly mitigated by using design solutions, and thirdly offset by compensating for unavoidable negative impacts elsewhere through ecological compensation.

Tools have been developed in the UK, Germany and Australia to assess the no net loss of biodiversity and to measure natural values on a habitat basis. One of these tools, the Biodiversity Metric, was tested in Espoo in 2022 as part of Kera’s Roadmap to Carbon Neutrality and Sustainability. The tool provides a biodiversity score that provides guidance for avoiding negative environmental impacts and makes visible the change in natural values and the need for compensation. In Kera, the score was used to increase the understanding of how to measure biodiversity and its change in an old industrial and logistics area to be converted into a residential area.

The challenge with foreign tools is to translate and adapt them to Finnish conditions. According to Landscape Architect Mari Soini, “In Kera’s case, the challenge in interpreting the score was that the tool is new in Finland, has not been used much so far and is still in the development phase.” The Biodiversity Metric tool was developed during Kera’s testing to be better suited to Finland’s natural conditions and characteristics, but in Soini’s opinion, a wider use of the tool in Espoo would require more comprehensive development work and adaptation to Finnish conditions.

One of the challenges in applying the tool to Espoo is that construction often requires space from forests and wooded areas. Such areas are given high scores in the original calculation models due to their scarcity. In Finnish conditions, where forests and wooded areas are abundant, the need for compensation in terms of surface area is many times higher than in Central Europe.

To prevent biodiversity loss and safeguard urban nature, information is needed on the overall impact of plans on biodiversity and ecosystem services. In addition to tools for assessing the negative impacts of individual development projects and the potential need for compensation (e.g. Biodiversity Metric), there is a need for tools for city and district-wide assessments.

The regional green factor developed in Sweden is suitable for a variety of urban ecology and ecosystem services assessments, particularly at the district scale. The regional green factor was tested in Espoo in 2022 as part of the Suburban Pride project funded by the Ministry of the Environment in the Matinkylä area. The pilot revealed that the tool can be used to assess the diversity, connectivity and integrity of natural areas, but that it does not currently take into account the different habitat types present in the area.

In the future, the aim is to develop the tool, including from a biodiversity perspective, in the project ARVO – Assessing and Strengthening Green Structure in Urban Land Use Planning, launched in 2023. The main objective of the joint project between Aalto University, Green Building Council Finland and the cities of Helsinki, Espoo and Vantaa is to strengthen the green structure in densely built-up cities.

Tools to support land use planning can be used to guide planning to better take into account natural values and ecosystem services, and to assess the achievement of set targets. These tools are useful for impact assessment, and they can be used to steer plan solutions in a positive direction in terms of biodiversity and ecosystem services.

In addition to the tools assessed, other means were identified in Espoo that commit land use planning to the pursuit of objectives related to natural values and green areas. These include detailed plan regulations and commitments in land use agreements.

The starting point for introducing and developing these tools should be on building on existing tools. For example, the City of Espoo has access to data on green structure, green area types and green services, as well as a city block-specific green factor. At different planning phases, there is a need for easy-to-use tools that allow each planner to carry out lighter preliminary examinations. It is necessary to allocate working time for the development and implementation of these tools as well as for the training on their use in order to ensure their appropriate use and benefits as part of land use planning processes.

In a densifying urban structure, in addition to public green areas, the vegetation of plots and city blocks plays a key role in addressing the challenges of the built environment. Vegetation has positive effects, for example, in managing stormwaters caused by increasing heavy rainfall and in preparing for heat waves by levelling temperature differences and providing shade.

The purpose of the green factor tool is to guide the planning of plots and city blocks towards more sustainable and greener solutions that support the diversity of vegetation in yards and the natural management of stormwater. The green factor describes the ratio of vegetation and various stormwater management solutions to the total plot area. The different elements of a yard are given a weighting in the tool, and the scorecard completed by the calculation gives a green factor value for the whole yard, which is compared to the target level set for the plot.

The Espoo City Council decided on the use of the green factor in the Housing and Land Use Principles on 12 June 2023. Before that, the green factor had already been piloted in detailed planning in Espoo for several years.

“The green factor has steered the design of yards to be greener and more pleasant, and encouraged the use of permeable surfaces and ground-level yard solutions,” says Landscape Architect Ina Westerlund.

The good experiences gained from the piloting led to the development of Espoo’s green factor tool, which was completed at the end of 2023. According to Westerlund, one developmental aspect of the tool has been its emphasis from the perspectives of supporting biodiversity, ecological quality of vegetation and mitigation of biodiversity loss.

“The green factor itself does not measure the biodiversity of a plot or the difference between the baseline and the plan. However, Espoo’s green factor tool aims to encourage the implementation of solutions that support biodiversity in plot and block yards,” says Landscape Architect Aino Leskinen.

Espoo’s green factor tool includes a nature counter that describes the quality of the green elements on a plot from the perspective of biodiversity. The calculator uses a four-level verbal description to describe the achievement of biodiversity-promoting solutions, depending on whether the whole supports biodiversity sufficiently.

According to Leskinen, biodiversity in yards can be supported, for example, by increasing the diversity, layering and indigenousness of the planned vegetation. Increasing the amount of decaying wood, providing nesting sites and habitats for the yard’s fauna as well as favouring flowering and crop-producing species can also support biodiversity in a yard.

Westerlund and Leskinen emphasise that the green factor and the nature counter cannot solve all biodiversity loss or human-induced changes in the built environment, but they can steer urban greenery in a direction that supports species and the preservation of their habitats. At its best, yard greenery that takes biodiversity into account acts as a ‘stepping stone’ in the ecological network and supports a green or blue network.