General

The primary purpose of the forest network study is to illustrate the current state of the forest ecological network in the Turku area, including forests and wooded areas. The forest network consists of forest network areas, ecological connections between them, and markings that describe the functionality and development potential of these connections. The forest network areas, with their classifications, indicate the general location of forests and wooded areas in the current situation and serve as a background for the network connections. The study highlights gaps and vulnerable points in the connections and identifies areas for future development. The forest network study was completed in summer 2022, and the data is updated as needed.

Explanation of Designations Used in the Study

Forest Network Areas

Forest network areas indicate the general location of existing tree cover, following the current zoning plan. These areas are divided into three ownership types: city-owned, privately owned, and leased areas. Based on size and forest characteristics, the areas are classified into four categories, consistent across ownership types:

Core forests are the largest and most continuous forest areas, forming the foundation of the forest network. Forests and woodlands are smaller than core forests but still feature layered vegetation and undergrowth, often playing a crucial role in the network. Wooded parks include tree-covered parts of built park areas, especially important in densely built urban areas. Wooded support areas are smaller than woodlands and often lack forest vegetation, such as yard trees or wooded wastelands.

Tree Rows

Tree rows consist of individual trees planted in lines, marked especially where they connect to the forest network. Existing tree rows are categorized by ownership: city, private, or leased land. Additionally, planned tree rows in future zoning are marked separately.

Connections

Forest network connections represent wooded routes used by species to move between forest areas, forming the ecological network. Connections are categorized by ownership and ecological significance:

Main connections are the most important, linking forests and core forests. Regional connections link main connections, often through smaller forests, and are vital in areas like the city center. Local connections complement other connections, typically narrower and ecologically weaker, but still locally significant.

Barrier Effects

Barrier effect markings indicate points where connections are interrupted, affecting their functionality. They are classified by width:

• Very strong (40–60 m)
• Strong (20–40 m)
• Moderate (10–20 m)

Critical Points

Critical points are vulnerable areas in the network, often involving multiple ownership types and/or significant barrier effects.

Sources

Forest network areas are partly derived and modified from forest plot data managed by the City of Turku’s maintenance department and open forest resource data from the Finnish Forest Centre (4/2022, CC BY 4.0). Smaller forest and wooded areas were manually digitized using aerial imagery and canopy models. Valuable forest areas were compiled from environmental protection data, maintenance department forest plots, and Forest Centre data. Connections and their classifications were defined based on forest areas and supported by environmental and zoning data.