Forest connectivity in the Barents Region

The important role of connectivity of protected areas in boreal landscapes has been recognized among ecologist for a couple of decades (Crooks & Sanjayan 2006, Hanski 1999, Rochelle ym. 1999, Taylor ym. 1993). Only a well-connected network of habitats has the capacity to maintain high biodiversity. In small and isolated habitat islands there is a great risk to lose species. If the protected area network is well connected recolonizations from other areas are possible. Large core areas with natural or near to natural disturbance regime and ecosystem services are less prone to population fluctuations and thus ensure maintenance of viable populations of forest species. Such core areas are vital components of protected area networks.

Some of the HCV forests recognized in this project could be characterized as important core areas, but are not yet included in the present protected area network. Preservation of smaller and unprotected HCV forests as well as nature management in commercial forests surrounding protected areas would support the long-term viability of the protected area networks.

According to the Aichi Biodiversity Target 11 it is important to establish ecologically representative and well-connected systems of protected areas. This is clearly needed to reduce further degradations and fragmentation of forest habitats.

This project has not carried out any comprehensive analysis of connectivity of protected areas and HCV forests as data on HCV forests has been collected with somewhat different methods in each country. Furthermore, a detailed analysis would have been beyond the scope of this project. However, several maps

produced by the project provide a good visual overview on the location of different kind of valuable forests areas and their connections. The maps also illustrate corridors (including ecological mega-corridors) as well as gaps, pinch points and barriers between these areas. There is a need to carry out more careful analyses of the connectivity of protected area networks in each country separately and in the Barents area as whole. In order to get ecologically more relevant result also the southern part of the coniferous zone should be involved in such analyses on the connectivity of the Northern European taiga.

This study has produced maps of spruce-dominated and pine-dominated coniferous forests on mineral soils (maps 9 and 10). These maps are based on moving window analyses where the distance to the closest coniferous forest of either type along a two kilometer radius shows the abundance of these forests in the landscape. This is an example of rough connectivity analyses over large area for these spruce- and pine-dominated forests. It reveals that there are different possibilities to establish connections between spruce- and pine-dominated HCV forests, and certain parts of the Barents Region and particular areas in each country would have a different role in maintaining these type of forests.

Some aspects of connectivity have been highlighted in this study by the help of the permeability concept (Pullin 2002, Rob ym. 2004, Ingegnoli 2015).

Permeability maps illustrate the features of a landscape from the point of view of connectivity and survival of species. The concept takes into account movement of animals and other groups of organisms and the connectivity of habitats as well as structure of surrounding ecosystems. Land use and management practices may affect the permeability and connectivity of landscapes in several ways. For instance, marginal land in rural areas may enhance green infrastructure, and the permeability of certain recently non-permeable or semi-permeable environments can be increased with ecosystem restoration and nature management. This may for instance include restoration of ditched mires and bogs.

Different species utilize and are dependent on different biotopes. For example, for some forest animals, natural wetlands may be less permeable than croplands or even roads (excluding perhaps the largest highways); for some other forest species most open areas are non-permeable. Therefore, a valid analysis of nature area integrity, fragmentation and connectivity should concern only groups of species having more or less similar habitat preferences and ways of moving between different parts of fragmented natural areas. Species groups having different preferences should be analyzed separately.

This study has produced a map that presents the overall forest cover

connectivity for generalist forest species (map 25). The map has been produced by combining several Corine Land Cover classes and applying the permeability concept. All kind of forests are considered to be permeable – at least for certain generalist forests species – whereas the permeability of other land cover types is lower, varying from semi-permeable to non-permeable. A change in permeability between classes can be abrupt or more gradual. All types of forests (deciduous, mixed, coniferous) have been combined in the analysis and they belong either to HCV forests or to other forests in the class Permeable. Different kind of naturally open and sparsely vegetated areas (tundra and mountain vegetation, wetlands like mires and bogs, screes and rocky habitats, shoreline areas including dunes and beaches) and certain human induced open vegetation especially in agricultural environments (like arable fields and pastures) form the Semi-permeable class.

The Semi-permeable class also contains environments like most roads, excluding motorways and wide trunk roads connecting larger cities. These roads belong to the class Non-permeable. In addition the Non-permeable class includes mainly urban and man-made areas (cities, towns, mine areas) as well as recent

non-vegetated clear-cuts and burned areas. Large water areas like the White Sea and the Baltic and big lakes (like Ladoga, Onega etc.) are not included in the permeability classes, although they are often dispersal barriers for many forest species.

Scale is important when producing permeability overviews: if an individual area of semi-permeable land becomes large enough, it actually starts to function as an area of permeable land for many species. On the other hand, if a non-permeable area is small enough like small clearings, roads, lakes, rivulets etc., they can be semi- or completely permeable for many forest species. However, even small clearings etc can be dispersal barriers for certain forest species. Outside HCV forests, in the class permeable, there are mainly successional stands of managed forests. Overall, in a longer time perspective, permeable forests that are not regarded as HCV forests but located between high conservation value forests or protected areas provide possibilities to build ecological connections and improve the quality of particular sites by restoration and nature management.

The map (map 25), based on permeability classes, is probably especially relevant when illustrating the needs of some generalist forest species with good mobility and dispersal ability. Many large mammals and several forest dwelling migratory birds, and certain insects and fungi that can easily disperse over open areas and small water bodies and which have a good far-distance dispersal ability, belong to this group. For many forest species that use also young successional stands or are dependent on typical boreal tree species, the permeable forest landscape is still well connected. These include many vertebrates, insects, fungi, bryophytes and lichens. Forest species strictly related to old-growth successional stands or particular structural characters of natural forests (e.g. large logs or old snags,

138 Reports of the Finnish Environment Institute 33 | 2017

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Permeable Semi-permeable

Semi-permeable, agricultural land

”Silver Taiga”

The map of permeability classes (map 25) shows some interesting features of the study area with regard to biogeography, forest management history, location of high conservation forests and the possibilities to improve forest connectivity between countries and bioclimatic zones. There are very few natural dispersal barriers in the taiga of the study area in the east-west direction, excluding the mountain chains of the Urals in the east and the Scandes in the west. However, the wide low valley of the river Northern Dvina, with a lot of natural wetlands divides the otherwise well-connected forest landscape. For many forest species this is not necessarily a real barrier and there are several forested corridors crossing the valley especially in the north.

The general pattern of permeability reveals differences also within the countries.

Through the study area the amount of HCV forests decreases towards south except in close vicinity of mountain chains. This is in accordance with the forest management history. The texture of permeability of landscape changes and becomes more heterogenic and fine-grained towards west of the Northern Dvina valley. In terms of permeable and semi-permeable habitat patches, the landscape is more mosaic in the Nordic countries and the Republic of Karelia as well as the western parts of Arkhangelsk Region as compared to the Republic of Komi.

This is a consequence of both natural differences and management history. At the same time the geomorphological mosaic of mires, forests and lakes is more fine-grained and diverse in landscapes towards and on the Fennoscandian shield.

However, at the border between Finland and Russia there is again a clear change in permeability pattern. In Finland and Sweden where forest management history is rather similar, the amount of semi-permeable sites increases and HCV forests are concentrated to the northern part of the northern boreal zone and the border between Finland and Russia. In the Nordic countries rather small management units of commercial forests are fragmented by an extensive network of forest roads.

In these countries many HCV forests below the northern boreal zone are islands in a landscape that is semi- or non-permeable with regard to threatened or decreasing forest species.

Photo: Olli ManninenPhoto: Olli Manninen Mountain birch forest in Muotkajärvi, Enontekiö Municipality, Lapland, Finland. Low impact by reindeer grazing.

Mountain birch forest in Annenvaara, Inari Municipality, Lapland, Finland. Intermediate impact by reindeer grazing.

IV

In document Protected areas and high conservation value forests in the Barents Euro-Arctic Region – Sweden, Finland and Russia (sivua 138-143)