In mixed forests restoration can mean removing spruce. Photo: Björn Nordén.

Forest restoration

Forest restoration is important to secure value creation, biodiversity, carbon capture and climate adaptation for the future. 

Forest restoration can entail many different actions depending on the degree of degradation and the goals that are set. In the Scandinavian countries, the forest cover is high in most regions and the need for afforestation is low, but the ecological status in the present forests (plantations) is often low and motivates actions for the restoration for biodiversity. 

Forest restoration can occur at various scales from microhabitats and individual species, via the “stand” or forest scale, to entire landscapes. The examples from our research activities below are arranged from smaller to larger scale.

A compelling reason for stepping up the efforts of forest restoration is the big and increasing need for climate adaptation. Especially the very dominant Norway spruce plantations are subject to rapidly increasing climate risks. To secure value creation, biodiversity, and carbon capture for the future, threatened temperate deciduous forests need to be restored on land planted with Norway spruce. Development within forestry (based on research) is needed to assure increased planting and use of temperate deciduous trees such as oak, beech, (disease resistant) ash and other alternatives. We study aspects of this transition in several projects and develop new activities within this area.

An example of the effect of the cyclone Gudrun that hit southern Sweden on Jan 8th 2005. Many deciduous trees were still standing after the spruce trees hit the ground. Photo Björn Nordén.

Oak veteranisation

Veteranisation is a method where young trees are actively damaged to create habitats for organisms normally associated with older trees. This is nothing new as we have been veteranising trees for thousands of years through pollarding, for example. We know that pollarding results in the trees hollowing more quickly than unmanaged trees (Sebek et al., 2013). The idea behind veteranisation is thus to try and mimic nature, using tools. The techniques used should not kill the trees, but instead encourage the decay process to develop at a younger age, in living trees. The aim thus being to shorten the delivery time for habitats found otherwise only in old trees. These techniques should never be carried out on ancient or other veteran trees that already contain valuable habitat. Veteranised trees cannot be a replacement for ancient trees that have gone through the natural aging process, but they may provide a bridge over an age gap and help to reduce the risk for random extinction of species because many sites with old trees are small and fragmented.

In a study six years after veteranisation, we showed that the various methods had differing impacts on the fungal communities in the trees, and that endophytic fungi still dominated over decaying species. A study of decay formation and fungal fruitbody will be performed in autumn 2022.

The veteranisation treatments. Drawing: Per Axell.

An example of the effect of the cyclone Gudrun that hit southern Sweden on Jan 8th 2005. Many deciduous trees were still standing after the spruce trees hit the ground. Photo Björn Nordén.

Translocation methods for endangered species

Erioderma pedicellatum (boreal felt lichen; trønderlav) is a globally and nationally critically endangered (CR) species. The last European population is found at a single site in Hedmark. The species occurs on spruce branches and requires a combination of a lot of moisture and light, high pH, and cool temperatures. In a study of E. pedicellatum, we develop methods to identify suitable sites for translocation, to transfer thalli, and to monitor populations. We also study other lichen species and how to adapt translocation techniques to individual species. A general conclusion is that you need a very good field knowledge of your species and detailed insight into its ecology for long-term successful translocations. As an example, our work with Ricasolia and Lobaria species showed that land mollusk grazing can be a major limiting factor if thalli are placed on the wrong kind of trees or too low on the tree trunks, which is not an intuitive result and shows the need for experimental evaluation.

Gauslaa Y, Johlander S, Nordén B (2018): Gastropod grazing may prevent reintroduction of declining N-fixing epiphytic lichens in broadleaved deciduous forests. Fungal Ecology 35: 62-69. 10.1016/j.funeco.2018.06.009.

Boreal felt lichen Erioderma pedicellatum. Photo: Björn Nordén.

Transforest

Expansion of agriculture and other land-use has during the last millennium led to a steep decline of temperate deciduous forest, a biome of outstanding importance for biodiversity. However, the total area and standing volume of temperate deciduous trees are now increasing due to re-colonization on abandoned (marginal) agricultural land. Most of the recent forests within the boreonemoral zone in Scandinavia is a mix of deciduous trees and Norway spruce, and management approaches may be needed to restore biodiversity and ecosystem services. Based on national forest inventories there are > 100.000 hectares of 40–80-year-old mixed forest with temperate deciduous trees to in Norway and Sweden. At 26 field sites we studied the effects on biodiversity of restoration cutting by removal of spruce. Creating a semi-open canopy favored flowering plants, pollination, regeneration of oak, and recreation value. 

Read more about Transforest (nina.no)

One of the sites in TransForest after partial cutting. Photo: Björn Nordén.

Det svenske eikeprosjektet

Vi samarbeider med dette langtidsprosjektet som startet i år 2000 og studerer hvilken effekt delvis hogst av eikedominerte skoger har på mange organismegrupper.

Les mer om Ekprojektet. 

Østmarka national park plan

At the larger, landscape scale, emulation of natural disturbance regimes can be included in restoration plans. In a report on the planned national park in Østmarka, Oslo, we presented a plan on how to restore habitats created by small-scale gap dynamics as well as larger scale forest fires. 

Hardy Geranium Geranium bohemicum is an example of a plant occurring almost exclusively after forest fire. Photo Rannveig Jacobsen.

SATS project restoring moving targets

In this project, we studied the future impact of climate change on climatic suitability for various tree species in Fennoscandia. Coniferous forest suitability will retract considerably.

The first two panels show predicted probability of occurrence (based on National Forest Inventory data and climate, soil, topography) of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) at present, and in 2070 (yellow highest, blue lowest as shown on scale). The third panel shows the change between present and 2070 (blue decrease, red increase as shown on scale).

Nordic seminar on forest restoration

Aug 29-31 2022 we will arrange a seminar and workshops on the theme of forest restoration in Scandinavia. More information and possibilities for contribution will be published here.