Natural forest expansion is the natural establishment of secondary forest on non-forested land. In Europe, it has largely been caused by farmland abandonment, with forest cover increasing by 300,000km2 (about the size of Italy) since 1950. This pattern is set to continue in the coming decades, paving the way for further forest expansion across 200,000km2 of EU farmlands under high risk of abandonment.
Rural development and forestry policies mainly support high-intensity land management and afforestation under the EU Common Agricultural Policy (CAP). Despite forests having expanded across much of Europe, European countries have virtually neglected the opportunities that it could bring for EU goals to tackle the twin crises of biodiversity loss and climate change.
A recent review paper, “Can natural forest expansion contribute to Europe’s restoration policy agenda? An interdisciplinary assessment” aims to spark a conversation about the potential of natural forest expansion to help meet targets under the EU Biodiversity and Forest Strategies for 2030 as well as the European Climate Law. The paper gives an interdisciplinary assessment of the opportunities and challenges associated with natural forest expansion, concluding with key policy recommendations. This article summarises the paper, which you can read in full here (in free open access).
Natural forest expansion: a balancing act of opportunities and challenges
The return of non-planted forests offers opportunities in the context of forest restoration efforts in Europe. It can serve as a cost-effective nature-based solution, restoring nature’s contributions to people’s lives in both abandoned rural areas and urban fringes. It can also help with climate change mitigation by increasing carbon stored in forests, as well as enhance local biodiversity and ecosystem functioning. However, it also presents challenges such as increased wildfire risks. Societal perceptions of natural forest expansion vary according to social, economic, cultural, political and geographical contexts.
Maximising the potential of natural forest expansion therefore requires a thorough consideration of contexts and trade-offs.
The paper gives an overview of opportunities and challenges presented by natural forest expansion for five environmental and socio-economic contexts:
- Biodiversity
- Climate change mitigation and adaptation
- Forestry and economic use
- Societal perceptions
- Policymaking
1. Biodiversity
The effects of natural forest expansion on biodiversity and conservation are highly context-specific, with winners and losers, so it’s important that benefits and trade-offs are weighed up with other land uses.
Novel forests can quickly recover biodiversity and the defragmentation of habitats
Novel forests formed by natural forest expansion are often colonised quickly by generalist species, so can quickly approach similar levels of taxonomic and functional diversity to long-existing managed forests. Natural forest expansion has also broadly contributed to forest connectivity and defragmentation across Europe, offering benefits for forest-dwelling bird species.
Novel forests can’t compensate for the loss of unique and complex biodiversity
While secondary forests can quickly become habitats for generalist species, the arrival of specialists and the development of complex networks of biotic interactions takes much longer. This means that secondary forests can’t compensate for the loss of old growth forests and their unique biodiversity. Other potential challenges include the expansion of invasive species and conservation management of species-rich habitats formed by historical livestock farming.
2. Climate change mitigation and adaptation
Novel forests bring opportunities for carbon sequestration
Natural forest expansion holds considerable opportunities for climate change mitigation through carbon sequestration and storage. This potential is linked not just to the increase in forest area, but also the fact that the trees grow on former croplands and pastures. These soils have higher nitrogen and phosphorus content, promoting greater tree growth and carbon storage than in more saturated soils of long-existing forests. So long as wildfire risk is managed, natural forest expansion and growth could hence offset a significant amount of carbon emissions.
In turn, ecological and evolutionary processes involved in natural succession can help secondary forests increase their own resistance (capacity to withstand) and resilience (capacity to recover) to climate change and contribute to the adaptation of wooded landscapes as a whole.
Carbon sequestration potential and land abandonment zones don’t always match up
A key constraint for natural forest expansion to support climate change mitigation is the mismatch between the geographical areas of highest carbon sequestration potential and those where land abandonment occurs. For instance, projected future land abandonment is mostly predicted to occur in areas with restricted plant growth potential, such as the Mediterranean region.
3. Forestry and economic uses
Novel forests could lay the foundations for forest-based circular economies
Increased timber and other forest biomass from natural forest expansion brings potential for a forest-based circular economy. Novel forests can also provide non-timber forest products and other ecosystem services that can be economically valuable to local communities, such as bioenergy and the production of fungi, fruits, herbs and game. Recreation and local tourism could also be sources of income.
In addition to economic opportunities, forest management interventions such as tree harvesting, pruning, species diversification and the introduction of grazing may provide environmental co-benefits: lowering risk of canopy fire; reducing tree density to increase water yields and increasing human accessibility for recreational use.
Forest use could be hampered by factors that caused original land abandonment
The socioeconomic factors that triggered agricultural land abandonment in the first place may hamper forest use options, for example accessibility for mechanised harvesting, local labour availability and the regional demand for products. Technical innovations could potentially help with addressing these challenges in the future.
4. Societal perceptions
Cultural beliefs define stakeholders’ perceptions of novel forests
Natural forest expansion following land abandonment is multi-dimensional. It is connected to agriculture and rural development, nature conservation and forestry. In studies across Spain and France, local stakeholders showed a range of perceptions and attitudes towards it.
Some have a ‘fatalist’ attitude, associating land abandonment with agricultural decline and its negative consequences for livelihoods. Other common attitudes are characterised as ‘pro-forest management’ or ‘pro-nature’, with the former wanting new forest resources to benefit the local economy and the latter considering the opportunities that natural forest expansion offers for nature conservation and ecotourism.
Generational, educational and geographical contexts shape perceptions
Natural forest expansion is often viewed more negatively in rural areas and more positively in peri-urban areas. Younger communities in more urban areas are likely to value the nature and leisure aspects of novel forests, while older, rural groups involved in former land use practices are likely to prefer cultivated landscapes characterised by agricultural mosaics. These groups are more likely to focus on the perceived harms arriving with novel forests, in particular increased fire hazards. Wildfires are also a concern in more urban areas with higher population densities.
This presents a potential conflict regarding the spatial distribution of natural forest expansion. While it often (but not exclusively) occurs in sparsely populated regions, the strongest demand for recreational landscapes and forests occurs in peri-urban areas. In other words, forest restoration building on natural forest expansion tends to be least accepted by society where it is technically most feasible.
5. Policymaking
There is potential and rationale for more recognition of natural forest expansion in policy
The EU Forest Strategy for 2030 acknowledges the potential of natural forest expansion as an important way of increasing forest cover, and it may play an increasingly important role under the EU Restoration Law currently being debated. However, the phenomenon is still not explicitly addressed in most EU policies, where the focus has typically been on active afforestation. On the other hand, the fact that natural forest expansion occurs without the need for active policymaking and management often makes it difficult to handle under established governance procedures that are adapted to ‘active’ policymaking.
As a consequence, political neglect is still the rule despite natural forest expansion offering cost-effective opportunities from a policy perspective.
Policy recommendations
Based on their overview of the available evidence, the authors of the paper suggest the following policy recommendations:
- Recognise and integrate natural forest expansion as a tool in European forest restoration
- Support interdisciplinary research and monitoring on novel forests
- Develop regional strategies that place forest restoration management into the context of local needs
In summary, policymakers should take natural forest expansion into account as a cost-effective and feasible tool for nature restoration in the EU and beyond, while not losing sight of associated challenges and trade-offs with other policy objectives.