Research updates

The EU Biodiversity strategy for 2030 calls for strict protection for primary and old-growth forests in Europe, leading to more efforts to identify and monitor them. Remote sensing offers a wide range of data and methods which can support the mapping of forests and their properties. Hirschmugl et al. explore parameter-based approaches such as using airborne laser scanning (ALS) data, direct approaches using machine learning algorithms, and indirect approaches via predictions based on existing data.

Burrascano et al. make extensive and comprehensive data on forest management, structural attributes and multi-taxon biodiversity available in a single, harmonized and publicly explorable platform. They harmonize and merge 34 datasets on forest biodiversity, exploring the links between different forms of sustainable forest management and biological and functional diversity. Knowledge and research gaps include boreal, Mediterranean, thermophilous and floodplain forests.

A dataset and accompanying article developed in collaboration by the EC’s Joint Research Centre and European National Forest Inventory experts presents harmonized statistics and maps of forest area, biomass stock and their share available for wood supply in the year 2020, and statistics on gross and net volume increment in 2010-2020 for 38 European countries. The work harmonizes the sample-based National Forest Inventory data, generally differing in terms of timing, methods and definitions.

The unexpected inflow of wood resources from disturbance-induced salvage logging (e.g. windthrow or bark beetle outbreak) can undermine the stability of forest-based value chains. Asada et al.’s econometric analysis examined short-term value chain resilience in AT, CZ, DE, FI and SE under such supply shocks. The results illustrate the importance of distinguishing quality grades of wood as lower quality pulpwood tends to decrease in price, while higher quality roundwood increases in price through a shortage effect.

The multitude of forestry terms used in European biodiversity studies hinders comparability and makes the assessment of the impacts of forest management on biodiversity highly context-dependent. Trentanovi et al. developed a harmonized terminology for vegetation and forest management-related information by taking a novel bottom-up and top-driven review process. The standards they propose could be adapted to other geographical areas and extended to other forest interventions.

Widescale drainage of wood-covered peatlands has promoted forest growth but also increased soil greenhouse gas emissions, exacerbated by clearcutting. Lehtonen et al. see continuous cover forestry (CCF) as a promising option for mitigation. They simulated four management scenarios for Finnish forests, including a business-as-usual scenario with clearcutting. Results show CCF has potential for emission reduction without compromising wood production despite the leakage of harvests to sites with mineral soils.

European national inventories assess forest resources, meaning the contribution of urban and agricultural trees to national-level carbon stocks is largely unknown. Using maps from 3-metre resolution nanosatellite imagery across Europe, Liu et al. found that in several countries and regions tree cover outside forests exceeds 15% of national tree cover. Urban areas can have a relatively high tree cover with a considerable contribution to the national aboveground biomass.

While deadwood volume is assessed in forest inventories, data about its carbon and density depending on the extent of decay is limited. Neumann et al. used data collected in Austrian forests to estimate deadwood carbon by measuring deadwood volume and decay classes. They found that decay reduces deadwood density significantly, while the carbon fraction increases moderately with decay. Their method can improve the accuracy of assessment of deadwood carbon content based on forest inventories data.

Increasing evidence shows fires cause a shift in soil microbial communities which play a central role in forest carbon and nutrient cycling. To test how soil heating affects microbial functions, researchers heated a forest soil at 200°C or 450°C. Soil heating temporarily altered microbial functions and reduced soil functional diversity. Heating-induced nutrient availability stimulated grass growth, which increased the response to several substrates and increased functional diversity to values similar to unheated controls.

In a European-scale analysis of fire activity in response to increasing summer aridity, Grünig et al. used a multi-decadal, spatially explicit dataset of 64,448 fire events mapped from satellite data. They found that consistent climate sensitivity of forest fire regimes across biomes is significant, projecting that potential maximum fire size and maximum burn severity will increase across all biomes of Europe. The authors see a need for improved fire management and firefighting strategies.

Forest disturbances are increasing in Europe, but geospatial data describing them are often scattered. The Database of European Forest Insect & Disease Disturbances (DEFID2) allows researchers across Europe to share their geospatial reference records of insect and disease disturbances in European forests. Curated by the JRC, DEFID2 currently contains 650,000 harmonized georeferenced records mapped as polygons or points, complemented by the FORWIND database on windthrow events.

Remote sensing science often focuses on a particular data source or methodological development rather than the operational use of derived information. Fassnacht et al. see slow user-uptake, technical issues related to forest inventories, and map validation as challenges in using remote sensing in forest inventory and monitoring programmes. They recommend sharing success stories, addressing real-world problems, and promoting best practices to increase the user-uptake of new technologies.

A deeper understanding of forest ecosystems and their complex interaction with social-economic dimensions and benefits is needed to support forestry and the forest industry to contribute holistically to sustainable development goals. Raihan reviews the ways in which forestry contributes to society economically and explores recent dynamics in European forest resources and European forestry industry trends, as well as the European policy context.

The effects of forest management on biodiversity are difficult to measure. However, many forest species rely on specific structures that may be modified by forest management. Zeller et al. analysed 85 studies to identify above-ground structural attributes that could be used to further develop biodiversity monitoring and forest management. Canopy gaps and structural attributes related to old-growth forests (e.g., stand age, share of large old trees) were mostly positively correlated with species richness.

A deeper understanding of forest ecosystems and their complex interaction with social-economic dimensions and benefits is needed to support forestry and the forest industry to contribute holistically to sustainable development goals. Raihan reviews the ways in which forestry contributes to society economically and explores recent dynamics in European forest resources and European forestry industry trends, as well as the European policy context.