Main pressures affecting Europe's forests

Disturbance events like droughts, fires, windstorms and floods are pressures from extreme weather events exasperated by climate change.

Information on the status and trends in the world's forests is regularly collected, evaluated, and disseminated through the Global Forest Resources Assessment (FRA). Standardized country reports are updated every five years. Read more on the FRA site.

Impacts of disturbances on Europe's forests

Generally the damage to forests is difficult to identify, but insects and abiotic factors are the most predominant sources of disturbance and forest damages.

Forest area (kha), and share of forest (%), by damaging agents 2015

 

Insect outbreaks in the EU27, kha/year

 

Disease in the EU27, kha/year

 

Severe weather in the EU27, kha/year

 

Deforestation

In Europe, common cause for deforestation is building of new infrastructure, e.g., urban expansion and mining.

Deforestation in the EU27, kha/year

 

Climate change impacts

Forests are directly linked to climate change by removing or emitting greenhouse gasses. While forests normally remove carbon dioxide from the atmosphere, they also emit large quantities of carbon dioxide back to the atmosphere after a destructive natural disturbance or large-scale forest management operation. The highest emissions occur when a forest area is lost permanently through land use change i.e., an area is deforested.

Forest Fires

Forest losses due to fires have increased in the past years. Fires have more than doubled (an approximately 210% increase) for the years 2016–2018 compared with the average number of fires from 2004–2015. There is great variability between years in the amount of burned area but last years have been extreme. Several large fires affected several European countries in 2017 and 2018, both years with record droughts and heatwaves, and 2020 and 2021 were many times over the long-term average.

Europe Forest fires map of DG ECHO, see maps under https://erccportal.jrc.ec.europa.eu/getdailymap/docId/3893 and https://erccportal.jrc.ec.europa.eu/ECHO-Products/Maps/Maps-Old/Daily-maps

Burn area in each country in 2020 by CORINE land class

 

Forest fire projections

More severe fires and expansion of the fire-prone area are projected in most regions of Europe as shown in the two scenarios below. The maps show the fire risk expressed as change in fire weather index (%) in 2071-2100 compared to the present climate.

European Forest Fire Information System (EFFIS) became operational in 2000 and monitors the fire activity in the EU. The total burnt in protected areas in 2019 was over three times that recorded in 2018.

2 C global warming

4-6C global warming

Source: Projections of Fire Weather Index (PESETA III) provided by Joint Research Centre of the European Commission (JRC)

Pollution

In addition to climate change, pollution is a significant pressure for European forests. While nitrogen deposition has significantly decreased in many parts of Europe, it still causes a risk of eutrophication to many forests stands (ICP, 2018).

Landscape fragmentation

Fragmentation is the partitioning of ecosystems by infrastructures like roads, powerlines and railways. Human traffic channels fracture the landscape and affect animal populations in four ways: decreased habitat amount and quality, increased mortality due to vehicles, reduced access to resources on the other side of the road, and separation of populations into smaller and more vulnerable fractions.

Forest fragmentation impacts ecological processes, such as habitat provision, gene flow, pollination, and wildlife dispersal. Forest fragmentation reduces seed dispersal, limits pollination and hinders animal mobility. This, in turn, limits the resilience of forests to pressures like storms, reduces biodiversity, and the adaptability of forest species to climate change. Pressure from forest fragmentation is increasing at the local scale due to agricultural expansion or abandonment, housing or transport infrastructure.

Landscape fragmentation 2018, number of meshes per 1000 km2

Source: Fragmentation by major roads of large forest complexes. European Environment Agency (EEA)

Native species causing large-scale disturbances

Many native species can cause large-scale forest disturbances. Below are some examples of such species.

Examples of native species of concern to European forests

beetle.jpg

Ips typographus by Gilles San Martin

CC BY 2.0

moth.jpg

Lymantria dispar by Ettore Balocchi.

CC BY 2.0

deer.jpg

Cervidae by Jin Kemole.

CC BY 2.0

European spruce bark beetle (Ips typographus) is one of the most serious and destructive pests of spruce in its native range of Asia and Europe. It is common throughout the entire natural range of Norway spruce in Europe and also occurs in plantations in Western Europe, outside the natural range of the host (Source). In recent years, large outbreaks have occurred in Czech Republic, Germany, Poland, Slovakia and Sweden. Climate change may facilitate the spread of this pest as it benefits from the longer growing seasons, hot and dry summers that weaken its host Norway spruce as well as storms that damage the trees producing ideal breeding habitats.

Gypsy moth (Lymantria dispar) is a significant defoliator of a wide range of broadleaf and even conifer trees. While low population levels can exist for many years without causing significant damage, severe outbreaks can occur resulting in severe defoliation, growth loss, dieback and sometimes tree mortality. This moth is considered a significant pest in both its native and introduced ranges. (Source)

Deer (Cervidae) can significantly hinder forest regeneration. Roe deer, red deer, fallow deer and elk can hinder the regeneration of some tree species as they browse on the tree saplings. For example, in Scandinavia, elk limit the regeneration of broadleaved trees and Scots pine. In Central and Estern Europe red and roe deer are the main herbivores. For example, the regeneration of the silver fir has been low for years due to heavy browsing pressure.

Invasive species

Invasive species are non-native plants, animals, pathogens and other species that may cause harm to the native biodiversity and ecosystems of Europe. For example, pine-wood nematode has caused mortality of pine trees in large parts of Portugal and also in Spain, forbidding the wood trade from those regions to others to prevent the spread of the pest. Invasive species introductions in Europe are increasing across all taxonomic groups. The introduction of invasive species has been increasing exponentially in the last 50 years, and show no signs of slowing. (For more see the Biodiversity FISE page)

Cumulative number of introduced alien plant species to Europe over time

 

Examples of invasive alien species of concern to European forests

Racoon dog (Nyctereutes procyonoides)

Extracted from IAS brochure species

  • The Racoon dog is native to Eastern Asia and wild populations are currently established in 14 Member States
  • Successful carnivore with high reproductive capacity and adaptive behaviour is a threat to biodiversity since it is a generalist that feeds on many native species like rodents, reptiles, waterfowl, and insects.
  • Vector of rabies, ticks, worms, and other parasites which are a threat to native wildlife and humans
  • The EU plan of action includes eradication of new populations and ban on keeping or selling this species

Grey squirrel (Sciurus carolinensis)

Extracted from IAS brochure species

  • Native to North America
  • Introduced in Italy, Ireland and UK
  • Main threat of the red squirrel due to its competitive nature and preference for urban areas.
  • Causes significant ecological and economic damage through habitat stripping

Asian Hornet (Vespa velutina nigrithorax)

Extracted from IAS brochure species

  • Native to Southeast Asia
  • Introduced likely through imported goods
  • Predator of honeybees, wasps, hoverflies and other important pollinators
  • Losses of many hives and due to its aggression, high adaptability have had serious effects on native biodiversity, and caused significant economic damage
  • Nests are actively being destroyed as an EU-policy action

Muntjac deer (Muntiacus reevesi)

Extracted from IAS brochure species

  • Native to South Asia
  • Introduced to European parks in 1900s
  • Established in 5 member states (BE, DE, DK, IR, NL)
  • This species can overgraze, especially in large herds, and can destroy protected areas. Grazing can also prevent coppice growth.
  • EU has a sales ban, phasing out of zoos and ownership prevention.
  • Nests are actively being destroyed as an EU-policy action

Kudzu vine (Pueraria lobata)

Extracted from IAS brochure species

  • Native to Asia
  • So far it has been introduced only in Italy and Switzerland
  • Difficult to manage if established. It can affect structures and recreational facilities, overgrow native forest species and negatively impact crop production.
  • There is a ban on sales, and planting and eradication off new populations is advised to reduce damage if growth continues

Pallas squirrel (Callosciurus erythraeus)

Extracted from IAS brochure species

  • Native to Southeast Asia
  • Introduced to France in 1970s as a pet and since escaped to parks, forests and gardens
  • Established in 4 member states (IT, NL, BE, FR)
  • Very adaptive, generalist feeder, can strip bark and have important economic damage, as well as outcompete native species
  • EU has a sales ban, phasing out of zoos and ownership prevention.
  • Banned for trade

Invasive alien tree species

In contrast, invasive alien tree species tend to spread and conquer local ecosystems and reduce biodiversity by outcompeting other vegetation and changing the food chain. (Source: Introduced tree species in European forests: challenges and opportunities)

Intensity of pressure from Invasive Alien Species across Europe's forests

Source: Assessment of Ecosystems and their Services: An EU ecosystem assessment

Further information

The EASIN - European Alien Species Information Network, is an initiative of the Joint Research Centre of the European Commission. EASIN facilitates the exploration of existing Alien Species information from a variety of distributed information sources through freely available tools and interoperable web services, compliant with internationally recognized standards.

The EASIN web tools and services can be used freely and independently by policymakers, researchers, stakeholders and users from the public, while ownership of the data remains within its source, which is properly cited and linked.

policymakersEASIN enables easy access to data and information on Alien Species occurring in Europe, aiming to assist policymakers and scientists in their efforts to tackle biological invasions.

The EASIN RESTful Web Services enable users to query and retrieve species information from the EASIN Catalogue in the form of JSON objects, and occurrences geospatial information from the EASIN Geo Database; the latter is provided in the form of Well Known Text geometries contained within JSON objects.

The services main web page is at https://easin.jrc.ec.europa.eu/api