The forest area of āāthe European Union has been constantly changing throughout the centuries, but in recent decades we are experiencing a very clear change in trend: European forests grow faster than they are cut down in virtually all Member States. Behind this seemingly good news lies a long, complex, and nuanced story about how we use land, how we manage forests, and how climate change and pollution are impacting forest productivity.
Today, EU forests cover approximately 159 million hectares, around 40% of the community territoryThat is, about four times the area of āāSweden. But it wasn't always like this: for centuries, intensive land useāagriculture, grazing, and the collection of firewood and leaf litterādrastically reduced European forest cover. Fortunately, since the 20th century, the situation has changed. Let's take a closer look at what's happening with forest growth in the EU, why forests are growing faster, how this growth is measured, and what role forest management, climate, and public policies play.
How forest area has changed in the European Union
European forestry history is a succession of felling, recovery, and changes in land useFor centuries, many territories were deforested to clear land for farming, obtain fuel, and build infrastructure. Paleoecological and environmental history studies show that much of Europe lost forest cover intensely over the last millennia.
From the 20th century onwards, especially after the Second World War, a reversal of the trendThe forests began to expand again. This āreturn of the forestā is due to several factors, such as the modernization of agriculture (which allows for greater production on less land), rural depopulation, and the active planting of forest stands for productive, protective, or ecological restoration purposes.
Currently, the EU's forest area amounts to approximately 159 million hectares, which represents about 40% of the Earth's surface of the Union. However, the distribution is very uneven: Finland has around 74% of its territory covered by forests and Sweden around 69%, while countries like Ireland or the Netherlands barely reach 11%, and Malta remains at around 1%.
Since 2000, European statistics point to an increase in forest cover of around 8 million additional hectaresThis expansion includes both planned repopulation and the natural recolonization of old abandoned fields and pastures, especially in rural regions experiencing demographic decline.
The growth in wood volume per hectare This has also changed: the EU average is around 162 mĀ³ of standing timber per hectare of forest, with significant national differences, ranging from about 60 mĀ³/ha in Spain to nearly 390 mĀ³/ha in Luxembourg. Not only is there more forested area, but each hectare tends to accumulate more biomass than in the past.
Growth, timber stocks and balance between increases and felling
When we talk about āforest growthā, it is not enough to count hectares; the crucial thing is to understand how much volume of wood and biomass is added each year and how much is extracted. This is determined using concepts such as net annual increase, timber harvests, and the balance between the two.
The net annual increase reflects the amount of timber that trees add each year to standing timber stocks, discounting natural mortality. In parallel, āremovalsā or harvests encompass the intentionally harvested wood due to forestry activities, but do not include catastrophic damage such as fires, gales or pests, which are accounted for separately in other indicators.
The available figures show that in 23 of the 24 EU Member States with recent data, Forests grow more than they are cut downThis means that the net annual increase consistently exceeds annual timber removals. For reference, in 2019 total timber removals in EU forests were around 497 million mĀ³ (under bark), while the net increase was even greater, meaning that standing biomass continued to rise.
This āgrowth surplusā varies considerably between countries. Romania tops the list with a difference of approximately 40 million mĀ³ of growth above the short-term In a recent year, Sweden and Poland also show very high balances, with around 26 million mĀ³ of net increase over extractions. At the opposite extreme, Estonia is the only country that recorded a year with more timber extracted than added to stocks.
If natural losses (fires, wind, pests, diseases) are added to the equation, the balance changes slightly, but the overall picture remains the same. For example, considering both removals and natural losses, Ireland led the relative increase in stocks In a recent year, with a net growth of +3,6%, followed by Denmark with +3,2%. Estonia, on the other hand, showed a value close to -0,6%, having a level of utilization and losses close to or greater than the natural increase.
This gap between growth and extraction It is an indicator that Eurostat uses as an approximation of the level of sustainability of forest management, as it suggests, broadly speaking, whether timber capital is increasing or depleting. However, it should be interpreted with caution: it does not reflect the structural quality of forests or their ecological status, only the volume balance.
Forest management and multiple functions of European forests
EU forests are not simply a timber storehouse: they are managed with a view to balance between production, conservation and social usesThe relative importance of each function varies greatly depending on the country and region, but overall it can be said that the European model has been oriented towards sustainability and multifunctionality for decades.
In some areasāespecially in northern and eastern Europeāthe main objective is wood productionIn some areas, the focus is on well-defined harvesting schedules and heavy mechanization. In others, however, the priority is biodiversity conservation, soil and water protection, natural hazard prevention, and recreational and landscape use. This is reflected in decisions such as the intensity of thinning, the choice of species, and the extent of areas with limited management.
Since the 90s, a trend towards forms of silviculture has become established.close to natureor āconservation-oriented managementā, which favors more complex structures than the old monospecific and regular forests. Although the dominant model is still, in many places, the uniform-age forest with clear-cutting and some tree retention, a progressive shift towards selective thinning, regeneration in small clearings, and mixing of species is observed.
Harvesting cycles vary enormously depending on the type of forest and the production objective. In plantations of fast-growing species such as eucalyptus, certain pines, or some fir varieties, the Shifts can be between 10 and 30 yearsIn temperate forests of Central Europe, with species such as beech or oak, rotations often extend beyond 80 years and can easily exceed 200 years when large diameters or specific ecological values āāare sought.
The transition from simple, uniform stands to more structurally diverse forests responds both to ecological considerationsāgreater resilience to pests, droughts, or stormsāand to a growing social demand for more natural forest landscapesHowever, the implementation of these practices varies greatly between countries, landowners, and types of forest.
Key forest species and changes in forest composition
The choice of tree species is one of the most important decisions in forestry, as it determines the productivity, resistance to disturbances, and the type of products obtainedFor centuries, European forest managers favored a handful of species with high timber value and good suitability for industrial uses.
Among the most economically relevant and widely distributed species in the EU are the Scots pine (Pinus sylvestris), red spruce or common spruce (Picea abies), the pedunculate and sessile oaks (Quercus robur and Q. petraea) and the European beech (Fagus sylvatica)Pine and spruce, in particular, have been planted extensively both within and outside their natural range, expanding westward and southward beyond their original range.
Historically, the preference for these conifers over many broadleaf trees can be explained by several reasons. On the one hand, they are species with relatively rapid growthThey are capable of producing marketable timber in shorter timeframes, which allowed them to meet the growing demand for wood associated with population growth and post-war reconstruction. Furthermore, they tolerate degraded and nutrient-poor soils better, which are very common after centuries of intensive use such as grazing or the collection of leaf litter for livestock bedding.
From an industrial point of view, Scots pine and spruce wood offer clear advantages: straight trunks, long fibers and few defects (knots, twists, internal stresses), which facilitates its use in sawmills and in the pulp and paper industry. Its processing is energy efficient and its physical properties fit well with European construction and processing standards.
Finally, management also plays a role: the aforementioned conifers respond well to relatively simple silvicultural schemes, which was once very attractive to standardize repopulation techniques and treatments on a large scale. This led to a massive expansion of pine and fir forests, often in areas where beech or oak trees would naturally have dominated.
In recent decades, however, a shift towards a greater presence of broadleaf trees and mixed stands In many regions, particularly in Central Europe, the increase in storms, fires, and insect infestations, along with the vulnerability of some single-species stands to climate change, has prompted managers to diversify. More beech, oak, and other broadleaf trees are being planted, and the mixing of conifers and broadleaf trees is being encouraged to increase resilience.
It is important to remember that species composition is not always the result of a planting decision. In southern Europe, for example, many recent forests originate from the natural expansion onto abandoned agricultural landsIn such cases, the species that become established depend largely on seed availability, dispersal capacity, pressure from herbivores (ungulates such as deer and roe deer, which can inhibit the establishment of broadleaf trees), and soil characteristics. Furthermore, historical agricultural practices displaced forests from the best lands, so many present-day forests are located on poorer soils or in harsher climatic conditions.
Why are European forests growing faster: factors and scientific debate
The continuous increase in timber volume in European forests since the mid-20th century has sparked intense debate about its causes. Statistics from several countries show that the annual growth per hectare (net increase) It has increased almost constantly for decades, although in recent years it seems to be starting to stabilize in some areas.
Possible causes have been cited, including improved forest inventories (which may be better measuring actual growth), increase in atmospheric COā concentrationClimate change (milder winters, longer growing seasons), nitrogen deposition from pollution, the abandonment of practices such as extensive grazing or leaf litter collection, the aging of stands and, of course, changes in forest management.
The contribution of each of these factors has been widely discussed. For example, some studies have qualified the direct role of COā as a fertilizer, pointing out that nutrient and water limitations, as well as the age of the stands, They restrict the effect of ācarbon fertilizationā in mature forests. Other studies have highlighted the importance of nitrogen deposition as the main driver of increased growth, especially in managed and relatively young forests.
The most recent analyses combine field monitoring data with simulation models and indicate that the main drivers of increased forest productivity in Europe are, in combination, the modern forest management (better treatments, repopulation, selection of species and origins, timely thinning) and nitrogen deposition, in addition to interactions between this deposition, the increase in COā and changes in the climate.
All of this has meant that, for decades, European forests have acted as a important carbon sinkThey absorbed more COā from the atmosphere through photosynthesis than they released through the decomposition of organic matter and the combustion of biomass. However, signs of āsaturationā of this carbon sink are beginning to appear in some regions, whether due to the aging of the forests, changes in climate (droughts, heat waves), or increases in extraction and disturbances.
It is worth noting that, although logging has increased in absolute volume in recent decades, it has done so more slowly than growth itselfThus, the total stock of standing timber has continued to increase since at least the end of the Second World War. The question for the coming decades is whether this pattern will continue or whether climate change, coupled with a possible intensification of the timber-based bioeconomy, will ultimately reduce the capacity of European forests to continue accumulating carbon.
Forest data science: how growth and climate impact are measured
Behind the figures on the growth of European forests there are networks of experimental plots and highly complex climate and forestry databasesOne example is the use of long-term monitoring plots in nine European countries, managed by multiple institutions and coordinated since the late 19th century by organizations such as the Association of German Forest Research Stations and, later, the International Union of Forest Research Organizations.
In these plots, typically between 2000 and 5000 mĀ², the diameter of all trees at 1,3 m height is measured periodically (every 3ā12 years), as well as the height of a sample of 30ā50 representative individuals, and it is recorded which trees are removed or die. These data are used to estimate the volume of wood per hectare and its increase in each interval, using species-specific volume functions and allometric models that allow converting volume into aboveground biomass.
From these successive measurements, the periodic annual increase in biomass (PAI) is calculated, which allows analysis of how the growth of a specific mass evolves over timeIn addition, it is possible to estimate the total yield (standing biomass plus extracted or dead biomass up to a certain age) and the so-called "mean annual increment" (MAI), which serves to identify the age at which average production is maximized.
To connect this local data with the climate context, databases such as the European Commission's JRC MARS are used, which provides daily climate information to 25 x 25 km resolution for all of Europe. These series are used to calculate indices such as the Climate-Vegetation-Productivity Index (CVP), which integrates parameters such as mean annual temperature, temperature range, annual precipitation, length of the growing season, and radiation. The CVP has historically been used to map the productive potential of forests worldwide.
By applying statistical models, the temporal trend of the CVP can be studied at each point of the climate grid since 1975, classifying the zones according to whether the conditions for forest growth improve, worsen, or remain stableThis provides a spatial view of how the āproductive climateā of European forests is changing, distinguishing areas with moderate, strong, or deteriorating conditions.
In parallel, growth equations such as the Hugershoff function are used, which describes the typical evolution of the annual increment as a function of age (acceleration phase, peak, and subsequent decline). By logarithmic transformation of this function, it is possible to fit mixed linear models that incorporate fixed effects (age, year of mass establishment, temporal trend) and random effects to reflect differences between species, trials, or plotsThis allows for comparisons, for example, of the growth trends of species such as Scots pine, spruce, beech, or oak in different climatic contexts.
This type of analysis even allows us to evaluate how the growth of the same speciesāfor example, Scots pine, present in many European regionsāvaries in areas where the CVP index has improved greatly, improved little, remained unchanged, or worsened, offering a nuanced picture of the effects of climate on productivity.
Taken together, all this information paints a picture in which European forests have gained area, volume, and productivity in recent decades, driven by management practices, atmospheric nitrogen inputs, and climatic conditions that, until now, have been favorable to growth in many areas. At the same time, warning signs are increasing related to droughts, fires, storms, and pests, as well as pressure to harvest more timber as part of the transition to a low-carbon bioeconomy. Maintaining this delicate balance between produce, conserve and protect the climate It will be one of the EU's major forestry challenges in the coming years.