Results of the 2022 National Forest Inventory

The forest in Germany has an average growing stock of 335 cubic meters per hectare. This makes Germany one of the countries in Europe with the highest stock levels. With a total of 3.7 billion cubic meters, there is more wood in German forests than in any other country in the European Union.

The ongoing calamities caused by drought and bark beetle infestation since 2018 has caused a massive loss of spruce stocks. Compared to the 2017 carbon inventory, the growing stock has decreased by 220 million cubic meters or 18.2 percent. On average across all tree species, it is roughly at the level of the 2012 National Forest Inventory.

Compared to 2012, the volume of spruce has decreased by around 190 million cubic meters and that of ash by around 12 million cubic meters. In all other tree species groups, the growing stock has increased: For pine, the increase is 23.6 million cubic meters, for beech 46.5 million cubic meters and for oak 48.1 million cubic meters.

Douglas fir showed the largest relative increase in stocks at 32 percent. Despite the small area share, the Douglas fir stock increased by 22.7 million cubic meters. The reason for this lies in the productivity (15.4 cubic meters per hectare per year) of the tree species and its high proportion of vigorous young trees.

The growing stock of thick trees has continued to increase. This trend has continued since the 2002 National Forest Inventory. This means that the growing stock is shifting further into the thickness classes with a diameter greater than 40 centimetres at breast height. Below this, the timber stock has decreased. This trend is particularly evident in conifers. This is a challenge for the marketing of coniferous wood in particular, as the sawmill industry is predominantly geared towards processing weak and medium-strength coniferous wood between 20 and 40 centimetres in diameter.

The increment amounts to around 9.4 cubic meters per hectare and year, or 101.5 million cubic meters annually nationwide. Compared to the 2012 National Forest Inventory, increment has decreased by around 20 percent.

This large decline is largely determined by three factors:

• the calamity-related failure of the spruce,
• the ageing trend of the forest
• the long-term drought

In the period from 2012 to 2022, an average of 72.6 million cubic meters of raw wood (harvested solid cubic meters without bark) per year or 6.7 cubic meters per hectare and year were used in Germany (2012: 75.7 million cubic meters per year, 7 cubic meters per hectare and year). At 6.8 cubic meters per hectare and year, the amount of timber harvested in private forests remained almost the same as in the 2012 National Forest Inventory (7 cubic meters per hectare and year). The difference in wood use between ownership sizes has decreased. The private forest in all size classes is now used as intensively as the state forest land.

Currently, 87 percent of the forest area can be used for timber without restriction. However, wood is not used everywhere. On seven percent of the total forest area, utilization is only partially expected. Six percent of the area is not used at all, although there are major differences between the different types of ownership. In the state forest of the federal government and the federal states, eleven percent of the area is not expected to be used for timber, while in the corporate forest and private forest this only applies to just under four percent. Compared to the last inventory, the area with restrictions has increased further.

Currently, pines, spruces, beeches and oaks characterize the face of our forests. Spruce has given way to pine as the most common tree species. The tree species have different regional focuses.

The main distribution area of the pine is the north-east German lowlands from Lower Saxony to Brandenburg and Saxony. Other main areas are the Palatinate Forest, the Rhine-Main lowlands and the Upper Palatinate basin and hills. At 2.4 million hectares, pine is the tree species with the largest distribution (21.8 percent), although it also lost 41,000 hectares between the last two federal forest inventories.

Spruce often forms the forests from the foothills of the Alps to the high altitudes of southern and south-western Germany and in the low mountain ranges of north-eastern Bavaria. In the low mountain ranges such as the Harz, Solling, Bergisches Land, Sauerland, Rothaargebirge, Thuringian Forest and the Ore mountains, it has become considerably less important since 2018 due to storms, droughts and the resulting mass proliferation of bark beetles. Compared to the 2012 National Forest Inventory, it has lost 460,000 hectares in area and now stands on 2.3 million hectares or 20.9 percent of the forest area.

The beech is mainly found in the low mountain ranges from the Swabian-Franconian Alb to the Palatinate Forest, Vogelsberg, Eifel, Odenwald and Spessart to the Solling. While its distribution was still at 15.6 percent in the 2012 BWI, its distribution has increased by 130,000 hectares to 1.8 million hectares or 16.6 percent. Beech is currently showing significant damage due to the drought, which is hardly reflected in the BWI 2022.

Oak is particularly prevalent in the Palatinate Forest, the Spessart and the warm lowlands of Germany. Its share has increased from 10.4 to 11.5 percent, or by 119,000 hectares to 1.3 million hectares. Oaks are also suffering from the drought, with the result that mass infestation by the oak splendid beetle can be observed regionally. Oaks are dying and the structure and existence of entire stands as oak forests are threatened.

Compared to the BWI 2012, the forests in Germany have become older. In 2022, over 30 percent of our forests will be older than 100 years, and over 20 percent older than 120 years. In the 2012 inventory, only 14 percent of the forest area was older than 120 years.

The forest will be 82 years old on average in 2022. Despite the forest damage caused by storms, drought and bark beetle infestation and the associated loss of old trees, it has become five years older compared to 2012.

Compared to the 2012 BWI, the age of the spruce has fallen by six years to 62 years. The age of the pine has increased by eight years to 85 years. The oldest conifer species on average is and remains the fir with 98 years. It is surpassed by the oak with 107 years, which is thus on average another five years older than in the BWI 2012. The beech follows with 102 years, having become only slightly older with a difference of two years. At 52 years, Douglas fir is the youngest tree species despite an increase of seven years, partly because it can already be used and regenerated at a comparatively early age of between 61 and 80 years due to its rapid growth.

In the case of conifers, the first age class (up to 20 years old) continues to decline, the second and third age classes show a significant loss of area, which is likely to be caused primarily by the bark beetle from 2018 onwards, while the higher age classes show an increase in area. An exception is the fifth age class, in which many conifers reach their age of utilization. In the case of deciduous trees, the influence of declining utilization is evident in the higher age classes. The areas there have increased significantly in the last two national forest inventory periods.

The increase in old trees promotes biodiversity. This is because old trees are more likely than young trees to have special microhabitats such as coarse bark, crown deadwood, board roots, branch breaks or woodpecker cavities. Many rarer species that specialize in certain stages of decay are also dependent on these microhabitats. In addition, old trees are an attractive eye-catcher for forest visitors.

From a climate protection perspective, there are two aspects to increasing the age of the forest: firstly, the growth per hectare and thus the additional carbon sequestration and climate protection effect decreases at a higher age. Secondly, climate change can alter the site conditions in such a way that other tree species are now adapted to the new conditions. These new tree species must be introduced through forest management. This requires the use of existing older trees, which reduces the average age. Consequences for biodiversity, on the other hand, must be weighed up. For example, the retention of ecologically particularly valuable tree individuals must be integrated into the management.

Important characteristics for the structural diversity of a forest are its horizontal and vertical structure, i.e. its mixture of tree species and the layering in the canopy. A forest in which different tree species stand side by side and the canopies of several layers of trees stand on top of each other offers diverse habitats for animals and plants. It can also react better to unfavorable environmental influences and pathogens due to the diversity of species, structures and genomes.
 
An essential element of the horizontal structure of the forest is the extent of the tree species mix. Mixed forests characterize 79 percent of German forests (2012: 76 percent). Still relatively little mixed are pine forests with 61 percent or spruce forests with 75 percent mixed area. All other stand types are more mixed.

Natural regeneration is the predominant type of regeneration in German forests, accounting for 91 percent of young stands. It has increased by six percentage points compared to the last BWI. 220,000 hectares or 7.1 percent of the young stocking originated from planting. They are mainly found in Douglas fir stands. Less than one percent of the young stocking is the result of sowing or growth as coppice.