Hainich-Dün – Biodiversity Exploratories

1,300

km²

Area

With an area of 1,300 km² and a population density of about 116 inhabitants per km², the Hainich-Dün region is the most densely populated exploratory.

258 – 550

m a.s.l.

Elevation

The Hainich frames the Thuringian Basin and surrounding farmland as an extensive, forested ridge. With 16,000 ha, it is one of the largest contiguous deciduous forest areas in Germany. The Dün in the north covers an area of 270 km² and about half of it is forested.

500 – 800

mm

Annual precipitation sum

Precipitation varies from the high-precipitation west of the ridges to the drier eastern lowlands. The medium-fresh sites are dominated by red beech forests with extensive wild garlic stands.

The Hainich-Dün exploratory encompasses the regions of Hainich and Dün as well as the Upper Eichsfeld. The Hainich is an extensive, forested mountain ridge whose eastern direction is joined by the lower-lying, mainly agriculturally used area of the Thuringian Basin. With 16,000 ha, the Hainich is one of the largest contiguous deciduous forest areas in Germany. In 1997, the 7,500 ha Hainich National Park was opened, and its core zone was declared a UNESCO World Natural Heritage Site in 2011. The Dün is also a mountain ridge with an extension of 270 km² of which about half is forested. Characteristic for the Mittelhainich as well as the Dün is the selection cutting forest management.

Facts

Area	1,300 km²
Annual precipitation sum	500-800 mm
Elevation	258-550 m a.s.l.; highest point: “Alter Berg” in 494 m a.s.l.
Typical plant species	Wood anemone, large stands of wild garlic, mercury, spring snowflake
Dominant forest type	European (mixed) beech forests
Characteristic management types	Selection-cutting forests (so-called “Plenterwald”) organised in forest cooperatives; extensively managed grasslands grazed by sheep forming juniper heath
Specific information	With 16,000 ha one of the largest continuous deciduous forest areas in Germany. Forest sites of the national park since 1935 unmanaged and out of use.

Landscape

In the Hainich-Dün region there is a wide spectrum of differently used forests. In the last 50 years or so, natural forests have been able to develop in the area of the national park, which are very close to the original deciduous forests of Central Europe. In the Mittelhainich as well as in the Dün there is a special form of forest management, the so-called selection-cutting forest management. Trees of different species are removed individually or in small groups after reaching a certain stem diameter. This is in contrast to beech old-growth forests, which are managed on a large scale.
The dominant tree species of the Hainich-Dün is the red beech, which is often mixed with mixed tree species such as ash, sycamore maple, mountain elm, oak and linden. In spring, early bloomers such as wood anemone, wild garlic, mercury, and spring snowflake dominate the forest landscape. The forest is home to demanding forest dwellers such as the wildcat, highly endangered deadwood beetles and fungi.

The grassland of the Hainich-Dün region is surrounded by small-scale structures of settlements, large-scale forests and extensive farmland. Most of the grassland is managed by agricultural cooperatives, the share of individual private farms is small. While the meadows are partly intensively managed and characterized by frequent mowing or intensive fertilization, extensively managed grassland in the Hainich-Dün region is primarily characterized by sheep grazing. Juniper heaths created by this form of farming can be found in Craula and Oberdorla, among other places, and their small bodies of water provide habitats for whinchat and barred warbler, for red-backed shrike and wryneck, for great crested newt and yellow-bellied toad.

Picture: The photo shows a panoramic view over the treetops of the forest in the Hainich National Park. At the bottom right, a part of a treetop path built on stilts can be seen.

Extensive, natural beech forests develop in the unmanaged core area of the Hainich National Park

Picture: The photo shows a fallen tree in an unfoliated forest with tinder fungi growing on its trunk.

Deadwood provides a variety of habitats and helps sustain deadwood-dwelling species

Picture: The photo shows a landscape in autumn with a green meadow in the foreground, a valley with a settlement in the middle and wooded hills in the background.

The forest areas of the Hainich are surrounded by small settlements, arable land, meadows, pastures and limestone grasslands

Geology

The Hainich, Dün and Upper Eichsfeld regions belong to the “Thuringian Basin and Marginal Plates” landscape. The precipitation varies, depending on the location, between 500-800 mm per year: The ridge areas in the west are rich in precipitation, the low areas of the Thuringian Basin in the east are poor in precipitation. The soils of the study region developed predominantly from limestone (Upper Muschelkalk) with a variable loess overburden and silty, loamy and clayey soil types dominate. When the loess cover was high, the soil development was mainly from loess. Since very different amounts of loess were deposited, the thickness of the solum varies greatly. While the calcareous weathered loams are often carbonate-rich, the pH of the soil horizons developed from loess is often between 5-6. Frequently, the loess-rich soils develop a clayey stagnant horizon due to strong leaching and subsequent stagnant waterlogging. The predominant soil types in the Hainich-Dün region include lessive and gley – on steeply sloping slopes and hilltops rendzines occur. Otherwise brown earths dominate. The soils of the intensively farmed Thuringian Basin are among the most fertile in Germany.

Picture: The photo shows a flock of sheep in a green pasture, with a forest in the background.

Sheep grazing as the original form of farming in the Hainich keeps the extensively managed grassland open.

Picture: The photo shows three men in the forest holding and aligning a core drill rig for soil sampling.

The soils of the Biodiversity Exploratories are regularly examined for nutrient ratios, material flows and the composition of the soil flora and fauna

Picture: The photo shows a sunlit clearing in a summer forest, overgrown with grass, shrubs and young trees. Along the edge of the clearing grow tall conifers, some with brown crowns. Behind the conifers are deciduous trees

As part of the large-scale FOX experiment, a large number of trees were removed from various forests.

Plot selection

Using inventories from 1.000 plots surveyed per exploratory, 100 so-called Experimental plots (EP) (50 in forest and 50 in grassland) were selected and permanently marked. These 100 plots cover the widest possible range of land use intensities in the region, but differ as little as possible in other variables such as soil type. In forest, these experimental plots have a size of 100 x 100 m, and in grassland, 50 x 50 m. Each of the plots is equipped with a climate measurement station within a 3 x 3 m fenced area.

Depending on effort and cost, experiments can be conducted not only on all 100 EPs, but also on subsets of 50 (so-called MIP, medium research intensity) or 18 (so-called VIP, very intensively studied plots) study plots.

In the Hainich-Dün Exploratory, 3 additional VIPs were selected which cover a region-specific land use type: the selection-cutting forests („Plenterwald“).

Forest

The forest experimental plots are located in unmanaged natural beech forests (Hainich National Park), in selection-cutting beech forests (so-called „Plenterwälder“ in Langula and Keula), in managed age-class forests dominated by beech (Westerwald, Geney, Sollstedt, Zehnsberg, Behringen, Mühlhausen), and dominated by spruce (Mühlhausen, Anrode).

The forest experimental plots (n = 50) cover the following land use types:

Spruce – Age-class forest (AKL) – young timber
Spruce – AKL – old timber
Beech – thicket
Beech – AKL – young timber
Beech – AKL – old timber
Beech – AKL – multiple layered
Beech-mixed forest (< 70 % beech) thicket
Beech-mixed forest (< 70 % beech) young timber
Beech-mixed forest (< 70 % beech) AKL old timber
Beech-selection-cutting forest
Beech – unmanaged – old timber

Grassland

Grassland experimental plots include unfertilized grassland grazed by sheep, fertilized mowed pastures grazed mostly by suckler cows and calves or by young cattle, and intensively managed meadows with high mowing frequency or high fertilization (manure).

The grassland experimental plots (n = 50) cover the following land use types:

Meadows – fertilized with 1-2 mowing events
Mown pastures – fertilized and grazed by sheep or cattle
Pastures – unfertilized and grazed by cattle
Pastures – dry grassland communities grazed by sheep

Picture: The map shows the grassland and forest areas of the Hainich-Dün area. The positions of the grassland experimental plots of the biodiversity exploratories are marked with small colored squares. — Experimental plots in grassland at the Hainich-Dün Exploratorium

Acknowledgement

The Exploratories cooperate with a large number of different institutions and persons, such as authorities, agencies and the owners and tenants of the study plots. For this we would like to say “thank you”.

Landowners, tenants, managers, forestry offices, nature conservation authorities and protected area managers allow us access to the study areas. This is crucial for the scientific success of the Biodiversity Exploratories. We therefore sincerely thank all persons and institutions for their good and long-standing cooperation. We are also enriched by the intensive and long-standing exchange of information between scientists from the Biodiversity Exploratories and representatives from agriculture, forestry and nature conservation. We therefore look forward to continuing this dialogue in the future.

For our partners in practice, we provide practice-relevant research results from the Biodiversity Exploratories on the page Praxis.Wissen (in German) briefly and in a generally understandable way.

Website of the protected area: