For more than 1,000 years there have been records of how Kottenforst has been used. This book tells of the most important stages - from the first known document to today's sustainability goals.

This map was created more than 200 years ago. It is one of the so-called Tranchot maps, which were compiled after the invasion of the French revolutionary troops in 1794.

The first written mention of the Kottenforst goes back to the Roman-German Emperor Otto II. In 973 he confirmed the hunting rights for the king and the aristocracy, and extended them to the archbishops of Cologne. The latter were also granted the right to permit deforestation. The document outlined the boundaries of the Kottenforst area, and these are still roughly valid for today.

But where does the name Kottenforst come from? Its origin is even older than the document written in 973. It can be traced back to the first settlements of the Celts. "Kotten" derives from the Celtic word "coat" for forest area. The term " Forst " was used in the Middle Ages to refer to uninhabited forests.

From the Middle Ages to the end of the 19th century middle forest management was the typical form of forest management. Some trees – mostly oaks – were left standing; the hornbeams and lime trees that grew between them were used for firewood about every 20 years. Because they were considered to be strong trees, the oaks were then used as timber for building purposes. Furthermore, people could drive pigs into the forest, to be fattened by the acorns and beechnuts.

Middle forest management was abandoned around 1870 in favour of high forest management. In a high forest, trees grow from seedlings or plantations and are not cut down until they have reached the desired size. High forest management was the starting point for many modern forestry concepts.

Beheaded (or ghost) beech trees in the Kottenforst originate from the time when people grazed their cattle there. Their cattle, pigs, goats and sheep fed on acorns, beechnuts and the fresh shoots of trees and bushes. Young trees hardly had an opportunity to grow. It was as if the forest floor had been swept clean.

People needed the forest not only for pasture, but also for firewood and timber. This is why they cut the beeches at a height of about 2 metres. New branches sprouted from the places where they had been cut, and these were beyond the reach of the hungry grazing animals. In turn, the new branches were regularly cut and used. Tree trunks thickened where they had been cut. This led to the development of typical 'beheaded' beech trees with their cluster-like branches. Today their gnarled stems and branches look quite spooky. Whether they are inhabited by truly wondrous creatures is a matter for your imagination.

At the beginning of the 18th century there was less forest in Germany than today. The forests had been cleared, overused and destroyed. Wood was not only used for cooking and heating. It was also needed for mining and to heat furnaces for glass, ceramics and metal production. The shortage of wood threatened to turn into an economic crisis.

This was also recognized by Hans Carl von Carlowitz, a chief mining officer from Saxony, who wrote a famous book about forestry entitled "Sylvicultura oeconomica". There he demanded that only as much wood be used as is being grown.

This principle of sustainability is one of the most important pillars of modern forestry. Since then the forest areas in Germany have grown again. However, in Germany the consumption of wood is about twice as much as can be sustainably produced in its own forests. As a result, wood must also be purchased abroad.

The area was invaded by French revolutionary troops in 1794. To herald the end of Electoral rule they organised the last major hunt for red deer. As a sign of the new political order, the shot game was distributed to the citizens of Bonn. This hunt resulted in the extermination of red deer in the Kottenforst.

In 1815, after the withdrawal of the French forces, Prussia took over the administration of the Rhineland. In the following decades forestry administration was reorganized and extensive reforestations were carried out in the Kottenforst. Plantations of deciduous trees and fast-growing conifers were an important basis for the beginnings of industrialisation.

In a series of reform measures, the initial Prussian forestry office in Kottenforst was renamed the Kottenforst-Ville Forestry Office in 1995; and finally in 2007 the Rhein-Sieg-Erft Regional Forestry Office.

Today the forests are an important recreational area and can compensate for the noise and stress of city life. Many citizens of Bonn visit the Kottenforst to enjoy nature, peace and quiet and good air, or to exercise. Since 1989 they have also been able to obtain information about the forest habitat from the 'Haus der Natur'.

In addition, wood is felled and game is hunted in the forests. In the past the forest even had other functions: Starting in the Middle Ages, people came to the forest to graze their animals, cut firewood, timber for buildings and coalmines; to extract charcoal and collect leaves for stable litter.

In 1987, the World Commission on Environment and Development published the so-called Brundtland Report entitled "Our Common Future". This was a milestone in the sustainability debate. It led to the topic being discussed worldwide and the issue of sustainability being applied to many areas of life. Development is considered sustainable if it "meets present-day needs without jeopardising the ability of future generations to meet their own needs and choose their own lifestyles".

In other words, the idea is that people today get what they need to live, while at the same time striving to make it possible for future generations to do the same. To this end it is urgently necessary to overcome poverty in the developing countries. In addition, the high standard of living in the industrial nations must not endanger nature preservation and thus our forests. Because they are the basis of our existence.

In 1992 the United Nations organised a worldwide environmental conference in Rio de Janeiro attended by some 10,000 delegates. One of the many results of the conference was Agenda 21, which states that sustainable development is only possible if all countries of the world actively pursue and implement social, ecological and economic goals.

Subsequently Germany also adopted a national sustainability strategy based on Agenda 21. Today the issue is firmly anchored at all levels from federal to local politics: including Bonn.

In 1997 Bonn adopted the objectives of Agenda 21 and set up a Local Agenda Office. Agenda 21 projects include the "Rheinische Affaire" campaign for fair-trade coffee in towns and parishes in the Rhineland, the Paper Angels campaign to sensitise schoolchildren to the sustainable use of paper, and sustainability reports for the Federal City of Bonn.

Founded as early as 1990, the "Climate Alliance of European Cities with Indigenous Rainforest Peoples" recognised at an early stage the importance of rainforests for climate protection, and the possibility of protecting them by supporting indigenous peoples in their appropriate way of life.

Since 1995, the city of Bonn has been a member of the Climate Alliance, which today comprises more than 1,700 cities, parishes and districts from 27 European countries. This makes the Climate Alliance the world's largest city network dedicated to climate protection.

In recognition of the influence of our lifestyles on endangered peoples and places around the world, the members combine local action with global responsibility.

The Bonn city forest has been managed in a natural manner for many decades. In 1998 it received the international seal of approval of the Forest Stewardship Council (FSC), and one year later the certificate of the Naturland Association. Both certify ecological and sustainable forestry.

The criteria are strict. These include, for example, that only native trees and shrubs should be grown in the forest and that the wood should be harvested with care. Deforestation is excluded. Fertilizers and pesticides are prohibited. The proportion of dead wood in the forest must be at least 10%. Hunting must be based on the needs of the forest. It is particularly important for the ecosystem that reference areas be established to allow the forest to flourish totally free of human influence.

The City of Bonn has designated more than 10% of its forest areas as reference areas, where no management occurs and the forest can develop naturally without human influence. Wood from the Bonn city forest, such as building and construction timber, is also marketed on a regional basis.

In the ICLEI (International Council for Local Environmental Initiatives) network, cities, municipalities and regions from all over the world work together for a sustainable future. The City of Bonn has been a member since 1999. ICLEI's world headquarters has been located in Bonn since 2010. In 2018 Bonn's Lord Mayor, Ashok Sridharan, was elected President of the network.

Mayors from all over the world have come to Bonn four times to discuss sustainability; and also during the World Conference on Nature Conservation in 2008 and the World Climate Conference in 2017. The first Bonn Biodiversity Report and the first Biodiversity Action Programme for the city were prepared as part of an ICLEI project. Bonn exchanges information with other ICLEI cities on many aspects of nature and species conservation.

In 2004 parts of today's Kottenforst nature reserve were designated as a nature reserve for the first time; the reserve was extended in 2013. The reasons are obvious. The Kottenforst is one of the largest interconnected natural forest areas with a nationally significant presence of middle-spotted, grey-headed and black woodpeckers. The oak/hornbeam forests and beech forests also provide habitats for other endangered animal species like the red kite, yellow-bellied toad and the Agile frog.

This is why the Kottenforst was registered with the European Commission in 2000 as a bird conservation area and a habitat for flora and fauna. Thus the Kottenforst belongs to the Europe-wide system of protected areas, "Natura 2000".

The Kottenforst has been managed in a natural manner for decades. Biotope trees are designated and the proportion of dead wood is constantly increasing. Since 2014, the LIVE+ project "Kottenforst und Ville" (together with the Rhein-Sieg-Erft Regional Forestry Office and the Bonn/Rhein-Erft Biological Station e. V.), has been committed to maintaining the region's important oak forest communities. A medium-sized area of oak forest has been created, drainage ditches have been closed in some areas of the Kottenforst, species-rich open-land biotopes have been restored and amphibian waters have been created and restored.

In accordance with its designation as a protected area, the Kottenforst is still open to visitors. It is therefore important to observe a few rules:

• Always stay on the paths.
• Keep dogs on a leash.
• Do not damage plants.
• Do not light fires.
• Do not leave refuse in the forest.

In 2015 the United Nations confirmed the common task of tackling global challenges like poverty, hunger, gender inequality and the protection of the planet. Agenda 2030 comprises 17 Sustainable Development Goals (SDGs), which are intended to contribute to a world characterised by ecologically sustainable, socially just and economically efficient action.

The Federal City of Bonn adopted its first municipal sustainability strategy in 2019, and the 17 goals were translated into concrete measures. In particular, the 'Haus der Natur' contributes to the following three goals: