Entrance
RE:GENERATION
CLIMATE CHANGE IN A NATURAL WORLD HERITAGE SITE - WHAT WE CAN DO ABOUT IT
Park Sanssouci, 27. 4. – 31. 10. 2024
Man-made climate change is a phenomenon that manifests itself worldwide not only in floods and prolonged periods of heat: In Sanssouci Park, part of our precious UNESCO World Heritage Site, almost 80 per cent of the trees are already affected by extreme heat, intense sunlight and prolonged drought. Our dedicated gardeners have long been researching new methods to strengthen the resilience of our trees. Each of these actions is aimed at preserving this important habitat for animals and plants. Trees are also living ‘air conditioners’, purify the air and ensure our mental and physical well-being, and in this exhibition at the Prussian Palaces and Gardens Foundation Berlin-Brandenburg we would like to share our findings with you and start a dialogue. Discover 30 exhibition stations in the park that offer insights into our strategies and progress and give you ideas on how you can become active yourself. Numerous events invite you to learn and discuss together, because there is a lot to gain—if we think now about how we want to view our world, how a strong public service can succeed and what good coexistence looks like. Welcome to the ‘Re:Generation’!
It’s in our hands!
How can we best help the climate? Reducing our own carbon footprint is an important step, but it’s not enough. We often come up against boundaries, as our economic system is still in the midst of transformation. So we have to rethink everything: if we move beyond our personal sphere of influence, we can change the basic parameters of our lifestyle. Our greatest influence does not lie in consumerism, rather in our joint commitment. This is known as one’s ‘climate handprint’. In this exhibition we would like to introduce you to people and initiatives who do something for the climate and for nature, but above all for the local community, too. At each station you will and suggestions on how you can get involved as well. We can still achieve everything together if we act decisively. Become part of the ‘Re:Generation’!
Sustainable exhibition?
In this exhibition we want to keep CO2 emissions as low as possible. For this reason, we have rented construction site elements from regional companies for the exhibition architecture. The scaffolding elements and traffic signs will be re-used on building sites and in road traffic following the exhibition. The printed tarpaulins are made of PVC-free material and will be used again later on, for creative purposes, for example.
Station 1
Automatic Watering
The 96 small, pyramid-shaped yew trees are an indispensable design element of the baroque castle terraces. Even a tree that was missing or too small would distort the historic garden appearance. Like all conifers, yew trees evaporate water all year round. They normally thrive in the shade, but here they are exposed to the blazing sun. So regular watering is vital for healthy growth. So-called pop-up sprinklers guarantee that exactly the right amount of water reaches the pyramid trees’ roots. Gardeners programme the sprinklers based on their experience. Many lawns and flower beds in the park are also watered with this system. This way, neither water nor gardeners’ time is wasted.
Climate Number
291 dry days* in Potsdam annually.
*Average number of days with less than two litres of precipitation per m2 per year from 2010 to 2020.
And now?
The schoolchildren’s project ‘Back to the roots– “Ketchup” projects’ of the Marie Juchacz primary school in Golm has been awarded the 2023 Potsdam Climate Prize. It takes as its theme the return of rain and tap water to trees, flowers and insects that is lost due to the sealing of surfaces and usage. In order to reveal the monthly amount of water recycling, to keep up-to-date, and to catch up on the subject of saving water, the schoolchildren built a ‘catch up bottle diagram’ made of ketchup bottles. Each ketchup bottle represents the standardised monthly quantity of recycled water.
Station 2
Toxic-free path maintenance
The climate is ne when all is green and sprouting. But in the historical gardens, weeds do not fit the artistically intended look of the park. In the days of kings, many gardeners cultivated the park. They removed the wild growth with hoes and picks. In recent decades herbicides have been employed. The SPSG has not used these poisons since 2018, as they harm creatures, disturb nature’s cycle and lead to species extinction. Currently we keep the surfaces free of vegetation using steam or gas flames. But this method requires a great deal of time and energy. These methods can also endanger insect lives. For this reason, we continue to look for better solutions.
Climate Number
7x more work without the use of herbicides.
And now?
Do you want to help us maintain the park? Come to the Join-In Session on 8. 6. 2024, where we will work together to remove unwanted weeds in the Cherry Garden for 1.5 hours. Our employees will reveal fascinating details about the history of the Cherry Garden while offering tips on how to cultivate your own garden. For example, you can learn what plants are grown in the Cherry Garden to guard against pests.
Station 3
Energy: purely plant-based
At SPSG* preservation is key. An important design element is this parterre: twice a year it is planted with a mix of colours and forms, after historical models. Yet different resources are needed to grow and cultivate the plants. So, gardeners grow some 38,000 plants annually for these beds in the park’s nursery. We aim to operate more sustainably by using biomass from felled park trees rather than natural gas to generate the heat of the future. For the circular economy, green waste will be le‑ on site or composted. Solar panels generate energy for workshops.
Climate Number
500.000 plants per year are cultivated in the park nursery for the Sanssouci, Babelsberg, Peacock Island, Glienicke and Caputh parks.
And now?
The BAUERei Potsdam in Grube is both a community-based farm and an extra-curricular learning centre where sustainable farming methods can be experienced at first hand. 120 members currently finance this small-scale farm just outside Potsdam with the purchase of regional fruit and vegetables. With a trial subscription, you receive regional, seasonal organic vegetables every week for three months, which helps support humus formation and biodiversity. The farm café opens every Thursday.
Station 4
Watering for more growth
Many trees suffer from a lack of water. How can we help these trees? With watering bags, for example. The bags have holes through which the poured-in water seeps into the ground. But: watering bags are only helpful for young trees. It makes sense not to place the sack right next to the trunk as the tree could rot due to the continual dampness. Moreover, the growth of the roots may falter, as they no longer make the effort to grow to where the water drips from the trees. Water from the watering bag right on the trunk only reaches the roots below it. These remain short with few branches. The tree lacks stability.
Climate Number
75l of water in one watering bag. If you fill this 9 times, then you have approximately the annual rainfall in Potsdam in 2023 (685 litres per m²).
And now?
Would you like to promote nature in cities? Clean and fill up a watering bag. One bag waters a tree for about nine hours only. The bags have to be cleaned regularly to prevent the holes from getting blocked or the pouch from getting damaged by small rodents. Use a soft cloth for best effect.
Station 5
Water infrastructure in Sanssouci
A) Just don’t seal it up!
Paths and streets in cities sealed with concrete or asphalt allow no water to pass through. Failing to reach plant roots or the groundwater, it flows into the sewer system unused. Floods result during heavy rainfall. And this is happening with greater frequency due to climate change. Rainwater can seep through into the earth directly through the layers of the so-called-water-bound path surfaces found in the foundation’s parks. However, much time and effort are required for the construction and maintenance of such paths. For this reason, please do not cycle on the paths, rather on the asphalted economy path.
Climate Number
12 ha unsealed paths exist in Sanssouci park.
B) On dry land
The groundwater table lies between 0.5 and 2.5 metres below the earth’s surface in central Sanssouci Park. Normally, that is no problem as the growth of the young trees’ roots adapts to the location. Old trees also cope well with the usual annual fluctuations. In recent years, however, rainfall at certain times has been low, or so much rain fell at once that the earth could not absorb the water. The groundwater level dropped dramatically at times. The roots of older trees in particular cannot follow the water level. The lack of water makes many trees more susceptible to diseases and pests. In addition, powerful UV rays, ozone pollution and storms threaten the trees’ vigour.
Climate Number
100cm below the long-term average was the groundwater level in April 2018.
C) The River Havel runs through Sanssouci
No drinking water flows to irrigate Sanssouci Park. Since 1842 water from the Havel has been used. In earlier times, the water was pumped from the Steam Engine Building to the Ruinenberg by means of a steam-powered machine along a 2.5 km-long pipe system. Nowadays, modern electrical pumps convey water into the 8,000 m³ reservoir on the mountain. That corresponds to approximately the contents of 44,000 bath tubs. Due to the difference in height of 38 metres, the water is forced out of the reservoir into the pipes, making the fountains gush. Then the water flows back into the River Havel via the park ditch and the Schafgraben. However, more and more often we hear: “stop the water!” when there are extended dry periods. On those days, no more water may be taken from the Havel. At present, only 50 km of the total of 70 km of pipes in Sanssouci Park may be used. Renovating all the pipes in the park is a future task for the SPSG.
Climate Number
70km of historical water pipes available in Sanssouci Park service water.
D) Rain at the right time
Climate change can be seen ever more clearly in Brandenburg, too. Is the shortage of water alone to blame for this? Scientists assume that the quantity of rainfall in Brandenburg will not decline drastically. What will change, however, is the distribution and type of rainfall. Dry periods will increase and heavy rain will occur on and off. Dried-out soil cannot absorb water, making it flow o, leaving the soil dry. Climate models show that in summer above all, significantly less rain will fall*. This means a greater probability of dry periods and the danger of heat waves. Moreover, trees need rain especially in the summer months so they can carry out photosynthesis and grow. In this process, plants produce oxygen which we breathe. This makes photosynthesis a vital process for life on earth.
Climate Number
346 LITERS PER SQUARE METRE was the annual rainfall in Potsdam in the especially dry year of 2018 (in comparison with a long-term average of 558 litres per square metre).
And now?
Do you live in an area that is at risk of flooding during heavy rainfall? Important factors here are slopes and flowing waters. The degree to which the ground is sealed and the capacity of the of the sewerage system also play a role. Take a look at the heavy rain hazard map for Potsdam and find out about heavy rain precautionary obligations.
Station 6
Systematic watering
Water is precious. Even when watering woody plants, it must not be wasted. Since 2016, drip tubes have been put under the hedges in the western Pleasure Garden. Water beads out of their fine openings, seeping directly into the plants’ root area. Gardeners can then water easily, sparingly and precisely. This is especially useful when the water evaporates quickly in hot summers. This technique was developed in Israel around 1960 to produce fruit and vegetables economically. Drip irrigation is now standard worldwide in intensive horticulture. But the tubes’ tiny openings block easily. As Sanssouci Park is irrigated with water from the River Havel, that can happen quickly. Every few years the plastic tubes need replacing.
Climate Number
6km of hoses of drip irrigation are located in the eastern and western areas of the Pleasure Garden.
And now?
Gardeners from all over the world at the ‘Nuthegold’ School and Integration Garden in Schlaatz know how to yield a harvest despite a drought. A few tips for you: used plastic bottles with small holes in the lids drip-irrigate the plant stem. In mixed beds the pumpkin acts like a sunscreen casting shadow around it. It protects the ground from drying out. And watering takes place only before 8 a.m. and after 7 p.m.
Station 7
Small trees, plenty of hope
With greater frequency, park trees from nurseries are dying a few years after planting. They have grown up under the best conditions: in good soil, with sufficient water and fertiliser. Yet they often cannot cope with the nutrient-poor soil in the parks and dry periods and so die. Our experience with trees from so-called natural regeneration is completely different. These young oaks have sprouted from seed and carry the genetic ‘experience’ of their parents, trees which have been in the parks for decades. The strongest of these trees, which are around three to five years old, will soon be transplanted to various locations throughout the park. The younger they are when transplanted, the better they will grow. Presumably they will withstand drought and heat well on account of their genes.
And now?
Every year our park gardeners collect seeds from healthy trees in the park and re-sow them at selected places. Would you like to help them do this, so learning a lot from the gardeners about this approach and looking after a historical garden?
Station 8
Make the future happen
A small, informal grove of trees is to be re-created here based on historical garden plans. For this, oaks and hornbeams were planted 15 years ago. The gardeners planted them very densely so that they push upwards in their need for light, developing straight trunks. Visitors will later be able to see far into the park from underneath the treetops. To make this possible, only around a fifth of the trees are allowed to remain. In the past, we would have had to chop down the surplus trees. To preserve the valuable trees, we now use a tree spade to transplant them to another location in the park. Here you can see a hole created in this way.
And now?
The Potsdam resident Natalie Kramp began her training at the SPSG* in 2019 and has reinforced the team as a gardener specialised in gardening and landscape building. She says: ‘The varied and creative work and dealing with historical planting plans fills me with enthusiasm every single day.’
Station 9
The life of trees
A) Save living art
Gardens are living artworks we can walk through. We use them to relax in and experience both nature and history. The unique complexes of the Prussian Gardens, Palaces and Collections belong to the UNESCO World Heritage Sites. The Prussian Palaces and Gardens Foundation maintains 738 hectares of parkland and is tasked with preserving these for future generations to experience, too. In their essence, these gardens are formed by the trees. Garden architects used them to design the parks’ distinctive appearance. Changes in the climate have led to a great number of the woody plants dying at present at a rate and on a scale never seen before. That’s why we must grow plants in the next few years that are suited to present and future conditions. Yet such plants must t into the spatial composition, too.
B) The trees suffering
The severe changes in the climate are reducing the life expectancy of the trees in the park, in some cases drastically. Problems arise from prolonged periods of dryness, immense heat and high ozone values, strong ultraviolet radiation, bad weather with storms, heavy rain and a lack of air humidity. The bark on trees gets sunburnt, leading to colonisation by insects and fungi. Leaves, branches and crowns dry out, trees die in huge numbers and rapidly. Our aim is to rejuvenate the tree population with many measures. In this way, we and our descendants shall experience the parks looking as they did shortly after they were created: small trees standing on expansive areas, revealing their space-defining effect earliest after 30 years. For gardens to achieve their finished appearance, it may even be necessary for 50 or 100 years to pass.
Climate Number
80% of trees in Sanssouci Park are damaged.
C) The life of trees
In the palace park there are trees of all ages, from seedlings and saplings to oaks that are 350 years old. When compared with this lifespan, a human life passes by quickly. Let’s take a look at the stages in the life of a tree: after years of growing, the tree has an extensive crown which remains intact for a long time. The annual shoots then slowly get shorter. Gardeners call this ‘growing backwards’. The tree gradually reduces its metabolism and becomes dry from the top down, branch by branch. Fungi decompose the wood. Moisture, dry periods and heat accelerate the decay of the woody tissue. The tree finally enters the soil as humus. The basis for the trees’ age and appearance is determined by their genetic make-up. The location, nutrients and water supply also have an important influence, however.
D) The best climate technology? The tree.
Trees are true wonders of nature, playing a key role in moderating the effects of climate change. They produce oxygen vital for life and store CO2 that is harmful to the climate. Overall, German forests store some 127 million tons of it per annum. Moreover, trees cool down the ambient temperature. That is an important factor in view of increasingly hot summers. Trees also prevent the soil from being eroded by heavy rainfall as the roots keep the soil together and rain cannot fall to the ground unimpeded. Here, too, the great value of the parks and woods becomes clear. All the greater the challenge, when we consider how much trees suffer from the climate crisis and die in large numbers.
E) ‘Reading’ Tree Discs
The majority of these tree discs originate from sick trees which were felled in Sanssouci Park in 2024. One can read a lot of information from tree discs: You can count growth rings, but also see the damage patterns that have weakened the tree. We explain some of them in the following.
Fungal Infestation and Rot
The inside of the tree disc from the pendunculate oak (No. 1) has been hollowed out. Harmful fungi have decomposed the heartwood so that it has gradually crumbled away. Only the outer wall beneath the bark has survived. The tree became less and less stable so it had to be felled for safety reasons.
Insect Infestation
On the tree disc of the Japanese pagoda tree (No. 12) one can clearly see the worm grooves of insects that have burrowed their way into the heartwood. In the medium-term, together with fungi and moisture penetration, this leads to rot and the loss of the tree’s stability.
Bark Loss
The trees are supplied with water and nutrients via transport pathways beneath the bark. In the event of damage to the bark the tree can no longer supply itself optimally. Although the heartwood of the robinia (No. 15) is one of the hardest types of wood in Europe, this robust tree died from the complete loss of its bark.
F) What does our future sound like?
The [Uncertain] Four Seasons is a global project that re-composed Vivaldi’s ‘The Four Seasons’ for every orchestra of the world based on climate data. To this end scientists, composers, developers, and musicians came together in order to adjust Vivaldi’s original composition from 1725 to the year 2050. The goal: to get more countries to sign the Leaders’ Pledge for Nature. The score was altered by employing the latest climate models from the IPCC report, which assume there will be no concerted global efforts to limit greenhouse gas emissions. This resulted in music that distorts the landscape of 1725: In some variations the birds have fallen silent, in others the storms are more intense or the rivers no longer flow.
Tree Numbers and Histories
Tree no. EI 1193. Littleleaf lime. Age: 20 years. Circumference: 55 cm. Diameter: 17 cm
In 2003 we had a hot summer with temperatures rising to over 40 °C in mid-August for the first time in Germany. A lack of rain dramatically exacerbated the drought problem. The grain withered in the fields, trees shed their leaves, small rivers and even a number of dam lakes even dried up completely. Due to the record low river levels inland navigation was suspended in many areas.
Tree no. EI 1205. Pendunculate Oak. Age: 50 years. Circumference: 85 cm.
Diameter: 27 cm.
In 1974 the summer in central Europe was rainy and cool. Some people worried about the beginning of a new ice age. At the same time countries south of the Sahara (Sahel) were in the grip of a seven year drought. The vegetation withered, wells dried up, cattle herds died and millions of people were threatened with starvation. The famine led to political unrest and the beginning of an emigration of the population to more southerly, higher rainfall countries.
Tree no. RA 297. Littleleaf lime. Planted 1977-78. Age: 52 years. Circumference: 133cm. Diameter: 42 cm.
In 1976 Germany experienced an unprecedented summer heatwave! In July and August temperatures regularly rose above 30 °C and there was no rain for weeks. As a likely consequence of this drought and the lower ground water level countless beech trees died in Sanssouci Park in 1977 / 78.
Tree no. WL 297. Ash. Age: 260 years. Circumference: 253 cm. Diameter: 80 cm.
1764: The last third of the 18th century saw a series of cold winters with extreme frost. During the lifetime of Frederick the Great large sections of the vines and fruit trees froze on the terraces of Sanssouci Palace. As a result the terraces were completely covered with glass in order to better protect the plants from frost. The winter of 1788/89 was so cold that nearly all the cherry trees in front of the New Chambers and many yew trees in the park froze.
Tree no. WL 375. Beech, planted around 1912 for the silver jubilee of Kaiser Wilhelm II. Age: 112 years. Circumference: 310 cm. Diameter: 99 cm.
The year 1912 began with an extremely cold winter, a much too dry spring, followed by extreme summer rain with few days of sun. The rainfall in parts of Germany was around three times the average. Rivers broke their banks and in some places the harvest rotted in the fields.
Tree no. SI 90. Oak. Age: 280 years. Circumference: 357 cm. Diameter: 114 cm.
In 1744 Frederick the Great began with the landscaping of Sanssouci Park. The weather conditions at this time appear to have been advantageous for the growth of trees and shrubs. According to various historical records it appeared to rain frequently in Germany, the temperature in summer was average and the winters were not too cold.
Tree no. EL 211. Oak, planted around 1690. Age: 334. Circumference: 600 cm. Diameter: 191 cm.
In 1690, in the former Electorate of Brandenburg, there could be no thought of Sanssouci Park. It was only in 1701 that the Kingdom of Prussia was founded on the coronation of Frederick I in Königsberg (today’s Kaliningrad) Large parts of today’s park featured a loose collection of oak trees where the farmers drove their pigs in autumn to be fattened.
Tree no. BW 33. Copper Beech, planted around 1840. Age: 184. Circumference: 670 cm. Diameter: 213 cm.
In 1840 Frederick William IV became king. During his reign Germany was transformed through the industrial revolution. As a result of industrialisation increasing quantities of greenhouse gases have been emitted, intensifying the human-made climate crisis. In 1843 Alexander von Humboldt spoke of how humankind was changing the climate through its behaviour.
G) Work to be done in the park
Large trees, 120 to 180 years old, shape the appearance of Sanssouci Park. At first glance this may appear to be a healthy, flourishing park. Yet on closer examination we can see that most of the trees have been harmed. These signs of aging are not normal, for the trees are diseased and dying at a rapid rate. The consequences of climate change are driving this process.
Remodelling and reconstruction are required, a process that will last many decades. What’s needed are durable woody plants that can cope with a lot of sunlight, heat and dry periods. For this we are selecting sturdy young beeches and oaks that have already been matched genetically to the available location. They are cultivated either on location or in a tree nursery. In addition, we collect fruits from stable individual trees for sowing and plant resistant trees species that in appearance resemble the trees presently found.
And now?
The ‘Tree referendum (German: BaumEntscheid)’ is an initiative of volunteers who want to make Berlin weatherproof by 2030. The aim is to protect urban greenery, especially trees, and prepare the city for future climatic changes. The Bäume-Plus-Gesetz (Trees Plus Act) provides politicians with concrete measures and is intended to oblige them to promote urban greenery and reduce heat islands.
Heinrich Strößenreuther, Multiple climate NGO founder: ‘We are launching the tree referendum (German: BaumEntscheid) to make Berlin weather- and heatproof in a decade’s time. Because we want to be able to live in our city tomorrow, even when it gets hot and dry. Help us do this, get in touch with us!’
Génica Schäfgen, Head of Ecosia Germany: ‘The consequences of climate change, especially heat, are a major threat to all people living in the city. Politicians are making plans and declarations of intent to counter this. But we are failing to implement them. That’s why we need the tree referendum (German: BaumEntscheid). First in Berlin and then hopefully in all major cities.’
Station 10
Real survival artists
How does a tree become resistant to weather stress? What helps is a location that offers sufficient nutrients. Some trees can also adapt to unfavourable environmental conditions, meaning they develop resistance. Gardeners can pass this property on to following generations of tree. For example, they graft a young shoot of a resistant beech onto a stem of a beech of the same species or select vigorous specimens from germinating seeds. Trees in dense groups can ‘help’ each other. Their canopy of leaves shades the ground and the sensitive bark of the neighbouring tree. Competition for light and nutrients also makes individual trees more resistant than their neighbours.
And now?
World Heritage contribution for the future: Make a donation as a symbolic ‘entrance ticket’ for our children, grandchildren and great-grandchildren. Support the Prussian Palaces and Gardens Foundation so that future generations in 50 or 100 years can still visit and enjoy these unique parks.
Station 11
Convincing doppelganger
Part of what makes historical parks distinctive are certain tree species. In Sanssouci Park these are above all the beech and hornbeam, and the pendunculate and sessile oak. Their shape and the appearance of their bark and leaves are what characterise the gardens. They cannot be replaced by random other species. Yet under the pressure of climatic changes, the gardeners are searching for similar looking trees that can better withstand the increasingly adverse weather conditions. So we experiment here with the Hungarian oak, the Turkey oak and the downy oak. As they come from countries south of Germany, they can stand heat and dry conditions better than our native trees.
And now?
Not every tree has to travel a long way: every year we collect seeds here in the park, too, and sow them. Would you like to join in and get the chance to talk with our gardeners?
In October we are organizing a seed collection event on 12. 10. 2024. For event information, see here: www.spsg.de/regeneration-programm
Station 12
Reaching for the ‘Silver Axe’
Chopping down healthy, precious trees? Something many people fail to understand, but it can happen in a historical park. Even though we, too, are pleased with every sapling that has grown on its own, not all of them can remain in the artistic garden. Maple growth can cover entire areas if gardeners do not remove it in time. Trees that have grown too close together compete for light and water and damage one another. And some trees simply do not fit into the garden’s artistic concept. For this reason, those responsible in the garden department must always carefully weigh up which trees remain and which have to be removed with the ‘silver axe’. This term was coined by the garden designer Prince Hermann von Pückler-Muskau
(1785–1871).
And now?
Surely you too have difficult decisions to make in your workplace to ensure your future. The regional association ‘Gemeinwohl-Ökonomie Berlin-Brandenburg e. V.’ assists companies and associations in making their own assessment of the common good. This looks into the question of whether all the activities in the organisation are focused on the common good.
Station 13
A heart for trees
This tree is a 150-year-old sessile oak. Its parents will have experienced the period before Sanssouci Park. It stills look rather vigorous, even though several wooded branches had to be removed and the crown is slowly getting thinner. It can be disturbing to realise this. After all, trees do so much for us and our health. When hugging the tree, the body can absorb its energy. Oaks stimulate the circulation, for example. You can try it, too. Notice the typical smell and the rough texture of the oak bark.
And now?
Constanze Meyer is a psychotherapist and part of Psychologists / Psychotherapists-4Future Berlin. She supports activists in dealing with their own climate anxiety, organises workshops with activists and politicians and educates about resilience. With their books, the psychologists explain what happens in our heads when we deal with the climate crisis.
Station 14
The New Tree University in Branitz
The Tree University was founded by Prince Pückler near Cottbus after 1846. It served to grow impressive trees that would be transplanted at a more advanced age and size. This special tree nursery in the inner park of Branitz yielded plants, adapted to the barren soil of Lusatia, until 1945. To this day, they form the majority of the 30,000 trees in the Branitz park landscape. Revived by the Stiftung Fürst-Pückler-Museum in 2011, this tree university supplies the park with climate-resilient trees in times of drought, heat, and extreme weather events. Native species, which are adapted to the region, as well as those from warmer and drier regions, such as Lebanon and the Balkans, are propagated here. The “New Branitz Tree University“ is currently being developed in Branitz on 12.5 hectares as a unique experimental tree nursery. Germany‘s largest federally funded model project for historic gardens in a changing climate is using scientific methods to trial adapted woody plants and genetically safeguard rare historic varieties.
Station 15
Welcome to the forum!
A) Here you can…
… just take a seat and chat with others while having something to drink. The coffee bike is open regularly from Monday to Sunday from 11 a.m. to 5 p.m. (exceptions may occur).
… take part in events. You can find the entire events programme via QR-Code.
… every Saturday and Sunday from 3 pm to 4 pm you can meet and talk to someone from the exhibition. Go into detail when the subject or event is something practical. You can also network, ask questions and voice your opinion.
Just come on by!
B) What do you think?
It’s not just Sanssouci Park that is changing as a result of the climate crisis, but everything around us too. We are interested in your opinion on this topic: Write your answers to our questions on the workshop panel. We would also be delighted if you would take part in our survey about the exhibition.
Station 16
Research for culture and climate
In the KERES* research project, the SPSG, together with its partners from academia, have investigated the effects of climate change on different cultural assets in Germany. We have collaborated with institutes of the Fraunhofer Gesellschaft ‑ as well as the GERICS Climate Service Center Germany. Future climate scenarios were created specially for the Potsdam region. According to these, storms and heavy rainfall will increase further in the coming years, as will dry and hot summers. We are developing strategies for the long-term protection of the gardens on this basis.
Climate Number
15 hot days in 2023 measured in Berlin and Brandenburg. Hot days are those with 30°C temperature or higher. This number has doubled in the last 40 years.
And now?
Climate change is resulting in ever more frequent periods of extreme heat. This is a problem not only for the domestic flora; people can suffer greatly as a result, too. Good to know that there are ‘cool places in Potsdam’: on the map of the capital Potsdam, you can find advice on where great heat can be tolerated most agreeably. This is continuously updated by the Special Office of Public Health Service. Sanssouci Park is represented as well, with 13 cool places - yet another reason to protect the park.
Station 17
Great capricorn beetle in action
The great capricorn beetle (Cerambyx cerdo) is a beetle up to 5 cm long that feeds on the wood of living trees. Though rarely found, it does leave behind visible traces: holes in the tree bark and bore dust on the trunk. The holes can easily be recognised on this old oak tree. The beetle was considered a forest pest up until the 20th century and today is threatened by extinction. It prefers already weakened oaks in a sunny location. There are many of these insects in Sanssouci due to the climate. The great Capricorn beetle is an important species of local fauna in Potsdam, which has found one of the few remaining refuges in the Palace Park.
And now?
Benedikt Cziesla is a climate networker on the platform ‘Climate Connect’ which operates on a voluntary basis for projects to protect the climate. It brings people together at the Potsdam location, advising on new project ideas such as the founding of an energy cooperative or a city farm. He studied sociology and political science, is involved in Extinction Rebellion and volunteers in a cycle repair shop.
Station 18
We are rebuilding
By the end of the year construction on a new ecological gardening facility will be completed. The building will have workshop and recreation rooms for gardeners, offices, storage space and garages for two of the three Sanssouci Park districts. Long in planning, the new building is made with a sustainable, environmentally friendly timber frame construction. A paradise for insects and birds will be created on the 1,500 m² greenified roof. It also functions as am temporary water reservoir. As the roof offers the building optimal insulation against heat and cold, no additional air conditioning is needed. Heating is provided by wood chips from the trunks and branches of dead park trees.
And now?
What does your home look like? There are many ways to make your four walls more energy-efficient while reducing high energy costs and rising CO₂ prices across Europe. Heating, solar panels, insulation: the German government subsidises installation costs with targeted programmes. Seek advice from independent experts at the Consumer Advice Centre. A wide range of information for private households is on offer, often free of charge.
Station 19
Plant Climate Culture - Researching the climate in your own garden
Together with citizen scientists, the botanical gardens in Berlin, Halle, Jena, Leipzig and Potsdam are observing selected plant species over a two-year period. When do they sprout, flower, bear fruit and wither? What influence does the city climate have? Are these life phases shifting in some way? Does this impact biodiversity? In dialogue with citizens and collaboration with local politicians, we are searching for solutions to help create a sustainable design with life quality for our urban green areas.
Climate Number
200 citizen scientists have laid ‘climate beds’ in Berlin, Halle, Jena, Leipzig and Potsdam where they are collecting scientific data together.
And now?
You, too, can become part of a research project! Climate change, genealogy or art history — as a citizen scientist, you can support science by collecting evidence, closely observing facts or sorting data, for example. Thanks to digital technologies such as the smartphone, this is possible for every one of us. You can check the project database on the platform ‘mit:forschen! Gemeinsam Wissen schaffen’ to see which topic arouses your curiosity, and get involved in research.
Station 20
Medicine for weak trees
Not only do we plant new trees, we also want to save valuable old trees, like this beech. Possible solutions were investigated in 2022 in a research project in Sanssouci by the Leibniz-Institut für Agrartechnik und Bioökonomie. Nutrient-rich sludge was introduced into the soil around the beech tree. The humic substances contained in the sludge are intended to promote soil life and root growth in the tree. Soil samples show that there is significantly more organic matter and species-rich fungi. The soil stores water better and for longer, and the tree can absorb more nutrients. It is visibly doing better.
Climate Number
4,4t of carbon dioxide (CO₂) have already been removed from the air by this beech tree.
And now?
Money is an important part of regeneration: What you do with your savings and how you invest it. More and more people are saving their money in a sustainable or cooperative bank as a way to invest in sustainable economies and renewable energies. You can also use your money sustainably by symbolically adopting a part of Sanssouci Park. A donation supports park maintenance and helps the SPSG cope with climate change. In addition, your donation is tax-deductible.
Station 21
A tree nursery
A tree nursery already existed 200 years ago near to the New Palace. The garden architect Peter Joseph Lenné (1789–1866) had founded it. Over the next few years, the SPSG will set up a tree nursery here to grow trees and shrubs that will hopefully be better adapted to the effects of climate change.
Climate Number
211 dead trees in the park 2023. Our gardeners determine the health of the trees in the park every year and record it in an overview.
And now?
How can we develop professionally, too? If you have given thought to a safe job connected to the subject of the climate, then take a look online at ‘Climate jobs’. Skilled workers in this field are highly sought after for us to reach our climate goals. These include mechatronic technicians, for example, or roofers, who make our buildings fit for the future in terms of energy. Urban and transport planners find smart solutions for the transition in traffic. And foresters take care of our forests, preparing them for climate change.
Station 22
Greedy moth
Since the beginning of this millennium the leaf mining moth, with its typical damage to horse chestnut leaves, has been found in Brandenburg, too. While the great loss of leaf mass does not kill the trees, it does weaken them greatly. They are less resistant to climate-driven stress or to the attacks of viruses and other parasites.
And now?
To curb the spread of the horse chestnut leaf mining moth, the fallen leaves can be swept up in autumn and destroyed. Support our gardeners at the SPSG in this work and learn first-hand how long this micromoth has been causing mischief in Sanssouci, and how the infestation of our trees can be combated. When? Saturday, 21. 9. 2024, 11 a.m.
Station 23
How can we spot ‘deaf seed’?
If beeches suffer from a lack of water, they put all their strength into roots, wood and foliage. Their fruit, the beechnuts, are then so-called ‘deaf seed’: small, light and flat, and unable to germinate. The tree is thus unable to reproduce.
And now?
Johannes Herweg is a forester in Potsdam. In his work, he is daily confronted with the ongoing climate change: the forests in Brandenburg are exposed to the risk of fire and weakened by long periods of heat in summer. He has tips for those who want to help the forest: ‘For example, anyone can get involved in voluntary planting projects, such as those organised by Wikiwoods, Bergwaldprojekt or Deutschland Forstet auf.’
Station 24
Why do healthy branches break off?
Whenever healthy branches break off old trees as the case here, we speak of ‘green branch drop’. That can occur during and after long periods of dryness and heat, especially with oaks and beeches. A lack of water and damage to roots prevent the tree being able to provide for all the branches. It then separates itself from some branches.
And now?
Maybe you have noticed our parking rules at the entrances? The strict guidelines exist above all to protect us all from damage that occurs increasingly, such as falling branches. Maintaining parking rules also helps to preserve the flora and fauna and overall appearance of the park. As a not-for-profit organisation the SPSG saves costs for repairs and replanting. All those who adhere by these rules are doing something good for nature in the park, as well as taking no risks with their health.
Station 25
Plenty of seeds, few chances?
Trees reproduce by means of seeds. They contain the complete germinating elements of the plants. If beeches produce many beechnuts like this one, we quickly assume the tree is fine. But sometimes it is a kind of last stand: the tree mobilises all remaining powers for a major production of seeds to ensure the survival of its species.
And now?
The ornamental plant gardener Fabian Pawlak has been working in Sanssouci Park nursery since 2009, cultivating plants for the SPSG’s famous ornamental beds. So, he helps preserve historical species and varieties, too. He loves his work: ‘I contribute to the preservation of our historical heritage, enabling visitors from all over the world to make a small journey back to the past. The great challenge is to adapt the park to climate change without altering the historical total work of art.’
Station 26
Still diseased despite water?
Trees often suffer from climate change although they are near to water. Presumably, in long periods of heat more water may evaporate through the stomata of the leaves than the trees can absorb through the roots. Some trees then shed leaves or small branches. The tree crown becomes bare or even dies.
And now?
Many climate policies need to be created by federal politicians: speed limits, pro-climate homes, just funding etc. So GermanZero as a citizens’ lobby is talking with federal leaders. ‘We help those interested to come on board and present MPs with real solutions,’ says Sophie Apel from the Berlin team. ‘Many welcome constructive dialogue. More now approach us on their own. That motivates me!’
Station 27
Claws on the tree?
Dryness, heat and a lack of water lead to signs of deficiency which we can see in the treetops. Short, bent twigs, so-called claws, frequently form on the outer sprouts. The trees lack the power to form long branches and to grow high. The crowns become bare and eventually the tree dies.
And now?
Another factor saps the trees’ energy: competition with other trees. The Norway maple is one of the most common trees in Germany due to its resilience. Yet it is not a welcome sight in the park as it competes for roots with our young oaks and beeches. So we have to remove it from where it is not wanted. Help out on one campaign day, quiz our gardeners about trees and maintaining heritage gardens! When? Saturday, 15. 6. 2024, 11 a.m.
Station 28
Autumn leaves in summer?
Increasingly, dry leaves can be seen on the trees in summer. They dry out when temperatures and UV radiation are very high for a long period. When the tree sheds its leaves, it can still draw nutrients from the leaves. If dried leaves remain on the tree, the metabolism is already so impaired that the tree is dying.
And now?
Marie-Luise Lampe has been with the Voluntary Fire Brigade since 2004 and an active member of the deployment department in Potsdam, Central Defence Location, since 2018. ‘In my work I love working with a wide range of people and to do something meaningful’, says the Head Fire Fighter. For her climate protection is also catastrophe prevention: climate change increasingly leads to vegetation fires due to dry ground, while ever more powerful storms uproot even healthy trees.
Station 29
What are dormant eyes?
The crown of this lime tree has withered due to dryness and heat. Numerous so-called dormant buds are growing on the lower part of the trunk. These are buds that are laid in summer and can sprout in spring. The leaves of these so-called stump sprouts now take over the vital process of photosynthesis.
And now?
Plant and water along with us! You, too, can emulate the impressive work of the park gardeners in Sanssouci. The ‘People’s Beds’ campaign allows you to get involved in turning our city green, to sow and water plants in barren wasteland or in tree areas, for example. The added value is immense: these areas create insect habitats, help cool down Potsdam during hot periods, and transform the dominant grey-brown tones into bright and lovely colours.
Station 30
Trees can also get sunburn
Trees can also get sunburn — like this beech here. Too much sunlight on its thin bark damages the protein structures underneath the bark and disrupts the tree’s enzyme balance. The bark dries out, cracks and peels o‑. Then harmful fungi, animals and rot can weaken the tree. Sometimes, it may even die.
And now?
Wanted: reinforcement! Much love and time is needed to maintain this garden heritage site. This is special work at a great place, with an ambitious mission: to preserve a UNESCO world heritage site for posterity. Motivated newcomers to our gardeners’ team are always welcome. Apply for a job as a garden specialist at SPSG and help preserve the park with its full diversity of plants for future generations.
