Every Tree Counts: Why Tree Protection Is Crucial for Architecture

Tree protection is a responsibility, not just a law.
Architecture must protect trees already during the planning phase.
When, how, and why is protection crucial? What should we pay attention to, and what vision does the industry have for the future?
We asked Stefan Heimig.
Read on to discover how tree care shapes our cities, our environment, and our future.

greeen!: What role does a tree play in terms of biodiversity and nature conservation?

Stefan: A tree is actually a microcosm – a huge topic. Especially in terms of species protection, which has been neglected for far too long, it’s increasingly coming into focus. Take, for example, a large oak or a linden tree: such a tree typically hosts between 300 and 400 different species within its structure — that’s simply a fact.

greeen!: What significance does a tree have for us humans, beyond species conservation?

Stefan: Many people forget what a tree provides — completely free of charge. Without trees, there would be no oxygen, and without oxygen, there would be no us. A tree, however, can easily exist without humans — but we cannot exist without it. It’s a simple equation: trees were here long before us, and they will still stand when we are long gone. That’s not sarcasm, just pure realism.

greeen!: What ecological benefits does a large tree provide?

Stefan: The ecological benefits of a large tree are enormous and often completely underestimated.
Take, for example, a large oak with a crown spread of 25 to 35 meters. This tree produces enough oxygen each year for at least 100 people. But because breathing is something we take for granted, this value is hardly appreciated. Only when it’s missing do we realize how essential it truly is.

In addition, trees have a significant impact on the climate. They provide shade, cool their surroundings, and counteract heat stress in cities. If we look at Switzerland, where landslides are increasing, or southern Italy, where temperatures reach 50 to 55 degrees, we can see how severe the climatic problems already are. The dimensions are immense. I’m not trying to paint things black, but to describe reality clearly.

greeen!: When is the right time to transplant trees, and how does it work in practice?

Stefan: Ideally, this should be done in winter when the tree’s metabolism slows down. For deciduous trees, it works much better then. In midsummer, it’s almost impossible because the stress on the tree is simply too high.

The company Opitz, for example, has a very high success rate — around 80% for transplanted trees. That’s impressive, especially for large specimens, since it requires enormous machinery, large mobile cranes, and extensive expertise. I always say: if we are capable of building wind turbines 150 meters tall, we should also be able to transplant a 40-meter tree. Anything else is hard to comprehend — and politics also plays a role here

greeen!: What dangers arise for trees when roots are damaged during construction, and what preventive measures are useful?

Stefan: It’s a simple fact: as soon as roots are injured or torn, there’s a high risk that fungi, viruses, or bacteria will enter the tree through the open wounds. Such infections can weaken the entire tree or even cause it to die.

Every tree must be considered individually. Factors like vitality, structure, and species play a crucial role. A healthy hornbeam, for example, can often compensate for injuries better, as it quickly and effectively seals them off. Other species react much more sensitively — their roots die back faster after damage, and fungal infestations are more common.

Root damage doesn’t just affect a tree’s nutrient supply but also its stability. Even a 10% loss of root mass is considered severe; at 15%, it’s typically classified as total damage, since the tree can no longer properly nourish itself or remain securely anchored in the ground. The problem worsens in summer because water uptake is limited, and the tree must expend extra energy for wound closure. Without sufficient energy, aggressive fungi such as Kretzschmaria deusta(Brittle Cinder Fungus) can kill a tree in a short time.

To minimize such risks, protective measures should be implemented well in advance — ideally a year before any soil or construction work begins. That’s a “golden rule” of tree protection. In general, tree experts should be involved early in the planning process to ensure the long-term vitality and stability of trees.

greeen!: How do you view current climate targets and our social responsibility in dealing with the climate crisis?

Stefan: To be honest, it makes me anxious. We’re facing a mountain of problems, and what we’re seeing now is just a preview. I spoke with a professor who said very clearly: the political statements around the 1.5-degree target are simply not realistic. We must expect a 4- to 5-degree rise — at least. Our landmasses heat up much faster than the oceans. That’s not an opinion; that’s physics.

Of course, I understand the need for raising awareness. I’ve given climbing courses for children, lectures, and tried for years to build consciousness. But at some point, you lose enthusiasm when you realize how strong the resistance is. What’s clear is this: we need a radical change in thinking — true awareness and, above all, appreciation. Because this appreciation isn’t just a nice addition — it’s essential for survival. Without it, we’ll perish. That’s basic biology and climate science.

Politics plays a central role in this. It’s not about shifting all responsibility onto politicians, but we do need clear frameworks, decisions, and pathways. Unfortunately, we too often experience blockades and a lack of accountability. Many decision-makers prefer to pass on responsibility rather than take it — and that only worsens the problem.

greeen!: Why is tree protection on construction sites becoming increasingly important?

Stefan: Tree protection on construction sites is indeed becoming more and more important. Municipalities handle the issue quite differently. Some take a pragmatic approach and try not to politicize it, while others are more dependent on political structures. A good example is the city of Hamburg, which has had strict regulations for many years — a true pioneer in this area.

It’s not just about ecology but also economics. The cost of restoring or preserving damaged mature trees is enormous compared to the cost of protective measures during construction. Take, for instance, a large beech tree 35 meters tall: if this tree is damaged during construction, it will die within just a few growing seasons. Stabilizing it again is almost impossible. And a damaged tree poses dangers — when it loses dry wood from its upper parts, we’re not talking about a few kilos but tons that can fall.

The welfare benefits of such a tree are enormous — yet still far too often underestimated.

greeen!: Why is tree protection so important to you personally, and what is your vision for its future?

Stefan: In my work, I’ve saved as many trees as possible — and that’s when you realize just how urgently we need to act. We tree specialists have long understood the necessity: what’s needed now is massive and rapid action. You simply can’t put a monetary value on a tree — its ecological value is priceless.

My wish is that in the green sector, and everywhere else where this understanding already exists, we don’t always have to accept losses. We need a higher success rate in preservation so that our work doesn’t just limit damage, but truly secures the future.

Thank you, Stefan, for your wonderful work and your time with us.
We wish you continued success and hope for greater awareness in our society — so that tree protection becomes a stronger priority.

Learn more about Baumpflege Heimig:
https://baumpflege-helmig.de

Curious about our Schwarz-Weiß 06 project?
https://www.greeenarchitects.eu/projekte/default-c99c6d7e046e39863d9b0c4a6567c163/