How long does it take for nature values to be restored?
We are often told that “for every tree that is cut down, at least two new ones are planted”. It is a slogan that is meant to reassure. It makes us believe that the forest is a renewable resource that quickly recovers. But the argument ignores the ecological time aspect and nature’s often slow rhythm. This is highlighted in a report from the Swedish Forest Agency: The time it takes for the forest to heal its wounds is not counted in decades, but in centuries – and in some cases the damage is irreversible.
When we talk about “forestry” today, we usually refer to conventional clear-cutting with rotation periods of 60 to 80 years. This is the time it takes for a stand of spruce or pine to become economically viable to harvest again. But nature does not count in quarterly reports. Nature counts in generations, in slow decomposition and in ancient ecological connections.
According to the Swedish Forest Agency’s in-depth evaluation of the environmental objective Living Forests (Report 2022:12), the gap between forestry cycles and nature’s recovery time is frighteningly large. Cutting down a forest with high conservation values cannot be repaired by planting new trees. Structures that have taken hundreds of years to build are lost – and complex ecosystems can be lost forever.
The report lists concrete examples of how long it takes to recreate the habitats that disappear during clear-cutting:
- Swamp forests and mulch (the nutrient-rich wood meal in old trees): Over 300 years.
- Decomposed, coarse pines: Between 500 and 1000 years.
- Very old oaks: Over 1000 years.
Compare this with the short rotation cycles of clear-cutting – a fertilized tree plantation that is cut down after 60-80 years. The equation doesn’t add up. When we clear-cut an old forest, we erase habitats that require up to ten times as long to recreate as we give them. That is the definition of unsustainable use.
Lost “biological healing ability”
It’s not just about time. It is also about where the forest is. The report highlights a concept that is crucial to understanding the crisis: “Biological healing capacity”.
In the past, when the landscape was varied and even the managed forests contained a large proportion of natural forest qualities, nature could heal itself. The distances between the valuable forests were short. If a forest burned or was felled, there were large populations of species nearby that could spread and recolonize the area.
Today, the situation is reversed. The biologically valuable forests are highly fragmented – small green islands in a sea of clear-cuts and young plantations. The endangered species live in small, isolated populations. Even if we were to succeed in recreating an environment, it is not certain that the species will find their way there. The distances are too long and the populations too weak. Clear-cutting has destroyed the infrastructure of the ecosystem.
Continuity – not new planting – is the key
The report clearly shows that the best nature conservation is not to try to repair what has been destroyed, but not to destroy it in the first place.
Estimates from northwestern Sweden show that forests with retained continuity – i.e. forests that have not been exposed to modern clear-cutting – have a unique ability to develop high conservation values. The absence of modern forestry measures has allowed the forest to age and develop freely, creating a varied and dynamic environment with good conditions for rich biodiversity.
The clear-cutting model, on the other hand, is an ecological dead end. “Starting over” with a bare surface and new plants can never replace the value of continuity. A simple deciduous forest can be recreated in 60 years, but the complex systems of fungi, insects and lichens that depend on thousand-year-old oaks or five-hundred-year-old pines will never return in the foreseeable future if we continue to cut the chain.
If we are serious about preserving Sweden’s biodiversity, we must realize that certain values cannot be replanted. They must be allowed to remain. Protecting the last real forests is not just an option – it is a necessity. Because when the last old-growth forests fall, it doesn’t take a generation for them to come back. It takes a millennium or more.
Source: Swedish Forest Agency, Report 2022:12 – Living forests, in-depth evaluation 2023 (page 38).