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Wednesday, 19 August 2026 in
BC1 Business Channel One
The memory of the futureSharing innovation knowledge through authentic stories

Biodiversity loss in the city

🎬 Multilingual subtitles
✍️ By: Team BC1.NL

Biodiversity is declining right around us, not only in the Amazon

Biodiversity or variety of life, is gradually decreasing. More and more we’re warned about this.
What exactly is the loss of biodiversity and where does it happen? Looking for answers we set out with Ton Eggenhuizen, urban ecologist in Almere, the Netherlands. Because in the city there’s loss of biodiversity too.

All the green in the city forms one ecosystem

The city council of Almere has passed the ‘Vision Ecology’. According to Ton with the purpose ‘to give more attention to the rich nature in the city, hoping everyone will contribute to this. The ‘Vision Ecology’ is based on the three Cs: the C of connecting, the C of connecting and the C of connecting. Beatrixpark AlmereWe want to connect natural areas with each other, but also to connect people with nature.
Maybe that is most important. Connecting people with nature and also connect the naturally present context with your plants. The latter is harder, but what we actually mean with that, is we don’t want to make to much nature. We want to use the opportunities the soil, the climate and the water system offer to produce an ecological system. So, not too much ‘creating’, but simply seizing the opportunities that the system gives us.
 

A hedgehog cannot live on one garden, so gardens have to connect

Ton tells about the importance to connect natural areas. Nature in the cityBy this he doesn’t only mean the parks and green areas of the city, but also the gardens of the residents. ‘For example, if you make your garden hedgehog friendly and your neighbors have a hard fence with a concrete edge at the bottom, then that hedgehog has nowhere to go. Then you can make a beautiful hedgehog-friendly garden, but that hedgehog needs many more gardens, he can’t live on one garden.’

More trees in the city help, but only if council and residents coordinate

trees with water sproutsIf we plant more plants in our gardens at home or at work, and the municipality plants more trees, will that be the solution, or do we have to do more? Ton thinks these are important steps. He does indicate, however, that it is best to coordinate that.

In the long run green is cost effective, but budgets think in four or five years

No, says Ton, that also has to do with your perspective of time. It may be expensive in the short term, but in the long term it’s even cost efficient and makes money. However our budgets are often for a very short time frame. For example take greenery and playing outside, children who play outside are healthier. Less suffering of obesity. Horse chestnut leaf miner in a leafObesity causes heart problems later on, when those children are 50 years old. But that will be in 50 years, while the budgets we have now are often for one or four or five years. And those avoided health costs, that’s over a much longer period of time. So we have to learn to look at much longer periods, we really have to make a big change in that.

Curious to hear more from Ton? Watch the video.

Also interesting:
Circularity, a necessity to maintain profitability
Natural farming better for biodiversity

Frequently asked questions

This is a short summary of the film. Watch the video above for the full story.

How do trees help against heat stress in the city?
Plants draw water up from the soil and evaporate it, and as they evaporate they cool down, so trees and shrubs act as a natural air conditioner. A tree is therefore about ten times as effective as a parasol; it is much cooler under a tree, even if some sun still shines through. Tiled gardens with black tiles instead retain heat and release it again at night.
How do you recognise a sick tree in the city?
Because the same species was planted everywhere in the 1970s, 80s and 90s. Once a disease gets in, they all have it. In the film this shows in ash trees with epicormic shoots: branches growing straight up, a sign that the sap flow in the tree has been interrupted by a fungus. Beeches are now being planted between the sick ash trees, because the rest will go the same way in time.
What does depaving your garden do for wildlife?
Paving, and black paving in particular, holds a lot of heat during the day and releases it again at night. Water also stays on top of it and cannot drain away. Plants do the opposite: they draw water out of the soil and evaporate it, and in doing so they cool down. That is the natural air conditioning a paved garden lacks.
What is the horse chestnut leaf miner?
A tiny moth whose caterpillar lives inside the leaf of a chestnut tree. The black specks in the leaf are its droppings. Where the leaf has been eaten it no longer lives, so the amount of living leaf decreases. One speck is no disaster, but a tree covered in them has little resistance left. A healthy plant produces substances to fend off feeding damage; once it loses that resistance, such insects take over.
Where can I watch the full film?
These questions and answers are a short summary. Watch the full film "Biodiversity loss in the city" with all insights, examples and background at https://www.bc1.eu/biodiversity-loss-in-the-city/