Urban ponds as an oasis of biodiversity

A pond lined with flowering waterfalls and shaded trees, the pond can provide a peaceful break from the stress of everyday life for those sitting on benches in the park next to it. In addition to promoting happiness, ponds are important for collecting rainwater. Furthermore, they are home to many of the city’s smallest residents. The entire ecosystem is hidden beneath the surface.

“These ponds serve their purpose. In addition to conserving biodiversity, one of their functions is to purify water. They also provide many other ecosystem services. For example, It has educational value.

“Instead of hiring a bus and leaving town, schools can take students and students with nets or buckets and take hundreds of meters to the pond. You can really easily find them on their biology. You can learn. Ecosystem services are free services that we humans get from ponds,” says Frank Johansson, professor of conservation biology at the Department of Ecology and Genetics.

He leads the research project “Conserving Biodiversity in Urban Ponds,” which stocks small faunas of insects, snails and worms in 80 ponds in Stockholm. These are relatively small ponds with a surface area of ​​about 100 x 100 meters. Some ponds are natural, while others such as rainwater ponds are artificial.

“The rainwater pond is designed to collect all the water from the streets and hard surfaces when it rains. The sediments can settle there before releasing water into the natural water. Therefore, It’s a purification process. The pond acts as a filter. It also applies to natural ponds,” explains Johansson.

The best pond

The main goal of his research project was to investigate what the best pond should look like to benefit both people and biodiversity.

“We invented ponds and measured the hosts of surrounding variables: their size, their amount of vegetation, their amount of vegetation, their area of ​​construction, how they are, how they are, how they are There are vegetation in many forests, nutrients, and the amount of nutrients, which studied about 20 of these environmental variables and could then be correlated with biodiversity,” says Johansson.

A decline in species may thrive

On average, they found 40-50 species in each pond, but there were also ponds that contained seven or eight different species. However, rare species are more frequent in these settings, so species diversity is not necessarily negative. Some species of population declined also appeared in the pond. Two examples of declining species that appear to thrive in urban ponds are the great crested newt and the large white-faced darter.

“In optimal ponds, we have shown that about 50% of the water surface should be covered with vegetation and blue water should also be opened. What happens frequently is that ponds grow overgrown, and then many species want It showed that it is a lot of species. More open water will disappear,” says Johansson.

Explosive rocks are not a good choice

So, who would like to build a rich water oasis for diving beetles, dragonflies, water striders and other creatures, and for beetles, dragonflies, water striders and other creatures? According to Johansson, a good start is to avoid using blasted rocks and create a soft bottom. This is highly regarded by most pond residents, especially the species that live in the bottom sediments.

Another important thing he points out is not to put fish in the pond. It may look good, but it’s a bad thing for biodiversity as fish are greedy eaters of large insects, the top predators of waters when the fish is not present.

From pond to pond

One thing he singles out as specifically encouraging high species diversity in urban environments is that he has several types of ponds that can meet the habitat requirements of various organisms is.

“Of course, it’s really important that the ponds aren’t that far apart, as there’s a need for a population and species to disappear and spread to the next one. “It’s fine,” Johansson says.

It’s not just the distance between the ponds that matter. Equally important, the ponds must be connected with green spaces so that creatures can move between them. This does not necessarily mean a big park. A ditch, a small stream, a tree, or some bushes will be enough.

But does the location of the pond make a difference? Do wealthy municipal ponds have more wildlife than stolen suburban areas? The researchers also investigated this.

“We went 500 meters from the pond and drew circles around it, looking at socioeconomic factors. We looked at the people’s earnings, what education they received, ethnic background, etc. These factors made the impact. I wanted to see if I gave it or not.

“This is shown in the US. For example, biodiversity is high in areas where there were many rich, well-educated people. However, this was not the case in our study. “There is no biodiversity that is lower or higher than any pond in a municipality,” says Johansson.

The best pond for biodiversity

50% of the water surface must be covered with vegetation. There is vegetation around the pond, but it should not be too shaded. Just the right amount of nutrition. Place the tarmac and do not pave it to the edge of the pond. It has as much green as possible to the edges. A size of 100 x 100 meters is sufficient. Enough maintenance, most importantly, to keep vegetation inside and around the pond. Do not use blasted rocks when building a pond. Many creatures are like soft bottoms. Do not put fish in the pond. They eat large insects that keep the numbers of small creatures down. Make sure that creatures can travel between the pond and other ponds through interconnected green spaces.