Healthy ecosystems buzz with dragonflies

Urban disconnect

For Huang, the issue reflects a disconnect between ecological health and ideas about what a city should look like.

A healthy wetland may contain withered plant stems that are dormant during the winter, and the aboveground vegetation can appear dry or decaying.

Riverbanks pose a similar challenge. A gently sloping shoreline with vegetation is generally more welcoming to wildlife than a vertical concrete wall. Plants create shelter and the gradual transition between land and water allows birds and small animals to move between the two environments.

The soil itself is also important, Huang added. Gently sloping soil banks provide bottom-dwelling species with both food and habitats.

However, Huang is also pragmatic about the realities of urban infrastructure designs that need to coexist with ecological systems. She accepts that urban rivers need to carry floodwater, that space is limited, and that soft riverbanks can erode.

The challenge is not to eliminate infrastructure, but to make it more hospitable to wildlife, Huang said.

She cited examples of sensitive design ideas such as stone embankments with gaps and irregular surfaces to provide shelter for wildlife. Sloping gabion banks are more wildlife-friendly than stepped ones and provide a gentler transition between land and water and better habitats for wetland species, she said.

Ecological restoration, Huang said, is ultimately about finding the best possible balance within the limitations of a particular site.

As for dragonflies, she believes their worth in balancing an ecosystem goes beyond preying on mosquitoes. They are both hunters and a food source for animals such as frogs and birds. "If one part of the chain disappears, the system changes," Huang said.

She said one of the most important contributions city residents can make to helping maintain this balance is simply acting as observers of nature.

The return of dragonflies to parts of Beijing does not mean the work of restoring urban ecosystems is finished. Clean water alone is not enough, and a healthy ecosystem cannot be rebuilt overnight.

On Friday evenings, Feng and his team take children to the Liangshui River for outdoor insect observation activities. There, participants encounter creatures they might otherwise never notice.

For Feng, this reflects a broader shift in the way people see nature in urban settings.

A river is not simply infrastructure carrying water through a city. A park is not just a landscaped space filled with trees and lawns.

With the right conditions, both can become habitats. And dragonflies, he believes, are among the most visible signs of whether those conditions exist.