Healthy ecosystems buzz with dragonflies

Rich diversity

China is one of the world's most important homes of dragonfly diversity, with more than 980 known species. Yet most people are familiar with only the handful that occasionally flash past their eyes on a summer afternoon.

Zhang Haomiao, a researcher at the Kunming Institute of Zoology, published The Illustrated Guide to Dragonflies of China in 2019, a two-volume work that documents 820 dragonfly species found in the country.

The book runs to 1,460 pages and includes more than 3,500 color photographs. It represents one of the most comprehensive attempts to document China's dragonfly diversity. Zhang's guide is, in part, an attempt to make that diversity visible.

A dragonfly hovering over a pond may belong to a species of the insect that has its own habitat requirements and ecological role. The more closely entomologists look, the more complicated the picture becomes.

That complexity is why Huang believes that improving water quality, while essential, is only the beginning.

For years, urban water management focused primarily on pollution. Was the water black and foul-smelling? Did it meet the required environmental standard?

Those questions remain important. But Huang believes people's understanding of a healthy water system is becoming broader.

The question is increasingly not just whether the water is clean, but whether it can support life.

When a restored river has clean water but little wildlife, Huang asks a simple question: What is missing?

Perhaps there are too few aquatic plants. Perhaps there are not enough small organisms to support larger animals. Perhaps the shoreline provides nowhere for wildlife to hide, feed or reproduce.

The answer is not simply to release more fish into the water. "A healthy ecosystem needs different levels of life," Huang said.

She said ecological restoration is not only about creating a finished landscape, but also setting a process in motion.

One major challenge is that cities often prefer nature to look neat. Old reeds are cut down, dead vegetation is removed, riverbanks are straightened and shorelines are covered in stone or concrete. But what looks tidy to humans may offer little to wildlife.

Huang recalled observing a rare dragonfly in Beijing that to the untrained eye is easy to miss. Brownish in color, it blends into dry, yellow reeds.

Its breeding habitat includes reed beds in early spring, before the landscape has turned green. But old reeds are often removed as part of routine maintenance or fire prevention work. "When the yellow reeds are all removed, the breeding habitat becomes very limited," Huang said.

She and other nature enthusiasts have encouraged park managers to leave more vegetation standing where possible.

The benefits extend beyond dragonflies. Old reeds can also provide habitats for birds during winter.