It is Shanghai's second-largest wetland park only after the Chongming Dontan Wetland on Chongming Island.

A winding plank walkway lets visitors approach the river and enjoy the wetland on either side. Small fish swim about, crabs crawl on the mudflats, egrets strut about and wing their way above, seagulls dive downward to catch fish.

Paotaiwan (Emplacement) Wetland Park in Shanghai's northern Baoshan District, an ecological paradise, was built three years ago where vast heaps of steel slag and junk were encroaching. [Shanghai Daily]

"Many egrets arrived in our wetland in the big snow period early last year," says Liu Shengde, deputy Party secretary of the Shanghai Baoshan Greening Management Bureau. "It was so amazing to see them strut around on the white snow."

Apart from the natural wetland, the park also has gardens and man-made forest, lawns, hills, waterfalls and streams. There are more than 13,000 trees of 53 varieties, including ginkgo, maple, cherry, bay and camphor, as well as 300,000 bushes of 77 varieties. Flowers are abundant in all seasons.

This is a place where visitors can get close to nature, but just three years ago it presented a totally different and very grim picture.

"Industrial refuse like steel slag was piling up all over. There was unauthorized construction and junkmen gathered there, making it a dirty and dangerous place," says Yang.

The wetland at Wusong estuary came into being ages ago. Its special location, the "throat" of both Huangpu and Yangtze rivers, made it a stronghold for China's coastal defense over the years.

An emplacement was built there to guard the interior in the Qing Dynasty (1644-1911), thus it was called "Paotaiwan."

It was important in the Opium Wars (1840-42), the War of Resistance Against Japanese Aggression (1937-45) and the Chinese Civil War (1945-49). After liberation, naval, air and land forces were garrisoned nearby. A hill was built upon waste steel and used for military purposes in the 1960s. It was covered with greenery and known as Paotai Hill.