A few of the countless birds that inhabit the wetlands in the Yellow River Delta.	An autumn scene in the wetland.

WETLANDS are a vital link in the global ecosystem, the "kidneys of the earth" filtering water flows and providing a fertile habitat for countless organisms. The Yellow River Delta National Nature Reserve in North China is a particularly rich "biological supermarket" packed with 1,922 species of plants and animals.

Founded in October 1992, the reserve is the largest wetland in China’s warm-temperate zone, covering an area of some 153,000 hectares. Fed by the vast amount of sediment carried here every year by the Yellow River, the wetland is growing by around 1,300 hectares annually.

Vegetation covers around 55 percent of the reserve, with plant types including Suaeda salsa, Chinese tamarisk, reeds, wild soybeans and kendir, a plant sometimes used in traditional Chinese medicine. Most of these plants are widely found across the reserve.

Overhead, the skies are filled with thousands of soaring birds, especially during the migratory season. Of the 283 species found in the area, over 200 are migratory. The wetland is a major stop-over point, winter habitat and breeding ground for birds traveling from the Northeast Asian mainland and West Pacific. The area is so populous and important in these birds’ movements that it’s become known to researchers as the "avian international airport."

Nine species of bird found in the reserve are under national category-one protection: the red-crowned, hooded and white crane; the bustard; the Oriental white stork; the black stork; the golden eagle; the ern; and the Chinese merganser. A further 41 species are under national category-two protection, including swans and gray cranes. The endangered species’ populations are growing steadily under the protected conditions afforded them in the delta. For example, over 1,500 Saunders gulls, or 18.8 percent of the species' global population can now be found here. Similarly, more than 350 Oriental white storks live in the reserve, or 11.7 percent of the world's total.

With all this abundant life, the wetland has almost limitless scientific research value. Ecologists study the formation and evolution of newly formed land as it develops, while ornithologists study the bird life and habits of migratory species. For biologists the reserve constitutes a vast gene bank. And soil and water conservationists use the wetland as a barometer for measuring the health of the Yellow River. The area is listed under the Ramsar Convention, an intergovernmental treaty signed in 1971 which provides a framework for international cooperation in the conservation of wetlands.

For general visitors to the area, whether they’re strolling in the Chinese tamarisk forest, angling near the reed marshes, or dancing with the red-crowned cranes, the Yellow River Delta National Nature Reserve represents the perfect harmonious union of nature and man.