KUNMING, July 7  -- Southwest China's Yunnan Province ranked highest in the country for wetland biodiversity with 563,500 hectares of wetlands, according to a provincial government report released on Monday.

Yunnan harbors four types of wetlands, representing all types of inland freshwater wetlands found in the country, the report of Yunnan's second wetland resources survey said.

The province is home to 241,800 hectares of riverine wetlands, 118,500 hectares of lake wetlands, 32,200 hectares of marsh wetlands and 171,000 hectares of artificial wetlands.

Yunnan's wetland animal and plant species topped the country in number. Its wetlands are home to 2,274 species of higher plants and 1,006 species of vertebrates.

Wetlands, called the "kidneys of the earth," are one of the world's three major ecosystems, along with forests and oceans.

By 2013, there were four wetlands in Yunnan listed as wetlands of International Importance according to the Ramsar Convention. There are 17 wetland nature reserves in the province for a total of 158,100 hectares of wetlands under protection.

Aimed at easing the shrinking and pollution of wetlands, Yunnan is striving to restore natural wetland ecosystems and protect the province's unique wetland varieties, said Hou Xinhou, vice governor of Yunnan.