Wetlands in China have expanded steadily over the past five years, growing by 202,600 hectares and making a significant contribution to water quality and environmental protection, an official from the National Forestry and Grassland Administration said on Tuesday.

Between 2016 and last year, China established 201 national wetland parks, said Li Yan, deputy head of the administration's wetland management office.

At a news conference on Tuesday, Li said China had 899 national wetland parks by the end of 2020 and nearly half of the country's wetlands are protected by some level of government.

Tuesday was World Wetlands Day, marking the date of the adoption of the Convention on Wetlands on Feb 2, 1971, in Ramsar, Iran.

China joined the convention on July 31, 1992. By the end of 2019, the country had 57 wetland nature reserves listed as major wetlands for protection under the convention, covering a total of nearly 7 million hectares.

Wetlands-lakes, rivers, marshes and coasts-are the most threatened ecosystem, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, an independent international body. Wetlands are also vital feeding and breeding grounds for migratory birds.

"Wetlands are not only essential for ecological functions such as maintaining biodiversity, controlling floods and the removal of pollutants, but also serve necessary economic functions in rice and fish production, transportation and hydropower energy," Li said.

Conservation of wetlands in China is crucial, as it ranks fourth in wetland area in the world with 65.9 million hectares, 10 percent of the world's wetland areas, according to the World Wildlife Fund.

China also has some of Asia's most important wetlands, such as Poyang Lake and Asia's longest river, the Yangtze, and is the source country of major rivers such as the Lancang River, the upper reach of the Mekong River.

However, previous WWF research showed China's wetlands were severely threatened by degradation over past decades due to pollution, climate change and overexploitation.

On Tuesday, the administration released a report showing that wetland areas in the 57 key Chinese wetlands listed in the convention increased by 2,479 hectares from 2018 to 2019, thanks to measures that included returning farmland to wetland and the removal of some fish farms.

"China is practicing our commitment to the convention and promoting an eco-friendly road for a sustainable development," Li said. "Also, we will make continuing efforts to speed up the legislative process for laws on wetlands protection."

She said several major projects focusing on wetland protection will be conducted in some major areas, such as the Yangtze River and the Beijing-Tianjin-Hebei province cluster.