BEIJING -- Beijing plans to restore or create 2,200 hectares of wetlands this year, according to local greening authorities.

In 2017, the city restored more than 1,700 hectares of wetlands and created some 680 hectares, bringing the new and restored wetlands area to 8,000 hectares over the past five years, according to the municipal gardening and greening bureau.

Beijing has six nature reserves for wetlands, with a total area of more than 20,000 hectares, in addition to 10 state- or city-level wetland parks.

Known as the "kidneys of the earth," wetlands play a crucial role in water purification, flood control and maintaining bio-diversity.

Beijing's wetlands, covering 3 percent of the city's area, are home to nearly 50 percent of plants and three quarters of wild animals in Beijing.

The national capital will start a new round of afforestation, aimed at adding 1 million mu (66,700 hectares) of forests, greenbelts and wetlands by 2022. A previous campaign from 2012 to 2015, which saw more than 54 million trees planted, brought the city's forest coverage rate to 41 percent from 37.6 percent.