The annual economic value of wetlands and mudlands across Japan is estimated at 1.4 trillion-1.6 trillion yen (about $13.8 billion-15.7 billion) in such forms as water purification and supply of foods, the Environment Ministry said in a report released Friday.
The report indicated that these natural assets are valuable and their preservation is important.
Wetlands and mudlands clean up water and offer foods, materials and recreation sites for the Japanese people, ministry officials said.
The ministry calculated the values of these natural assets. In the case of water-cleaning capacity, the ministry set out the costs for building and maintaining water purification plants.
The ministry's study covered some 850 swamp sites of about 110,000 hectares, which included the Kushiro wetland on Japan's northernmost main island of Hokkaido and the Oze marshland which stretches over the three prefectures of Fukushima, Gunma and Niigata on Japan's main island of Honshu.
It also covered some 1,300 mudland site totaling 50,000 hectares which include the Fujimae tidal flat in Aichi Prefecture on Honshu and the Ariake Sea which is surrounded by Fukuoka, Saga, Nagasaki and Kumamoto prefectures on the southernmost main island of Kyushu.
The report showed that swamps produced an estimated annual economic value of 840 billion-970 billion yen a year and mudlands 610 billion yen.
Government data show that the size of swamps across the country was reduced by about 60 percent and that of mudlands by some 40 percent due to human activities, such as development, in the past 100 years.
The study noted that behind the loss in the size of swamps and mudlands is a lack of exact knowledge of the value of those natural assets.
In 2007, Germany called for promoting studies on the economic value of natural assets.
A report, which was filed with the 2010 conference in Nagoya of the signatories to the 1992 Convention on Biological Diversity, noted the amount of global economic losses might reach $4.5 trillion a year if no protective measures for natural assets are taken.