WELLINGTON, Dec. 18 (Xinhua) -- Scientific evidence in a new report on long-term wetland loss in New Zealand's Southland shows the country's wetlands urgently need better protection, Conservation Minister Eugenie Sage said on Tuesday.

Published online in the New Zealand Journal of Ecology, the scientific report detailed wetland loss in Southland by analyzing and comparing satellite images of wetlands taken in 1990 and 2012. This covers a longer timeframe than any other Southland wetland loss study.

"The study's timeframe is significant," Sage said, adding that after 1990, legislative tools were put in place to help protect the natural environment such as the Resource Management Act 1991, and agencies such as the Department of Conservation (DOC) and regional councils were formed.

Ideally, the rate of wetland loss would decrease with legislative protection, but in fact the report said the rate of wetland loss in Southland has been 0.5 percent per year since 1990, or a rate of 157 hectares lost per year, she said, adding, "If we add areas that have been partially drained, the rate goes up to a 1-percent decline per year."

The report showed that of the 32,814 hectares of wetland in the study area, 3,452 hectares have been completely lost and a further 3,493 hectares are at risk due to the presence of drainage and declines in vegetation. This represents a 23-percent decline since 1990.

Mapping indicates that conversion from wetland to agricultural and horticultural land uses accounts for 60 percent of the wetland loss, and 97 percent of the wetland loss or degradation has occurred outside conservation reserves and is predominantly on private land.

The minister said the report adds weight to evidence that more must be done to protect wetlands.

Wetlands are an integral part of a healthy landscapes and ecosystems, functioning as nature's "kidneys" to filter and protect water quality, she said, adding wetlands function as nature's sponges as they capture sediment and nutrients, slowly filtering water to drought-prone areas and providing home for rare and threatened wildlife and plants.

The DOC is investigating options for wetland sites to be protected under the Ramsar Convention on Wetlands, and the department is also working with the Ministry for the Environment to develop policy to improve wetlands protection, Sage said.