LISBON – The WWF environmental group urged Portugal on Tuesday to expand its cork forests to act as a barrier against accelerating desertification of its south due to global warming.

Portugal is the world’s largest producer of cork used in wine bottles but the density of trees in cork forests has fallen in recent years, threatening increased desertification as the dry, hot climate of the south moves north.

Because cork trees are not cut down and water is retained in the forests because of falling leaves, they are uniquely environmentally sustainable, WWF said in a study. The bark of individual trees is cut for cork only every nine years.

The group said in a study carried out together with the country’s Higher Institute of Agronomy that a 20 percent expansion of the current area of cork trees could stop desertification at its current limits by 2020.Failure to expand cork forests and tree density could raise desertification levels to more than one kilometre per year.”

Cork trees have every potential to act as a barrier to desertification,” said Angela Morgado, communications and fundraising officer at the WWF in Portugal.

Due to cork trees’ ability to grow in relatively dry climates and if average temperatures continue rising due to global warming, the WWF recommended that cork be planted further north in Portugal to reduce the threat of desertification.

Cork currently represents 2.7 percent of Portugal’s exports and the cork industry employs up to 14,000 people.(Reporting by Axel Bugge) *Story Date:* 18/6/2008 All Contents (c) Reuters News Service 2008