Image copyright Getty Images Image caption Experts fear valuable genetic resources within the world's forest could be lost forever

Forest species are coming under increasing pressure from human activities and climate change, and face the risk of extinction, the UN warns.

The Food and Agriculture Organization (FAO) has published a global action plan to improve management of the world's forest genetic resources.

It describes forest ecosystems as "essential refuges for biodiversity".

The call for action comes ahead of a key UN forestry meeting, which is being held in Rome at the end of June.

"Data from 86 countries illustrate that insufficient awareness of the importance of forest genetic resources... often translate into national policies that are partial, ineffective or non-existent," explained Linda Collette, secretary of the FAO Commission on Genetic Resources for Food and Agriculture (CGRFA).

"Only about 3% of the world's tree species are actively managed," she added.

"Governments need to act and implement the global plan of action."

The action plan describes forest genetic resources (FGR) as the "heritable materials maintained within and among tree and other woody plant species that are of actual or potential economic, environmental, scientific or societal value".

The document identifies 27 priorities, which have been grouped into four areas:

Improving the availability of, and access to, information on FGR

Conservation of FGR

Sustainable use, development and management of FGR

Policies, institutions and capacity-building

It say genetic diversity forms the "mainstay of biological diversity", enabling species to adapt to changing environments, such as climate change and emerging diseases.

The plan adds: "FGR provide a direct food source for human and animals, even at times when annual crops fail."

Food and nutrition security

The release of the global action plan coincided with the publication of another report, The State of the World's Forest Genetic Resources, described as the first of its kind.

Image caption Woody plants play a pivotal role in food security, as well as providing timber and fuel

Building on data from 86 national reports, the FAO document covers 8,000 woody species (trees, shrubs, palms and bamboo) that are among the most utilised by humans.

It found that a third of these species, about 2,400, were actively managed specifically for their products and/or services.

The report concluded: "The high number of species used and their multiplicity and services indicates the enormous value of FGR.

"It suggests their great potential to support agriculture, forestry and environmental sustainability, as well as food and nutrition security, if better evaluated and developed."

FAO assistant director-general for forestry Eduardo Rojas-Briales observed: "Forests provide food, goods and services which are essential to the survival and well-being of all humanity.

"This report constitutes a major step in building the information and knowledge based required for action towards better conservation and better management of the planet's precious forest genetic resources," he added.