So what have we got?

This knowledge is essential if we are to conserve and sustainably manage forests across the globe.

A major project is underway to document the state of world's forest genetic resources. Coordinated by the United Nations Food and Agriculture Organization (FAO), it will provide information vital for the conservation and use of tree species that provide millions of people with food, timber, medicines and fodder.

FAO has already produced 'State of the World' reports on plant and animal genetic resources, with a focus on agricultural crops and livestock. In 2007 the FAO Commission on Genetic Resources for Food and Agriculture decided to produce a report on trees. In April 2011, the World Agroforestry Centre hosted a workshop in Nairobi, in collaboration with FAO and Bioversity International, which provided guidance to experts from 33 African nations on how to collect and collate information. The country reports from individual African countries will be combined with those from nations elsewhere to produce a global synthesis.

The fact that we do not know precisely how many tree species there are in the world – estimates range up to 100 000 – says much about our imperfect knowledge. "We could lose a lot of species, and forest genetic diversity, before we even know precisely what we've got, including species and provenances that could provide valuable goods and services," says Lars Graudal, Director of Research at Forest and Landscape Denmark (FLD), one of the organizations contributing to the new report. "That's why it is so important to document the state of these resources now."

Deforestation and over-exploitation are already threatening the genetic diversity of many species. In East Africa, to give just one example, there are at least 30 tree species which are known to have anti-malarial properties (see story on page 12). As forest land has been converted to other uses, and harvesting pressures have risen, some of these species have become rarer, with serious implications for the health care of rural communities that do not have access to, or cannot afford, modern medicines.

Ian Dawson, a World Agroforestry Centre consultant geneticist who helped to organize the workshop, estimates that most African countries will identify 30 to 40 tree species that are important to forest harvesters, smallholders who practice agroforestry and local communities. "I also anticipate that some countries will identify endemic species that do not have particular human uses at present, but may be important for conservation because of their ecosystem functions or, simply, their rarity," he says.

The State of the World report, due to be published in 2013, will provide an insight into the threats and possible development potential of hundreds of tree species. It will help policymakers and scientists identify gaps in knowledge and formulate action plans to conserve and use important tree genetic resources. As Oudara Souvannavong, a senior forestry officer at FAO, told participants at the workshop: "This knowledge is essential if we are to conserve and sustainably manage forests across the globe."