Enhanced investment in protecting fragile agricultural biodiversity is vital to sustaining the livelihoods of the rural poor, the head of the United Nations rural development arm said on Thursday.

Agricultural biodiversity can improve productivity and nutrition, enhance livelihoods, and respond to environmental challenges and food insecurity, said Kanayo F. Nwanze, the president of the UN International Fund for Agriculture (IFAD).

The UN agency has "long recognized that poor rural people and their communities are not only dependent on agricultural biodiversity, but also they are important custodians of it," he said.

The United Nations has designated 2010 as the International Year of Biodiversity, and a week-long celebration in Rome is capping off on Saturday, which is International Biodiversity Day.

Human beings share the planet with as many as 13 million different living species, including plants, animals and bacteria, according to the Convention on Biological Diversity (CBD).

Focus is intensifying on biodiversity and natural resources -- central to the lives of many, especially indigenous peoples -- due to their contributions to food supply, shelter, medicines and others.

Biodiversity is also essential, IFAD said, for boosting poor farmers' and indigenous peoples' resilience to climate change, pests, diseases and other threats.

"We can help protect and enhance biodiversity if we draw on the generations of knowledge accumulated by farming communities and indigenous peoples because these people are best placed to recognize their local needs and understand their local conditions," Nwanze said.