Leslie Clark, a California artist, creates 'fixed points' along nomads' routes to bring health care and education to Niger.

At the Doli school for nomads, the teacher pounds on a hubcap each morning to summon children. Many don't hear it because they are too far out in the bush, scouring the scorched land for pastures to nourish their herds.

Supplying education and health care to nomads in northern Niger is no easy task. But it is essential to a strategy hatched by Leslie Clark, a California artist and founder of the Nomad Foundation, which helps nomads hang onto their lifestyle in the world's poorest country.

In northern Niger, tribes of Tuareg and Wodaabe nomads shuttle herds around the flat, semiarid grasslands of the Sahel, a belt of land across Africa that divides the uninhabitable Saharan dunes from fertile farmland farther south. It is starkly beautiful land, where stripped acacia trees stand out like lightning bolts against a vast blue-gray horizon.

Life is barely sustainable in the parched Sahel. Nevertheless, pastoral nomads cling fiercely to traditions that are 1,000 years old.

But now they face new risks: desertification - the encroachment of the Sahara on pasturelands - and infiltration by the North African branch of Al Qaeda into their lawless territory.

"With changing environmental and political situations," Ms. Clark says, "there are adaptations that have to be made. We're trying to help them adapt."

Clark's first contact with nomads came when she was a young artist traveling through Africa 20 years ago. Transfixed, she began guiding tours to finance her extended periods living among tribes, during which she would spend countless hours painting and learning how to sound out and throat-cluck local dialects.

In the past five years, Clark has steered the Nomad Foundation, the small nonprofit she founded and presides over with support from Rotary Club grants and private donations, into increasingly ambitious humanitarian ventures.

Most aid groups are deterred by the difficulties of working with nomads - "very dispersed, small populations in the middle of nowhere," Clark says. But she believes that the rising poverty and insecurity among nomads will require increased aid.

A breakthrough came in 2005, Clark says, when she teamed up with Muhammad "Sidi" Mamane, a gifted and widely connected elected representative of the nomads, whom she tapped to serve as her foundation's on-the-ground representative. Sidi fought in the Tuareg rebellion of the early 1990s but later decided to turn to democratic channels to make changes.

"I realized the best way to fight," he says, "is within a democratic framework that allows social and economic development of the population."

Helping nomads is a unique challenge: How do you provide health care and education without requiring that nomads settle down? Their solution is to build up a "fixed point" within range of the migratory routes used by the nomads.

At Doli, for example, the Nomad Foundation dug a well, set up a cereal bank, built a two-room school, and hired a teacher to manage it. …