Early every morning on school holidays and weekends, Eric Ndung'u heads off to herd his family's goats in the plains of Kisaju, south of Nairobi. While herding, Ndung'u hunts birds using a slingshot.

But he's found a new use for his slingshot too: Planting trees.

Before he leaves with the goats, the 11-year-old runs to Nicholas Waweru's house to get a packet of seed balls, made of charcoal dust, cassava starch and tree seeds.

The balls work as ammunition to bring down birds - and, left behind on the ground, they gradually break down, releasing tree seeds to take root.

In an effort to combat deforestation and rebuild the nation's depleted forests, Kenyans are trying some novel approaches, among them recruiting herder boys - as well as hot air balloonists and paragliders - to the cause.

Waweru works with Teddy Kinyanjui, a conservationist living in Nairobi's Kabete estate, who makes the slingshots and seed balls.

Using seeds provided by the Kenya Forest Research Institute, Kinyanjui researches what trees grow best in each area, then manufactures seed balls designed for that area.

The conservationist said he inherited his love of trees from his late father, Maxwell Kinyanjui, a professor at the University of Nairobi who was well known for his conservation efforts - including the invention of an environmentally friendly charcoal stove.

As part of reforestation efforts, he also planted a forest near Kisaji - one his son now takes care of.

The pair's efforts are part of a broader push in Kenya to combat forest loss. The United Nations recommends that countries maintain at least 10 percent of their land in forest - but Kenya has only 7 percent forest.

Image: Thomson Reuters Foundation/Dominic Kirui

Not so tasty

Packing tree seeds in charcoal dust - provided by a charcoal briquette-making firm - gives them a better chance of sprouting, Kinyanjui said.

"After research, we found out that 95 percent of tree seeds are eaten up by insects or animals such as goats or birds," he said.

"You can imagine if you just took a handful of seeds and threw them down on the ground, and waited for three more months until the rains come - it's just going to get eaten by something," he said.

But the charcoal dust deters animals, he said - and when the rains arrive, they wash the coating away, allowing the seeds to sprout.

Kinyanjui has helped distribute about 2 million tree seeds across the country, focusing in areas where charcoal making has led to deforestation.

To encourage herder boys to use the seed balls, Kinyanjui organizes shooting competitions, with those able to hurl the balls furthest winning certificates.

He's also persuaded aeroplane companies, hot air balloon owners, and paragliders to fling the balls, and sells some to corporations, who distribute them to customers and staff as part of corporate social responsibility campaigns.

He recognises not all the trees will sprout and survive, particularly with hungry goats foraging in many areas. But "this is better than nothing", he said.

Protecting and expanding forests is one of the cheapest and surest ways to curb climate change, experts say.

"Trees and forests play an essential role in mitigating the impact of climate change. Planting trees is one of the most important things we can do to contribute to the health of the planet," said UN Secretary General António Guterres, at a forum on forests in March.

Kenya has made a particular effort to plant trees since late 2017 and early 2018, when a particularly severe drought hit the country. Scientists say forests can help regulate rainfall.

The forest protection push has included efforts to evict people who encroach on forest land and a logging ban issued by the country's deputy president earlier this year.

But plenty of obstacles remain to regrowing Kenya's forests.

"In Kenya, the biggest challenge is corruption that leads to the poor management of forests," said Psamson Nzioki, of the Climate Governance Integrity Programme at Transparency International–Kenya.

"You find the forest guards are the ones burning charcoal instead of protecting the trees," Nzioki said.

Image: Thomson Reuters Foundation/Dominic Kirui

Cover for thieves?

Not everyone has been happy about Waweru's tree planting push. Community members in Kisaju at first demanded he and the boys pick up and remove all the seed balls spread in the area, something he called "a very tiresome experience".

"They knew we were planting trees but said that they did not want them since thieves would hide in them and steal their cattle", Waweru said.

But in time people have come around. Douglas Ole Lenku, a cattle herder, said he now understands that more trees means more rain - and that's good for his animals.

"We will be happy as Maasai (people) if the trees bring rain because the drought is almost killing us and our animals," he said.

Ole Lenku, in fact, now has a slingshot of his own.