As Farmland Grows, the Trees Fight Back

Tuesday, Aug. 25, 2009

By Bryan Walsh

Farms vs. forests — that's the usual dynamic intropical countries, where the growth of agriculture often comes at the expenseof trees. In nations like Brazil and Indonesia — where deforestation is behindthe vast majority of carbon emissions — rain forests are not just cutdown for logging but also burned to make room for new farms and pastureland. Asmore people need more food — and biofuels as well — there's a riskthat we could see many of our remaining virgin rain forests wiped outcompletely.

But a major new study indicates that farms and forests maynot be as incompatible as we often assume. Using detailed satellite imagery,scientists from the World Agroforestry Centre (WAC) found that on almost halfof all farmed landscapes around the world, landowners are either sparing someexisting trees or planting new ones, leading to what the study calls"significant" tree cover. In fact, on more than 1 billion hectares(2.5 billion acres) of farmland, which is twice the size of the Amazon, treecover exceeds 10%. That's a huge increase from previous estimates, which wereas low as 50,000 hectares. (See pictures of the effects of global warming.)

This unexpected shift in the trend of clear-cutting and -burningis a result of what's known as agroforestry, an increasingly popular practice,which according to Dennis Garrity, the Nairobi-based director-general of theWAC, could be a "real compensation for deforestation." Farmers areplanting trees on their property not because they want to suck up carbondioxide — at least, not yet. Rather, trees can add value to agriculture.Fruit and nut trees provide additional income or even subsistence food,especially in times of drought, since trees are generally hardier than crops.Trees also provide salable commodities like coffee, rubber, gum and timber. Andeven if a stand of trees doesn't produce anything worth selling or eating, itstill creates shade, protects against erosion and preserves water quality.

Trees are present more among farmlands in the dense tropicalareas of Southeast Asia and Central America, along with much of South America.The proportion is lower in sub-Saharan Africa — although Nobel Peacelaureate Wangari Maathai's Green Belt Movement has helped plant more than 30million trees for Africa's poor. The difference seems to come down mostly tosupport for tree-planting by governments or NGOs like Maathai's. In placeswhere agroforestry is encouraged this way, trees are far likelier to bloom thanin places where farmers are given no such guidance. (See TIME's special reporton the environment.)

And that's where the international community can help.Planting new trees on farmland could provide a needed carbon sink, especiallyif tropical deforestation continues. Right now agroforestry isn't a major partof international climate-change policy, but delegates at the U.N.global-warming summit in Copenhagen that will convene in December could changeall that. By putting a greater carbon value on trees planted on farmlandthrough a cap-and-trade program that would give companies a carbon credit forgrowing and maintaining trees, we could encourage the growth of agroforestry.It's not a perfect compensation for continued deforestation — whole,virgin rain forests have an enormous ecological value that can't be replicatedby agroforestry — but it's a realistic fallback. "This is a win-wininvestment opportunity for the world," says Garrity. It's also a rare bitof green good news.