Farmlands Have Significant Tree Cover, Says Study

By: Michael Simire on August 25th, 2009

By Michael Simire

Scientists from the World Agroforestry Centre (ICRAF) in Nairobi, Kenya have challenged the view that agriculture in the developing world helps to cause massive deforestation.

Using satellite imagery, the agroforesters say they have found that almost half of all farmed landscapes worldwide include significant tree cover.

The findings were announced at the opening of the 2nd World Congress of Agroforestry held  in the Kenyan capital in August. ICRAF is one of 15 centres supported by the Consultative Group on International Agricultural Research (CGIAR).

This is the first study to quantify the extent to which trees are a vital part of farmland in all regions of the world. It reveals that on more than one billion hectares –  46 percent of the world’s farmlands, home to more than half a billion people – tree cover exceeds 10 percent.

“The area revealed in this study is twice the size of the Amazon basin, and shows that farmers are protecting and planting trees spontaneously,” said Dr Dennis Garrity, the Centre’s Director General.

“The problem is that policymakers and planners have been slow to recognise this phenomenon and take advantage of the beneficial effect of planting trees on farms. Trees are providing farmers with everything from carbon sequestration, to nuts and fruits, to windbreaks and erosion control, to fuel for heating and timber for housing.

“Unless such practices are brought to scale in farming communities worldwide, we will not benefit from the full value trees can bring to livelihoods and landscapes.”

“Though the researchers could not establish precisely the products and services that trees are providing, previous agroforestry research has documented a wide range of uses for trees on farms.

“These include fertiliser trees for improving crop yields and enhancing soil health; fruit trees for nutrition; fodder trees to feed livestock; timber and fuelwood trees to provide shelter and energy; medicinal trees; and trees that provide global commodities such as coffee, rubber, nuts, gums and resins.  Equally important on the service side are uses such as erosion control, water quality and biodiversity.

“If planted systematically on farms, trees could improve the resilience of farmers by providing them with food and income,” said Tony Simons, Deputy Director General at ICRAF. “For example, when crops and livestock fail, trees often withstand drought conditions and allow people to hold over until the next season.”

“What trees essentially provide to farmers is choice – choice of enterprise, choice of market, choice for diversification, choice for low labour requirements, choice for multiple functions,” Simons said.

“Developing country farmers are spoilt for choice. Whilst Western Europe has some 250 native tree species and North America has a larger set of 600, the developing tropics have a staggering 50,000 species to manage and utilise. The priority is to find the right tree for the right place for the right use.”

Previous estimates of the amount of farmland devoted to agroforestry have ranged from as low as 50,000 to as high as 307 million hectares. But the estimates were not derived from detailed remote sensing data as  this assessment was.

In this case the scientists were able to measure the amount of tree cover on each square kilometre of the world’s 22.2 million square kilometres of farmland.