Managing Firewood Trees Sustainably in a Dry Climate

12 May 2008 11.42am

The Caatinga (pronounced "ca-tin-gaa") of Northeast Brazil covers an area about two-thirds the size of western Europe. Most of the vegetation is semi-arid scrub forest with small thorny trees and shrubs, cacti and dry grasses. During the brief summer rainy season many annual flowers burst into bloom, but the vegetation soon disappears during the dry season, and long droughts are common.

Despite the harsh environment, the Caatinga is home to about one-third of the population of Brazil, many of whom are extremely poor. In this difficult environment it is all too easy to use up natural resources like firewood faster than it can re-grow.

Different ways of cutting the wood and the season that it is cut can affect the survival and productivity of the trees. Kew scientists set up experiments in Brazil to compare how well trees regrow if they are cut in different ways and at different times of year. They hope to learn the best techniques to help local people to manage their woodlands in a sustainable way.

Four tree species in the Caatinga that burn well or produce good charcoal are catingueira (Caesalpinia pyramidalis), marmeleiro (Croton sonderianus), jurema preta (Mimosa tenuiflora) and jurema de imbira (Mimosa ophthalmocentra).

Mimosa tenuiflora, a valuable fuelwood tree

There are different ways of cutting wood from trees. Coppicing - cutting the trunk at ground level - encourages new shoots to sprout from the base. Pollarding is cutting the trunk at head height. Like coppicing it encourages new branches to sprout, but out of the reach of grazing cattle. In the third method - crown thinning - individual branches are just cut from a growing tree Italics.

 

The scientists are surveying over 5000 trees and local schoolchildren help with the huge job of monitoring the regrowth after each cutting treatment.

The experiment is still continuing, but early results show that Mimosa trees cut in the wet season do not survive as well as those cut in the dry season, whereas Caesalpinia and Croton trees can be cut in either season.

These experiments are helping scientists to offer good advice to local people to help them make the best use of the trees around them, while at the same time protecting a fragile natural habitat.

For more information on Kew's work in Brazil see:

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