Wildfire Fuels Debate Over Land-Burning in Africa
for National Geographic News
|June 4, 2004|
Last October Madagascar's Ibity Massif was engulfed in flames. The
mountain is famous among botanists, because as many as 20 plant species
found there grow nowhere else in the world.
Neither unique plants nor fire are unusual on Madagascar, an island nation off the southeast coast of Africa. An estimated 80 percent of the Madagascan flora is endemic. Fires, both natural and human-caused, have burned seasonally dry parts of the island with clockwork regularity for millennia.
But the blaze that scorched Ibity seven months ago was particularly badand now scientists are hoping that they can use surveys of the plant population before the fire to monitor how the mountain vegetation recovers from such a catastrophe, if at all. The fire, it is hoped, may have provided a rare opportunity to understand how burning may have contributed to the widespread destruction of Madagascar's once mighty forests and grasslandsand how plants may eventually make a comeback.
Most of Madagascar's fires are started by cowherds (to encourage the growth of tender shoots for their cattle), cattle rustlers (to hide their tracks), hunters (to flush out game), farmers (to clear the land of forest for agriculture)or even by sparring political groups (to demonstrate that their rivals do not have control of an area). One study determined that an average of 600,000 hectares (1.5 million acres) was burned each year between 1984 and 1996.
The relentless burning of Magadascar is controversial. Some experts believe that fires started by people are the root cause of the destruction of the great majority of the island's indigenous forests and grasslands. Others believe that much of the island's vegetation has adapted to the periodic fires, and that the erosion is attributable to a combination of many causes.
Every year a portion of Ibity Massif burns, usually the result of fires intentionally lighted to encourage new grass growth. The fires are generally lighted on old pasturelands on the lower slopes and farther out on the rolling grasslands of the high plateau.
"But the October 2003 fire was unusually extensive, in that practically the whole site was burnt," said Chris Birkinshaw, a biologist with the Missouri Botanical Garden who is stationed in Antananarivo, Madagascar's capital city.
The October fire coincided with a field trip to Madagascar by members of the National Geographic Society's Committee for Research and Exploration. Stunned by the inferno, the committee awarded Birkinshaw emergency funding to study the fire's effect on Ibity's unique flora.
The fire is inseparable from the Madagascan agriculture and ranching economy. Birkinshaw said, however, that almost no research has been done to determine the effect of the frequent burning on Madagascar's native plants.
The sense among conservationists, he said, is that current rates of burning "are too frequent and impoverishing ecosystems." He hopes the current study will help reveal an answer to the question of how much fire is good for Madagascar's biodiversity.
According to preliminary results from the study, few mature plants died in the inferno and regrowth of species was rapid.
"Fire is normally considered as the number one enemy of conservationists, so some here would be surprised to find out that a number of Malagasy species are adapted to fire and indeed would probably decline in the absence of this condition," Birkinshaw said.
Although the finding on mature plants is encouraging, Birkinshaw said younger vegetation may be more seriously impacted by fire. Woody rootstocks and thick bark protect mature plants, adaptations that seedlings are too young to have.
This October, Birkinshaw and his colleagues plan to burn small plots on Ibity to more closely study the impact on younger plants.
"I think one wouldn't want to give the impression that fire is good for Madagascar's biodiversityit isn't, especially at its current frequency. But without wishing to leap to conclusions at the start of the study, we will likely find some species for which the ideal environmental conditions would include an occasional burn," he said.
Christian Kullan environmental scientist at Monash University in Melbourne, Australia, and author of the book Isle of Fire: The Political Ecology of Landscape Burning in Madagascaris not surprised by the preliminary findings.
"Since fire has always played a role in Malagasy environments, some species are favored by the presence of fire," he said. Prior to the seasonal burning of fields by farmers and ranchers, intense lightning-caused fires swept across the island, he added.
When humans arrived on Madagascar about 1,500 years ago, they used fire to sculpt the landscape to their needs, according to Kull. The biggest changes were in the highlands, where a mix of woodlands, savanna, and open areas became dominated by grasslands.
When the French colonized Madagascar in 1896, administrators, conservationists, and scientists sought to control the rates of burning to stem the loss of forests and prevent soil erosion.
Laws intended to punish burning were carried over when Madagascar won independence in 1960 and are still enforced today.
However, Kull said anecdotal evidence and government data suggest that rates of burning have remained consistent for the past century. This burn rate serves Malagasy needs to renew pasture, fight brush encroachment, and prevent the buildup of fuels, he said
"The main difference is that with a hundred years of government antifire activity, people now burn out of sight, at night, when nobody is looking," he said.
Birkinshaw said that a group of about 200 local villagers, including women and children, banded together to beat out the Ibity fire last October out of social responsibility and fear of being blamed "for not doing anything."
Given the steady rates of burning over the past hundred years, conservationists are concerned it is eroding the island's biodiversity.
"The ideal frequency of burning is unknown and would depend on the desired abundance of fire-tolerant versus fire-intolerant speciessomething that is probably subjective. But presumably one would want to approach the natural state," Birkinshaw said.
According to Kull, determining the ideal rate of burning is a complex process. Madagascan farmers "use fire to shape biodiversity to their needs. From a botanical perspective, this probably means less species. But from a human perspective, this is what we do," he said.
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