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Wednesday, November 2, 2011

Battle Forest and Savanna

bioma data
Bioma data (princeton.edu)
Forest and savanna has significance for the life of another creature. Imbalance between them can cause harm to other beings. The cause of this imbalance is very much determined by human factors. Uncontrolled land use and climate change is caused by human activities. Savanna fires keep a low tree cover and prevent forests from encroaching on the Grassland. When tree cover is high, as in a forest, fires can not spread as easily, halting the savanna's advance into the forest. 

But the Princeton team's Findings suggest savanna wildfires That Could be heavily influenced by factors Such as climate change, road construction and fire-prevention measures. Less rainfall can result in an uptick in fires That can transform a forest into a savanna, just as breaking up the landscape through road construction and natural Disrupt blazes fire control and allow a forest to sprout where there once was a savanna.

Researchers suspect that these factors led to the forest and savanna, South America and Africa, will be mutually interfere. Regardless of which wins, whether it be forest or savanna, a change from one biome to another biome, will be very difficult to reverse the condition as before.

"The changeover from one biome to the other - within the which can Happen Several Decades - can be extremely Difficult to reverse once it has Happened", explained lead author Carla Staver, a doctoral student in the laboratory of co-author Simon Levin, the Moffett Professor of Biology in Princeton's Department of Ecology and Environmental Biology. She and Levin worked with co-author Sally Archibald, a senior research scientist at the Council for Scientific and Industrial Research in South Africa.

Unfortunately, plants and animals that live in forests or savannah is very difficult to transition from one biome to another biome. Thus it is very possible to lose a few plants and animals endemic. Some losses can also occur. For example, a cattle rancher, will lose their jobs due to the expanded forest area of savanna. When the forest penetrated the land of savanna grass productivity will decline, while cattle in desperate need of grass.

The team's work provides among the first experimental evidence that fire feedback — the ecological effect of fires — is the dominant force in maintaining the division between forests and savannas, and that it can determine where the habitats flourish. The researchers used satellite data of fire distributions — combined with climate and soil data, as well as satellite data of tree cover — to survey the tropical and subtropical regions of Africa, Australia and South America.

The researchers found that the frequency of fires determines whether forest or savanna will dominate an area more than other factors such as rainfall, seasons and soil texture, especially in areas with moderate precipitation. Regular fires prevent trees from establishing and savannas from turning into forest. A lack of fires allows a forest to develop, which in turn excludes future fires.

As a result of human actions, climate change more quickly, use land more quickly, which could interfere with the natural fire. The fact, forest and savanna fires are very common nowadays, as a result of rapidly occurring changes in the biome. Suppose, the world's climate has returned to normal, reverse biome as before remains a very difficult thing. "Savanna systems are very resilient across a range of climatic and herbivore variation, in regard to fire. Forest systems are less so, except under very high rainfall where fire cannot be regular," said Walker, who had no role in the Princeton research but is familiar with it.

"In the case of rainforests, once they are in a state where fire can play a role and therefore keep the system in a savanna state, it is extremely difficult to prevent fires from recurring, and so the chances of a savanna state getting back to rainforest are small.  In the original forest state, the amount of dry fuel in the ground layer is insufficient for fire to take hold and 'run.'"

"At the moment, we can't say that one is winning out over the other," Staver said. "We can come up with examples where savannas are encroaching into forests and forests are encroaching into savannas. Both are happening extensively, and both are really huge issues that are likely to become even more important."

This study has been reported in the journal Science, dated October 13, funds this research supported by the Foundation Andew W. Mellon.

Source: princeton.edu

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