This release is available in German.
Until recent decades the Atlantic Rainforest covered a large area of today's Brazil from Amazonas to present-day Argentina. In the 1970s, after years of deforestation, this rain forest was almost completely destroyed, mainly replaced by cattle pastures. This study reveals an unexpected aspect of deforestation. Thorsten Dittmar's team and colleagues from Brazil and the USA show that the common practice of slash and burn left huge amounts of charcoal in the soil. This charcoal is washed out by rainfalls and transported by rivers into the Atlantic Ocean. The soluble fraction of charcoal is composed of extremely stable carbon compounds. The authors conclude that the amounts of these compounds dissolved in the ocean will increase due to human civilization. So far, the effects on marine microorganisms and the global carbon cycle are unknown.
Since way back mankind used fire to shape Earth's vegetation. This was common practice in the 16th century when European settlers came to Brazil, and the beginning of the end of the rain forest. Slash and burn during the centuries reduced its size of 1.3 million to a mere 100,000 square kilometers. What was left was 200-500 millions tons of charred carbon in the soils. These remnants are complex and extremely stable carbon compounds. During the rainy seasons the water elutes the soluble fractions and transports the carbon to the Atlantic Ocean, affecting biogeochemical cycles for centuries and millenia.
In earlier times, the Atlantic rain forest covered a large track of today's Brazil, reaching from 5 to 28 degree south latitude with an area of 1.3 million square kilometers. Until the midst of the 19th century about 95 per cent was intact, but the growing demand for cattle pastures led to massive slash and burn practice which ceased in 1973 leaving only 15 per cent of the
|Contact: Dr. Thorsten Dittmar|