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Forest Fires Drive Expansion Of Savannas In The Heart Of The Amazon

Publicado em 05 maio 2021

White-sand savannas are increasing in the heart of the Amazon in consequence of recurring forest fires, in line with a research revealed in the journal Ecosystems.

The research was supported by FAPESP, and carried out by Bernardo Monteiro Flores, presently a postdoctoral fellow in ecology at the Federal University of Santa Catarina (UFSC) in Brazil, and Milena Holmgren, a professor in the Department of Environmental Sciences at Wageningen University in the Netherlands.

“The edges of the Amazon Rainforest have long been considered the most vulnerable parts owing to expansion of the agricultural frontier. This degradation of the forest along the so-called ‘deforestation arc’ [a curve that hugs the southeastern edge of the forest] continues to occur and is extremely troubling. However, our study detected the appearance of savannas in the heart of the Amazon a long way away from the agricultural frontier,” Flores informed Agência FAPESP.

The authors studied an space of floodplains on the center Negro River close to Barcelos, a city about 400 km upstream of Manaus, the capital of Amazonas state, the place areas of white-sand savanna are increasing, though forest ecosystems nonetheless predominate. They blame the rising frequency and severity of wildfires in the wider context of world local weather change.

“We mapped 40 years of forest fires using satellite images, and collected detailed information in the field to see whether the burned forest areas were changing,” Flores stated. “When we analyzed tree species richness and soil properties at different times in the past, we found that forest fires had killed practically all trees so that the clayey topsoil could be eroded by annual flooding and become increasingly sandy.”

They additionally discovered that as burnt floodplain forest naturally recovers, there’s a main shift in the sort of vegetation, with native herbaceous cowl increasing, forest tree species disappearing, and white-sand savanna tree species changing into dominant.

Less resilient

Where do the savanna tree species come from? According to Flores, white-sand savannas are half of the Amazon ecosystem, protecting about 11% of the biome. They are historic savannas and really totally different from the Cerrado with its excellent biodiversity, but even so they’re dwelling to many endemic plant species. They are known as campinas by the native inhabitants. Seen from above, the Amazon is an ocean of forest punctuated by small islands of savanna. The seeds of savanna crops are distributed by water, fish and birds, and are extra doubtless than forest species to germinate after they attain a burnt space with degraded soil, repopulating the space involved.

“Our research shows native savanna cover is expanding and may continue expanding in the Amazon. Not along the ‘deforestation arc,” the place unique grasses are spreading, however in distant areas all through the basin the place white-sand savannas exist already,” Flores stated.

It is necessary to emphasize that in the Amazon floodplain forest is much much less resilient than upland terra firma forest. It burns extra simply, after which its topsoil is washed away and degrades far more quickly. “Floodplain forest is the “Achilles heel’ of the Amazon,” Holmgren said. “We have subject proof that if the local weather turns into drier in the Amazon and wildfires develop into extra extreme and frequent, floodplain forest will likely be the first to break down.”

These two elements—a drier local weather, and extra extreme and frequent fires—are already in play as half of the ongoing local weather change disaster. The research reveals that wildfires in the center Negro space throughout the extreme 2015-16 El Niño burned down an space seven occasions bigger than the whole space destroyed by hearth in the previous 40 years.

“The additional loss of floodplain forest could result in huge emissions of carbon stored in trees, soil and peatlands, as well as reducing supplies of resources used by local people, such as fish and forest products. The new discoveries reinforce the urgency of defending remote forest areas. For example, a fire management program should be implemented to reduce the spread of wildfires during the dry season,” Flores stated.


Flammable floodplains are weak spot of Amazon forest

More data:
Bernardo M. Flores et al, White-Sand Savannas Expand at the Core of the Amazon After Forest Wildfires, Ecosystems (2021). DOI: 10.1007/s10021-021-00607-x

Citation:
Forest fires drive expansion of savannas in the heart of the Amazon (2021, May 4)
retrieved 4 May 2021
from https://phys.org/news/2021-05-forest-expansion-savannas-heart-amazon.html

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