Arquivo da tag: Manejo florestal

Forests follow unexpected—and surprisingly fast—paths to recovery (Anthropocene Magazine)

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anthropocenemagazine.org

A new study found that carbon, nitrogen and soil density in cleared forests reached 90% of levels in untouched forests after 1 to 9 years. They key was leaving them alone.

By Warren Cornwall

February 16, 2022

Forests follow unexpected—and surprisingly fast—paths to recovery

A new study found that carbon, nitrogen and soil density in cleared forests reached 90% of levels in untouched forests after 1 to 9 years. They key was leaving them alone.

Jungles grow with such abandon they can obscure entire civilizations beneath roots and vines. That fertility could prove vital in the race to heal the scars of deforestation.

Tropical forests burned and cleared for farming and ranching in Central and South America and West Africa can bounce back in little more than a century, with some key features recovering in decades, according to new research.

While not a panacea for the destruction of ancient jungles across the globe, scientists say the findings suggest that if left to themselves, many of these places could regain the lush forests that are rich havens of biodiversity that also suck carbon from the atmosphere.

“These regrowing forests cover vast areas, and can contribute to local and global targets for ecosystem restoration,” said Lourens Poorter, an ecologist at Wageningen University in the Netherlands, who was part of the research.

Tropical jungles like the Amazon have been called the lungs of the planet for good reason. Fueled by abundant water, long growing seasons and fertile soils, forests ringing the planet’s equatorial middle can suck vast amounts of carbon from the atmosphere and provide a home for two-thirds of the world’s species.

But this richness has also made them a target for loggers, ranchers and farmers, ranging from small-time settlers to huge agricultural companies. Today, less than 50% of tropical rainforests are still standing.

As conservationists work to protect tropical landscapes, questions surround the fate of former forests turned into pasture and farmland. In the tropics in the Americas alone, an estimated 28% of forests are regrowing after being cleared. So a team of 90 scientists from research centers across the globe set out to see how these lands recovered.

Because such recovery can stretch for decades, the researchers sought to fast-forward through the process by simultaneously examining 77 sites at different stages of growth, including some old-growth forests. Places had been cleared and then abandoned for more than a century in some cases, and as little as a year in others. The locations covered both dry and wet forests, sprinkled across Central and South America and coastal west Africa.

At each location, the researchers measured a dozen key indicators of different kinds of ecological dynamics, including the makeup of the soil, leaf and stem size, how many plants fixed nitrogen in the soil, the total mass of all plants, the largest tree, and the diversity of plant species.

The forests followed unexpected paths to recovery. Scientists were surprised to see how quickly the soils recovered. Carbon, nitrogen and soil density reached 90% of levels in untouched forests after 1 to 9 years. Likewise, the functional composition of plants in the forests – the size of tree leaves, the density of wood in trees and presence of nitrogen-fixing trees – happened sooner than predicted, taking between 3 and 27 years to approach old-growth conditions, the researchers reported in Science.

The rapid soil recovery indicates that soil nutrients were buffered from slash-and-burn agriculture or enhanced by people as they burned foliage or planted nitrogen-fixing grasses, the scientists surmised. Most of the study plots were also not subject to high-intensity farming that can suck nutrients from the soil.

Some features of the forest flora also came back quickly. Fast-growing plants that first reclaim open ground gave way to more shade-tolerant plants relatively quickly, and plants returned by resprouting from seeds left by cleared plants.

“Nature will take care of it if we let it,” said Clemson University ecologist Saara DeWalt, who contributed data from forests in Panama that she has tracked since the 1990s. “Restoration of tropical forests should rely on natural regeneration. It’s the most efficient way to do it. It’s the most ecologically efficient. It’s the most economically efficient.”

Some kinds of recovery took much longer. The cleared areas took between 27 and 119 years for the total mass of greenery and the largest tree size to approach pristine conditions. It took 12 decades for the full panorama of species found in old-growth tropical forests to appear in re-growing forests.

Even that, however, is “notably fast” given the complexity of tropical forests, the scientists noted. The overall picture is one of resilience after farming or ranching, as long as it’s not too intensive and there is forest nearby to provide seeds. “If there’s no source for seeds, heavily degraded soils, and no way for animals to get there, that’s going to be a problem,” DeWalt said. “There will be times when planting will be necessary.”

Poorter, et. al. “Multidimensional tropical forest recovery.” Science. Dec. 9. 2021

Ancient Indigenous forest gardens promote a healthy ecosystem, says study (Native News Post)

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nativenewspost.com

An aerial view of a forest garden. Credit: SFU

A new study by Simon Fraser University historical ecologists finds that Indigenous-managed forests—cared for as “forest gardens”—contain more biologically and functionally diverse species than surrounding conifer-dominated forests and create important habitat for animals and pollinators. The findings are published today in Ecology and Society.

According to researchers, ancient forests were once tended by Ts’msyen and Coast Salish peoples living along the north and south Pacific coast. These forest gardens continue to grow at remote archeological villages on Canada’s northwest coast and are composed of native fruit and nut trees and shrubs such as crabapple, hazelnut, cranberry, wild plum, and wild cherries. Important medicinal plants and root foods like wild ginger and wild rice root grow in the understory layers.

“These plants never grow together in the wild,” says Chelsey Geralda Armstrong, an SFU Indigenous Studies assistant professor and the study lead researcher. “It seemed obvious that people put them there to grow all in one spot—like a garden. Elders and knowledge holders talk about perennial management all the time.”

“It’s no surprise these forest gardens continue to grow at archeological village sites that haven’t yet been too severely disrupted by settler-colonial land-use.”

Ts’msyen and Coast Salish peoples’ management practices challenge the assumption that humans tend to overturn or exhaust the ecosystems they inhabit. This research highlights how Indigenous peoples not only improved the inhabited landscape, but were also keystone builders, facilitating the creation of habitat in some cases. The findings provide strong evidence that Indigenous management practices are tied to ecosystem health and resilience.

“Human activities are often considered detrimental to biodiversity, and indeed, industrial land management has had devastating consequences for biodiversity,” says Jesse Miller, study co-author, ecologist and lecturer at Stanford University. “Our research, however, shows that human activities can also have substantial benefits for biodiversity and ecosystem function. Our findings highlight that there continues to be an important role for human activities in restoring and managing ecosystems in the present and future.”

Forest gardens are a common management regime identified in Indigenous communities around the world, especially in tropical regions. Armstrong says the study is the first time forest gardens have been studied in North America—showing how important Indigenous peoples are in the maintenance and defense of some of the most functionally diverse ecosystems on the Northwest Coast.

“The forest gardens of Kitselas Canyon are a testament to the long-standing practice of Kitselas people shaping the landscape through stewardship and management,” says Chris Apps, director, Kitselas Lands & Resources Department. “Studies such as this reconnect the community with historic resources and support integration of traditional approaches with contemporary land-use management while promoting exciting initiatives for food sovereignty and cultural reflection.”

More information:
Chelsey Geralda Armstrong et al, Historical Indigenous Land-Use Explains Plant Functional Trait Diversity, Ecology and Society (2021). DOI: 10.5751/ES-12322-260206

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Ancient Indigenous forest gardens promote a healthy ecosystem, says study (2021, April 22)
retrieved 22 April 2021
from https://phys.org/news/2021-04-ancient-indigenous-forest-gardens-healthy.html

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Ancient Indigenous forest gardens promote a healthy ecosystem (Science Daily)

Date: April 22, 2021

Source: Simon Fraser University

Summary: A new study by historical ecologists finds that Indigenous-managed forests — cared for as ‘forest gardens’ — contain more biologically and functionally diverse species than surrounding conifer-dominated forests and create important habitat for animals and pollinators.

A new study by Simon Fraser University historical ecologists finds that Indigenous-managed forests — cared for as “forest gardens” — contain more biologically and functionally diverse species than surrounding conifer-dominated forests and create important habitat for animals and pollinators. The findings are published today in Ecology and Society.

According to researchers, ancient forests were once tended by Ts’msyen and Coast Salish peoples living along the north and south Pacific coast. These forest gardens continue to grow at remote archaeological villages on Canada’s northwest coast and are composed of native fruit and nut trees and shrubs such as crabapple, hazelnut, cranberry, wild plum, and wild cherries. Important medicinal plants and root foods like wild ginger and wild rice root grow in the understory layers.

“These plants never grow together in the wild,” says Chelsey Geralda Armstrong, an SFU Indigenous Studies assistant professor and the study lead researcher. “It seemed obvious that people put them there to grow all in one spot — like a garden. Elders and knowledge holders talk about perennial management all the time.”

“It’s no surprise these forest gardens continue to grow at archaeological village sites that haven’t yet been too severely disrupted by settler-colonial land-use.”

Ts’msyen and Coast Salish peoples’ management practices challenge the assumption that humans tend to overturn or exhaust the ecosystems they inhabit. This research highlights how Indigenous peoples not only improved the inhabited landscape, but were also keystone builders, facilitating the creation of habitat in some cases. The findings provide strong evidence that Indigenous management practices are tied to ecosystem health and resilience.

“Human activities are often considered detrimental to biodiversity, and indeed, industrial land management has had devastating consequences for biodiversity,” says Jesse Miller, study co-author, ecologist and lecturer at Stanford University. “Our research, however, shows that human activities can also have substantial benefits for biodiversity and ecosystem function. Our findings highlight that there continues to be an important role for human activities in restoring and managing ecosystems in the present and future.”

Forest gardens are a common management regime identified in Indigenous communities around the world, especially in tropical regions. Armstrong says the study is the first time forest gardens have been studied in North America — showing how important Indigenous peoples are in the maintenance and defence of some of the most functionally diverse ecosystems on the Northwest Coast.

“The forest gardens of Kitselas Canyon are a testament to the long-standing practice of Kitselas people shaping the landscape through stewardship and management,” says Chris Apps, director, Kitselas Lands & Resources Department. “Studies such as this reconnect the community with historic resources and support integration of traditional approaches with contemporary land-use management while promoting exciting initiatives for food sovereignty and cultural reflection.”

Journal Reference:

  1. Chelsey Geralda Armstrong, Jesse E. D. Miller, Alex C. McAlvay, Patrick Morgan Ritchie, Dana Lepofsky. Historical Indigenous Land-Use Explains Plant Functional Trait Diversity. Ecology and Society, 2021; 26 (2) DOI: 10.5751/ES-12322-260206

Long Before Making Enigmatic Earthworks, People Reshaped Brazil’s Rain Forest (N.Y.Times)

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By  JOANNA KLEIN FEB. 10, 2017

New research suggests people were sustainably managing the Amazon rain forest much earlier than was previously thought. Jenny Watling 

Deep in the Amazon, the rain forest once covered ancient secrets. Spread across hundreds of thousands of acres are massive, geometric earthworks. The carvings stretch out in circles and squares that can be as big as a city block, with trenches up to 12 yards wide and 13 feet deep. They appear to have been built up to 2,000 years ago.

Were the broken ceramics found near the entrances used for ritual sacrifices? Why were they here? The answer remains a mystery.

There are 450 geoglyphs concentrated in Brazil’s Acre State. Jenny Watling 

For centuries, the enigmatic structures remained hidden to all but a few archaeologists. Then in the 1980s, ranchers cleared land to raise cattle, uncovering the true extent of the earthworks in the process. More than 450 of these geoglyphs are concentrated within Acre State in Brazil.

Since the discovery, archaeological study of the earthworks and other evidence has challenged the notion that the rain forests of the Amazon were untouched by human hands before the arrival of European explorers in the 15th century. And while the true purpose of the geoglyphs remains unknown, a study published on Monday in The Proceedings of the National Academy of Sciences offers new insight into the lives of the ancient people who lived in the Amazon. Thousands of years before the earthworks were built, humans were managing the forests, using what appear to be sustainable agricultural practices.

“Our study was looking at the environmental impact that the geoglyph builders had on the landscape,” said Jennifer Watling, an archaeologist at the University of São Paulo, Brazil, who conducted the research while a student at the University of Exeter in Britain. “A lot of people have the idea that the Amazon forests are pristine forests, never touched by humans, and that’s obviously not the case.”

Dr. Watling and her team reconstructed a 6,000-year-old environmental history of two geoglyph sites in the Amazon rain forest. To do this, they searched for clues in soil samples in and around the sites. Microscopic plant fossils called phytoliths told them about ancient vegetation. Bits of charcoal revealed evidence of burnings. And a kind of carbon dating gave them a sense of how open the vegetation had been in the past.

About 4,000 years ago, people started burning the forest, which was mostly bamboo, just enough to make small openings. They may have planted maize or squash, weeded out some underbrush, and transported seeds or saplings to create a partly curated forest of useful tree products that Dr. Watling calls a “prehistoric supermarket.” After that, they started building the geoglyphs. The presence of just a few artifacts, and the layout of the earthworks, suggest they weren’t used as ancient villages or for military defenses. They were likely built for rituals, some archaeologists suspect.

Dr. Watling and her colleagues found that in contrast with the large-scale deforestation we see today — which threatens about 20 percent of the largest rain forest in the world — ancient indigenous people of the Amazon practiced something more akin to what we now call agroforestry. They restricted burns to site locations and maintained the surrounding landscape, creating small, temporary clearings in the bamboo and promoting the growth of plants like palm, cedar and Brazil nut that were, and still are, useful commodities. Today, indigenous groups around the world continue these sustainable practices in forests.

“Indigenous communities have actually transformed the ecosystem over a very long time,” said Dr. Watling. “The modern forest owes its biodiversity to the agroforestry practices that were happening during the time of the geoglyph builders.”