Deforestation

Global 30m Landsat Tree Canopy Version 4 NASA

Deforestation: The conversion of forest to another land use or the long-term reduction of the tree canopy cover below a 10 percent threshold. Deforestation implies the long-term or permanent loss of forest cover and its transformation into another land use.

Every second, a forest the size of a football field is cut down.
14,800 square miles of forest are lost every year. This is roughly the same size as Switzerland.
In 2019, approximately 9 million acres of rainforests were destroyed.
Deforestation causes approximately $2 trillion to $4.5 trillion in lost biodiversity each year.
4.2% of the world’s tree cover loss was between 1990 and 2020.
By 2030, there may be only 10% of the world’s rainforests left.
Agriculture is responsible for approximately 80% of tropical forest loss.

Using satellite data from the past two decades, scientists are starting to pinpoint which crops and farming styles have lasting impacts on forests-NASA Landstat

People have been deforesting the Earth for thousands of years, primarily to clear land for crops or livestock.

Direct causes of deforestation are agricultural expansion, wood extraction (e.g., logging or wood harvest for domestic fuel or charcoal), and infrastructure expansion such as road building and urbanization. Rarely is there a single direct cause for deforestation. Most often, multiple processes work simultaneously or sequentially to cause deforestation.

The world’s total forest area is just over 4 billion hectares, corresponding to 31 percent of the total land area or an average of 0.6 ha per capita. The five most forest-rich countries (the Russian Federation, Brazil, Canada, the United States of America and China) accounted for more than half of the total forest area. Ten countries or areas had no forest at all and an additional 54 had forest on less than 10 percent of their total land area.

At present the rate of deforestation and loss of forest from natural causes is still alarmingly high, but is slowing down. At the global level, it decreased from an estimated 16 million hectares per year in the 1990s to around 13 million hectares per year in the last decade.

NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview and Landsat data from the U.S. Geological Survey

At the same time, afforestation and natural expansion of forests in some countries and areas reduced the net loss of forest area significantly at the global level. The net change in forest area in the period 2000–2010 was estimated at -5.2 million hectares per year (an area about the size of Costa Rica), down from -8.3 million hectares per year in the period 1990–2000. However, most of the loss of forest continued to take place in countries and areas in the tropical regions, while most of the gain took place in the temperate and boreal zones, and in some emerging economies.

Impacts of Deforestation: Biodiversity Impacts

Although tropical forests cover only about 7 percent of the Earth’s dry land, they probably harbor about half of all species on Earth. Many species are so specialized to microhabitats within the forest that they can only be found in small areas. Their specialization makes them vulnerable to extinction. In addition to the species lost when an area is totally deforested, the plants and animals in the fragments of forest that remain also become increasingly vulnerable, sometimes even committed, to extinction. The edges of the fragments dry out and are buffeted by hot winds; mature rainforest trees often die standing at the margins. Cascading changes in the types of trees, plants, and insects that can survive in the fragments rapidly reduces biodiversity in the forest that remains. People may disagree about whether the extinction of other species through human action is an ethical issue, but there is little doubt about the practical problems that extinction poses.

First, global markets consume rainforest products that depend on sustainable harvesting: latex, cork, fruit, nuts, timber, fibers, spices, natural oils and resins, and medicines. In addition, the genetic diversity of tropical forests is basically the deepest end of the planetary gene pool. Hidden in the genes of plants, animals, fungi, and bacteria that have not even been discovered yet may be cures for cancer and other diseases or the key to improving the yield and nutritional quality of foods—which the U.N. Food and Agriculture Organization says will be crucial for feeding the nearly ten billion people the Earth will likely need to support in coming decades. Finally, genetic diversity in the planetary gene pool is crucial for the resilience of all life on Earth to rare but catastrophic environmental events, such as meteor impacts or massive, sustained volcanism.

Soil Impacts

With all the lushness and productivity that exist in tropical forests, it can be surprising to learn that tropical soils are actually very thin and poor in nutrients. The underlying “parent” rock weathers rapidly in the tropics’ high temperatures and heavy rains, and over time, most of the minerals have washed from the soil. Nearly all the nutrient content of a tropical forest is in the living plants and the decomposing litter on the forest floor.

Importance of Forests

Forests and air

Over 40 percent of the world's oxygen is produced from the rainforests.
Forests contribute to the balance of oxygen, carbon dioxide and humidity
in the air.

Forests and water

A tree releases 8-10 times more moisture into the atmosphere than the
equivalent area of the ocean.
Forests protect watersheds which supply fresh water to rivers.
Loss of forests could affect rainfall patterns globally, especially in food
growing regions in Latin America, the American mid-West and Central Asia.
Deforestation leads to soil erosion and rivers being silted, which reduces
access to clean wate

Forests and biodiversity

Forests are home to over 80% of terrestrial biodiversity.
In the Amazon basin alone, more than 1,300 species of forest plants are
used for medicinal or cultural purposes.
12% of the world’s forests are designated for the conservation of biological
diversity (FRA 2010).
Deforestation of closed tropical rainforests could account for the loss of as
many as 100 species a day.

Forests build resilience to natural disasters

Nearly 330 million hectares of forest are designated for soil and water
conservation, avalanche control, sand dune stabilization, desertification
control or coastal protection. (FRA 2010)
Mangrove forests act as a barrier against tsunamis, cyclones and
hurricanes.
‘Green Wall for the Sahara’ The European Union and African Union are
implementing a project to build a ‘green wall’ of trees across the Sahara
to push back desertification and to secure agriculture and livelihoods in
the sahelo-saharan zone.

Forests and land

Forests cover 31% of global land area
Forests and tree cover combat land degradation and desertification by stabilizing soils, reducing water and wind erosion and maintaining nutrient cycling in soils.

Healthy forests, healthy people

Tropical forests provide a vast array of medicinal plants used in healing and healthcare, worth an estimated $108 billion a year.
More than a quarter of modern medicines originate from tropical forest plants.
Forests curb infectious diseases. Undisturbed tropical forests can have a moderating effect on insect- and animal-borne disease:
- 40% of the world’s population lives in malaria infested regions. Heavily deforested areas can see a 300 fold increase in the risk of malaria infection compared to areas of intact forest.
- 72% of emerging infectious diseases transmitted from animals to humans come from wildlife as opposed to domesticated animals. Deforested areas increase contact between wildlife and humans and affect pathogen transmission.

Forests are our livelihoods/wealth

1.6 billion people around the world depend on forests for their livelihoods and daily subsistence needs.
The global gross value-added in the forestry sector is US$ 468 billion.
The global trade in primary wood products is US$ 235 billion.
Tropical forests provide pollination services to agriculture valued at US$12 billion per year.
Given that more than 1 billion hectares of degraded areas throughout the world are suitable for forest landscape restoration, community-based forest management could be woven into other existing rural economic activities.

DEFORESTATION IN BRAZIL: 60-70 percent of deforestation in the Amazon results from cattle ranches while the rest mostly results from small-scale subsistence agriculture. Despite the widespread press attention, large-scale farming (i.e. soybeans) currently contributes relatively little to total deforestation in the Amazon. Most soybean cultivation takes place outside the rainforest in the neighboring cerrado grassland ecosystem and in areas that have already been cleared. Logging results in forest degradation but rarely direct deforestation. However, studies have showed a close correlation between logging and future clearing for settlement and farming

An estimated 13,235 square kilometres of rainforest have been lost in 2020-21 – a 22 per cent increase in deforestation over one year, and the highest level since 2006

Credit:NASA,Mongabay,USGS, Woods Hole Research Center,UNEP