Of the 3.04 trillion trees in the world, the tropical and subtropical forests have the highest number of trees at approximately 1.39 trillion. Photo: H.Vibhu
There are just 3.04 trillion trees in the world, data from the first spatially continuous map of forest tree density suggests. The estimate of the ratio of trees per person is 422:1.

Though 3.04 trillion trees is an “order of magnitude higher” than previous estimate, the number of trees cut down each year is a staggering 15.3 billion and the global forest cover loss is approximately 192,000 sq. km per year. As a result, the global number of trees has reduced by as much as 46 per cent since the start of human civilisation. These are some of the results of a study published today in the journal Nature.

As per the study, a tree is defined as a “plant with woody stems larger than 10 cm diameter at breast height.”

Of the 3.04 trillion trees in the world, the tropical and subtropical forests have the highest number of trees at approximately 1.39 trillion (nearly 43 per cent), followed by boreal regions (0.74 trillion trees accounting for 24.2 per cent) and finally the temperate regions at 0.61 trillion trees (21.8 per cent). While the tropical forests have the highest number of trees, they have also witnessed the highest rate of tree loss.

Though the tropical forests have the highest number of trees, the tree density is highest in the forested regions of the Boreal and Tundra regions, the study notes. In the northern latitudes the deficient moisture and low temperatures allow only the stress-tolerant coniferous tree species to establish. The coniferous tree species, by default, reach highest densities.

Till date, scientists have relied on satellite images to provide estimates of global forest area. As a result, it was not possible to know the number of trees. For this study, T. W. Crowther, the first author from Yale University, Connecticut, U.S. and others used nearly 4,30,000 ground-sourced measurements of tree density from all the continents except Antarctica to generate a global map of forest trees.

Forested areas were found even in regions that are generally regarded as being bereft of them — deserts, tundra and grasslands.

Though warmth and water availability led to an increase in tree density, a negative relationship was found in many regions. For instance, in the case of flooded grasslands and tropical dry forests, the benefits of water availability did not result in increased tree density. This was because the forested land was put to agricultural use.

“The negative relationships between tree density and anthropogenic land use exemplify how humans contend directly with natural forest ecosystems for space,” they write. “Although the rates of forest loss are currently highest in tropical regions, the scale and consistency of this effect across all forested ecosystems highlight how historical land-use decisions have shaped natural ecosystems on a global scale.”

A dense forest greatly influences a vast array of biotic and abiotic processes, and the current data helps in providing insights into ecological dynamics. The data is also critical in guiding local, national and global reforestation/afforestation measures.


Earth has 3 Trillion Trees but They’re Falling Fast
WASHINGTON
Reuters




Earth is home to just over 3 trillion trees the redwoods of California, the olive trees of Tunisia, the cherry trees of Japan, the eucalyptus of Australia and so many more but they are being lost at an alarming rate because of human activities.

Those are the findings of researchers who on Wednesday unveiled the most comprehensive assessment of global tree populations ever conducted, using data including satellite imagery and ground-based tree density estimates from more than 400,000 locations worldwide. The estimate of 3.04 trillion trees an estimated 422 for every person is about eight times higher than a previous estimate of 400 billion trees that was based on satellite imagery but less data from the ground.

The new findings leave abundant reason for concern with people at the root of the problem.

The number of trees has fallen by about 46 percent since the start of human civilization and each year there is a gross loss of 15 billion trees and a net loss of 10 billion, said Yale University ecologist Thomas Crowther, who led mas Crowther, who led the study published in the journal Nature.

“There are current ly fewer trees than at any point since the start of human civili z a t i o n a n d t h i s number is still falling at an alarming rate,“ he said. “If anything, the scale of these numbers just highlights the need to step up our efforts if we are going to begin to repair some of these effects on a global scale.“

Crowther said a wide range of hu man activities deplete forested land.Conversion of land for agriculture his orically has had the biggest impact on orests but industrial and urban development also have had huge effects, Crowther said. As the global human population grows, the net loss of trees worldwide also mahy increase, Yale researcher Henry Glick said.

“Trees are some of the most prominent and important organisms on the planet,“ Crowther said. “Trees provide a wide range of important ecosystem services for humans. They store water and nutrients, stabilize the soil, provide habitats for plants and animals, offset the impacts of climate change by absorbing carbon dioxide and they generate the oxygen that we need to breath.“

The study found that while the highest tree densities were in the sub-Arctic re gions of Russia, Scandinavia and North America, the largest forested areas were in the tropics, home to about 43 percent of the global tree total.

Source: Economic Times today.


Not only the trees are disappearing but the species dependent on them are also disappearing at the same pace. Unfortunately we do not have any estimates of these species. Human being command nearly two-third earth surface and rest is left for about 8.7 million species.. unjustified distribution of resource.


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