HOW MANY TREES ARE BEING CUT DOWN EACH YEAR?

     
A new study published in Nature estimates the planet has 3.04 trillion trees.

Bạn đang xem: How many trees are being cut down each year?

The research says 15.3 billion trees are chopped down every year.It also estimates that 46% of the world’s trees have been cleared over the past 12,000 years.

When it comes to lớn the world’s forests, two of the commonly asked questions are “How many trees are on Earth?” và “How many trees are cut down each year?” A new study proposes answers: three trillion và 15.3 billion.

The research, published today in the journal Nature, is based on a combination of satellite imagery, on-the-ground inventories, & computer modeling led by Thomas Crowther of the Netherlands Institute of Ecology. Crowther conducted the research while at Yale University.

“Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to lớn comprehend their global extent và distribution,” Crowther was quoted as saying in an article posted on Yale’s web site.

Hear this article being read aloud here via tinhdaudua.com.vn’s podcast:

Pittsfield State Forest in Massachusetts. Photo by Rhett A. Butler.

“They store huge amounts of carbon, are essential for the cycling of nutrients, for water và air quality, and for countless human services. Yet you ask people to estimate, within an order of magnitude, how many trees there are & they don’t know where to begin. I don’t know what I would have guessed, but I was certainly surprised to lớn find that we were talking about trillions.”

Three trillion trees is far higher than the previous leading estimate of 400 billion trees. The wide discrepancy is the result of the more comprehensive methodology used by the research team.

“The diverse array of data available today allowed us to build predictive models to lớn estimate the number of trees at each location around the globe,” said Yale postdoctoral student Henry Glick, second tác giả of the study.

Xem thêm: Thời Gian Biểu Hợp Lý Cho Học Sinh Lớp 10, Hướng Dẫn Cách Lập

Image highlighting the ecoregions (shapefiles provided by The Nature Conservancy) from which the 429,775 ground-sourced measurements of tree mật độ trùng lặp từ khóa were collected. Shading indicates the total number of plot measurements collected in each ecoregion. A global forest bản đồ was overlaid in green lớn highlight that collected data span the majority of forest ecosystems on a global scale. B, The median and interquartile range of tree mật độ trùng lặp từ khóa values collected in the forested areas of each biome. Image và caption courtesy of Nature.

The research broke down tree cover by biome & country, finding the highest density in boreal forests, which altogether house 750 billion trees, or about a quarter of the world’s total. The largest extent of forests exist in the tropics, which have 1.3 trillion trees, or 43 percent of the planet’s trees. The differences make intuitive sense given the high diversity & larger kích cỡ of trees in the tropics versus sub-arctic regions.

By country, Russia had the most trees at 642-698 billion. It was followed by Canada (318-361 billion trees), Brazil (302-338 billion), the United States (222-228 billion), and đài loan trung quốc (140-178 billion). The highest mật độ trùng lặp từ khóa among countries with significant amounts of forest cover was Finland, with more than 72,000 trees per square kilometer. It was followed by Slovenia, Sweden, và Taiwan.

*
Redwood forest in Muir Woods, California. Photo Rhett A. Butler.
*
Temperate rainforest on Washington’s Olympic Peninsula. Photo by Rhett A. Butler
*
Temperate forest in New Hampshire. Photo by Rhett A. Butler

The study also estimated current and historical rates of tree cover loss. It said that the number of trees worldwide has fallen 46 percent since the dawn of agriculture 12,000 years ago and more than 15 billion trees are felled every year.

That loss has significant implications for the planet in terms of climate change, biodiversity, and human well-being, according to lớn Crowther.

“We’ve nearly halved the number of trees on the planet, & we’ve seen the impacts on climate and human health as a result,” he said. “This study highlights how much more effort is needed if we are to restore healthy forests worldwide.”

*
Rainforest in Sabah, Malaysia. Photo by Rhett A. Butler.

CITATION: T. W. Crowther et al (2015). Mapping tree mật độ trùng lặp từ khóa at a global scale. Nature dooi:10.1038/nature14967 Published online 02 September 2015


Review questions for educators

These questions can help provide a framework for exploring topics presented in this story.

Xem thêm: Miền Cần Thơ Gạo Trắng Nước Trong, Về Miền Gạo Trắng Nước Trong

Why are trees important?What forests have the highest density of trees?What country has the most trees?How has the number of trees in the world changed over time?What percentage of trees have been lost?

Test your knowledge.