Posted on 09/02/2015 10:56:17 AM PDT by Red Badger
The global map of tree density at the square-kilometer pixel scale. Credit: Crowther, et al
A new Yale-led study estimates that there are more than 3 trillion trees on Earth, about seven and a half times more than some previous estimates. But the total number of trees has plummeted by roughly 46 percent since the start of human civilization, the study estimates.
Using a combination of satellite imagery, forest inventories, and supercomputer technologies, the international team of researchers was able to map tree populations worldwide at the square-kilometer level.
Their results, published in the journal Nature, provide the most comprehensive assessment of tree populations ever produced and offer new insights into a class of organism that helps shape most terrestrial biomes.
The new insights can improve the modeling of many large-scale systems, from carbon cycling and climate change models to the distribution of animal and plant species, say the researchers.
"Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to comprehend their global extent and distribution," said Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry & Environmental Studies (F&ES) and lead author of the study.
"They store huge amounts of carbon, are essential for the cycling of nutrients, for water and air quality, and for countless human services," he added. "Yet you ask people to estimate, within an order of magnitude, how many trees there are and they don't know where to begin. I don't know what I would have guessed, but I was certainly surprised to find that we were talking about trillions."
The study was inspired by a request by Plant for the Planet, a global youth initiative that leads the United Nations Environment Programme's "Billion Tree Campaign." Two years ago the group approached Crowther asking for baseline estimates of tree numbers at regional and global scales so they could better evaluate the contribution of their efforts and set targets for future tree-planting initiatives.
At the time, the only global estimate was just over 400 billion trees worldwide, or about 61 trees for every person on Earth. That prediction was generated using satellite imagery and estimates of forest area, but did not incorporate any information from the ground.
The new study used a combination of approaches to reveal that there are 3.04 trillion trees—roughly 422 trees per person.
Crowther and his colleagues collected tree density information from more than 400,000 forest plots around the world. This included information from several national forest inventories and peer-reviewed studies, each of which included tree counts that had been verified at the ground level. Using satellite imagery, they were then able to assess how the number of trees in each of those plots is related to local characteristics such as climate, topography, vegetation, soil condition, and human impacts.
"The diverse array of data available today allowed us to build predictive models to estimate the number of trees at each location around the globe," said Yale postdoctoral student Henry Glick, second author of the study.
The resulting map has the potential to inform scientists about the structure of forest ecosystems in different regions, and it can be used to improve predictions about carbon storage and biodiversity around the world.
"Most global environmental data is thematically coarse," said Matthew Hansen, a global forestry expert from the University of Maryland who was not involved in the study. "The study of Crowther et al. moves us towards a needed direct quantification of tree distributions, information ready to be used by a host of downstream science investigations."
The highest densities of trees were found in the boreal forests in the sub-arctic regions of Russia, Scandinavia, and North America. But the largest forest areas, by far, are in the tropics, which are home to about 43 percent of the world's trees. (Only 24 percent are in the dense boreal regions, while another 22 percent exist in temperate zones.)
The results illustrate how tree density changes within forest types. Researchers found that climate can help predict tree density in most biomes. In wetter areas, for instance, more trees are able to grow. However, the positive effects of moisture were reversed in some regions because humans typically prefer the moist, productive areas for agriculture.
In fact, human activity is the largest driver of tree numbers worldwide, said Crowther. While the negative impact of human activity on natural ecosystems is clearly visible in small areas, the study provides a new measure of the scale of anthropogenic effects, highlighting how historical land use decisions have shaped natural ecosystems on a global scale. In short, tree densities usually plummet as the human population increases. Deforestation, land-use change, and forest management are responsible for a gross loss of over 15 billion trees each year.
"We've nearly halved the number of trees on the planet, and we've seen the impacts on climate and human health as a result," Crowther said. "This study highlights how much more effort is needed if we are to restore healthy forests worldwide."
Researchers from 15 countries collaborated on the study.
More information: Nature, DOI: 10.1038/nature14967
Journal reference: Nature
Here in The South, we have ‘Tree Farms’ of pine trees used for pulp wood. They are planted in rows just like any other crops and are way denser than the normal forest.
They are genetically selected trees provided by the paper companies, for fast growth and straightness of trunks.
My brother-in-law had a summer job back in 1977 when he was 16, planting these types of trees on recently cleared swampy forest land.
Those trees he planted have grown, been harvested and new trees planted in their place and are ready to be harvested again.........................
Professor Wilhelm Augustus von Liebwinkel-Gonzalez of the famed Prague Institute of Forestry postulates that an insufficient number of the world's population were paying attention during Monty Python's first season, which featured the highly educational guide 'How To Recognize Different Types Of Tree From Quite A Long Way Away'.
I confess to being a frequent offender when it comes to overlooking trees. There's a common larch in my neighbor's yard that I thought was an accordion. Now I understand why I always got bark under my fingernails when I tried to play Lady of Spain on it.
Dog-paddling in the shallow end of the gene pool, I remain,
SM
When I was in Germany, back in 2000, We were driving thru a rural area on a narrow road, with huge trees lining both sides of the road very close to the road surface. There were signs spaced about every hundred feet or so that depicted a car smashed into a tree and a red circle with a line thru it, and some German words under it. It’s meaning was clear: DO NOT RUN INTO TREES!.............
Most were dwarf's...
About the only thing I miss about SoCal.
They thought those trees were just fellow liberals
THe death of the American Chestnut and the extinction of the Passenger Pigeons are not linked. This extensive article on their demise says that their prime food was acorns and beechnuts. Pigeons were well on their way out decades before 1904, and it was people and the railroads that did it according to this:
https://www.audubon.org/magazine/may-june-2014/why-passenger-pigeon-went-extinct
Another aspect that I read a while ago is that they needed a flock of a certain size to stimulate their breeding hormones. By the time they only had a few specimens left, they could no longer promote breeding. If they try to restore the PP, they will have to build a big enough flock to create that stimulus. A major task.
This link from the American Chestnut Foundation answers many questions: http://www.acf.org/Q&A.php
Here is one commercial source that claims resistance. Unfortunately, they only deliver to some states. However they have extensive material on how, when, where to grow them, diseases, etc.: http://www.chestnuthilltreefarm.com/?gclid=CN_EjMvp28cCFUcXHwodxvMAGg
This Georgia based company mentions no restrictions on shipping: https://www.willisorchards.com/product/american-chestnut-tree#.VejBEflVikp
The impression I get is that while there might not be certified resistant Chestnut trees, you can manage to grow them, especially if your soil is not already infected. The grow quickly and start producing early and are not extinct, merely rare in the wild.
They used to roost and mate in eastern Michigan (among probably other places); their carcasses were in big demand as the primary source of squab, and they just sat on the branches making sounds. Mowing them down with shot was a way of earning a living (probably a kind of poor one) and recovery of the species was difficult because lumbering cleaned out nearly the entire state before 1920 (the last big old-growth tree around here was about three or four miles west, and was cut before US involvement in WWI).
Well, sure, we got the current number of trees wrong by over 600 percent, but we DEFINITELY know the number of trees at the beginning of human civilization!
Of course, in the evolution of the planet, crops, plants, shrubs, etc all may be nature's intended replacement for trees, but Liberals know better, and will ensure that their plans pre-empt Nature or mankind. Their faith is stronger than either of those enemies.
A—At night they do. During the day, they give off oxygen.
Leave it to a FReeper to split hairs and assault us with useless details. LOL
(Thanks)
Don’t forget this important part of that...
“While they are growing, they take up more carbon dioxide overall than they give out”
I suspect it’s a good deal more.
**** “7.5x more than scientists thought” ****
And that is just in my back yard
I gather you are not familiar with the Younger Fill and the argument Emmett Scott gave for its origin in his book Mohammed and Charlemagne Revisited.
There is a layer of silt in the Mediterranean that dates to the rise of Islam, and, Scott argues, provides archaeological evidence for Pirenne's thesis that the rise of Islam was the cause of the Western European Dark Ages. A great deal of modern desert in North Africa and Palestine had been the breadbasket of the Roman Empire, and its desertification was cause by overgrazing after the Muslim conquest -- Muslims taking the attitude that land, including agricultural land, owned by non-Muslims was grazing range for the herd animals of Muslims. Wind erosion of the overgrazed former farms created the Younger Fill, and left behind the modern deserts of Palestine and coastal Libya.
Desert expansion is, sometimes the result of human activity, in the form of overgrazing in already arid, but not quite desert, conditions.
Yes, I’m familiar and I don’t buy it.
There’s no way they had herds large enough to over graze that region.
This is more population control crap.
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