A forest is an area with a high density of trees (or, historically, a wooded area set aside for hunting). Actually, many definitions of a forest exist. These plant communities cover large areas of the globe and function as carbon dioxide sinks, animal habitats, hydrologic flow modulators, and soil conservers, constituting one of the most important aspects of the Earth's biosphere.
Forests can be found in all regions capable of sustaining tree growth, at altitudes up to the tree-line, except where natural fire frequency is too high, or where the environment has been impaired by natural processes or by human activities.
As a general rule, forests dominated by angiosperms (broadleaf forests) are more species-rich than those dominated by gymnosperms (conifer or needleleaf forests), although exceptions exist (for example, species-poor aspen and birch stands in northern latitudes).
Forests sometimes contain many tree species within a small area (as in tropical rain and temperate deciduous forests), or relatively few species over large areas (e.g., taiga and arid montane coniferous forests).
Forests are often home to many animal and plant species, and biomass per unit area is high compared to other vegetation communities. Much of this biomass occurs below-ground in the root systems and as partially decomposed plant detritus. The woody component of a forest contains lignin, which is relatively slow to decompose compared with other organic materials such as cellulose or carbohydrate.
Forests are differentiated from woodlands by the extent of canopy coverage: in a forest the branches and foliage of separate trees often meet or interlock, although there can be gaps of varying sizes within an area referred to as forest. A woodland has a more continuously open canopy, with trees spaced further apart, which allows more sunlight to penetrate to the ground between them.
Among the major forested biomes are:
Classification
Forests can be classified in different ways and to different degrees of specificity. One such way is in terms of the biome in which they exist combined with leaf longevity of the dominant species (whether they are evergreen or deciduous). Another distinction is whether the forests composed predominantly of broadleaf trees, coniferous (needle-leaved) trees, or mixed.
F o r e s t m a n a g e m e n t
T h e s c i e n t i f i c s t u d y o f f o r e s t s i s r e f e r r e d t o a s f o r e s t e c o l o g y , w h i l e t h e m a n a g e m e n t o f f o r e s t s i s o f t e n r e f e r r e d t o a s f o r e s t r y , o f t e n w i t h t h e g o a l o f s u s t a i n a b l e r e s o u r c e e x t r a c t i o n .
F o r e s t e c o l o g i s t s c o n c e n t r a t e o n f o r e s t p a t t e r n s a n d p r o c e s s e s , u s u a l l y w i t h t h e a i m o f e l u c i d a t i n g c a u s e a n d e f f e c t r e l a t i o n s h i p s . F o r e s t e r s o f t e n f o c u s o n w o o d e x t r a c t i o n a n d s i l v i c u l t u r e , i n c l u d i n g t r e e r e g e n e r a t i o n a n d g r o w t h p r o c e s s e s .
F o r e s t s c a n b e a l t e r e d w h e n l o g g i n g , f o r e s t f i r e s , a c i d r a i n , h e r b i v o r e s , o r d i s e a s e s , a m o n g o t h e r t h i n g s , c a u s e d a m a g e t o t r e e s . I n t h e U n i t e d S t a t e s , m o s t f o r e s t s h a v e h i s t o r i c a l l y b e e n a f f e c t e d b y h u m a n s t o s o m e d e g r e e , t h o u g h i n r e c e n t y e a r s i m p r o v e d f o r e s t r y p r a c t i c e s h a s h e l p e d r e g u l a t e o r m o d e r a t e l a r g e s c a l e o r s e v e r e i m p a c t s . H o w e v e r t h e U n i t e d S t a t e s F o r e s t S e r v i c e e s t i m a t e s t h a t e v e r y y e a r a b o u t 1 . 5 m i l l i o n a c r e s ( 6 , 0 0 0 k m ² ) o f t h e n a t i o n' s 7 5 0 m i l l i o n a c r e s ( 3 , 0 0 0 , 0 0 0 k m ² ) o f f o r e s t l a n d i s l o s t t o u r b a n s p r a w l a n d d e v e l o p m e n t . I t i s e x p e c t e d t h a t t h e S o u t h a l o n e w i l l l o s e 2 0 t o 2 5 m i l l i o n a c r e s ( 8 0 , 0 0 0 t o 1 0 0 , 0 0 0 k m ² ) t o d e v e l o p m e n t .
Facts About Forests Wikipedia
Team reveals oldest fossilized forest PhysOrg - February 29, 2012
An international team, including a Cardiff University researcher, who previously found evidence of the Earth's earliest tree, has gone one step further. The research team has now unearthed and investigated an entire fossil forest dating back 385 million years.
Giant Vines & Towering Trees: Ancient Forest Unearthed Live Science - February 29, 2012
One of the earliest forests in the world was home to towering palmlike trees and woody plants that crept along the ground like vines, a new fossil find reveals. The forest, which stood in what is now Gilboa, N.Y., was first unearthed in a quarry in the 1920s. But now, a new construction project has revealed for the first time the forest floor as it stood 380 million years ago in the Devonian period.
Poland's Mysterious Crooked Forest Discovery - June 29, 2011
In a tiny corner of western Poland a forest of about 400 pine trees grow with a 90 degree bend at the base of their trunks - all bent northward. Surrounded by a larger forest of straight growing pine trees this collection of curved trees, or "Crooked Forest," is a mystery. Planted around 1930, the trees managed to grow for seven to 10 years before getting held down, in what is understood to have been human mechanical intervention. Though why exactly the original tree farmers wanted so many crooked trees is unknown.
First-of-Its-Kind Map Details the Height of the Globe's Forests Science Daily - July 21, 2010
Giant Sequoias Yield Longest Fire History from Tree Rings Science Daily - April 21, 2010
A 3,000-year record from 52 of the world's oldest trees shows that California's western Sierra Nevada was droughty and often fiery from 800 to 1300, according to new research.
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First discovery of the female sex hormone progesterone in a plant PhysOrg - February 4, 2010
This Tree's a Lady! Live Science - February 4, 2010
Trees evolved camouflage defense against long extinct predator: First evidence of camouflage defense in plants PhysOrg - July 22, 2009
The Lost Forests of America Live Science - April 24, 2009
Giant Underground Fossil Forests Show Record of Warming National Geographic - September 9, 2008
Ancient trees recorded in mines BBC - September 9, 2008
Spectacular fossil forests have been found in the
coal mines of Illinois by a US-UK team of researchers.
Study: Tree Leaves Have Built-In Thermostat Live Science - June 11, 2008
"Methuselah" Tree Grew From 2,000-Year-Old Seed National Geographic - June 12, 2008
The oldest-sprouted seed in the world is a 2,000-year-old plant from Jerusalem, a new study confirms. "Methuselah," a 4-foot-tall (1.2-meter-tall) ancestor of the modern date palm, is being grown at a protected laboratory in the Israeli capital.
Oldest Living Tree Found in Sweden - 9,550 years old National Geographic - April 14, 2008
California wildfires of October 2007 Wikipedia
Singapore's "Magic Monkey" Trees Inspire Cult, Cynics September 27, 2007
Monkey Tree Phenomenon Wikipedia
Texas: Mysterious 'Fairyland' Spider Web Found Live Science - August 30, 2007
Ancient forest found in Hungary BBC - August 12, 2007
Giant Fossil Rain Forest Discovered in Illinois National Geographic - April 25, 2007
A giant fossilized rain forest has been unearthed in an Illinois coal mine.
Preserved by a major ancient earthquake, the forest covers four square miles
(a thousand hectares) and features an abundance of huge leaf impressions,
large trunks of extinct trees, and tree-size horsetail plants, the researchers said.
Ancient Rainforest Revealed in Coal Mine Live Science - April 23, 2007
Scientists exploring a mine have uncovered a natural Sistine chapel showing
not religious paintings, but incredibly well preserved images of sprawling tree
trunks and fallen leaves that once breathed life into an ancient rainforest.
Replete with a diverse mix of extinct plants, the 300-million-year-old fossilized
forest is revealing clues about the ecology of EarthÕs first rainforests.
Earth's First Rainforest Unearthed PhysOrg - April 23, 2007
Newfound Fossils Reveal Secrets of World's Oldest Forest National Geographic - April 18, 2007
Until now, however, scientists could only speculate what type of tree the Gilboa stumps, designated Eospermatopteris, represented. "What we found in the last couple of years was evidence of what the top of these things looked like," Stein said. The new fossils indicate that the fossil trees belong to a previously known plant group called cladoxylopsids, Stein said. Scientists suspected the fernlike cladoxylopsids were large, but experts never had more than the branches to work with, Stein added. "What we got here is like a double whammy," he said. "On the one hand, we know Eospermatopteris is these great stumps. On the other hand we have real evidence for how big the cladoxylopsids actually were."
Brigitte Meyer-Berthaud is a paleobotanist with the National Center for Scientific Research in Montpellier, France. She said the new fossils are surprising because they indicate Earth's first trees evolved without the aid of leaves and horizontal branches. "It was probably so advantageous to be bigger than the others that they achieved [height] even if they didn't have the proper organs," she said. Meyer-Berthaud, who co-authored an accompanying article on the new research, identified in 1999 a different type of tree called Archaeopteris as the earliest modern tree.
These trees, which date to around 385 million to 359 million years ago, had horizontal branches, leaves, and an extensive root system. Such structures are considered important to achieve treelike stature and are common to most trees in temperate and tropical areas today. The Gilboa forest dates to 385 million years ago, and the group of cladoxylopsids that includes the Gilboa trees was widespread around the world from about 385 million to 400 million years ago. Stein noted that these early trees played a major role in establishing Earth's first terrestrial ecosystems. "Trees really dominate those kinds of environments they're found in. They really are the entire fabric in which an entire ecology fits in a terrestrial realm," he said.
How Ancient Forests Looked -- Understanding the full appearance of the Gilboa trees allows scientists to infer what the entire forest ecosystem was like. For example, since the Gilboa trees lacked leaves, sunlight would have filtered down to the forest floor. And the trees, like modern palms, likely dropped their branches on a yearly or seasonal cycle, filling the forest floor with woody litter suitable for arthropods such as spiders and insects. The trees also would have removed carbon dioxide from the atmosphere, causing global temperatures to drop, Stein added. The traits of the Gilboa trees are found in many tree types throughout history, he noted. "The traits cannot all be traced back to the same common ancestor, so it's clearly a recurrent evolved form," he said. "The reason for that is probably ecology, probably something to do with a way of being a large tree or a large plant. It's one way to do it, and it is now clearly the oldest way," he added.
World's First Tree Reconstructed Live Science - April 18, 2007
WorldÕs first tree reconstructed MSNBC - April 18, 2007
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