Portal:Trees
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The Trees Portal
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In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. In wider definitions, the taller palms, tree ferns, bananas, and bamboos are also trees.
Trees are not a monophyletic taxonomic group but consist of a wide variety of plant species that have independently evolved a trunk and branches as a way to tower above other plants to compete for sunlight. The majority of tree species are angiosperms or hardwoods; of the rest, many are gymnosperms or softwoods. Trees tend to be long-lived, some reaching several thousand years old. Trees evolved around 370 million years ago, and it is estimated that there are around three trillion mature trees in the world currently.
A tree typically has many secondary branches supported clear of the ground by the trunk, which typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees the trunk is surrounded by a layer of bark which serves as a protective barrier. Below the ground, the roots branch and spread out widely; they serve to anchor the tree and extract moisture and nutrients from the soil. Above ground, the branches divide into smaller branches and shoots. The shoots typically bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development.
Trees usually reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms, bananas, and bamboos also produce seeds, but tree ferns produce spores instead.
Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In much of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture. Because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, and they play a role in many of the world's mythologies. (Full article...)
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Did you know? - show different entries
- ... that the Paget Marsh Nature Reserve in Bermuda has been called the "best surviving example of native cedar, palmetto (pictured), and mangrove forests", yet at one point the island lost 99% of its cedar trees?
- ... that a canopy walkway connects seven tree tops in Ghana's Kakum National Park?
- ... that the ivory curl tree can grow 30 m (100 ft) tall in its natural rainforest habitat?
- ... that the trumpet tree, a fast-growing tree native to the American tropics, is considered one of the hundred worst invasive alien species in the world?
- ... that the installation of an artificial Christmas tree in Brussels prompted an online petition against it with 25,000 signatures?
- ... that a white oak tree with a trunk circumference of over 26 feet (7.9 m) grew near Wolf Run until it was cut down in 1852?
- ... that the blue nuthatch (pictured) protects its corneas from falling debris when prospecting on trees by contracting the bare skin around its eyes – an adaptation apparently unique to the species?
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General images
- Image 8Share of land that is covered by forest (from Forest)
- Image 11Diagram of secondary growth in a eudicot or coniferous tree showing idealised vertical and horizontal sections. A new layer of wood is added in each growing season, thickening the stem, existing branches and roots. (from Tree)
- Image 18People trees, by Pooktre (from Tree)
- Image 22Proportion of forest in protected areas, by region, 2020 (from Forest)
- Image 23Tall herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)
- Image 24Share of forest area in total land area, top countries (2021) (from Forest)
- Image 26Olive trees in Pakistan (from Trees of Pakistan)
- Image 27Since the 13th century, the Niepołomice Forest in Poland has had special use and protection. In this view from space, different coloration can indicate different functions. (from Forest)
- Image 35Roof trusses made from softwood (from Tree)
- Image 36Even, dense old-growth stand of beech trees (Fagus sylvatica) prepared to be regenerated by their saplings in the understory, in the Brussels part of the Sonian Forest. (from Forest)
- Image 394000 years old Cypress of Abarqu is the oldest tree in Iran and the second oldest tree in the world. (from List of trees of Iran)
- Image 41Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)
- Image 45The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world. (from Forest)
- Image 49World production of selected forest products (from Forest)
- Image 50Proportion and distribution of global forest area by climatic domain, 2020 (from Forest)
- Image 53Priest River winding through Whitetail Butte with lots of forestry to the east—these lot patterns have existed since the mid-19th century. The white patches reflect areas with younger, smaller trees, where winter snow cover shows up brightly to the astronauts. Dark green-brown squares are parcels (from Forest)
- Image 54Selling firewood at a market (from Tree)
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