Portal:Trees

The Trees Portal

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 trees reaching several thousand years old. Trees evolved around 400 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. Flowering plants have their seeds inside fruits, while conifers carry their seeds in cones, and 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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The United Kingdom, being in the British Isles, is ideal for tree growth, thanks to its mild winters, plentiful rainfall, fertile soil and hill-sheltered topography. In the absence of people, much of Great Britain would be covered with mature oaks as well as savannah-type of plains, except for Scotland. Although conditions for forestry are good, trees face threats from fungi, parasites and pests. Nowadays, about 13% of Britain's land surface is wooded. European countries average 39%, but this varies widely from 1% (Malta) to 66% (Finland). As of 2021, government plans call for 30,000 hectares to be reforested each year.^{[needs update]} Efforts to reach these targets have attracted criticism for planting non-native trees, or trees that are out of place for their surroundings, leading to ecological changes.

The UK's supply of timber was depleted during the First and Second World Wars, when imports were difficult, and the forested area bottomed out at under 5% of Britain's land surface in 1919. That year, the Forestry Commission was established to produce a strategic reserve of timber. (Full article...)

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... that the Easter egg tree (pictured) in Saalfeld, Thuringia, was decorated with 10,000 Easter eggs in 2012?
... that the most popular species for Christmas trees in Denmark and most of Europe is the Caucasian fir?
... that seed of the African teak tree is largely dispersed by fruit bats?
... that Trichia decipiens live on deadwood of conifers and leaf trees all year around?
... that Aecidium mori causes mulberry rust disease on the mulberry flowering plant, which decreases the quantity of leaves on the trees?
... that the satinleaf tree is endangered in its native Florida, but an invasive weed in Hawaii?
... that the Brown Treecreeper spirals up and down tree trunks while foraging?

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The tree line is the edge of a habitat at which trees are capable of growing and beyond which they are not. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually low temperatures, extreme snowpack, or associated lack of available moisture). The tree line is sometimes distinguished from a lower timberline, which is the line below which trees form a forest with a closed canopy.

At the tree line, tree growth is often sparse, stunted, and deformed by wind and cold. This is sometimes known as krummholz (German for "crooked wood"). (Full article...)

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General images

The following are images from various tree-related articles on Wikipedia.

Image 1Tall herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)
Image 2Yellow cassia, an ornamental tree with yellow flowers (from Tree)
Image 3Cracked thorny skin of a Aesculus tree seed (from Tree)
Image 4A section of yew (Taxus baccata) showing 27 annual growth rings, pale sapwood and dark heartwood (from Tree)
Image 5Recently stripped cork oak (Quercus suber) (from Tree)
Image 6World production of selected forest products (from Forest)
Image 7European larch (Larix decidua), a coniferous tree which is also deciduous (from Tree)
Image 8Broadleaf forest in Bhutan (from Forest)
Image 9Since 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 10Share of forest area in total land area, top countries (2021) (from Forest)
Image 11The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world. (from Forest)
Image 12A young red pine (Pinus resinosa) with spread of roots visible, as a result of soil erosion (from Tree)
Image 13Latvian Pine Forest in Ķegums Municipality (from Forest)
Image 14Casentinesi Forests, Italy (from Forest)
Image 15Selling firewood at a market (from Tree)
Image 16Form, leaves and reproductive structures of queen sago, Cycas circinalis (from Tree)
Image 17Dormant buds of ash, Fraxinus excelsior (from Tree)
Image 18The General Sherman Tree, thought to be the world's largest by volume (from Tree)
Image 19Northern beech (Fagus sylvatica) trunk in autumn (from Tree)
Image 20Share of land that is covered by forest (from Forest)
Image 21Lepidodendron, an extinct lycophyte tree (from Tree)
Image 22Trees in art: Weeping Willow, Claude Monet, 1918 (from Tree)
Image 23Common ash (Fraxinus excelsior), a deciduous broad-leaved (angiosperm) tree (from Tree)
Image 24A forest near Vinitsa, North Macedonia (from Forest)
Image 25Redwood tree in northern California redwood forest, where many redwood trees are managed for preservation and longevity, rather than being harvested for wood production (from Forest)
Image 26Even, 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 27Buds, leaves, flowers and fruit of pedunculate oak, Quercus robur (from Tree)
Image 28Roof trusses made from softwood (from Tree)
Image 294000 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 30Proportion of forest in protected areas, by region, 2020 (from Forest)
Image 31Alnus glutinosa (from List of trees of Great Britain and Ireland)
Image 32Sugar maple (Acer saccharum) tapped to collect sap for maple syrup (from Tree)
Image 33Proportion and distribution of global forest area by climatic domain, 2020 (from Forest)
Image 34Buttress roots of the kapok tree (Ceiba pentandra) (from Tree)
Image 35An avenue of London planes (Platanus × hispanica) in a garden in Belgium. (from Tree)
Image 36Latex collecting from a rubber tree (Hevea brasiliensis) (from Tree)
Image 37Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)
Image 38Conifers in the Swabian alps (from Tree)
Image 39Wind dispersed seed of elm (Ulmus), ash (Fraxinus) and maple (Acer) (from Tree)
Image 40Informal upright style of bonsai on a juniper tree (from Tree)
Image 41Palms and cycads as they might have appeared in the middle Tertiary (from Tree)
Image 42Temperate rainforest in Tasmania's Hellyer Gorge (from Forest)
Image 43Buds, leaves and reproductive structures of white fir, Abies alba (from Tree)
Image 44The Daintree Rainforest (from Tree)
Image 45Neem tree at Sant Nenuram Ashram (from Trees of Pakistan)
Image 46Priest 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 47People trees, by Pooktre (from Tree)
Image 48Fraxinus excelsior (from List of trees of Great Britain and Ireland)
Image 49Forest in the Scottish Highlands (from Forest)
Image 50Burned forest on Thasos (from Forest)
Image 51Malus sylvestris (from List of trees of Great Britain and Ireland)
Image 52Olive trees in Pakistan (from Trees of Pakistan)
Image 53Garibaldi Provincial Park, British Columbia (from Forest)
Image 54Rowan tree in Wicklow, Ireland (from List of trees of Great Britain and Ireland)
Image 55Diagram 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 56Yggdrasil, the World Ash of Norse mythology (from Tree)