What are the importance of rivers and trees?

Answer 1

rivers....for irrigation,hydel power,transportation
trees....for clean air,fruits,wood,logs,

Answer 2

Rivers: 1. Source of water for gardening, cooking, washing and drinking 2. water transports boat, steamer. 3. Source of food like fish. 4. washing away the dirt 5. Nature's gift which gets recycled and keeps the ecology. 6. A beauty of nature.
Trees: 1. Serves as environmental watchdogs.
2. Fruit bearing trees - food 3. Timber for use of wood articles household, industrial etc., 4. Serves as a shelter on a hot/rainy day. 5. A living place for many birds (which are essential part of nature) 6. A flowering and green tree is a beauty.
VR

Answer 3

Rivers provide drinking, bathing, and farming water. Trees provide shade, food (fruit), home to birds and animals, wood for humans, and tree roots stabilize the ground.

Answer 4

what?? is that supposed to be a joke? oohh well i'll tell you anyway rivers give us water and also run into the ocean and trees give us air!!

Answer 5

to produce and hold life for other living species.

Answer 6

A river is a large natural waterway. The source of a river may be a lake, a spring, or a collection of small streams, known as headwaters. From their source, all rivers flow downhill, typically terminating in the ocean. The mouth, or lower end, of a river is known as its base level.

A river's water is normally confined to a channel, made up of a stream bed between banks. Most rainfall on land passes through a river on its way to the ocean. Smaller side streams that join a river are tributaries. The scientific term for any flowing natural waterway is a stream; so in technical language, the term river is just a shorthand way to refer to a large stream.

Topography

A river flowing over a slight change in topography.
Bridges are a popular way of crossing rivers, as seen here at the Buller River, West Coast, New Zealand.A river conducts water by constantly flowing perpendicular to the elevation curve of its bed, thereby converting the potential energy of the water into kinetic energy. Where a river flows over relatively flat areas, the river will meander: start to form loops and snake through the plain by eroding the river banks. Sometimes the river will cut off a loop, shortening the channel and forming an oxbow lake from the cut off section. Rivers that carry large amounts of sediment develop conspicuous deltas at their mouths. Rivers whose mouths are in saline tidal waters may form estuaries.

Over time, rivers cut away at their beds, eventually forming a more gentle gradient.




Youthful river - a river with a steep gradient that has very few tributaries and flows quickly. Its channels erode deeper rather than wider.
Mature river - a river with a gradient that is less steep than those of youthful rivers and flows more slowly than youthful rivers. A mature river is fed by many tributaries and has more discharge than a youthful river. Its channels erode wider rather than deeper.
Old river - a river with a low gradient and low erosive energy. Old rivers are characterized by flood plains.
Rejuvenated river - a river with a gradient that is raised by the earth's movement.
Where a river descends quickly over sloped topography, rapids with whitewater or even waterfalls occur. Rapids are often used for recreational purposes (see Whitewater kayaking). Waterfalls are sometimes used as sources of energy, via watermills and hydroelectric plants.

Rivers begin at their source in higher ground, either rising from a spring, forming from glacial meltwater, flowing from a body of water such as a lake, or simply from damp, boggy places where the soil is waterlogged. They end at their base level where they flow into a larger body of water, the sea, a lake, or as a tributary to another (usually larger) river. In arid areas rivers sometimes end by losing water to evaporation and percolation into dry, porous material such as sand, soil, or pervious rock. The area drained by a river and its tributaries is called its watershed, catchment basin or drainage basin. (Watershed is also used however to mean a boundary between drainage basins.)

Starting at the mouth of the river and following it upstream as it branches again and again, the resulting river network forms a dendritic (tree-like) structure that is an example of a natural random fractal.

Geopolitical boundaries
Rivers have been important historically in determining political boundaries.

The Orange River discharges into the Atlantic ocean and forms the International boundary between various provinces and countries along its route. The source of the Orange River is in the Lesotho mountains. The Lesotho Highlands Water Project was conceived to divert water from Lesotho into the Vaal River system, itself a tributary of the Orange River, to supply the water needs of the Gauteng province in South Africa. Water from the Delivery tunnel is discharged into the Ash River. The spot has become a popular Kayaking venue.

The Danube was a long standing border of the Roman Empire, and today forms most of the border between Bulgaria and Romania.

The Mississippi in North America, and the Rhine in Europe, are major east-west boundaries in those continents.

[edit]
Rating systems
International Scale of River Difficulty - The scale is used to rate rivers -- particularly those with rapids -- for navigation. Class I is the easiest and Class VI is the hardest.
Strahler Stream Order - The Strahler Stream Order is a method to rank rivers based on the connectivity and hierarchy of contributing tributaries. Headwaters are first order while the Amazon River is approximated as twelfth order. Approximately 80 percent of the rivers and streams on Earth are of the first and second order. Although widely used in the United States to gauge river size, this method suffers from a lack of consistency when defining a first order stream, as ephemeral and perennial streams are undifferentiated.
[edit]
Biology
The flora and fauna of rivers are much different from those of the ocean because the water is fresh (non-salty). Living things in a river must be adapted to the current of the moving water. For a detailed look at these processes, see lotic system ecology.

[edit]
Water quality
Human pollution of rivers is common, and few rivers in the world are free of man-made substances. The most common point source of pollutant is probably sewage piped into rivers, but chemical pollution is also common, and industrial accidents (and/or negligence) account for significant destruction of riparian biomes. Heated water discharged into rivers by power plants and factories also affects river biota. Non-point source pollutants such as diffuse pollution from agriculture, urbanisation, logging, construction activity and slash-and-burn techniques are all recognised as sources of sediment and other pollutants.

Techniques have been developed to analyze dispersal of water pollutants in river systems. For example the U.S. Environmental Protection Agency funded research to develop the DSSAM Model to assess the transport of soluble nitrogen, reactive phosphorus, total dissolved solids and dissolved oxygen in the Truckee River, which flows through both California and Nevada.

[edit]
Dams
In places where the elevation changes of a river are great, dams for hydroelectric plants and other purposes are often built. This disrupts the natural flow of the river, and creates a lake behind the dam. Often the building of dams affects the whole of the river, even the part above the dam, as migrating fish are hindered (see fish ladder), waterflow is no longer bounded by seasonal changes and sediment flow is blocked. Dams are useful in many ways, such as: providing hydro-electric power; acting as regulator of river flow so as to regulate the occurrence of flooding, which is especially important to wet-rice agriculture; and also to improve navigation and transport on the river. Often, dams such as Hoover Dam along Colorado River become famous tourist attractions. Critics of dams, especially 'green' advocates, argue that dams remove upper-river biodiversity such as through deforestation and forced migration of rural villages and indigenous tribes. Furthermore, trapping of river sediments behind the dams lead to salination and loss of nutrients for down-water fish. It also raises concern of earthquakes due to instablity of incompetent dams which have to support thousands of tonnes of sediments behind them. One very famous and problematic dam is the Aswan High Dam in the Nile.

[edit]
Flooding
Flooding is a natural part of a river's cycles. Human activity, however, has upset the natural way flooding occurs by walling off rivers and straightening their courses. Removal of bogs, swamps and other wetlands in order to produce farmland has reduced the absorption zones for excess water and made floods into sudden disasters rather than gradual increases in water flow. In ancient Egypt, life was made possible through the floods of the Nile and the accompanying silt and sediment which enriched the fields with fresh nutrients. Nowadays, since people have built on these floodplains, floods are disasters, causing untold property loss each year.

Human interference in the form of deforestation can also worsen conditions. The removal of vegetation leads to a reduction in interception (vegetation stopping precipitation) and the 'weakening' of soil since plant roots no longer hold it together. As a result there is a reduced Infiltration capacity (how much water the soil can hold) and greater infiltration (precipitation going into the ground). This leads to faster soil saturation and therefore greater overland flow (also known as surface runoff) and therefore, there are flash floods as the lag time decrease



Classification


An oak tree in DenmarkA tree is a plant form and trees occur in many different orders and families of plants. Trees thus show a wide variety of growth form, leaf type and shape, bark characteristics, reproductive structures, etc.

The earliest trees were tree ferns and horsetails, which grew in vast forests in the Carboniferous Period; tree ferns still survive, but the only surviving horsetails are not of tree form. Later, in the Triassic Period, conifers, ginkgos, cycads and other gymnosperms appeared, and subsequently flowering plants in the Cretaceous Period. Most species of trees today are flowering plants and conifers. The listing below gives examples of many well-known trees and how they are typically classified.

A small group of trees growing together is called a grove or copse, and a landscape covered by a dense growth of trees is called a forest. Several biotopes are defined largely by the trees that inhabit them; examples are rainforest and taiga (see ecozones). A landscape of trees scattered or spaced across grassland (usually grazed or burned over periodically) is called a savanna.

[edit]
Morphology

Leaves are an important feature of trees
Tree roots anchor the structure and provide water and nutrientsThe basic parts of a tree are the roots, trunk(s), branches, twigs and leaves. Tree stems consist mainly of support and transport tissues (xylem and phloem). Wood consists of xylem cells, and bark is made of phloem and other tissues external to the vascular cambium.

Trees may be broadly grouped into exogenous and endogenous trees according to the way in which their stem diameter increases. Exogenous trees, which comprise the great majority of modern trees (all conifers, and all broadleaf trees), grow by the addition of new wood outwards, immediately under the bark. Endogenous trees, mainly in the monocotyledons (e.g. palms), grow by addition of new material inwards.

As an exogenous tree grows, it creates growth rings. In temperate climates, these are commonly visible due to changes in the rate of growth with temperature variation over an annual cycle. These rings can be counted to determine the age of the tree, and used to date cores or even wood taken from trees in the past; this practice is known as the science of dendrochronology. In some tropical regions with constant year-round climate, growth is continuous and distinct rings are not formed, so age determination is impossible. Age determination is also impossible in endogenous trees.

The roots of a tree are generally embedded in earth, providing anchorage for the above-ground biomass and absorbing water and nutrients from the soil. It should be noted, however, that while ground nutrients are essential to a tree's growth the majority of its biomass comes from carbondioxide absorbed from the atmosphere (see photosynthesis). Above ground, the trunk gives height to the leaf-bearing branches, aiding in competition with other plant species for sunlight. In many trees, the arrangement of the branches optimizes exposure of the leaves to sunlight.

Not all trees have all the plant organs or parts mentioned above. For example, most palm trees are not branched, the saguaro cactus of North America has no functional leaves, tree ferns do not produce bark, etc. Based on their general shape and size, all of these are nonetheless generally regarded as trees. Indeed, sometimes size is the more important consideration. A plant form that is similar to a tree, but generally having smaller, multiple trunks and/or branches that arise near the ground, is called a shrub. However, no sharp differentiation between shrubs and trees is possible. Given their small size, bonsai plants would not technically be 'trees', but one should not confuse reference to the form of a species with the size or shape of individual specimens. A spruce seedling does not fit the definition of a tree, but all spruces are trees. Bamboos by contrast, do show most of the characteristics of trees, yet are rarely called trees.

[edit]
Champion trees
The world's champion trees can be considered on several factors; height, trunk diameter or girth, total size, and age. It is significant that in each case, the top position is always held by a conifer, though a different species in each case; in most measures, the second to fourth places are also held by conifers.

Tallest trees
The heights of the tallest trees in the world have been the subject of considerable dispute and much (often wild) exaggeration. Modern verified measurement with laser rangefinders combined with tape drop measurements made by tree climbers, carried out by the U.S. Eastern Native Tree Society has shown that most older measuring methods and measurements are unreliable, often producing exaggerations of 5% to 15% above the real height. Historical claims of trees of 114 m, 117 m, 130 m, and even 150 m, are now largely disregarded as unreliable, fantasy or outright fraud. The following are now accepted as the top five tallest reliably measured species:

Coast Redwood Sequoia sempervirens: 112.83 m, Humboldt Redwoods State Park, California (Gymnosperm Database)
Coast Douglas-fir Pseudotsuga menziesii: 100.3 m, Brummit Creek, Coos County, Oregon (Gymnosperm Database)
Sitka Spruce Picea sitchensis: 96.7 m, Prairie Creek Redwoods State Park, California (Gymnosperm Database)
Giant Sequoia Sequoiadendron giganteum: 93.6 m, Redwood Mountain Grove, California (Gymnosperm Database)
Australian Mountain-ash Eucalyptus regnans: 92.0 m, Styx Valley, Tasmania (Forestry Tasmania [pdf file])

A view of a tree from below; this may exaggerate apparent heightStoutest trees
The girth (circumference) of a tree is – or at least should be – much easier to measure than the height, as it is a simple matter of stretching a tape round the trunk, and pulling it taut to find the circumference. Despite this, U.K. tree author Alan Mitchell made the following comment about measurements of yew trees in the British Isles:

"The aberrations of past measurements of yews are beyond belief. For example, the tree at Tisbury has a well-defined, clean, if irregular bole at least 1.5 m long. It has been found to have a girth which has dilated and shrunk in the following way: 11.28 m (1834 Loudon), 9.3 m (1892 Lowe), 10.67 m (1903 Elwes and Henry), 9.0 m (1924 E. Swanton), 9.45 m (1959 Mitchell) .... Earlier measurements have therefore been omitted".
As a general standard, tree girth is taken at 'breast height'; this is defined differently in different situations, with most foresters measuring girth at 1.3 m above ground, while ornamental tree measurers usually measure at 1.5 m above ground; in most cases this makes little difference to the measured girth. On sloping ground, the "above ground" reference point is usually taken as the highest point on the ground touching the trunk, but some use the average between the highest and lowest points of ground. Some of the inflated old measurements may have been taken at ground level. Some past exaggerated measurements also result from measuring the complete next-to-bark measurement, pushing the tape in and out over every crevice and buttress.

Modern trends are to cite the tree's diameter rather than the circumference; this is obtained by dividing the measured circumference by π; it assumes the trunk is circular in cross-section (an oval or irregular cross-section would result in a mean diameter slightly greater than the assumed circle). This is cited as dbh (diameter at breast height) in tree literature.

A further problem with measuring baobabs Adansonia is that these trees store large amounts of water in the very soft wood in their trunks. This leads to marked variation in their girth over the year, swelling to a maximum at the end of the rainy season, minimum at the end of the dry season. Although baobabs have some of the highest girth measurements of any trees, no accurate measurements are currently available, but probably do not exceed 10-11 m diameter.

The stoutest species in diameter, excluding baobabs, are:

Montezuma Cypress Taxodium mucronatum: 11.42 m, Árbol del Tule, Santa Maria del Tule, Oaxaca, Mexico (A. F. Mitchell, International Dendrology Society Year Book 1983: 93, 1984).
Giant Sequoia Sequoiadendron giganteum: 8.85 m, General Grant tree, Grant Grove, California (Gymnosperm Database)
Coast Redwood Sequoia sempervirens: 7.44 m, Prairie Creek Redwoods State Park, California (Gymnosperm Database)
Largest trees
The largest trees in total volume are those which are both tall and of large diameter, and in particular, which hold a large diameter high up the trunk. Measurement is very complex, particularly if branch volume is to be included as well as the trunk volume, so measurements have only been made for a small number of trees, and generally only for the trunk. No attempt has ever been made to include root volume.

The top four species measured so far are (Gymnosperm Database):

Giant Sequoia Sequoiadendron giganteum: 1489 m³, General Sherman
Coast Redwood Sequoia sempervirens: 1045 m³, Del Norte Titan tree
Western Redcedar Thuja plicata: 500 m³, Quinault Lake Redcedar
Kauri Agathis australis: 400 m³, Tane Mahuta tree (total volume, including branches, 516.7 m³)
However, the Alerce Fitzroya cupressoides, as yet un-measured, may well slot in at third or fourth place, and Montezuma Cypress Taxodium mucronatum is also likely to be high in the list. The largest angiosperm tree is an Australian Mountain-ash, the 'El Grande' tree of about 380 m³ in Tasmania.

Oldest trees
The oldest trees are determined by growth rings, which can be seen if the tree is cut down or in cores taken from the edge to the centre of the tree. Accurate determination is only possible for trees which produce growth rings, generally those which occur in seasonal climates; trees in uniform non-seasonal tropical climates grow continuously and do not have distinct growth rings. It is also only possible for trees which are solid to the centre of the tree; many very old trees become hollow as the dead heartwood decays away. For some of these species, age estimates have been made on the basis of extrapolating current growth rates, but the results are usually little better than guesswork or wild speculation.

The verified oldest measured ages are (Gymnosperm Database):

Great Basin Bristlecone Pine Pinus longaeva: 4844 years
Alerce Fitzroya cupressoides: 3622 years
Giant Sequoia Sequoiadendron giganteum: 3266 years
Huon-pine Lagarostrobos franklinii: 2500 years
Rocky Mountains Bristlecone Pine Pinus aristata: 2435 years
Other species suspected of reaching exceptional age include European Yew Taxus baccata (probably over 3000 years) and Western Redcedar Thuja plicata.

The oldest verified age for an angiosperm tree is 2293 years for the Sri Maha Bodhi Sacred Fig (Ficus religiosa) planted in 288 BC at Anuradhapura, Sri Lanka; this is also the oldest human-planted tree with a known planting date.

[edit]
Major tree genera
[edit]
Flowering plants (Magnoliophyta; angiosperms)
[edit]
Dicotyledons (Magnoliopsida; broadleaf or hardwood trees)
Altingiaceae (Sweetgum family)
Sweetgum, Liquidambar species
Anacardiaceae (Cashew family)
Cashew, Anacardium occidentale
Mango, Mangifera indica
Pistachio, Pistacia vera
Sumac, Rhus species
Lacquer tree, Toxicodendron verniciflua
Annonaceae (Custard apple family)
Cherimoya Annona cherimola
Custard apple Annona reticulata
Pawpaw Asimina triloba
Soursop Annona muricata
Apocynaceae (Dogbane family)
Pachypodium Pachypodium species
Aquifoliaceae (Holly family)
Holly, Ilex species
Araliaceae (Ivy family)
Kalopanax, Kalopanax pictus
Birch tree (foreground) and maple tree (background) in fall.Betulaceae (Birch family)
Alder, Alnus species
Birch, Betula species
Hornbeam, Carpinus species
Hazel, Corylus species
Bignoniaceae (family)
Catalpa, Catalpa species
Cactaceae (Cactus family)
Saguaro, Carnegiea gigantea
Cannabaceae (Cannabis family)
Hackberry, Celtis species
Cornaceae (Dogwood family)
Dogwood, Cornus species
Dipterocarpaceae family
Garjan Dipterocarpus species
Sal Shorea species
Ericaceae (Heath family)
Arbutus, Arbutus species
Eucommiaceae (Eucommia family)
Eucommia Eucommia ulmoides
Fabaceae (Pea family)
Acacia, Acacia species
Honey locust, Gleditsia triacanthos
Black locust, Robinia pseudoacacia
Laburnum, Laburnum species
Pau Brasil, Brazilwood, Caesalpinia echinata
Fagaceae (Beech family )
Chestnut, Castanea species
Beech, Fagus species
Southern beech, Nothofagus species
Tanoak, Lithocarpus densiflorus
Oak, Quercus species
Fouquieriaceae (Boojum family)
Boojum, Fouquieria columnaris
Hamamelidaceae (Witch-hazel family)
Persian Ironwood, Parrotia persica
Juglandaceae (Walnut family)
Walnut, Juglans species
Hickory, Carya species
Wingnut, Pterocarya species
Lauraceae (Laurel family)
Cinnamon Cinnamomum zeylanicum
Bay Laurel Laurus nobilis
Avocado Persea americana
Lecythidaceae (Paradise nut family)
Brazil Nut Bertholletia excelsa
Lythraceae Loosestrife family
Crape-myrtle Lagerstroemia species
Magnoliaceae (Magnolia family)
Tulip tree, Liriodendron species
Magnolia, Magnolia species
Malvaceae (Mallow family; including Tiliaceae and Bombacaceae)
Baobab tree in South-Africa.Baobab, Adansonia species
Silk-cotton tree, Bombax species
Bottletrees, Brachychiton species
Kapok, Ceiba pentandra
Durian, Durio zibethinus
Balsa, Ochroma lagopus
Cacao (cocoa), Theobroma cacao
Linden (Basswood, Lime), Tilia species
Meliaceae (Mahogany family)
Neem, Azadirachta indica
Bead tree, Melia azedarach
Mahogany, Swietenia mahagoni
Moraceae (Mulberry family)
Eucalyptus bridgesiana on Red Hill, Australian Capital Territory.Fig, Ficus species
Mulberry, Morus species
Myristicaceae (Nutmeg family)
Nutmeg, Mysristica fragrans
Myrtaceae (Myrtle family)
Eucalyptus, Eucalyptus species
Myrtle, Myrtus species
Guava, Psidium guajava
Nyssaceae: a Dove tree in flowerNyssaceae (Tupelo family; sometimes included in Cornaceae)
Tupelo, Nyssa species
Dove tree, Davidia involucrata
Oleaceae (Olive family)
Olive, Olea europaea
Ash, Fraxinus species
Paulowniaceae (Paulownia family)
Foxglove Tree, Paulownia species
Platanaceae (Plane family)
Plane, Platanus species
Rhizophoraceae (Mangrove family)
Red Mangrove, Rhizophora mangle
Rosaceae (Rose family)
Rowans, Whitebeams, Service Trees Sorbus species
Hawthorn, Crataegus species
Pear, Pyrus species
Apple, Malus species
Almond, Prunus dulcis
Peach, Prunus persica
Plum, Prunus domestica
Cherry, Prunus species
Rubiaceae (Bedstraw family)
Coffee, Coffea species
Rutaceae (Rue family)
Citrus, Citrus species
Cork-tree, Phellodendron species
Euodia, Tetradium species
Salicaceae (Willow family)
Aspen, Populus species
Poplar, Populus species
Willow, Salix species

Yellow maple in fall.Sapindaceae (including Aceraceae, Hippocastanaceae) (Soapberry family)
Maple, Acer species
Buckeye, Horse-chestnut, Aesculus species
Mexican Buckeye, Ungnadia speciosa
Lychee, Litchi sinensis
Golden rain tree, Koelreuteria
Sapotaceae (Sapodilla family)
Argan, Argania spinosa
Gutta-percha, Palaquium species
Tambalacoque, or "dodo tree", Sideroxylon grandiflorum, previously Calvaria major
Simaroubaceae family
Tree of heaven, Ailanthus species
Theaceae (Camellia family)
Gordonia, Gordonia species
Stuartia, Stuartia species
Thymelaeaceae (Thymelaea family)
Ramin, Gonystylus species
Ulmaceae (Elm family)
Elm, Ulmus species
Zelkova, Zelkova species
Verbenaceae family
Teak, Tectona species
[edit]
Monocotyledons (Liliopsida)

Coconut Palm, a monocotyledonous tree.Agavaceae (Agave family)
Cabbage tree, Cordyline australis
Dragon tree, Dracaena draco
Joshua tree, Yucca brevifolia
Arecaceae (Palmae) (Palm family)
Areca Nut, Areca catechu
Coconut Cocos nucifera
Date Palm, Phoenix dactylifera
Chusan Palm, Trachycarpus fortunei
Poaceae (grass family)
Bamboos Poaceae subfamily Bambusoideae
Note that banana 'trees' are not actually trees; they are not woody nor is the stalk perennial.
[edit]
Conifers (Pinophyta; softwood trees)
Araucariaceae (Araucaria family)
Araucaria, Araucaria species
Kauri, Agathis species
Wollemia, Wollemia nobilis
Cupressaceae (Cypress family)
Cypress, Cupressus species
Cypress, Chamaecyparis species
Juniper, Juniperus species
Alerce or Patagonian cypress, Fitzroya cupressoides
Sugi, Cryptomeria japonica
Coast Redwood, Sequoia sempervirens
Giant Sequoia, Sequoiadendron giganteum
Dawn Redwood, Metasequoia glyptostroboides
Western Redcedar Thuja plicata
Bald Cypress, Taxodium species
Pinaceae (Pine family)
White pine, Pinus species
Pinyon pine, Pinus species
Pine, Pinus species
Spruce, Picea species
Larch, Larix species
Douglas-fir, Pseudotsuga species
Fir, Abies species
Cedar, Cedrus species
Podocarpaceae (Yellowwood family)
African Yellowwood, Afrocarpus falcatus
Totara, Podocarpus totara
Miro, Prumnopitys ferruginea
Kahikatea, Dacrycarpus dacrydioides
Rimu, Dacrydium cupressinum
Sciadopityaceae,
Kusamaki, Sciadopitys species
Taxaceae (Yew family)
Yew, Taxus species
[edit]
Ginkgos (Ginkgophyta)
Ginkgoaceae (Ginkgo family)
Ginkgo, Ginkgo biloba
[edit]
Cycads (Cycadophyta)
Cycadaceae family
Ngathu cycad, Cycas angulata
Zamiaceae family
Wunu cycad, Lepidozamia hopei
[edit]
Ferns (Pterophyta)
Cyatheaceae and Dicksoniaceae families
Tree ferns, Cyathea, Alsophila, Dicksonia (not a monophyletic group)
[edit]
Life stages

A moss-covered tree.The life cycles of trees, especially conifers, are divided into the following stages in forestry for survey and documentation purposes, though the boundaries between stages vary among foresters:

Seed
Seedling: the above-ground part of the embryo that sprouts from the seed
Sapling: After the seedling reaches 1 m tall, and until it reaches 7 cm in stem diameter
Pole: young trees from 7–30 cm diameter
Mature tree: over 30 cm diameter, reproductive years begin
Old tree: dominate old growth forest; height growth slows greatly, with majority of productivity in seed production
Overmature: dieback and decay become common
Snag: standing dead wood
Log/debris: fallen dead wood
Tree diameters are measured at height of between 1.3–1.5 m above the highest point on the ground at its base (known as "breast height"). The 7 cm diameter definition is economically based, from the smallest saleable stem size (for paper production, etc), and the 30 cm diameter is the smallest base diameter for sawlogs. Each stage may be uniquely perceptive to different pathogens and suitable for especially adapted arboreal animals.

[edit]
See also
Wikimedia Commons has media related to:
TreesLook up tree in Wiktionary, the free dictionary.Arboretum
Pinetum
Arboriculture (the care of trees)
Bonsai
Christmas tree
Dendrology (the study of trees)
Dendrochronology
Dendroclimatology
Ecology
Tree-line
Forestry
Deforestation
Plantation
Urban forestry
Woodland management
Fruit trees
List of famous trees
List of garden plants
Plants
Prehistoric plants
Tree climbing
Trees in mythology
Trees of the world
Trees of Britain and Ireland
Trees of Canada
List of U.S. state trees
Trees of The Caribbean Basin
Trees of Iran
List of trees of New Zealand
Wood
List of woods
Xiloteque