1.
Tree
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In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. 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. Trees are not a group but include a variety of plant species that have independently evolved a woody trunk. In looser senses, the palms, the tree ferns, bananas. Trees tend to be long-lived, some reaching several thousand years old, the tallest known tree, a coast redwood named Hyperion, stands 115.6 m high. Trees have been in existence for 370 million years and it is estimated that there are just over 3 trillion mature trees in the world. A tree typically has many secondary branches supported clear of the ground by the trunk and this trunk typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees it 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 divide into smaller branches and shoots. The shoots typically bear leaves, which light energy and convert it into sugars by photosynthesis, providing the food for the trees growth. Flowers and fruit may also be present, but some trees, such as conifers, instead have pollen cones and seed cones, others, such as tree ferns, 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 one of 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 parts of the world, forests are shrinking as trees are cleared to increase the amount of available for agriculture. Because of their longevity and usefulness, trees have always revered, with sacred groves in various cultures. Although tree is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the form of an elongated stem, or trunk. Trees are also defined by height, with smaller plants from 0.5 to 10 m being called shrubs
2.
Forest
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A forest is a large area dominated by trees. Hundreds of more precise definitions of forest are used throughout the world, incorporating factors such as density, tree height, land use, legal standing. According to the widely used Food and Agriculture Organization definition, forests covered four billion hectares or approximately 30 percent of the land area in 2006. Forests are the dominant terrestrial ecosystem of Earth, and are distributed across the globe, Forests account for 75% of the gross primary productivity of the Earths biosphere, and contain 80% of the Earths plant biomass. Forests at different latitudes and elevations form distinctly different ecozones, boreal forests near the poles, tropical forests near the equator, higher elevation areas tend to support forests similar to those at higher latitudes, and amount of precipitation also affects forest composition. Human society and forests influence each other in both positive and negative ways, Forests provide ecosystem services to humans and serve as tourist attractions. Forests can also affect peoples health, human activities, including harvesting forest resources, can negatively affect forest ecosystems. Although forest is a term of common parlance, there is no universally recognised precise definition, there are three broad categories of forest definitions in use, administrative, land use, and land cover. Land use definitions are based upon the purpose that the land serves. For example, a forest may be defined as any land that is used primarily for production of timber, land cover definitions define forests based upon the type and density of vegetation growing on the land. Such definitions typically define a forest as an area growing trees above some threshold and these thresholds are typically the number of trees per area, the area of ground under the tree canopy or the section of land that is occupied by the cross-section of tree trunks. Under such land cover definitions, and area of land only be defined as forest if it is growing trees, areas that fail to meet the land cover definition may be still included under while immature trees are establishing if they are expected to meet the definition at maturity. Under land use definitions, there is variation on where the cutoff points are between a forest, woodland, and savanna. Under some definitions, forests require high levels of tree canopy cover, from 60% to 100%, excluding savannas. Other definitions consider savannas to be a type of forest, the term was not endemic to Romance languages, and cognates in Romance languages, such as Italian foresta, Spanish and Portuguese floresta, etc. are all ultimately borrowings of the French word. The exact origin of Medieval Latin foresta is obscure, uses of the word forest in English to denote any uninhabited area of non-enclosure are now considered archaic. The word was introduced by the Norman rulers of England as a term denoting an uncultivated area legally set aside for hunting by feudal nobility. These hunting forests were not necessarily wooded much, if at all, however, as hunting forests did often include considerable areas of woodland, the word forest eventually came to mean wooded land more generally
3.
Wetland
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A wetland is a land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem. The primary factor that distinguishes wetlands from other forms or water bodies is the characteristic vegetation of aquatic plants. Wetlands play a number of roles in the environment, principally water purification, flood control, carbon sink, Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life. Wetlands occur naturally on every continent except Antarctica, the largest including the Amazon River basin, the West Siberian Plain, the water found in wetlands can be freshwater, brackish, or saltwater. The main wetland types include swamps, marshes, bogs, and fens, and sub-types include mangrove, carr, pocosin, the UN Millennium Ecosystem Assessment determined that environmental degradation is more prominent within wetland systems than any other ecosystem on Earth. International conservation efforts are being used in conjunction with the development of rapid assessment tools to people about wetland issues. Constructed wetlands can be used to treat municipal and industrial wastewater as well as stormwater runoff and they may also play a role in water-sensitive urban design. A patch of land that develops pools of water after a storm would not be considered a wetland. Wetlands have unique characteristics, they are distinguished from other water bodies or landforms based on their water level. Specifically, wetlands are characterized as having a table that stands at or near the land surface for a long enough period each year to support aquatic plants. A more concise definition is a community composed of hydric soil, Wetlands have also been described as ecotones, providing a transition between dry land and water bodies. In environmental decision-making, there are subsets of definitions that are agreed upon to make regulatory and policy decisions. A wetland is an ecosystem that arises when inundation by water produces soils dominated by anaerobic processes, There are four main kinds of wetlands – marsh, swamp, bog and fen. Some experts also recognize wet meadows and aquatic ecosystems as additional wetland types, the largest wetlands in the world include the swamp forests of the Amazon and the peatlands of Siberia. Under the Ramsar international wetland conservation treaty, wetlands are defined as follows, Article 2.1, may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six metres at low tide lying within the wetlands. Although the general definition given above applies around the world, each county, Wetlands generally include swamps, marshes, bogs and similar areas. This definition has been used in the enforcement of the Clean Water Act, some US states, such as Massachusetts and New York, have separate definitions that may differ from the federal governments. It is not uncommon for a wetland to be dry for long portions of the growing season, the most important factor producing wetlands is flooding
4.
Snag (ecology)
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In forest ecology, a snag refers to a standing, dead or dying tree, often missing a top or most of the smaller branches. In freshwater ecology it refers to trees, branches, and other pieces of naturally occurring wood found sunken in rivers and streams, when used in manufacturing, especially in Scandinavia, they are often called dead wood and in Finland kelo wood. Snags are an important structural component in forest communities, making up 10-20% of all present in old-growth tropical, temperate. Snags and downed woody debris represent a large portion of the woody biomass in a healthy forest. In temperate forests, snags provide critical habitat for more than 100 species of bird and mammal, dead, decaying wood supports a rich community of decomposers like bacteria and fungi, insects, and other invertebrates. Snags are optimal habitat for primary cavity nesters such as woodpeckers which create the majority of cavities used by secondary cavity users in forest ecosystems, woodpeckers excavate cavities for more than 80 other species and the health of their populations relies on snags. Most snag-dependent birds and mammals are insectivorous and represent a portion of the insectivorous forest fauna. There are many instances in which birds reduced outbreak populations of forest insects, such as woodpeckers affecting outbreaks of southern hardwood borers, snag creation occurs naturally as trees die due to old age, disease, drought, or wildfire. A snag undergoes a series of changes from the time the tree dies until final collapse, snag persistence depends on two factors, the size of the stem, and the durability of the wood of the species concerned. Snag Forests, or Complex Early Seral Forests, are ecosystems that occupy potentially forested sites after a stand-replacement disturbance, water hunting birds like the osprey or kingfishers can be found near water, perched in a snag tree, or feeding upon their fish catch. Snags are important as sites for biofilm growth and for shelter, in Australia, the role of freshwater snags has been largely ignored until recently, and more than one million snags have been removed from the Murray-Darling basin. Large tracts of the reaches of the Murray-Darling system are now devoid of the snags that native fish like Murray cod require for shelter. The damage such wholesale snag removal has caused is clearly enormous, most snags in these systems are river red gum snags. As the dense wood of river red gum is almost impervious to rot it is thought some of the river red gum snags removed in past decades may have been several thousand years old. Also known as deadheads, partially submerged snags posed hazards to early riverboat navigation, if hit, snags punctured the wooden hulls used in the 19th century and early 20th century. Snags were, in fact, the most commonly encountered hazard, in the United States, the U. S. Army Corps of Engineers operated snag boats such as the W. T. Preston in the Puget Sound of Washington State and the Montgomery in the rivers of Alabama to pull out, starting in 1824, there were successful efforts to remove snags from the Mississippi and its tributaries. Commercial enterprises market them abroad as dead wood or in Finland as kelo wood and they have been especially prized for their silver-grey weathered surface in the manufacture of vernacular or national romantic products
5.
Biogeochemical cycle
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In Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical substance moves through both the biotic and abiotic components of Earth. A cycle is a series of change which comes back to the starting point, water, for example, is always recycled through the water cycle, as shown in the diagram. The water undergoes evaporation, condensation, and precipitation, falling back to Earth, elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another through biogeochemical cycles. The term biogeochemical tells us that biological, geological and chemical factors are all involved, the circulation of chemical nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, and water etc. through the biological and physical world are known as biogeochemical cycles. In effect, the element is recycled, although in some there may be places where the element is accumulated or held for a long period of time. These newly studied biogeochemical cycles include the cycle, and the human-caused cycle of atrazine. Biogeochemical cycles always involve hot equilibrium states, a balance in the cycling of the element between compartments, however, overall balance may involve compartments distributed on a global scale. As biogeochemical cycles describe the movements of substances on the entire globe, the carbon cycle may be related to research in ecology and atmospheric sciences. Biochemical dynamics would also be related to the fields of geology and pedology, global biogeochemical cycles critical for life
6.
Habitat
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A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant, or other type of organism. The term typically refers to the zone in which the organism lives and it is the natural environment in which an organism lives, or the physical environment that surrounds a species population. Every organism has certain habitat needs for the conditions in which it will thrive, habitat types include polar, temperate, subtropical and tropical. The terrestrial vegetation type may be forest, steppe, grassland, the word habitat has been in use since about 1755 and derives from the Latin third-person singular present indicative of habitāre, to inhabit, from habēre, to have or to hold. Habitat can be defined as the environment of an organism. It is similar in meaning to a biotope, an area of environmental conditions associated with a particular community of plants. Generally speaking, animal communities are reliant on specific types of plant communities, some plants and animals are generalists, and their habitat requirements are met in a wide range of locations. The small white butterfly for example is found on all the continents of the world apart from Antarctica and its larvae feed on a wide range of Brassicas and various other plant species, and it thrives in any open location with diverse plant associations. Disturbance is important in the creation of biodiverse habitats, in the absence of disturbance, a climax vegetation cover develops that prevents the establishment of other species. Lightning strikes and toppled trees in tropical forests allow species richness to be maintained as pioneering species move in to fill the gaps created. Similarly coastal habitats can become dominated by kelp until the seabed is disturbed by a storm, another cause of disturbance is when an area may be overwhelmed by an invasive introduced species which is not kept under control by natural enemies in its new habitat. Terrestrial habitat types include forests, grasslands, wetlands and deserts, within these broad biomes are more specific habitats with varying climate types, temperature regimes, soils, altitudes and vegetation types. Many of these habitats grade into each other and each one has its own communities of plants. A habitat may suit a particular species well, but its presence or absence at any particular location depends to some extent on chance, on its dispersal abilities, freshwater habitats include rivers, streams, lakes, ponds, marshes and bogs. Although some organisms are found across most of these habitats, the majority have more specific requirements, similarly, aquatic plants can be floating, semi-submerged, submerged or grow in permanently or temporarily saturated soils besides bodies of water. Marine habitats include brackish water, estuaries, bays, the sea, the intertidal zone. Further variations include rock pools, sand banks, mudflats, brackish lagoons, sandy and pebbly beaches, the benthic zone or seabed provides a home for both static organisms, anchored to the substrate, and for a large range of organisms crawling on or burrowing into the surface. A desert is not the kind of habitat that favours the presence of amphibians, with their requirement for water to keep their skins moist, nevertheless, some frogs live in deserts, creating moist habitats underground and hibernating while conditions are adverse
7.
River delta
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A river delta is a landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or standing water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, River deltas are ecologically important as they provide coastline defense, are home to many species, and can impact drinking water supply. The tidal currents also cannot be too strong, as sediment would wash out into the body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time, the rivers velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta, when the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, as a result, sediment drops out of the flow and deposits. Over time, this single channel builds a deltaic lobe, pushing its mouth into the standing water, as the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation. As the slope of the channel decreases, it becomes unstable for two reasons. First, gravity makes the flow in the most direct course down slope. If the river breaches its natural levees, it out onto a new course with a shorter route to the ocean. Second, as its slope gets lower, the amount of stress on the bed decreases, which results in deposition of sediment within the channel. This makes it easier for the river to breach its levees, often when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a distributary network, another way these distributary networks form is from deposition of mouth bars. When this mid-channel bar is deposited at the mouth of a river and this results in additional deposition on the upstream end of the mouth-bar, which splits the river into two distributary channels. A good example of the result of this process is the Wax Lake Delta, in both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the shape of the delta as the channels move across its surface. Because the sediment is laid down in fashion, the shape of these deltas approximates a fan. The more often the flow changes course, the shape develops as closer to an ideal fan, the Mississippi and Ural River deltas, with their birds-feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape
8.
Huhu beetle
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The huhu beetle is the largest endemic beetle found in New Zealand, a member of the longhorn beetle family. Huhu is now used as the name for all stages of life of the beetle, but traditionally huhu was the Māori name for the larval stage. The whitish larvae are up to 70 millimetres long and normally feed on wood of gymnosperms. The native host plants are all associated with lowland podocarp forest and they are edible, and are said by some to taste like buttery chicken. As the huhu reaches maturity it ceases to bore and casts its skin and this still edible stage is known in Maori as tataka. It then develops wings and legs, and while it is still white, finally it emerges and flies off to reproduce and is known as a huhu beetle or to Maori as tunga rere. In this full adult stage it no longer eats food and only lives for approximately 2 weeks, the beetles are most active at night and are attracted by the lights of dwelling. Though not usually aggressive, huhu beetles are known to bite when mis-handled, witchetty grub Landcare Research - data
9.
Plant pathology
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Plant pathology is the scientific study of diseases in plants caused by pathogens and environmental conditions. Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes, not included are ectoparasites like insects, mites, vertebrate, or other pests that affect plant health by consumption of plant tissues. Control of plant diseases is crucial to the production of food. Plants in both natural and cultivated populations carry inherent disease resistance, but there are examples of devastating plant disease impacts. However, disease control is reasonably successful for most crops, plant diseases cause major economic losses for farmers worldwide. The Food and Agriculture Organization estimates indeed that pests and diseases are responsible for about 25% of crop loss, most phytopathogenic fungi belong to the Ascomycetes and the Basidiomycetes. The fungi reproduce sexually and asexually via the production of spores and other structures. Spores may be spread long distances by air or water, or they may be soilborne, Many soil inhabiting fungi are capable of living saprotrophically, carrying out the part of their life cycle in the soil. These are known as facultative saprotrophs, fungal diseases may be controlled through the use of fungicides and other agriculture practices. However, new races of fungi often evolve that are resistant to various fungicides, biotrophic fungal pathogens colonize living plant tissue and obtain nutrients from living host cells. Necrotrophic fungal pathogens infect and kill host tissue and extract nutrients from the dead host cells, see the powdery mildew and rice blast images, below. Significant fungal plant pathogens include, Fusarium spp, magnaporthe grisea Sclerotinia sclerotiorum Ustilago spp. The oomycetes are not true fungi but are fungus-like organisms and they include some of the most destructive plant pathogens including the genus Phytophthora, which includes the causal agents of potato late blight and sudden oak death. Particular species of oomycetes are responsible for root rot, despite not being closely related to the fungi, the oomycetes have developed very similar infection strategies. Oomycetes are capable of using effector proteins to turn off a plants defenses in its infection process, plant pathologists commonly group them with fungal pathogens. Significant oomycete plant pathogens Pythium spp and these are caused by species of Plasmodiophora and Spongospora, respectively. Most bacteria that are associated with plants are actually saprotrophic and do no harm to the plant itself, however, a small number, around 100 known species, are able to cause disease. Bacterial diseases are more prevalent in subtropical and tropical regions of the world
10.
Wildfire
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A wildfire or wildland fire is a fire in an area of combustible vegetation that occurs in the countryside or rural area. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago, wildfire’s occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems flora and fauna. Earth is an intrinsically flammable planet owing to its cover of vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning. Wildfires can be characterised in terms of the cause of ignition, their properties, the combustible material present. Wildfires can cause damage to property and human life, but they have beneficial effects on native vegetation, animals. Many plant species depend on the effects of fire for growth, however, wildfire in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behaviour and severity result from the combination of such as available fuels, physical setting. Strategies of wildfire prevention, detection and suppression have varied over the years, one common and inexpensive technique is controlled burning, permitting or even igniting smaller fires to minimise the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain species diversity and frequent burning of surface fuels limits fuel accumulation. Wildland fire use is the cheapest and most ecologically appropriate policy for many forests, fuels may also be removed by logging, but fuels treatments and thinning have no effect on severe fire behaviour. Wildfires can also be started in communities experiencing shifting cultivation, where land is cleared quickly and farmed until the soil loses fertility, forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. The most common cause of wildfires throughout the world. In Canada and northwest China, for example, lightning operates as the source of ignition. In other parts of the world, human involvement is a major contributor, in China and in the Mediterranean Basin, human carelessness is a major cause of wildfires. In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, Centralia, Pennsylvania and they can also flare up unexpectedly and ignite nearby flammable material. The spread of wildfires based on the flammable material present, its vertical arrangement and moisture content. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight, overall, fire types can be generally characterized by their fuels as follows, Ground fires are fed by subterranean roots, duff and other buried organic matter
11.
Ancient woodland
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In the United Kingdom, an ancient woodland is a woodland that has existed continuously since 1600 or before in England, Wales and Northern Ireland. Before those dates, planting of new woodland was uncommon, so a wood present in 1600 was likely to have developed naturally, the analogous American term is old-growth forest. In most ancient woods, the trees and shrubs have been cut down periodically as part of the management cycle, provided that the area has remained as woodland, the stand is still considered ancient. Since it may have cut over many times in the past. For many species of animal and plant, ancient woodland sites provide the sole habitat, Ancient woodland in the UK, like rainforest in the tropics, is home to rare and threatened species. For these reasons ancient woodland is often described as an irreplaceable resource, Ancient woodland is formally defined on maps by Natural England and equivalent bodies. Many ancient woodlands have legal protection of various types, but it is not automatically the case that any ancient woodland is protected, some examples of ancient woodland are nationally or locally designated, for example as Sites of Special Scientific Interest. Ancient woodlands also require consideration when they are affected by planning application. The National Planning Policy Framework published in 2012 is the government policy document relating to planning decisions affecting ancient woodland, the definition of ancient woodland includes two sub-types, Ancient semi-natural woodland and Planted ancient woodland site. Planted ancient woodland is an ancient woodland site where the species have been partially or wholly replaced with a non locally native species. These woodlands typically have a structure, with even aged crops of one or two species planted for commercial purposes. Many of these ancient woodlands were converted to conifer plantations following war-time fellings, some restored PAWS sites are now practically indistinguishable from ASNW. There is no method for reclassifying restored PAWS as ASNW. Sequences of pollen analysis are also indicators of forest continuity, the methodology involved studying the plants of known woodland sites and analysing patterns of occurrence to determine which species were most indicative of sites from before 1600. In England this resulted in the first national Ancient Woodland Inventory, Ancient woods were valuable properties for their owners, as a source of wood fuel, timber and forage for pigs. In southern England, hazel was particularly important for coppicing, the branches being used for wattle and daub in buildings, such old coppice stumps are easily recognised for their current overgrown state, now that the practice has largely disappeared. Large boles emerge from a stump in such overgrown coppice stools. The forest law was strictly enforced, by a hierarchy of foresters, parkers
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