The natural environment or natural world encompasses all biotic and abiotic things occurring naturally , meaning in this case not artificial . The term is most often applied to Earth or some parts of Earth. This environment encompasses the interaction of all living species , climate , weather and natural resources that affect human survival and economic activity. The concept of the natural environment can be distinguished as components:
109-469: An ecosystem (or ecological system ) is a system that environments and their organisms form through their interaction. The biotic and abiotic components are linked together through nutrient cycles and energy flows. Ecosystems are controlled by external and internal factors . External factors such as climate , parent material which forms the soil and topography , control the overall structure of an ecosystem but are not themselves influenced by
218-405: A cell wall . Newly dead animals may be covered by an exoskeleton . Fragmentation processes, which break through these protective layers, accelerate the rate of microbial decomposition. Animals fragment detritus as they hunt for food, as does passage through the gut. Freeze-thaw cycles and cycles of wetting and drying also fragment dead material. The chemical alteration of the dead organic matter
327-495: A food chain . Real systems are much more complex than this—organisms will generally feed on more than one form of food, and may feed at more than one trophic level. Carnivores may capture some prey that is part of a plant-based trophic system and others that are part of a detritus-based trophic system (a bird that feeds both on herbivorous grasshoppers and earthworms, which consume detritus). Real systems, with all these complexities, form food webs rather than food chains which present
436-614: A habitat . Ecosystem ecology is the "study of the interactions between organisms and their environment as an integrated system". The size of ecosystems can range up to ten orders of magnitude , from the surface layers of rocks to the surface of the planet. The Hubbard Brook Ecosystem Study started in 1963 to study the White Mountains in New Hampshire . It was the first successful attempt to study an entire watershed as an ecosystem. The study used stream chemistry as
545-598: A better environment for themselves, they are not human, hence beaver dams and the works of mound-building termites are thought of as natural. People cannot find absolutely natural environments on Earth,naturalness usually varies in a continuum, from 100% natural in one extreme to 0% natural in the other. The massive environmental changes of humanity in the Anthropocene have fundamentally effected all natural environments including: climate change , biodiversity loss and pollution from plastic and other chemicals in
654-441: A capacity to grow , respond to stimuli , reproduce and, through natural selection , adapt to their environment in successive generations. More complex living organisms can communicate through various means. An ecosystem (also called an environment) is a natural unit consisting of all plants, animals, and micro-organisms ( biotic factors) in an area functioning together with all of the non-living physical ( abiotic ) factors of
763-605: A central role over a wide range, for example, in the slow development of soil from bare rock and the faster recovery of a community from disturbance . Disturbance also plays an important role in ecological processes. F. Stuart Chapin and coauthors define disturbance as "a relatively discrete event in time that removes plant biomass". This can range from herbivore outbreaks, treefalls, fires, hurricanes, floods, glacial advances , to volcanic eruptions . Such disturbances can cause large changes in plant, animal and microbe populations, as well as soil organic matter content. Disturbance
872-504: A critical role in global nutrient cycling and ecosystem function. Phosphorus enters ecosystems through weathering . As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics). Calcium and sulfur are also produced by weathering, but acid deposition is an important source of sulfur in many ecosystems. Although magnesium and manganese are produced by weathering, exchanges between soil organic matter and living cells account for
981-641: A decreased food supply for the wildlife in an area. The atmosphere of the Earth serves as a key factor in sustaining the planetary ecosystem. The thin layer of gases that envelops the Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen , 21% oxygen , 1% argon , inert gases and carbon dioxide . The remaining gases are often referred to as trace gases. The atmosphere includes greenhouse gases such as carbon dioxide, methane, nitrous oxide and ozone. Filtered air includes trace amounts of many other chemical compounds . Air also contains
1090-515: A faster recovery. More severe and more frequent disturbance result in longer recovery times. From one year to another, ecosystems experience variation in their biotic and abiotic environments. A drought , a colder than usual winter, and a pest outbreak all are short-term variability in environmental conditions. Animal populations vary from year to year, building up during resource-rich periods and crashing as they overshoot their food supply. Longer-term changes also shape ecosystem processes. For example,
1199-423: A function-based typology has been proposed to leverage the strengths of these different approaches into a unified system. Human activities are important in almost all ecosystems. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Ecosystems provide a variety of goods and services upon which people depend. Ecosystem goods include
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#17327753345661308-695: A general level, for example, tropical forests , temperate grasslands , and arctic tundra . There can be any degree of subcategories among ecosystem types that comprise a biome, e.g., needle-leafed boreal forests or wet tropical forests. Although ecosystems are most commonly categorized by their structure and geography, there are also other ways to categorize and classify ecosystems such as by their level of human impact (see anthropogenic biome ), or by their integration with social processes or technological processes or their novelty (e.g. novel ecosystem ). Each of these taxonomies of ecosystems tends to emphasize different structural or functional properties. None of these
1417-669: A means of monitoring ecosystem properties, and developed a detailed biogeochemical model of the ecosystem. Long-term research at the site led to the discovery of acid rain in North America in 1972. Researchers documented the depletion of soil cations (especially calcium) over the next several decades. Ecosystems can be studied through a variety of approaches—theoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation. Studies can be carried out at
1526-526: A more important role in moving nutrients around. This can be especially important as the soil thaws in the spring, creating a pulse of nutrients that become available. Decomposition rates are low under very wet or very dry conditions. Decomposition rates are highest in wet, moist conditions with adequate levels of oxygen. Wet soils tend to become deficient in oxygen (this is especially true in wetlands ), which slows microbial growth. In dry soils, decomposition slows as well, but bacteria continue to grow (albeit at
1635-405: A number of common, non random properties in the topology of their network. The carbon and nutrients in dead organic matter are broken down by a group of processes known as decomposition. This releases nutrients that can then be re-used for plant and microbial production and returns carbon dioxide to the atmosphere (or water) where it can be used for photosynthesis. In the absence of decomposition,
1744-454: A pond from many other aquatic terrain features, such as stream pools and tide pools . Humans impact the water in different ways such as modifying rivers (through dams and stream channelization ), urbanization and deforestation . These impact lake levels, groundwater conditions, water pollution, thermal pollution, and marine pollution . Humans modify rivers by using direct channel manipulation. We build dams and reservoirs and manipulate
1853-417: A process known as denitrification . Mycorrhizal fungi which are symbiotic with plant roots, use carbohydrates supplied by the plants and in return transfer phosphorus and nitrogen compounds back to the plant roots. This is an important pathway of organic nitrogen transfer from dead organic matter to plants. This mechanism may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing
1962-401: A separate PEP carboxylase enzyme to prevent photorespiration , thus increasing the yield of photosynthesis processes in certain high energy environments. Many Archea require very high temperatures, pressures, or unusual concentrations of chemical substances such as sulfur ; this is due to their specialization into extreme conditions. In addition, fungi have also evolved to survive at
2071-692: A significant portion of ecosystem fluxes. Potassium is primarily cycled between living cells and soil organic matter. Biodiversity plays an important role in ecosystem functioning. Ecosystem processes are driven by the species in an ecosystem, the nature of the individual species, and the relative abundance of organisms among these species. Ecosystem processes are the net effect of the actions of individual organisms as they interact with their environment. Ecological theory suggests that in order to coexist, species must have some level of limiting similarity —they must be different from one another in some fundamental way, otherwise, one species would competitively exclude
2180-404: A slower rate) even after soils become too dry to support plant growth. Ecosystems are dynamic entities. They are subject to periodic disturbances and are always in the process of recovering from past disturbances. When a perturbation occurs, an ecosystem responds by moving away from its initial state. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance,
2289-462: A small effect on ecosystem function. Ecologically distinct species, on the other hand, have a much larger effect. Similarly, dominant species have a large effect on ecosystem function, while rare species tend to have a small effect. Keystone species tend to have an effect on ecosystem function that is disproportionate to their abundance in an ecosystem. An ecosystem engineer is any organism that creates, significantly modifies, maintains or destroys
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#17327753345662398-507: A variable amount of water vapor and suspensions of water droplets and ice crystals seen as clouds . Many natural substances may be present in tiny amounts in an unfiltered air sample, including dust , pollen and spores , sea spray , volcanic ash and meteoroids . Various industrial pollutants also may be present, such as chlorine (elementary or in compounds), fluorine compounds, elemental mercury , and sulphur compounds such as sulphur dioxide (SO 2 ). The ozone layer of
2507-468: A variety of approaches—theoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation. Biomes are general classes or categories of ecosystems. However, there is no clear distinction between biomes and ecosystems. Ecosystem classifications are specific kinds of ecological classifications that consider all four elements of
2616-443: A variety of goods and services upon which people depend, and may be part of. Ecosystem goods include the "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and medicinal plants . Ecosystem services , on the other hand, are generally "improvements in the condition or location of things of value". These include things like the maintenance of hydrological cycles , cleaning air and water,
2725-518: A variety of scales, ranging from whole-ecosystem studies to studying microcosms or mesocosms (simplified representations of ecosystems). American ecologist Stephen R. Carpenter has argued that microcosm experiments can be "irrelevant and diversionary" if they are not carried out in conjunction with field studies done at the ecosystem scale. In such cases, microcosm experiments may fail to accurately predict ecosystem-level dynamics. Biomes are general classes or categories of ecosystems. However, there
2834-405: Is an international synthesis by over 1000 of the world's leading biological scientists that analyzes the state of the Earth's ecosystems and provides summaries and guidelines for decision-makers. The report identified four major categories of ecosystem services: provisioning, regulating, cultural and supporting services. It concludes that human activity is having a significant and escalating impact on
2943-404: Is confined within a bed and stream banks . Streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity . The study of streams and waterways in general is known as surface hydrology . A lake (from Latin lacus ) is a terrain feature , a body of water that is localized to the bottom of basin . A body of water is considered a lake when it
3052-439: Is consumed by animals while still alive and enters the plant-based trophic system. After plants and animals die, the organic matter contained in them enters the detritus-based trophic system. Ecosystem respiration is the sum of respiration by all living organisms (plants, animals, and decomposers) in the ecosystem. Net ecosystem production is the difference between gross primary production (GPP) and ecosystem respiration. In
3161-567: Is followed by succession, a "directional change in ecosystem structure and functioning resulting from biotically driven changes in resource supply." The frequency and severity of disturbance determine the way it affects ecosystem function. A major disturbance like a volcanic eruption or glacial advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience such disturbances undergo primary succession . A less severe disturbance like forest fires, hurricanes or cultivation result in secondary succession and
3270-791: Is from the Old English wildeornes , which in turn derives from wildeor meaning wild beast (wild + deor = beast, deer). From this point of view, it is the wildness of a place that makes it a wilderness. The mere presence or activity of people does not disqualify an area from being "wilderness". Many ecosystems that are, or have been, inhabited or influenced by activities of people may still be considered "wild". This way of looking at wilderness includes areas within which natural processes operate without very noticeable human interference. Wildlife includes all non- domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over
3379-552: Is governed by three sets of factors—the physical environment (temperature, moisture, and soil properties), the quantity and quality of the dead material available to decomposers, and the nature of the microbial community itself. Temperature controls the rate of microbial respiration; the higher the temperature, the faster the microbial decomposition occurs. Temperature also affects soil moisture, which affects decomposition. Freeze-thaw cycles also affect decomposition—freezing temperatures kill soil microorganisms, which allows leaching to play
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3488-440: Is increasingly rare, wild nature (e.g., unmanaged forests , uncultivated grasslands , wildlife , wildflowers ) can be found in many locations previously inhabited by humans. Goals for the benefit of people and natural systems, commonly expressed by environmental scientists and environmentalists include: In some cultures the term environment is meaningless because there is no separation between people and what they view as
3597-521: Is inland, is not part of an ocean and is larger and deeper than a pond . Natural lakes on Earth are generally found in mountainous areas, rift zones and areas with ongoing or recent glaciation . Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the last ice age . All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of
3706-404: Is no clear distinction between biomes and ecosystems. Biomes are always defined at a very general level. Ecosystems can be described at levels that range from very general (in which case the names are sometimes the same as those of biomes) to very specific, such as "wet coastal needle-leafed forests". Biomes vary due to global variations in climate . Biomes are often defined by their structure: at
3815-528: Is primarily achieved through bacterial and fungal action. Fungal hyphae produce enzymes that can break through the tough outer structures surrounding dead plant material. They also produce enzymes that break down lignin , which allows them access to both cell contents and the nitrogen in the lignin. Fungi can transfer carbon and nitrogen through their hyphal networks and thus, unlike bacteria, are not dependent solely on locally available resources. Decomposition rates vary among ecosystems. The rate of decomposition
3924-482: Is termed its resistance . The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its ecological resilience . Resilience thinking also includes humanity as an integral part of the biosphere where we are dependent on ecosystem services for our survival and must build and maintain their natural capacities to withstand shocks and disturbances. Time plays
4033-421: Is the "best" classification. Ecosystem classifications are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems : a biotic component, an abiotic complex, the interactions between and within them, and the physical space they occupy. Different approaches to ecological classifications have been developed in terrestrial, freshwater and marine disciplines, and
4142-671: Is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The atmosphere is a chaotic system , and small changes to one part of the system can grow to have large effects on the system as a whole. Human attempts to control the weather have occurred throughout human history, and there is evidence that civilized human activity such as agriculture and industry has inadvertently modified weather patterns. Evidence suggests that life on Earth has existed for about 3.7 billion years. All known life forms share fundamental molecular mechanisms, and based on these observations, theories on
4251-430: Is the one originally developed by Wladimir Köppen . The Thornthwaite system , in use since 1948, uses evapotranspiration as well as temperature and precipitation information to study animal species diversity and the potential impacts of climate changes . Weather is a set of all the phenomena occurring in a given atmospheric area at a given time . Most weather phenomena occur in the troposphere , just below
4360-430: Is the outermost solid surface of the planet and is chemically, physically and mechanically different from underlying mantle . It has been generated greatly by igneous processes in which magma cools and solidifies to form solid rock. Beneath the lithosphere lies the mantle which is heated by the decay of radioactive elements . The mantle though solid is in a state of rheic convection . This convection process causes
4469-487: The Arctic Ocean . A river is a natural watercourse , usually freshwater , flowing toward an ocean , a lake , a sea or another river. A few rivers simply flow into the ground and dry up completely without reaching another body of water. The water in a river is usually in a channel , made up of a stream bed between banks . In larger rivers there is often also a wider floodplain shaped by waters over-topping
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4578-714: The World Ocean or global ocean. The deep seabeds are more than half the Earth's surface, and are among the least-modified natural environments. The major oceanic divisions are defined in part by the continents , various archipelagos and other criteria, these divisions are : (in descending order of size) the Pacific Ocean , the Atlantic Ocean , the Indian Ocean , the Southern Ocean and
4687-414: The air and water . More precisely, we can consider the different aspects or components of an environment, and see that their degree of naturalness is not uniform. If, for instance, in an agricultural field, the mineralogic composition and the structure of its soil are similar to those of an undisturbed forest soil, but the structure is quite different. Earth science generally recognizes four spheres,
4796-408: The lithosphere , the hydrosphere , the atmosphere and the biosphere as correspondent to rocks , water , air and life respectively. Some scientists include as part of the spheres of the Earth, the cryosphere (corresponding to ice ) as a distinct portion of the hydrosphere, as well as the pedosphere (to soil ) as an active and intermixed sphere. Earth science (also known as geoscience,
4905-408: The mitigation of greenhouse gases that are causing climatic changes, on developing adaptative strategies to global warming, to assist humans, other animal, and plant species, ecosystems, regions and nations in adjusting to the effects of global warming . Some examples of recent collaboration to address climate change and global warming include: A significantly profound challenge is to identify
5014-554: The resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other factors like disturbance, succession or the types of species present are also internal factors. Primary production is the production of organic matter from inorganic carbon sources. This mainly occurs through photosynthesis . The energy incorporated through this process supports life on earth, while
5123-421: The stratosphere . Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods of time. When used without qualification, "weather" is understood to be the weather of Earth. Weather occurs due to density (temperature and moisture) differences between one place and another. These differences can occur due to
5232-562: The surface of the Earth (an area of some 362 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas . More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Though generally recognized as several separate oceans, these waters comprise one global, interconnected body of salt water often referred to as
5341-431: The "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and medicinal plants . They also include less tangible items like tourism and recreation, and genes from wild plants and animals that can be used to improve domestic species. Ecosystem services , on the other hand, are generally "improvements in the condition or location of things of value". These include things like
5450-518: The Earth's atmosphere plays an important role in reducing the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes. Earth's atmosphere can be divided into five main layers. These layers are mainly determined by whether temperature increases or decreases with altitude. From highest to lowest, these layers are: Within
5559-415: The abiotic constituents of their biotope . A more significant number or variety of species or biological diversity of an ecosystem may contribute to greater resilience of an ecosystem because there are more species present at a location to respond to change and thus "absorb" or reduce its effects. This reduces the effect before the ecosystem's structure changes to a different state. This is not universally
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#17327753345665668-597: The above. Pressure and sound waves may also be considered in the context of marine or sub-terrestrial environments. Abiotic factors in ocean environments also include aerial exposure, substrate , water clarity , solar energy and tides . Consider the differences in the mechanics of C3 , C4 , and CAM plants in regulating the influx of carbon dioxide to the Calvin-Benson Cycle in relation to their abiotic stressors. C3 plants have no mechanisms to manage photorespiration , whereas C4 and CAM plants utilize
5777-480: The absence of disturbance, net ecosystem production is equivalent to the net carbon accumulation in the ecosystem. Energy can also be released from an ecosystem through disturbances such as wildfire or transferred to other ecosystems (e.g., from a forest to a stream to a lake) by erosion . In aquatic systems , the proportion of plant biomass that gets consumed by herbivores is much higher than in terrestrial systems. In trophic systems, photosynthetic organisms are
5886-400: The amount of energy available to the ecosystem. Parent material determines the nature of the soil in an ecosystem, and influences the supply of mineral nutrients. Topography also controls ecosystem processes by affecting things like microclimate , soil development and the movement of water through a system. For example, ecosystems can be quite different if situated in a small depression on
5995-502: The amount of light available, the amount of leaf area a plant has to capture light (shading by other plants is a major limitation of photosynthesis), the rate at which carbon dioxide can be supplied to the chloroplasts to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out photosynthesis. Energy and carbon enter ecosystems through photosynthesis, are incorporated into living tissue, transferred to other organisms that feed on
6104-612: The basin containing them. A pond is a body of standing water , either natural or human-made, that is usually smaller than a lake . A wide variety of human-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding and solar ponds designed to store thermal energy. Ponds and lakes are distinguished from streams by their current speed . While currents in streams are easily observed, ponds and lakes possess thermally driven micro-currents and moderate wind-driven currents. These features distinguish
6213-447: The biodiversity of the world ecosystems, reducing both their resilience and biocapacity . The report refers to natural systems as humanity's "life-support system", providing essential ecosystem services. The assessment measures 24 ecosystem services and concludes that only four have shown improvement over the last 50 years, 15 are in serious decline, and five are in a precarious condition. Biophysical environment In contrast to
6322-425: The biological manifestation of life is characterized by organization , metabolism , growth , adaptation , response to stimuli and reproduction . Life may also be said to be simply the characteristic state of organisms . In biology , the science of living organisms, "life" is the condition which distinguishes active organisms from inorganic matter , including the capacity for growth, functional activity and
6431-408: The carbon makes up much of the organic matter in living and dead biomass, soil carbon and fossil fuels . It also drives the carbon cycle , which influences global climate via the greenhouse effect . Through the process of photosynthesis, plants capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and oxygen . The photosynthesis carried out by all
6540-407: The case and there is no proven relationship between the species diversity of an ecosystem and its ability to provide goods and services on a sustainable level. The term ecosystem can also pertain to human-made environments, such as human ecosystems and human-influenced ecosystems. It can describe any situation where there is relationship between living organisms and their environment. Fewer areas on
6649-431: The channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of the hydrological cycle . Water within a river is generally collected from precipitation through surface runoff , groundwater recharge , springs and the release of water stored in glaciers and snowpacks. Small rivers may also be called by several other names, including stream , creek and brook. Their current
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#17327753345666758-428: The combustion of fossil fuels, ammonia gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust. Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems. When plant tissues are shed or are eaten, the nitrogen in those tissues becomes available to animals and microbes. Microbial decomposition releases nitrogen compounds from dead organic matter in
6867-414: The concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as "The whole system, ... including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not simply as natural units, but as "mental isolates". Tansley later defined
6976-425: The continual change preceding death. A diverse variety of living organisms (life forms) can be found in the biosphere on Earth, and properties common to these organisms—plants, animals , fungi , protists , archaea , and bacteria —are a carbon - and water-based cellular form with complex organization and heritable genetic information. Living organisms undergo metabolism , maintain homeostasis , possess
7085-401: The dead organic matter would accumulate in an ecosystem, and nutrients and atmospheric carbon dioxide would be depleted. Decomposition processes can be separated into three categories— leaching , fragmentation and chemical alteration of dead material. As water moves through dead organic matter, it dissolves and carries with it the water-soluble components. These are then taken up by organisms in
7194-447: The definition of ecosystems : a biotic component, an abiotic complex, the interactions between and within them, and the physical space they occupy. Biotic factors of the ecosystem are living things; such as plants, animals, and bacteria, while abiotic are non-living components; such as water, soil and atmosphere. Plants allow energy to enter the system through photosynthesis , building up plant tissue. Animals play an important role in
7303-624: The direction of the rivers and water path. Dams can usefully create reservoirs and hydroelectric power. However, reservoirs and dams may negatively impact the environment and wildlife. Dams stop fish migration and the movement of organisms downstream. Urbanization affects the environment because of deforestation and changing lake levels, groundwater conditions, etc. Deforestation and urbanization go hand in hand. Deforestation may cause flooding, declining stream flow and changes in riverside vegetation. The changing vegetation occurs because when trees cannot get adequate water they start to deteriorate, leading to
7412-649: The ecosystem or to gradual disruption of biotic processes and degradation of abiotic conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered "collapsed ". Ecosystem restoration can contribute to achieving the Sustainable Development Goals . An ecosystem (or ecological system) consists of all the organisms and the abiotic pools (or physical environment) with which they interact. The biotic and abiotic components are linked together through nutrient cycles and energy flows. "Ecosystem processes" are
7521-528: The ecosystem. Internal factors are controlled, for example, by decomposition , root competition, shading, disturbance, succession, and the types of species present. While the resource inputs are generally controlled by external processes, the availability of these resources within the ecosystem is controlled by internal factors. Therefore, internal factors not only control ecosystem processes but are also controlled by them. Ecosystems are dynamic entities—they are subject to periodic disturbances and are always in
7630-629: The environment required by one organism and consumed or otherwise made unavailable for use by other organisms. Component degradation of a substance occurs by chemical or physical processes , e.g. hydrolysis . All non-living components of an ecosystem, such as atmospheric conditions and water resources , are called abiotic components. In biology, abiotic factors can include water , light , radiation , temperature , humidity , atmosphere , acidity , salinity , precipitation , altitude, minerals , tides , rain , dissolved oxygen nutrients, and soil . The macroscopic climate often influences each of
7739-409: The environment. Central to the ecosystem concept is the idea that living organisms are continually engaged in a highly interrelated set of relationships with every other element constituting the environment in which they exist. Eugene Odum , one of the founders of the science of ecology , stated: "Any unit that includes all of the organisms (i.e.: the "community") in a given area interacting with
7848-482: The extinction of natural habitats, which in turn leads to a reduction in wildlife population. The most recent report from the Intergovernmental Panel on Climate Change (the group of the leading climate scientists in the world) concluded that the earth will warm anywhere from 2.7 to almost 11 degrees Fahrenheit (1.5 to 6 degrees Celsius) between 1990 and 2100. Efforts have been increasingly focused on
7957-586: The five principal layers determined by temperature there are several layers determined by other properties. The dangers of global warming are being increasingly studied by a wide global consortium of scientists. These scientists are increasingly concerned about the potential long-term effects of global warming on our natural environment and on the planet. Of particular concern is how climate change and global warming caused by anthropogenic , or human-made releases of greenhouse gases , most notably carbon dioxide , can act interactively and have adverse effects upon
8066-419: The flow of energy through a lake was the primary driver of the ecosystem. Hutchinson's students, brothers Howard T. Odum and Eugene P. Odum , further developed a "systems approach" to the study of ecosystems. This allowed them to study the flow of energy and material through ecological systems. Ecosystems are controlled by both external and internal factors. External factors, also called state factors, control
8175-542: The forests of eastern North America still show legacies of cultivation which ceased in 1850 when large areas were reverted to forests. Another example is the methane production in eastern Siberian lakes that is controlled by organic matter which accumulated during the Pleistocene . Ecosystems continually exchange energy and carbon with the wider environment . Mineral nutrients, on the other hand, are mostly cycled back and forth between plants, animals, microbes and
8284-538: The geographical sciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth . There are four major disciplines in earth sciences, namely geography , geology , geophysics and geodesy . These major disciplines use physics , chemistry , biology , chronology and mathematics to build a qualitative and quantitative understanding of the principal areas or spheres of Earth. The Earth's crust or lithosphere ,
8393-682: The landscape, versus one present on an adjacent steep hillside. Other external factors that play an important role in ecosystem functioning include time and potential biota , the organisms that are present in a region and could potentially occupy a particular site. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. The introduction of non-native species can cause substantial shifts in ecosystem function. Unlike external factors, internal factors in ecosystems not only control ecosystem processes but are also controlled by them. While
8502-408: The lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics . Volcanoes result primarily from the melting of subducted crust material or of rising mantle at mid-ocean ridges and mantle plumes . Most water is found in various kinds of natural body of water . An ocean is a major body of saline water and a component of the hydrosphere. Approximately 71% of
8611-421: The living and dead plant matter, and eventually released through respiration. The carbon and energy incorporated into plant tissues (net primary production) is either consumed by animals while the plant is alive, or it remains uneaten when the plant tissue dies and becomes detritus . In terrestrial ecosystems , the vast majority of the net primary production ends up being broken down by decomposers . The remainder
8720-406: The maintenance of hydrological cycles, cleaning air and water, the maintenance of oxygen in the atmosphere, crop pollination and even things like beauty, inspiration and opportunities for research. While material from the ecosystem had traditionally been recognized as being the basis for things of economic value, ecosystem services tend to be taken for granted. The Millennium Ecosystem Assessment
8829-405: The maintenance of oxygen in the atmosphere, crop pollination and even things like beauty, inspiration and opportunities for research. Many ecosystems become degraded through human impacts, such as soil loss , air and water pollution , habitat fragmentation , water diversion , fire suppression , and introduced species and invasive species . These threats can lead to abrupt transformation of
8938-433: The movement of matter and energy through the system, by feeding on plants and on one another. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter , decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes. Ecosystems provide
9047-472: The natural environment is the built environment . Built environments are where humans have fundamentally transformed landscapes such as urban settings and agricultural land conversion , the natural environment is greatly changed into a simplified human environment. Even acts which seem less extreme, such as building a mud hut or a photovoltaic system in the desert , the modified environment becomes an artificial one. Though many animals build things to provide
9156-410: The natural environmental dynamics in contrast to environmental changes not within natural variances. A common solution is to adapt a static view neglecting natural variances to exist. Methodologically, this view could be defended when looking at processes which change slowly and short time series, while the problem arrives when fast processes turns essential in the object of the study. Climate looks at
9265-514: The natural world, or their surroundings. Specifically in the United States and Arabian countries many native cultures do not recognize the "environment", or see themselves as environmentalists. Abiotic component In biology and ecology , abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems . Abiotic factors and
9374-409: The origin of life attempt to find a mechanism explaining the formation of a primordial single cell organism from which all life originates. There are many different hypotheses regarding the path that might have been taken from simple organic molecules via pre-cellular life to protocells and metabolism. Although there is no universal agreement on the definition of life, scientists generally accept that
9483-502: The other. Despite this, the cumulative effect of additional species in an ecosystem is not linear: additional species may enhance nitrogen retention, for example. However, beyond some level of species richness, additional species may have little additive effect unless they differ substantially from species already present. This is the case for example for exotic species . The addition (or loss) of species that are ecologically similar to those already present in an ecosystem tends to only have
9592-401: The overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. On broad geographic scales, climate is the factor that "most strongly determines ecosystem processes and structure". Climate determines the biome in which the ecosystem is embedded. Rainfall patterns and seasonal temperatures influence photosynthesis and thereby determine
9701-616: The phenomena associated with them underpin biology as a whole. They affect a plethora of species, in all forms of environmental conditions, such as marine or terrestrial animals . Humans can make or change abiotic factors in a species' environment. For instance, fertilizers can affect a snail 's habitat , or the greenhouse gases which humans utilize can change marine pH levels. Abiotic components include physical conditions and non-living resources that affect living organisms in terms of growth , maintenance , and reproduction . Resources are distinguished as substances or objects in
9810-438: The physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e.: exchange of materials between living and nonliving parts) within the system is an ecosystem." The human ecosystem concept is then grounded in the deconstruction of the human/nature dichotomy , and the emergent premise that all species are ecologically integrated with each other, as well as with
9919-400: The planet, and has a major impact on the environment, both positive and negative. Wildlife can be found in all ecosystems. Deserts, rain forests, plains, and other areas—including the most developed urban sites—all have distinct forms of wildlife. While the term in popular culture usually refers to animals that are untouched by civilized human factors, most scientists agree that wildlife around
10028-415: The planet, its natural environment and humans' existence. It is clear the planet is warming, and warming rapidly. This is due to the greenhouse effect , which is caused by greenhouse gases, which trap heat inside the Earth's atmosphere because of their more complex molecular structure which allows them to vibrate and in turn trap heat and release it back towards the Earth. This warming is also responsible for
10137-399: The plants in an ecosystem is called the gross primary production (GPP). About half of the gross GPP is respired by plants in order to provide the energy that supports their growth and maintenance. The remainder, that portion of GPP that is not used up by respiration, is known as the net primary production (NPP). Total photosynthesis is limited by a range of environmental factors. These include
10246-581: The primary nutrients (which are most limiting as they are used in largest amounts): Nitrogen, phosphorus, potassium. Secondary major nutrients (less often limiting) include: Calcium, magnesium, sulfur. Micronutrients required by all plants in small quantities include boron, chloride, copper, iron, manganese, molybdenum, zinc. Finally, there are also beneficial nutrients which may be required by certain plants or by plants under specific environmental conditions: aluminum, cobalt, iodine, nickel, selenium, silicon, sodium, vanadium. Until modern times, nitrogen fixation
10355-412: The primary producers. The organisms that consume their tissues are called primary consumers or secondary producers — herbivores . Organisms which feed on microbes ( bacteria and fungi ) are termed microbivores . Animals that feed on primary consumers— carnivores —are secondary consumers. Each of these constitutes a trophic level. The sequence of consumption—from plant to herbivore, to carnivore—forms
10464-419: The process of recovering from some past disturbance. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance, is termed its resistance . The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its ecological resilience . Ecosystems can be studied through
10573-607: The soil, react with mineral soil, or are transported beyond the confines of the ecosystem (and are considered lost to it). Newly shed leaves and newly dead animals have high concentrations of water-soluble components and include sugars , amino acids and mineral nutrients. Leaching is more important in wet environments and less important in dry ones. Fragmentation processes break organic material into smaller pieces, exposing new surfaces for colonization by microbes. Freshly shed leaf litter may be inaccessible due to an outer layer of cuticle or bark , and cell contents are protected by
10682-509: The soil, where plants, fungi, and bacteria compete for it. Some soil bacteria use organic nitrogen-containing compounds as a source of carbon, and release ammonium ions into the soil. This process is known as nitrogen mineralization . Others convert ammonium to nitrite and nitrate ions, a process known as nitrification . Nitric oxide and nitrous oxide are also produced during nitrification. Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to nitrogen gas ,
10791-445: The soil. Most nitrogen enters ecosystems through biological nitrogen fixation , is deposited through precipitation, dust, gases or is applied as fertilizer . Most terrestrial ecosystems are nitrogen-limited in the short term making nitrogen cycling an important control on ecosystem production. Over the long term, phosphorus availability can also be critical. Macronutrients which are required by all plants in large quantities include
10900-482: The spatial extent of ecosystems using the term " ecotope ". G. Evelyn Hutchinson , a limnologist who was a contemporary of Tansley's, combined Charles Elton 's ideas about trophic ecology with those of Russian geochemist Vladimir Vernadsky . As a result, he suggested that mineral nutrient availability in a lake limited algal production . This would, in turn, limit the abundance of animals that feed on algae. Raymond Lindeman took these ideas further to suggest that
11009-495: The statistics of temperature , humidity , atmospheric pressure , wind , rainfall , atmospheric particle count and other meteorological elements in a given region over long periods of time. Weather , on the other hand, is the present condition of these same elements over periods up to two weeks. Climates can be classified according to the average and typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme
11118-434: The sun angle at any particular spot, which varies by latitude from the tropics. The strong temperature contrast between polar and tropical air gives rise to the jet stream . Weather systems in the mid-latitudes , such as extratropical cyclones , are caused by instabilities of the jet stream flow. Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of
11227-775: The surface of the earth today exist free from human contact, although some genuine wilderness areas continue to exist without any forms of human intervention. Global biogeochemical cycles are critical to life, most notably those of water , oxygen , carbon , nitrogen and phosphorus . Wilderness is generally defined as a natural environment on Earth that has not been significantly modified by human activity. The WILD Foundation goes into more detail, defining wilderness as: "The most intact, undisturbed wild natural areas left on our planet – those last truly wild places that humans do not control and have not developed with roads, pipelines or other industrial infrastructure." Wilderness areas and protected parks are considered important for
11336-420: The survival of certain species , ecological studies, conservation , solitude, and recreation . Wilderness is deeply valued for cultural, spiritual, moral , and aesthetic reasons. Some nature writers believe wilderness areas are vital for the human spirit and creativity. The word, "wilderness", derives from the notion of wildness ; in other words that which is not controllable by humans. The word etymology
11445-428: The temperature, the humidity, and stability of their environment. For example, there is a significant difference in access to both water and humidity between temperate rain forests and deserts . This difference in water availability causes a diversity in the organisms that survive in these areas. These differences in abiotic components alter the species present by creating boundaries of what species can survive within
11554-416: The transfers of energy and materials from one pool to another. Ecosystem processes are known to "take place at a wide range of scales". Therefore, the correct scale of study depends on the question asked. The term "ecosystem" was first used in 1935 in a publication by British ecologist Arthur Tansley . The term was coined by Arthur Roy Clapham , who came up with the word at Tansley's request. Tansley devised
11663-411: The world is (now) impacted by human activities. It is the common understanding of natural environment that underlies environmentalism — a broad political , social and philosophical movement that advocates various actions and policies in the interest of protecting what nature remains in the natural environment, or restoring or expanding the role of nature in this environment. While true wilderness
11772-465: The year. On the Earth's surface, temperatures usually range ±40 °C (100 °F to −40 °F) annually. Over thousands of years, changes in the Earth's orbit have affected the amount and distribution of solar energy received by the Earth and influenced long-term climate. Surface temperature differences in turn cause pressure differences. Higher altitudes are cooler than lower altitudes due to differences in compressional heating. Weather forecasting
11881-677: Was the major source of nitrogen for ecosystems. Nitrogen-fixing bacteria either live symbiotically with plants or live freely in the soil. The energetic cost is high for plants that support nitrogen-fixing symbionts—as much as 25% of gross primary production when measured in controlled conditions. Many members of the legume plant family support nitrogen-fixing symbionts. Some cyanobacteria are also capable of nitrogen fixation. These are phototrophs , which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants. Other sources of nitrogen include acid deposition produced through
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