The biosphere is the biological component of earth systems, which also include the lithosphere, hydrosphere, atmosphere and other "spheres" (e.g. cryosphere, anthrosphere, etc.). The biosphere includes all living organisms on earth, together with the dead organic matter produced by them.
The biosphere concept is common to many scientific disciplines including astronomy, geophysics, geology, hydrology, biogeography and evolution, and is a core concept in ecology, earth science and physical geography. A key component of earth systems, the biosphere interacts with and exchanges matter and energy with the other spheres, helping to drive the global biogeochemical cycling of carbon, nitrogen, phosphorus, sulfur and other elements. From an ecological point of view, the biosphere is the "global ecosystem", comprising the totality of biodiversity on earth and performing all manner of biological functions, including photosynthesis, respiration, decomposition, nitrogen fixation and denitrification.
The biosphere is dynamic, undergoing strong seasonal cycles in primary productivity and the many biological processes driven by the energy captured by photosynthesis. Seasonal cycles in solar irradiation of the hemispheres is the main driver of this dynamic, especially by its strong effect on terrestrial primary productivity in the temperate and boreal biomes, which essentially cease productivity in the winter time.
The biosphere has evolved since the first single-celled organisms originated 3.5 billion years ago under atmospheric conditions resembling those of our neighboring planets Mars and Venus, which have atmospheres composed primarily of carbon dioxide. Billions of years of primary production by plants released oxygen from this carbon dioxide and deposited the carbon in sediments, eventually producing the oxygen-rich atmosphere we know today. Free oxygen, both for breathing (O2, respiration) and in the stratospheric ozone (O3) that protects us from harmful UV radiation, has made possible life as we know it while transforming the chemistry of earth systems forever.
As a result of long-term interactions between the biosphere and the other earth systems, there is almost no part of the earth's surface that has not been profoundly altered by living organisms. The earth is a living planet, even in terms of its physics and chemistry. A concept related to, but different from, that of the biosphere, is the Gaia hypotheses, which posits that living organisms have and continue to transform earth systems for their own benefit.
The term "biosphere" originated with the geologist Eduard Suess in 1875, who defined it as "the place on earth's surface where life dwells". Vladimir I. Vernadsky first defined the biosphere in a form resembling its current ecological usage in his long-overlooked book of the same title, originally published in 1926. It is Vernadsky's work that redefined ecology as the science of the biosphere and placed the biosphere concept in its current central position in earth systems science.
The biosphere is a core concept within Biology and Ecology, where it serves as the highest level of biological organization, which begins with parts of cells and proceed to populations, species, ecoregions, biomes and finally, the biosphere. Global patterns of biodiversity within the biosphere are described using biomes.
In earth science, the biosphere represents the role of living organisms and their remains in controlling and interacting with the other spheres in the global biogeochemical cycles and energy budgets. The biosphere plays a central role in the biogeochemical processing of carbon, nitrogen, phosphorus, sulfur and other elements. As a result, biogeochemical processes such as photosynthesis and nitrogen fixation are critical to understanding the chemistry and physics of earth systems as a whole. The physical properties of the biosphere in terms of its surface reflectance (albedo) and exchange of heat and moisture with the atmosphere are also critical for understanding global circulation of heat and moisture and therefore climate. Alterations in both the physics (albedo, heat exchange) and chemistry (carbon dioxide, methane, etc.) of earth systems by the biosphere are fundamental in understanding anthropogenic global warming.
Researchers make direct observations on the biosphere using global remote sensing platforms. Beginning in the 1980s (AVHRR), this effort has evolved into advanced remote sensing systems that can scan the entire surface of the earth at least once each day (MODIS). These observations are now used to quantify the activities of the biosphere, primarily in terms of vegetation cover and function, using spectral indices such as NDVI. Future remote sensing efforts will directly observe global patterns of carbon dioxide exchange with the biosphere caused by photosynthesis, respiration and the combustion of biomass and fossil fuels (OCO).
To better understand the biogeochemical cycles of carbon and other elements, and the role of biospheric processes like photosynthesis, respiration and the storage of carbon in soils and vegetation, researchers have developed a variety of global biogeochemical models (e.g. CASA). There are also global models of vegetation patterns across the biosphere that are driven by climate (e.g. LPJ). Modeling plays an especially important role in understanding biospheric patterns and processes because there is only one earth: it is impossible to conduct global experiments on the entire biosphere or complete global processes (though some consider our current use of fossil fuels to be such an experiment). Understanding how humans are altering the biosphere and other earth systems has become a very active area of study, with concerted global efforts originating in the 1970s with the Man and the Biosphere Programme of UNESCO (MAB), which also established a global system of biosphere reserves. Since the late 1980s, international scientific research on the biosphere has been coordinated by the International Geosphere-Biosphere Programme (IGBP) .
The Biosphere II
"experiments", which were conducted in the early 1990s in
Many now see this as a good analogy for the current changes in atmospheric composition we are causing by rapidly burning off the fossil carbon captured by plants over millions of years, and by our conversion of forests to croplands. By releasing carbon stored by the biosphere over geologic time back to the atmosphere at unprecedented rates, humans are causing rapid global warming, and this warming is further altering global biogeochemical cycles and patterns of biodiversity across the biosphere. Anthropogenic climate change together with land use change and other anthropogenic alterations of the biosphere and other spheres have now reached such a high level that some earth scientist are now calling for the recognition that we have now entered a new, human-dominated, geologic era: the anthropocene.
Clearly, we are in need of greater understanding of how to better manage our one and only biosphere for the long-term benefit of ourselves and all other organisms.
The ecosystem is a core concept in Biology and Ecology, serving as the level of biological organization in which organisms interact simultaneously with each other and with their environment. As such, ecosystems are a level above that of the ecological community (organisms of different species interacting with each other) but are at a level below, or equal to, biomes and the biosphere. Essentially, biomes are regional ecosystems, and the biosphere is the largest of all possible ecosystems.
Ecosystems include living organisms, the dead organic matter produced by them, the abiotic environment within which the organisms live and exchange elements (soils, water, atmosphere), and the interactions between these components. Ecosystems embody the concept that living organisms continually interact with each other and with the environment to produce complex systems with emergent properties, such that "the whole is greater than the sum of its parts" and "everything is connected".
The spatial boundaries, component organisms and the matter and energy content and flux within ecosystems may be defined and measured. However, unlike organisms or energy, ecosystems are inherently conceptual, in that different observers may legitimately define their boundaries and components differently. For example, a single patch of trees together with the soil, organisms and atmosphere interacting with them may define a forest ecosystem, yet the entirety of all organisms, their environment, and their interactions across an entire forested region in the Amazon might also be defined as a single forest ecosystem. Some have even called the interacting system of organisms that live within the guts of most animals as an ecosystem, despite their residence within a single organism, which violates the levels of organization definition of ecosystems. Moreover, interactions between ecosystem components are as much a part of the definition of ecosystems as their constituent organisms, matter and energy. Despite the apparent contradictions that result from the flexibility of the ecosystem concept, it is just this flexibility that has made it such a useful and enduring concept.
The term "ecosystem" was first coined by Roy Clapham in 1930, but it was ecologist Arthur Tansley who fully defined the ecosystem concept. In his classic article of 1935, Tansley defined ecosystems as "The whole system,… including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". The ecosystem concept marked a critical advance in the science of ecology, as Tansely specifically used the term to replace the "superorganism" concept, which implied that communities of organisms formed something akin to a higher-level, more complex organism—a mistaken conception that formed a theoretical barrier to scientific research in ecology. Though Tansely and other ecologists also used the ecosystem concept in conjunction with the now defunct concept of the ecological "climax" (a "final", or "equilibrium" type of community or ecosystem arising under specific environmental conditions), the concept of ecosystem dynamics has now replaced this. Eugene Odum, a major figure in advancing the science of ecology, deployed the ecosystem concept in a central role in his seminal textbook on ecology, defining ecosystems as: "Any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (ie: exchange of materials between living and nonliving parts) within the system is an ecosystem."
Ecosystems may be observed in many possible ways, so there is no one set of components that make up ecosystems. However, all ecosystems must include both biotic and abiotic components, their interactions, and some source of energy. The simplest (and least representative) of ecosystems might therefore contain just a single living plant (biotic component) within a small terrarium exposed to light to which a water solution containing essential nutrients for plant growth has been added (abiotic environment). The other extreme would be the biosphere, which comprises the totality of Earth's organisms and their interactions with each other and the earth systems (abiotic environment). And of course, most ecosystems fall somewhere in between these extremes of complexity.
At a basic functional level, ecosystems generally contain primary producers capable of harvesting energy from the sun by photosynthesis and of using this energy to convert carbon dioxide and other inorganic chemicals into the organic building blocks of life. Consumers feed on this captured energy, and decomposers not only feed on this energy, but also break organic matter back into its inorganic constituents, which can be used again by producers. These interactions among producers and the organisms that consume and decompose them are called trophic interactions, and are composed of trophic levels in an energy pyramid, with most energy and mass in the primary producers at the base, and higher levels of feeding on top of this, starting with primary consumers feeding on primary producers, secondary consumers feeding on these, and so on. Trophic interactions are also described in more detailed form as a food chain, which organizes specific organisms by their trophic distance from primary producers, and by food webs, which detail the feeding interactions among all organisms in an ecosystem. Together, these processes of energy transfer and matter cycling are essential in determining ecosystem structure and function and in defining the types of interactions between organisms and their environment. It must also be noted that most ecosystems contain a wide diversity of species, and that this diversity should be considered part of ecosystem structure.
By definition, ecosystems use energy and cycle matter, and these processes also define the basic ecosystem functions. Energetic processes in ecosystems are usually described in terms of trophic levels, which define the role of organisms based on their level of feeding relative to the original energy captured by primary producers. As always, energy does not cycle, so ecosystems require a continuous flow of high-quality energy to maintain their structure and function. For this reason, all ecosystems are "open systems" requiring a net flow of energy to persist over time—without the sun, the biosphere would soon run out of energy!
Energy input to ecosystems drives the flow of matter between organisms and the environment in a process known as biogeochemical cycling. The biosphere provides a good example of this, as it interacts with and exchanges matter with the lithosphere, hydrosphere and atmosphere, driving the global biogeochemical cycles of carbon, nitrogen, phosphorus, sulfur and other elements. Ecosystem processes are dynamic, undergoing strong seasonal cycles in response to changes in solar irradiation, causing fluctuations in primary productivity and varying the influx of energy from photosynthesis and the fixation of carbon dioxide into organic materials over the year, driving remarkable annual variability in the carbon cycle—the largest of the global biogeochemical cycles. Fixed organic carbon in plants then becomes food for consumers and decomposers, who degrade the carbon to forms with lower energy, and ultimately releasing the carbon fixed by photosynthesis back into carbon dioxide in the atmosphere, producing the global carbon cycle. The biogeochemical cycling of nitrogen also uses energy, as bacteria fix nitrogen gas from the atmosphere into reactive forms useful for living organisms using energy obtained from organic materials and ultimately from plants and the sun. Ecosystems also cycle phosphorus, sulfur and other elements. As biogeochemical cycles are defined by the exchange of matter between organisms and their environment, they are classic examples of ecosystem-level proceses.
Freshwater biomes are generally distinguished by characteristics such as water depth and whether the water is moving or standing. Major freshwater biomes include ponds and lakes, streams and rivers, and wetlands.
Marine biomes are generally distinguished by the depth of the water and whether there is a substrate on which organisms can attach. Important marine biomes include oceans, coral reefs, and estuaries. The ocean biome, the largest of all of the earth's biomes, can be divided into several zones including the shore/intertidal zone, the pelagic zone, the benthic zone, and the abyssal zone.
Humans have fundamentally altered global patterns of biodiversity and ecosystem processes. As a result, vegetation forms predicted by conventional biome systems are rarely observed across most of Earth's land surface. While not a replacement for existing biome systems, anthropogenic biomes provide an alternative view of the terrestrial biosphere based on global patterns of sustained direct human interaction with ecosystems, including agriculture, human settlements, urbanization, forestry and other uses of land. Anthropogenic biomes offer a new way forward in ecology and conservation by recognizing the irreversible coupling of human and ecological systems at global scales, and moving us toward an understanding how best to live in and manage our biosphere and the anthropogenic biomes we live in.
Ecological communities can share characteristics for a number of reasons. Classifying communities into biomes attempts to highlight the role of the physical environment in determining characteristics of communities.
Communities can also be classified into
biogeographical realms (e.g, Australasia, Antarctic, Afrotropic, Indo-Malayan,
The ecoregion, a relatively large unit of land that contains geographically distinct assemblages of natural communities, is a subset of a biome found within a biogeographic realm. The World Wildlife Fund has identified 825 terrestrial ecoregions, 450 freshwater ecoregions, and 229 marine ecoregions. Several distinct ecological communities may be found in a single ecoregion.
The environment in which the man and other organisms live is called the biosphere. The biosphere is made up of different regions that have different types of flora (plants) and fauna (animals). The types of organisms in an area are determined by various factors such as the climate, temperature, rainfall, etc.
The regions based on their physical and biological nature are classified into ecosystems. For example, pond ecosystem, evergreen forest ecosystem, desert ecosystem, etc. The organisms, in addition to being dependent on the environment for their needs, are also dependent on each other. This dependency is especially for food. This results in the presence of food chains and food webs.
Food Chain in Nature(P = producer, H = herbivore, C1 = carnivore order-1, C2 = carnivore order-2)
The food chains and other such interrelationships in the ecosystems create a balance in the environment that is called the ecological balance.
Man is also a part of these food chains and webs. However, man tries to modify the environment to suit his needs unlike the other components of the ecosystem. This has upset the delicate balance being maintained in the environment.
ATMOSPHERE : Atmosphere includes Chemical and Photochemical Reactions in the Atmosphere; Reaction of Atmospheric Nitrogen; Reaction of Atmospheric Oxygen; Water in the Atmosphere; Fog; Temperature etc.
FORESTS: Forests constitute a major part of the natural environment. There are many Forest Types; Classification of Forests includes Social Forestry and Community Forestry.
HYDROSPHERE: Refers to water related environment.
INDIAN RIVERS: River and their Major Tributaries are examples of water borne environment. River Ganga;; River Gomti; River Chambal; River Brahmaputra; River Yamuna; River Narmada constitute this aspect of the environment.
MOUNTAINS: Mountains are also major parts of natural environment. The Geography of the Himalaya its Sub-divisions; Agricultural Systems; Animal Husbandry; Grassland; Land Resources and Tourism; Forest Wealth Wildlife are important in this regard. Environmental Management of the Himalayas which includes Conserving and Managing the Depleting Resources of Plants; Conservation & Management of the Wildlife need to be looked into to maintain the ecological balance. Depleting forest resources, managing the hazards are yet another group of issues that have to be looked into.
An ecosystem (or ecological system) is a collection of communities of organisms and the environment in which they live. Ecosystems can vary greatly in size. Some examples of small ecosystems are tidal pools, a home garden, or the stomach of an individual cow.
An ecosystem is a group of living and non-living components interacting together on a given physical landscape. The size of an ecosystem is arbitrary and could be as small as a few square centimeters if you are looking at a soil microbial ecosystem; as large as thousands of square kilometers if you are looking a biome like the Great Plains ecosystem; or a few hectares if you are looking at a single forest stand ecosystem.
Major Components of Ecosystems
Ecosystems are composed of a variety of abiotic and biotic components that function in an interrelated fashion. Some of the more important components are: soil, atmosphere, radiation from the Sun, water, and living organisms.
Soils are much more complex than simple sediments. They contain a mixture of weathered rock fragments, highly altered soil mineral particles, organic matter, and living organisms. Soils provide nutrients, water, a home, and a structural growing medium for organisms. The vegetation found growing on top of a soil is closely linked to this component of an ecosystem through nutrient cycling.
The atmosphere provides organisms found within ecosystems with carbon dioxide for photosynthesis and oxygen for respiration. The processes ofevaporation, transpiration, and precipitation cycle water between the atmosphere and the Earth's surface.
Solar radiation is used in ecosystems to heat the atmosphere and to evaporate and transpire water into the atmosphere. Sunlight is also necessary forphotosynthesis. Photosynthesis provides the energy for plant growth and metabolism, and the organic food for other forms of life.
Most living tissue is composed of a very high percentage of water, up to and even exceeding 90%. The protoplasm of a very few cells can survive if their water content drops below 10%, and most are killed if it is less than 30-50%. Water is the medium by which mineral nutrients enter and are translocated in plants. It is also necessary for the maintenance of leaf turgidity and is required for photosynthetic chemical reactions. Plants and animals receive their water from the Earth's surface and soil. The original source of this water is precipitation from the atmosphere.
Ecosystems are composed of a variety of living organisms that can be classified as producers, consumers, or decomposers. Producers orautotrophs, are organisms that can manufacture the organic compounds they use as sources of energy and nutrients. Most producers are green plants that can manufacture their food through the process of photosynthesis. Consumers or heterotrophs get their energy and nutrients by feeding directly or indirectly on producers. We can distinguish two main types of consumers. Herbivores are consumers that eat plants for their energy and nutrients. Organisms that feed on herbivores are called carnivores. Carnivores can also consume other carnivores. Plants and animals supply organic matter to the soil system through shed tissues and death. Consumer organisms that feed on this organic matter, or detritus, are known as detritivores ordecomposers. The organic matter that is consumed by the detritivores is eventually converted back into inorganic nutrients in the soil. These nutrients can then be used by plants for the production of organic compounds.
Energy and Matter Flow in Ecosystems
Many of the most important relationships between living organisms and the environment are controlled ultimately by the amount of available incoming energy received at the Earth's surface from the Sun. It is this energy which helps to drive biotic systems. The Sun's energy allows plants to convert inorganic chemicals into organic compounds.
Only a very small proportion of the sunlight received at the Earth's surface is transformed into biochemical form. Several studies have been carried out to determine this amount. A study of an Illinois cornfield reported that 1.6% of the available solar radiation was photosythetically utilized by the corn. Other data suggests that even the most efficient ecosystems seldom incorporate more than 3% of the available solar insolation. Most ecosystems fixless than 1% of the sunlight available for photosynthesis.
Living organisms can use energy in basically two forms: radiant or fixed. Radiant energy exists in the form of electromagnetic energy, such as light.Fixed energy is the potential chemical energy found in organic substances. This energy can be released through respiration. Organisms that can take energy from inorganic sources and fix it into energy rich organic molecules are called autotrophs. If this energy comes from light then these organisms are called photosynthetic autotrophs. In most ecosystems plants are the dominant photosynthetic autotroph.
Organisms that require fixed energy found in organic molecules for their survival are called heterotrophs. Heterotrophs who obtain their energy from living organisms are called consumers. Consumers can be of two basic types: Consumer and decomposers. Consumers that consume plants are know as herbivores. Carnivores are consumers who eat herbivores or other carnivores. Decomposers or detritivores are heterotrophs that obtain their energy either from dead organisms or from organic compounds dispersed in the environment.
Once fixed by plants, organic energy can move within the ecosystem through the consumption of living or dead organic matter. Upon decomposition the chemicals that were once organized into organic compounds are returned to their inorganic form and can be taken up by plants once again. Organic energy can also move from one ecosystem to another by a variety of processes. These processes include: animal migration, animal harvesting, plant harvesting, plant dispersal of seeds, leaching, and erosion. The following diagram models the various inputs and outputs of energy and matter in a typical ecosystem.
Habitat - Laura - "the natural environment of an organism; place that is natural for the life and growth of an organism: a tropical habitat." [dictionary.com]
Habitats are found within a system of
interactions between organisms and their environment. Habitats vary in size and
are places where a group of living organisms live at the same time.
Parasite - (parasitism) "An organism that lives in or on and takes its nourishment from another organism. A parasite cannot live independently."⁴
Star Trek illustration of a parasite (rather gross) Note that the host is harmed by the parasite inside.³
Host -Mrs Van Meter - "an organism that harbors [another]... typically providing nourishment and shelter"
Symbiote (symbiotic) - The way two organisms interact (mutualism, predation, commensalism, parasitism are all categories of symbiosis)
Mutualism - A relationship where both organisms benefit.
Commensalism- Mrs. Van Meter - a relationship where one organism benefits and the other is neither benefitted nor harmed
Predator (prey) - Chris - "carnivorous animal or destructive organism: a carnivorous animal that hunts, kills, and eats other animals in order to survive, or any other organism that behaves in a similar manner"
Competition - Joey - http://www.biology-online.org/dictionary/Competition
competition- the use of the same limited resource by two or more species.
Population - Shawna group of organisms of the same species inhabiting a given area. (Shawn McCarthy) Community - Erin "an assemblage of interacting populations occupying a given area" - http://dictionary.reference.com/browse/community
Consumer - (which is the same as Heterotroph) Tianna - consumers are organisms (including us humans) that get their energy from producers, regarding the flow of energy through an ecosystem. For example, producers, (such as plants), make their own food by the process of photosynthesis. If we were to say, an organism ate this plant, than it would be a primary consumer. The animal that eats this animal is known as the second order consumer. And so on and so forth. Scientifically, all consumers are either herbivores, carnivores, omnivores or detrivores (decomposers and other organism that break down organic matter).
It is useful to remember that all consumers and producers belong in food chains consumers are the one that depend on producers to survive. then, the energy is now transfered to the consumers.
Herbivore - Tim - A herbivore is an animal that gets its energy from eating plants, and only plants. Can also eat parts of plants, but generally only the fruits and vegetables produced by fruit-bearing plants. Many herbivores have special digestive systems that let them digest all kinds of plants, including grasses. Herbivores need a lot of energy to stay alive. Many of them, like cows and sheep, eat all day long. There should be a lot of plants in your ecosystem to support your herbivores. If you put carnivores or some omnivores in your ecosystem, they'll eat your herbivores, so make sure you have enough herbivores to support them. "What is an