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 "spheres" of earth
systems. (Source: Institute for Computational Earth System Science)
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.
Coral Reef. (Source: Coral Reef Alliance Photobank)
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,
Neartic, Neotropic,
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.
Natural 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.
Ecologycal system
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