Changes

==Ecosystems==

==Ecosystems==

[[Loch Lomond]] in Scotland forms a relatively isolated ecosystem. The fish community of this lake has remained unchanged over a very long period.<ref>{{cite journal | last=Adams | first=C.E. | title=The fish community of Loch Lomond, Scotland : its history and rapidly changing status | journal=Hydrobiologia | year=1994 | volume=290 | issue=1-3 | pages=91-102 | url=http://cat.inist.fr/?aModele=afficheN&cpsidt=3302548 }}</ref>]]

[[Loch Lomond]] in Scotland forms a relatively isolated ecosystem. The fish community of this lake has remained unchanged over a very long period. [http://cat.inist.fr/?aModele=afficheN&cpsidt=3302548]  

All forms of life interact with the environment in which they exist, and also with other life forms.  In the 20th century this premise gave rise to the concept of '''ecosystems''', which can be defined as any situation where there is interaction between organisms and their environment.

All forms of life interact with the environment in which they exist, and also with other life forms.  In the 20th century this premise gave rise to the concept of '''ecosystems''', which can be defined as any situation where there is interaction between organisms and their environment.

Ecosystems are composed of a variety of [[abiotic]] and [[biotic]] components that function in an interrelated way.<ref>{{cite web |last=Pidwirny |first=Michael |year=2006 |work=Fundamentals of Physical Geography (2nd Edition) |title=Introduction to the Biosphere: Introduction to the Ecosystem Concept |url=http://www.physicalgeography.net/fundamentals/9j.html |accessmonthday=September 28|accessyear=2006}}</ref> The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms.

Ecosystems are composed of a variety of [[abiotic]] and [[biotic]] components that function in an interrelated way.[http://www.physicalgeography.net/fundamentals/9j.html] The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms.

Each living organism has a continual relationship with every other element that makes up its environment. Within the ecosystem, species are connected and dependent upon one another in the [[food chain]], and exchange [[energy]] and [[matter]] between themselves as well as with their environment.<ref>{{cite web |last=Pidwirny |first=Michael |year=2006 |work=Fundamentals of Physical Geography (2nd Edition) |title=Introduction to the Biosphere: Organization of Life |url=http://www.physicalgeography.net/fundamentals/9d.html |accessmonthday=September 28|accessyear=2006}}</ref></blockquote>

Each living organism has a continual relationship with every other element that makes up its environment. Within the ecosystem, species are connected and dependent upon one another in the [[food chain]], and exchange [[energy]] and [[matter]] between themselves as well as with their environment.[http://www.physicalgeography.net/fundamentals/9d.html]

Every species has limits of tolerance to factors that affect its survival, reproductive success and ability to continue to thrive and interact sustainably with the rest of its environment, which in turn may have effects on these factors for many other species or even on the whole of life.<ref>{{cite web |last=Pidwirny |first=Michael |year=2006 |work=Fundamentals of Physical Geography (2nd Edition) |title=Introduction to the Biosphere: Abiotic Factors and  the Distribution of Species |url=http://www.physicalgeography.net/fundamentals/9e.html |accessmonthday=September 28|accessyear=2006}} esp. section on "Abiotic Factors and Tolerance Limits."</ref> The concept of an ecosystem is thus an important subject of study, as such study provides information needed to make decisions about how human life may interact in a way that allows the various ecosystems to be sustained for future use rather than used up or otherwise rendered ineffective. For the purpose of such study, a unit of smaller size is called a ''[[microecosystem]]''. For example, an ecosystem can be a stone and all the life under it. A ''macroecosystem'' might involve a whole [[ecoregion]], with its [[drainage basin]].<ref>{{cite journal |last=Bailey |first=Robert G. |year=2004 |month=April |title=Identifying Ecoregion Boundaries |journal=Environmental Management |volume=34 |issue=Supplement 1 |url=http://www.fs.fed.us/institute/news_info/Identifying_ecoregion_boundaries.pdf |id={{doi|10.1007/s00267-003-0163-6}} }}</ref>

Every species has limits of tolerance to factors that affect its survival, reproductive success and ability to continue to thrive and interact sustainably with the rest of its environment, which in turn may have effects on these factors for many other species or even on the whole of life.[http://www.physicalgeography.net/fundamentals/9e.html]  esp. section on "Abiotic Factors and Tolerance Limits." The concept of an ecosystem is thus an important subject of study, as such study provides information needed to make decisions about how human life may interact in a way that allows the various ecosystems to be sustained for future use rather than used up or otherwise rendered ineffective. For the purpose of such study, a unit of smaller size is called a ''[[microecosystem]]''. For example, an ecosystem can be a stone and all the life under it. A ''macroecosystem'' might involve a whole [[ecoregion]], with its [[drainage basin]].[http://www.fs.fed.us/institute/news_info/Identifying_ecoregion_boundaries.pdf]

The following ecosystems are examples of the kinds currently under intensive study:

The following ecosystems are examples of the kinds currently under intensive study:

* [[oceanic]] ecosystems.

* [[oceanic]] ecosystems.

Another classification can be made by reference to its communities, such as in the case of a [[human ecosystem]]. Regional groupings of distinctive plant and animals best adapted to the region's physical [[natural environment]], latitude, altitude, and terrain are known as [[biome]]s. The broadest classification, today under wide study and analysis, and also subject to widespread arguments about its nature and validity, is that of the entire sum of life seen as analogous to a self-sustaining organism; a theory studied as [[Earth science|earth system science]] (less formally known as [[Gaia theory]]).<ref>{{cite journal | last = Lawton | first = John | title=Earth System Science | journal=Science | year=2001 | volume=292 | issue=5524 | pages=1965 | url=http://www.sciencemag.org/cgi/content/summary/292/5524/1965 }}</ref><ref>{{cite web | first =Stephan | last=Harding | year = 2006 | url = http://www.schumachercollege.org.uk/articles/college-articles/stephan/earthsystemscience.html | title = Earth System Science and Gaian Science | publisher = Schumacher College | accessdate = 2007-01-07 }}</ref>

Another classification can be made by reference to its communities, such as in the case of a [[human ecosystem]]. Regional groupings of distinctive plant and animals best adapted to the region's physical [[natural environment]], latitude, altitude, and terrain are known as [[biome]]s. The broadest classification, today under wide study and analysis, and also subject to widespread arguments about its nature and validity, is that of the entire sum of life seen as analogous to a self-sustaining organism; a theory studied as [[Earth science|earth system science]] (less formally known as [[Gaia theory]]).[http://www.sciencemag.org/cgi/content/summary/292/5524/1965] [http://www.schumachercollege.org.uk/articles/college-articles/stephan/earthsystemscience.html]

==Human interrelationship==

==Human interrelationship==