Ecosystem ecology

Ecosystem ecology is the integrated study of living (biotic) and non-living (abiotic) components of ecosystems and their interactions within an ecosystem framework. This science examines how ecosystems work and relates this to their components such as chemicals, bedrock, soil, plants, and animals.

Ecosystem ecology examines physical and biological structures and examines how these ecosystem characteristics interact with each other. Ultimately, this helps us understand how to maintain high quality water and economically viable commodity production. A major focus of ecosystem ecology is on functional processes, ecological mechanisms that maintain the structure and services produced by ecosystems. These include primary productivity (production of biomass), decomposition, and trophic interactions.

Studies of ecosystem function have greatly improved human understanding of sustainable production of forage, fiber, fuel, and provision of water. Functional processes are mediated by regional-to-local level climate, disturbance, and management. Thus ecosystem ecology provides a powerful framework for identifying ecological mechanisms that interact with global environmental problems, especially global warming and degradation of surface water.

This example demonstrates several important aspects of ecosystems:

  1. Ecosystem boundaries are often nebulous and may fluctuate in time
  2. Organisms within ecosystems are dependent on ecosystem level biological and physical processes
  3. Adjacent ecosystems closely interact and often are interdependent for maintenance of community structure and functional processes that maintain productivity and biodiversity

These characteristics also introduce practical problems into natural resource management. Who will manage which ecosystem? Will timber cutting in the forest degrade recreational fishing in the stream? These questions are difficult for land managers to address while the boundary between ecosystems remains unclear; even though decisions in one ecosystem will affect the other. We need better understanding of the interactions and interdependencies of these ecosystems and the processes that maintain them before we can begin to address these questions.

Ecosystem ecology is an inherently interdisciplinary field of study. An individual ecosystem is composed of populations of organisms, interacting within communities, and contributing to the cycling of nutrients and the flow of energy. The ecosystem is the principal unit of study in ecosystem ecology.

Population, community, and physiological ecology provide many of the underlying biological mechanisms influencing ecosystems and the processes they maintain. Flowing of energy and cycling of matter at the ecosystem level are often examined in ecosystem ecology, but, as a whole, this science is defined more by subject matter than by scale. Ecosystem ecology approaches organisms and abiotic pools of energy and nutrients as an integrated system which distinguishes it from associated sciences such as biogeochemistry.[1]

Biogeochemistry and hydrology focus on several fundamental ecosystem processes such as biologically mediated chemical cycling of nutrients and physical-biological cycling of water. Ecosystem ecology forms the mechanistic basis for regional or global processes encompassed by landscape-to-regional hydrology, global biogeochemistry, and earth system science.[1]

Ecoecolfigure1
Figure 1. A riparian forest in the White Mountains, New Hampshire (USA).

History

Ecosystem ecology is philosophically and historically rooted in terrestrial ecology. The ecosystem concept has evolved rapidly during the last 100 years with important ideas developed by Frederic Clements, a botanist who argued for specific definitions of ecosystems and that physiological processes were responsible for their development and persistence.[2] Although most of Clements ecosystem definitions have been greatly revised, initially by Henry Gleason and Arthur Tansley, and later by contemporary ecologists, the idea that physiological processes are fundamental to ecosystem structure and function remains central to ecology.

Silver Spring Model
Figure 3. Energy and matter flows through an ecosystem, adapted from the Silver Springs model.[3] H are herbivores, C are carnivores, TC are top carnivores, and D are decomposers. Squares represent biotic pools and ovals are fluxes or energy or nutrients from the system.

Later work by Eugene Odum and Howard T. Odum quantified flows of energy and matter at the ecosystem level, thus documenting the general ideas proposed by Clements and his contemporary Charles Elton.

In this model, energy flows through the whole system were dependent on biotic and abiotic interactions of each individual component (species, inorganic pools of nutrients, etc.). Later work demonstrated that these interactions and flows applied to nutrient cycles, changed over the course of succession, and held powerful controls over ecosystem productivity.[4][5] Transfers of energy and nutrients are innate to ecological systems regardless of whether they are aquatic or terrestrial. Thus, ecosystem ecology has emerged from important biological studies of plants, animals, terrestrial, aquatic, and marine ecosystems.

Ecosystem services

Ecosystem services are ecologically mediated functional processes essential to sustaining healthy human societies.[6] Water provision and filtration, production of biomass in forestry, agriculture, and fisheries, and removal of greenhouse gases such as carbon dioxide (CO2) from the atmosphere are examples of ecosystem services essential to public health and economic opportunity. Nutrient cycling is a process fundamental to agricultural and forest production.

However, like most ecosystem processes, nutrient cycling is not an ecosystem characteristic which can be “dialed” to the most desirable level. Maximizing production in degraded systems is an overly simplistic solution to the complex problems of hunger and economic security. For instance, intensive fertilizer use in the midwestern United States has resulted in degraded fisheries in the Gulf of Mexico.[7] Regrettably, a “Green Revolution” of intensive chemical fertilization has been recommended for agriculture in developed and developing countries.[8][9] These strategies risk alteration of ecosystem processes that may be difficult to restore, especially when applied at broad scales without adequate assessment of impacts. Ecosystem processes may take many years to recover from significant disturbance.[5]

For instance, large-scale forest clearance in the northeastern United States during the 18th and 19th centuries has altered soil texture, dominant vegetation, and nutrient cycling in ways that impact forest productivity in the present day.[10][11] An appreciation of the importance of ecosystem function in maintenance of productivity, whether in agriculture or forestry, is needed in conjunction with plans for restoration of essential processes. Improved knowledge of ecosystem function will help to achieve long-term sustainability and stability in the poorest parts of the world.

Operation

Biomass productivity is one of the most apparent and economically important ecosystem functions. Biomass accumulation begins at the cellular level via photosynthesis. Photosynthesis requires water and consequently global patterns of annual biomass production are correlated with annual precipitation.[12] Amounts of productivity are also dependent on the overall capacity of plants to capture sunlight which is directly correlated with plant leaf area and N content.

Net primary productivity (NPP) is the primary measure of biomass accumulation within an ecosystem. Net primary productivity can be calculated by a simple formula where the total amount of productivity is adjusted for total productivity losses through maintenance of biological processes:

NPP = GPP – Rproducer
Ecoecolfigure4
Figure 4. Seasonal and annual changes in ambient carbon dioxide (CO2) concentration at Mauna Loa Hawaii (Atmosphere) and above the canopy of a deciduous forest in Massachusetts (Forest). Data show clear seasonal trends associated with periods of high and low NPP and an overall annual increase of atmospheric CO2. Data approximates of those reported by Keeling and Whorf[13] and Barford.[14]

Where GPP is gross primary productivity and Rproducer is photosynthate (Carbon) lost via cellular respiration.

NPP is difficult to measure but a new technique known as eddy co-variance has shed light on how natural ecosystems influence the atmosphere. Figure 4 shows seasonal and annual changes in CO2 concentration measured at Mauna Loa, Hawaii from 1987 to 1990. CO2 concentration steadily increased, but within-year variation has been greater than the annual increase since measurements began in 1957.

These variations were thought to be due to seasonal uptake of CO2 during summer months. A newly developed technique for assessing ecosystem NPP has confirmed seasonal variation are driven by seasonal changes in CO2 uptake by vegetation.[15][14] This has led many scientists and policy makers to speculate that ecosystems can be managed to ameliorate problems with global warming. This type of management may include reforesting or altering forest harvest schedules for many parts of the world.

Decomposition and nutrient cycling

Decomposition and nutrient cycling are fundamental to ecosystem biomass production. Most natural ecosystems are nitrogen (N) limited and biomass production is closely correlated with N turnover.[16][17] Typically external input of nutrients is very low and efficient recycling of nutrients maintains productivity.[5] Decomposition of plant litter accounts for the majority of nutrients recycled through ecosystems (Figure 3). Rates of plant litter decomposition are highly dependent on litter quality; high concentration of phenolic compounds, especially lignin, in plant litter has a retarding effect on litter decomposition.[18][19] More complex C compounds are decomposed more slowly and may take many years to completely breakdown. Decomposition is typically described with exponential decay and has been related to the mineral concentrations, especially manganese, in the leaf litter.[20][21]

Ecoecolfigure5
Figure 5. Dynamics of decomposing plant litter (A) described with an exponential model (B) and a combined exponential-linear model (C).

Globally, rates of decomposition are mediated by litter quality and climate.[22] Ecosystems dominated by plants with low-lignin concentration often have rapid rates of decomposition and nutrient cycling (Chapin et al. 1982). Simple carbon (C) containing compounds are preferentially metabolized by decomposer microorganisms which results in rapid initial rates of decomposition, see Figure 5A,[23] models that depend on constant rates of decay; so called “k” values, see Figure 5B.[24] In addition to litter quality and climate, the activity of soil fauna is very important [25]

However, these models do not reflect simultaneous linear and non-linear decay processes which likely occur during decomposition. For instance, proteins, sugars and lipids decompose exponentially, but lignin decays at a more linear rate[18] Thus, litter decay is inaccurately predicted by simplistic models.[26]

A simple alternative model presented in Figure 5C shows significantly more rapid decomposition that the standard model of figure 4B. Better understanding of decomposition models is an important research area of ecosystem ecology because this process is closely tied to nutrient supply and the overall capacity of ecosystems to sequester CO2 from the atmosphere.

Trophic dynamics

Trophic dynamics refers to process of energy and nutrient transfer between organisms. Trophic dynamics is an important part of the structure and function of ecosystems. Figure 3 shows energy transferred for an ecosystem at Silver Springs, Florida. Energy gained by primary producers (plants, P) is consumed by herbivores (H), which are consumed by carnivores (C), which are themselves consumed by “top- carnivores”(TC).

One of the most obvious patterns in Figure 3 is that as one moves up to higher trophic levels (i.e. from plants to top-carnivores) the total amount of energy decreases. Plants exert a “bottom-up” control on the energy structure of ecosystems by determining the total amount of energy that enters the system.[27]

However, predators can also influence the structure of lower trophic levels from the top-down. These influences can dramatically shift dominant species in terrestrial and marine systems[28][29] The interplay and relative strength of top-down vs. bottom-up controls on ecosystem structure and function is an important area of research in the greater field of ecology.

Trophic dynamics can strongly influence rates of decomposition and nutrient cycling in time and in space. For example, herbivory can increase litter decomposition and nutrient cycling via direct changes in litter quality and altered dominant vegetation.[30] Insect herbivory has been shown to increase rates of decomposition and nutrient turnover due to changes in litter quality and increased frass inputs.[1][31]

However, insect outbreak does not always increase nutrient cycling. Stadler[32] showed that C rich honeydew produced during aphid outbreak can result in increased N immobilization by soil microbes thus slowing down nutrient cycling and potentially limiting biomass production. North atlantic marine ecosystems have been greatly altered by overfishing of cod. Cod stocks crashed in the 1990s which resulted in increases in their prey such as shrimp and snow crab[29] Human intervention in ecosystems has resulted in dramatic changes to ecosystem structure and function. These changes are occurring rapidly and have unknown consequences for economic security and human well-being.

Applications and importance

Lessons from two Central American cities

The biosphere has been greatly altered by the demands of human societies. Ecosystem ecology plays an important role in understanding and adapting to the most pressing current environmental problems. Restoration ecology and ecosystem management are closely associated with ecosystem ecology. Restoring highly degraded resources depends on integration of functional mechanisms of ecosystems.[33]

Without these functions intact, economic value of ecosystems is greatly reduced and potentially dangerous conditions may develop in the field. For example, areas within the mountainous western highlands of Guatemala are more susceptible to catastrophic landslides and crippling seasonal water shortages due to loss of forest resources. In contrast, cities such as Totonicapán that have preserved forests through strong social institutions have greater local economic stability and overall greater human well-being.[34]

This situation is striking considering that these areas are close to each other, the majority of inhabitants are of Mayan descent, and the topography and overall resources are similar. This is a case of two groups of people managing resources in fundamentally different ways. Ecosystem ecology provides the basic science needed to avoid degradation and to restore ecosystem processes that provide for basic human needs.

See also

References

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  2. ^ Hagen, J.B. (1992). An Entangled Bank: The origins of ecosystem ecology. Rutgers University Press, New Brunswick, N.J.
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  4. ^ Odum, E.P 1969. "The strategy of ecosystem development". in: Science 164:262-270.
  5. ^ a b c Likens, G. E., F. H. Bormann, N. M. Johnson, D. W. Fisher and R. S. Pierce. (1970). "Effects of forest cutting and herbicide treatment on nutrient budgets in the Hubbard Brook watershed-ecosystem". in: Ecological Monographs 40:23-47.
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  14. ^ a b Barford, C. C., ea. (2001). "Factors controlling long and short term sequestration of atmospheric CO2 in a mid-latitude forest". In: Science 294: 1688-1691
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  20. ^ Davey MP, B Berg, P Rowland, BA Emmett. 2007. Decomposition of oak leaf litter is related to initial litter Mn concentrations. Canadian Journal of Botany. 85(1). 16-24.
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Amy T. Austin

Amy Theresa Austin is an Argentinan ecologist. She is a Principal Research Scientist at the National Scientific and Technical Research Council in Argentina and a Professor at the Faculty of Agronomy, University of Buenos Aires.

In 1988, she received a Bachelor of Arts in Environmental Science at Willamette University and a Doctor of Philosophy in Biological Sciences at Stanford University in 1997.”

In 2018, she is awarded the L'Oréal-UNESCO For Women in Science Awards “For her remarkable contributions to understanding terrestrial ecosystem ecology in natural and human-modified landscapes.”

Athens Township, Isanti County, Minnesota

Athens Township is in Isanti County, Minnesota. The population was 2,322 in the 2000 census.

The township was named directly or indirectly after Athens, the capital of Greece.

Cedar Creek Ecosystem Science Reserve

The Cedar Creek Ecosystem Science Reserve is an ecological research site located primarily in East Bethel, Minnesota in the counties of Anoka and Isanti on the northern edge of the Minneapolis-Saint Paul metropolitan area. Encompassing 5,400 acres (22 km2) of native upland forests and prairie and lowland swamps and meadows, the site contains over 900 plots of long-term experimental research which evaluate plant competition and biodiversity. The herbivory research division examines animal and plant relationships. Led by prominent American ecologist G. David Tilman, the University schedules more than 130 faculty, post-doctoral researchers, graduate students, staff, and undergraduate researcher interns to the site as of 2006.Established in 1942 by the University of Minnesota, the site was designated a National Natural Landmark by the National Park Service in 1975 and 1980 under the Historic Sites Act. It received this designation in May 1975 from the United States Secretary of the Interior, giving it recognition as an outstanding example of the nation's natural history. The designation describes it as a

Relatively undisturbed area where three biomes meet (tall grass prairie, eastern deciduous forest and boreal coniferous forest), supporting 61 species of mammals and 259 species of birds . A nationally and internationally famous research center.

It was later designated by the National Science Foundation as a Long Term Ecological Research site in 1982. Minnesota ecologists purchased land parcels through 1929 until the University's acquisition in 1940. The site is currently operated by the University's College of Biological Sciences in cooperation with the Minnesota Academy of Science.Often considered to be the birthplace of the modern science of ecosystem ecology, the research site tested the first radio collars for animal tracking in the 1960s and developed prescribed burning techniques for savannas. The claim is attributed to limnologist Raymond Lindeman (1915-1942) who performed his PhD research on the ecological dynamics of Cedar Bog Lake located in the reserve. Linking Sir Arthur Tansley's coined term "ecosystem" to field research, his studies were influential in forming modern ecosystem ecology.Originally the site was officially designated the Cedar Creek Forest which takes its name for Cedar Creek that winds through East Bethel. The bog where the site initially began was informally called by professors "Decodon Bog." The site was known as Cedar Creek Natural History Area until its change in 2007.

Christopher B. Anderson

Dr. Christopher B. Anderson (born 31 December 1976 in North Carolina) is an American ecologist working in southern Patagonia's Tierra del Fuego Archipelago, shared between Chile and Argentina. Anderson obtained his B.S. in Biology with Honors from the University of North Carolina at Chapel Hill in 1999 and his Ph.D. in Ecology from the Odum School of Ecology - University of Georgia in 2006. His research in southern Patagonia has involved social entrepreneurial efforts, as well, such as the creation of the Omora Sub-Antarctic Research Alliance (USA), a non-profit dedicated to promoting research, education and conservation in Tierra del Fuego and southern Patagonia. Anderson and his colleagues also have developed long-term socio-ecological research platforms that attempt to link long-term academic endeavors with society to demonstrate the inextricable union between conservation and social well being. In 2005, this initiative was able to successfully apply to UNESCO to obtain the designation of the Cape Horn Biosphere Reserve.

Anderson was the founding coordinator of Chile's Long-Term Socio-Ecological Research Network, and from 2009-2011 was the Administrative Director of the Sub-Antarctic Biocultural Conservation Program, a binational effort between the University of North Texas and the Universiad de Magallanes. Currently, he is a Visiting Scientist at the Forestry Resources Lab at the Austral Center for Scientific Research in Ushuaia, Argentina, where his research focuses broadly on watershed ecosystem ecology and the role of invasive species in Tierra del Fuego, particularly the eradication of North American beavers. Honors for his research and teaching include a Fulbright Fellowship from the U.S. State Department, a National Security Education Program Grant from the U.S. Department of Defense, various National Science Foundation grants, a Tinker Foundation Award, and a UGA Excellence in Undergraduate Mentoring Award.

Ecosystem

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one-another, animals play an important role in the movement of matter and energy through the system. 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 other microbes.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 the ecosystem. Unlike external factors, internal factors are controlled, for example, decomposition, root competition, shading, disturbance, succession, and the types of species present.

Ecosystems are dynamic entities—they are subject to periodic disturbances and are in the process of recovering from some past disturbance. 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. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops.Resource inputs are generally controlled by external processes like climate and parent material. Resource availability within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Although humans operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.Biodiversity affects ecosystem functioning, as do the processes of disturbance and succession. Ecosystems provide a variety of goods and services upon which people depend.

Eugene Odum

Eugene Pleasants Odum (September 17, 1913 – August 10, 2002) was an American biologist at the University of Georgia known for his pioneering work on ecosystem ecology. He and his brother Howard T. Odum wrote the popular ecology textbook, Fundamentals of Ecology (1953). The Odum School of Ecology is named in his honor.

Functional Ecology (journal)

Functional Ecology is a bimonthly peer-reviewed scientific journal on organismal ecology publishing papers on physiological, behavioural, and evolutionary ecology, emphasising an integrative approach. The scope of the journal has changed over time. A recent editorial stated that the journal is increasing its coverage of community, evolutionary, and ecosystem ecology. The journal was established in 1987 and is published by Wiley-Blackwell on behalf of the British Ecological Society. The editor-in-chief is Charles Fox (University of Kentucky).

Guelta

A guelta (Arabic: قلتة‎, also transliterated qalta or galta; Berber: agelmam) is a pocket of water that forms in drainage canals or wadis in the Sahara. The size and duration will depend on the location and conditions. It may last year-round through the dry season if fed by a source such as a spring. When a river (wadi) dries up, there may be pockets of water remaining along its course (c.f. oxbow lake). In Western Sahara, gueltas correspond with oases.Some examples include Guelta d'Archei in Chad and Timia in Niger.

Howard T. Odum

Howard Thomas Odum (September 1, 1924 – September 11, 2002), usually cited as H. T. Odum, was an American ecologist. He is known for his pioneering work on ecosystem ecology, and for his provocative proposals for additional laws of thermodynamics, informed by his work on general systems theory.

International Biological Program

The International Biological Program (IBP) was an effort between 1964 and 1974 to coordinate large-scale ecological and environmental studies. Organized in the wake of the successful International Geophysical Year (IGY) of 1957-1958, the International Biological Program was an attempt to apply the methods of big science to ecosystem ecology and pressing environmental issues.

The IBP was organized under the leadership of C. H. Waddington beginning in 1962 and officially started in 1964, with the goal of exploring "The Biological Basis of Productivity and Human Welfare". In its early years, Canadian and European ecologists were the main participants; by 1968, the United States also became heavily involved. However, unlike other more successful applications of the big science model of scientific research, the IBP lacked a clear, socially and scientifically pressing goal. Many biologists, particularly molecular biologists and evolutionary ecologists, were sharply critical of the IBP, which they viewed as throwing money at ill-defined or relatively unimportant problems and reducing the freedom of scientists to choose their own research projects.The main results of the IBP were five biome studies, the largest of which were the Grassland Biome project and the Eastern Deciduous Forest Biome project (both of which had ties to Oak Ridge National Laboratory, which provided tracer isotopes for nutrient- and energy-flow experiments). Though the impact of these studies was modest, the IBP marked a dramatic increase in the scale of funding for ecosystem ecology, which remained high (relative to earlier levels) even after the conclusion of the program in June 1974. Far more influential than any of the IBP biome studies was contemporary Hubbard Brook ecosystem study of 1963-1968, which—lacking the hierarchical organization of IBP projects—grew gradually according to individual scientists' interest and involved more informal collaboration.One of the most influential IBP projects in Europe was the Solling Project in Lower Saxony (Germany), led by Heinz Ellenberg. Evidence from here proved decisive in the 1980s to track down acid rain as a major cause of forest decline.

In tropical areas, the LAMTO project held by French professor Maxime Lamotte in Ivory Coast provided a thorough analysis of the savannah energy budget and a profound knowledge of almost all biodiversity present in this savannah.

Odum School of Ecology

The Odum School of Ecology is a school within the University of Georgia and the successor of the UGA Institute of Ecology. It is named after Eugene Odum, renowned UGA biologist, the father of ecosystem ecology, and the founder of the Institute.

Oecologia

Oecologia is an international peer-reviewed English-language journal published by Springer since 1968 (some articles were published in German or French until 1976). The journal publishes original research in a range of topics related to plant and animal ecology.

Oecologia has an international focus and presents original papers, methods, reviews and special topics. Papers focus on population ecology, plant-animal interactions, ecosystem ecology, community ecology, global change ecology, conservation ecology, behavioral ecology and physiological ecology.

Oecologia had an impact factor of 3.011 (2012) and is ranked 37 out of 136 in the subject category "ecology".

Olevi Kull

Olevi Kull (22 June 1955, Rakvere – 31 January 2007, Tartu) was an Estonian professor at the University of Tartu known for his contribution to ecology. Following his death, a memorial fund was established by donations in his memory, which provides travel stipends to students in the fields of plant ecophysiology, forest ecology and ecosystem ecology.

Biosemiotician Kalevi Kull is his older brother.

Phage ecology

Bacteriophages (phages), potentially the most numerous "organisms" on Earth, are the viruses of bacteria (more generally, of prokaryotes). Phage ecology is the study of the interaction of bacteriophages with their environments.

Plant ecology

Plant ecology is a subdiscipline of ecology which studies the distribution and abundance of plants, the effects of environmental factors upon the abundance of plants, and the interactions among and between plants and other organisms. Examples of these are the distribution of temperate deciduous forests in North America, the effects of drought or flooding upon plant survival, and competition among desert plants for water, or effects of herds of grazing animals upon the composition of grasslands.

A global overview of the Earth's major vegetation types is provided by O.W. Archibold. He recognizes 11 major vegetation types: tropical forests, tropical savannas, arid regions (deserts), Mediterranean ecosystems, temperate forest ecosystems, temperate grasslands, coniferous forests, tundra (both polar and high mountain), terrestrial wetlands, freshwater ecosystems and coastal/marine systems. This breadth of topics shows the complexity of plant ecology, since it includes plants from floating single-celled algae up to large canopy forming trees.

One feature that defines plants is photosynthesis. Photosynthesis is the process of a chemical reactions to create glucose and oxygen, which is vital for plant life. One of the most important aspects of plant ecology is the role plants have played in creating the oxygenated atmosphere of earth, an event that occurred some 2 billion years ago. It can be dated by the deposition of banded iron formations, distinctive sedimentary rocks with large amounts of iron oxide. At the same time, plants began removing carbon dioxide from the atmosphere, thereby initiating the process of controlling Earth's climate. A long term trend of the Earth has been toward increasing oxygen and decreasing carbon dioxide, and many other events in the Earth's history, like the first movement of life onto land, are likely tied to this sequence of events.One of the early classic books on plant ecology was written by J.E. Weaver and F.E. Clements. It talks broadly about plant communities, and particularly the importance of forces like competition and processes like succession.

Plant ecology can also be divided by levels of organization including plant ecophysiology, plant population ecology, community ecology, ecosystem ecology, landscape ecology and biosphere ecology.The study of plants and vegetation is complicated by their form. First, most plants are rooted in the soil, which makes it difficult to observe and measure nutrient uptake and species interactions. Second, plants often reproduce vegetatively, that is asexually, in a way that makes it difficult to distinguish individual plants. Indeed, the very concept of an individual is doubtful, since even a tree may be regarded as a large collection of linked meristems. Hence, plant ecology and animal ecology have different styles of approach to problems that involve processes like reproduction, dispersal and mutualism. Some plant ecologists have placed considerable emphasis upon trying to treat plant populations as if they were animal populations, focusing on population ecology. Many other ecologists believe that while it is useful to draw upon population ecology to solve certain scientific problems, plants demand that ecologists work with multiple perspectives, appropriate to the problem, the scale and the situation.

Raymond Lindeman

Raymond Laurel Lindeman (1915 – June 29, 1942) was an ecologist whose graduate research is often credited with being a seminal study in field of ecosystem ecology.

Sharon J. Hall

Sharon J. Hall is an ecosystem ecologist and Associate Professor at the School of Life Sciences at Arizona State University. Her research focuses on ecosystem ecology and the ways that human activity interacts with the environment.

Systems ecology

Systems ecology is an interdisciplinary field of ecology, a subset of Earth system science, that takes a holistic approach to the study of ecological systems, especially ecosystems. Systems ecology can be seen as an application of general systems theory to ecology. Central to the systems ecology approach is the idea that an ecosystem is a complex system exhibiting emergent properties. Systems ecology focuses on interactions and transactions within and between biological and ecological systems, and is especially concerned with the way the functioning of ecosystems can be influenced by human interventions. It uses and extends concepts from thermodynamics and develops other macroscopic descriptions of complex systems.

Thomas Crowther (ecologist)

Thomas Ward Crowther (born 18 June 1986) is a British scientist specialising in ecosystem ecology and the chief scientific advisor to the UN's Trillion Tree Campaign. He is a tenure-track professor of Global Ecosystem Ecology at ETH Zürich where he formed the Crowther Lab. His work aims to generate a holistic understanding of the global scale ecological systems which regulate the Earth's climate.

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Ecology: Modelling ecosystems: Other components
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ecology
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