Limnology, is the study of inland aquatic ecosystems. The study of limnology includes aspects of the biological, chemical and geological characteristics and functions of inland waters; this includes the study of lakes, ponds, springs, streams and groundwater. A more recent sub-discipline of limnology, termed landscape limnology, studies and seeks to conserve these ecosystems using a landscape perspective, by explicitly examining connections between an aquatic ecosystem and its watershed; the need to understand global inland waters as part of the Earth System created a sub-discipline called global limnology. This approach considers the role of inland aquatic ecosystems in carbon cycling. Limnology is related to aquatic ecology and hydrobiology, which study aquatic organisms and their interactions with the abiotic environment. While limnology has substantial overlap with freshwater-focused disciplines, it includes the study of inland salt lakes; the term limnology was coined by François-Alphonse Forel who established the field with his studies of Lake Geneva.
Interest in the discipline expanded, in 1922 August Thienemann and Einar Naumann co-founded the International Society of Limnology. Forel's original definition of limnology, "the oceanography of lakes", was expanded to encompass the study of all inland waters, influenced Benedykt Dybowski's work on Lake Baikal. Prominent early American limnologists included G. Evelyn Hutchinson, Ed Deevey, E. A. Birge, C. Juday. Physical properties of aquatic ecosystems are determined by a combination of heat, currents and other seasonal distributions of environmental conditions; the morphometry of a body of water depends on the type of feature and the structure of the earth surrounding the body of water. Lakes, for instance, are classified by their formation, zones of lakes are defined by water depth. River and stream system morphometry is driven by underlying geology of the area as well as the general velocity of the water. Another type of aquatic system which falls within the study of limnology is estuaries.
Estuaries are bodies of water classified by the interaction of the ocean or sea. Wetlands vary in size and pattern however the most common types, marshes and swamps fluctuate between containing shallow and being dry depending on the time of year. Light zonation is the concept of how the amount of sunlight penetration into water influences the structure of a body of water; these zones define various levels of productivity within an aquatic ecosystems such as a lake. For instance, the depth of the water column which sunlight is able to penetrate and where most plant life is able to grow is known as the photic or euphotic zone; the rest of the water column, deeper and does not receive sufficient amounts of sunlight for plant growth is known as the aphotic zone. Similar to light zonation, thermal stratification or thermal zonation is a way of grouping parts of the water body within an aquatic system based on the temperature of different lake layers; the less turbid the water, the more light is able to penetrate, thus heat is conveyed deeper in the water.
Heating declines exponentially with depth in the water column, so the water will be warmest near the surface but progressively cooler as moving downwards. There are three main sections; the epilimnion is closest to the water surface and absorbs long- and shortwave radiation to warm the water surface. During cooler months, wind shear can contribute to cooling of the water surface; the thermocline is an area within the water column where water temperatures decrease. The bottom layer is the hypolimnion, which tends to have the coldest water because its depth restricts sunlight from reaching it. In temperate lakes, fall-season cooling of surface water results in turnover of the water column, where the thermocline is disrupted, the lake temperature profile becomes more uniform; the chemical composition of water in aquatic ecosystems is influenced by natural characteristics and processes including precipitation, underlying soil and bedrock in the watershed, erosion and sedimentation. All bodies of water have a certain composition of both inorganic elements and compounds.
Biological reactions affect the chemical properties of water. In addition to natural processes, human activities influence the chemical composition of aquatic systems and their water quality. Dissolved oxygen and dissolved carbon dioxide are discussed together due their coupled role in respiration and photosynthesis. Dissolved oxygen concentrations can be altered by physical and biological processes and reaction. Physical processes including wind mixing can increase dissolved oxygen concentrations in surface waters of aquatic ecosystems; because dissolved oxygen solubility is linked to water temperatures, changes in temperature affect dissolved oxygen concentrations as warmer water has a lower capacity to "hold" oxygen as colder water. Biologically, both photosynthesis and aerobic respiration affect dissolved oxygen concentrations. Photosynthesis by autotrophic organisms, such as phytoplankton and aquatic algae, increases dissolved oxygen concentrations while reducing carbon dioxide concentrations, since carbon dioxide is taken up during photosynthesis.
All aerobic organisms in the aquatic envir
Landscape architecture is the design of outdoor areas and structures to achieve environmental, social-behavioural, or aesthetic outcomes. It involves the systematic investigation of existing social and soil conditions and processes in the landscape, the design of interventions that will produce the desired outcome; the scope of the profession includes landscape design. A practitioner in the profession of landscape architecture is called a landscape architect. Landscape architecture is a multi-disciplinary field, incorporating aspects of botany, the fine arts, industrial design, soil sciences, environmental psychology, geography and civil engineering; the activities of a landscape architect can range from the creation of public parks and parkways to site planning for campuses and corporate office parks, from the design of residential estates to the design of civil infrastructure and the management of large wilderness areas or reclamation of degraded landscapes such as mines or landfills. Landscape architects work on structures and external spaces with limitations toward the landscape or park aspect of the design - large or small, urban and rural, with "hard" and "soft" materials, while integrating ecological sustainability.
The most valuable contribution can be made at the first stage of a project to generate ideas with technical understanding and creative flair for the design and use of spaces. The landscape architect can conceive the overall concept and prepare the master plan, from which detailed design drawings and technical specifications are prepared, they can review proposals to authorize and supervise contracts for the construction work. Other skills include preparing design impact assessments, conducting environmental assessments and audits, serving as an expert witness at inquiries on land use issues; the variety of the professional tasks that landscape architects collaborate on is broad, but some examples of project types include: Parks of General design and public infrastructure Sustainable development Stormwater management including rain gardens, green roofs, groundwater recharge, Green infrastructure, constructed wetlands. Landscape design for educational function and site design for public institutions and government facilities Parks, botanical gardens, arboretums and nature preserves Recreation facilities.
Coastal and offshore developments and mitigation Ecological Design any aspect of design that minimizes environmentally destructive impacts by integrating itself with natural processes and sustainabilityLandscape managers use their knowledge of landscape processes to advise on the long-term care and development of the landscape. They work in forestry, nature conservation and agriculture. Landscape scientists have specialist skills such as soil science, geomorphology or botany that they relate to the practical problems of landscape work, their projects can range from site surveys to the ecological assessment of broad areas for planning or management purposes. They may report on the impact of development or the importance of particular species in a given area. Landscape planners are concerned with landscape planning for the location, scenic and recreational aspects of urban and coastal land use, their work is embodied in written statements of policy and strategy, their remit includes master planning for new developments, landscape evaluations and assessments, preparing countryside management or policy plans.
Some may apply an additional specialism such as landscape archaeology or law to the process of landscape planning. Green roof designers design extensive and intensive roof gardens for storm water management, evapo-transpirative cooling, sustainable architecture and habitat creation. For the period before 1800, the history of landscape gardening is that of master planning and garden design for manor houses and royal properties, religious complexes, centers of government. An example is the extensive work by André Le Nôtre at Vaux-le-Vicomte for King Louis XIV of France at the Palace of Versailles; the first person to write of making a landscape was Joseph Addison in 1712. The term landscape architecture was invented by Gilbert Laing Meason in 1828, John Claudius Loudon was instrumental in the adoption of the term landscape architecture by the modern profession, he took up the term from Meason and gave it publicity in his Encyclopedias and in his 1840 book on the Landscape Gardening and Landscape Architecture of the Late Humphry Repton.
The practice of landscape architecture spread from the Old to the New World. The term "landscape architect" was
South America is a continent in the Western Hemisphere in the Southern Hemisphere, with a small portion in the Northern Hemisphere. It may be considered a subcontinent of the Americas, how it is viewed in the Spanish and Portuguese-speaking regions of the Americas; the reference to South America instead of other regions has increased in the last decades due to changing geopolitical dynamics. It is bordered on the west on the north and east by the Atlantic Ocean, it includes twelve sovereign states, a part of France, a non-sovereign area. In addition to this, the ABC islands of the Kingdom of the Netherlands and Tobago, Panama may be considered part of South America. South America has an area of 17,840,000 square kilometers, its population as of 2016 has been estimated at more than 420 million. South America ranks fourth in fifth in population. Brazil is by far the most populous South American country, with more than half of the continent's population, followed by Colombia, Argentina and Peru. In recent decades Brazil has concentrated half of the region's GDP and has become a first regional power.
Most of the population lives near the continent's western or eastern coasts while the interior and the far south are sparsely populated. The geography of western South America is dominated by the Andes mountains. Most of the continent lies in the tropics; the continent's cultural and ethnic outlook has its origin with the interaction of indigenous peoples with European conquerors and immigrants and, more locally, with African slaves. Given a long history of colonialism, the overwhelming majority of South Americans speak Portuguese or Spanish, societies and states reflect Western traditions. South America occupies the southern portion of the Americas; the continent is delimited on the northwest by the Darién watershed along the Colombia–Panama border, although some may consider the border instead to be the Panama Canal. Geopolitically and geographically all of Panama – including the segment east of the Panama Canal in the isthmus – is included in North America alone and among the countries of Central America.
All of mainland South America sits on the South American Plate. South America is home to Angel Falls in Venezuela. South America's major mineral resources are gold, copper, iron ore and petroleum; these resources found in South America have brought high income to its countries in times of war or of rapid economic growth by industrialized countries elsewhere. However, the concentration in producing one major export commodity has hindered the development of diversified economies; the fluctuation in the price of commodities in the international markets has led to major highs and lows in the economies of South American states causing extreme political instability. This is leading to efforts to diversify production to drive away from staying as economies dedicated to one major export. South America is one of the most biodiverse continents on earth. South America is home to many interesting and unique species of animals including the llama, piranha, vicuña, tapir; the Amazon rainforests possess high biodiversity, containing a major proportion of the Earth's species.
Brazil is the largest country in South America, encompassing around half of the continent's land area and population. The remaining countries and territories are divided among three regions: The Andean States, the Guianas and the Southern Cone. Traditionally, South America includes some of the nearby islands. Aruba, Curaçao, Trinidad and the federal dependencies of Venezuela sit on the northerly South American continental shelf and are considered part of the continent. Geo-politically, the island states and overseas territories of the Caribbean are grouped as a part or subregion of North America, since they are more distant on the Caribbean Plate though San Andres and Providencia are politically part of Colombia and Aves Island is controlled by Venezuela. Other islands that are included with South America are the Galápagos Islands that belong to Ecuador and Easter Island, Robinson Crusoe Island, Chiloé and Tierra del Fuego. In the Atlantic, Brazil owns Fernando de Noronha and Martim Vaz, the Saint Peter and Saint Paul Archipelago, while the Falkland Islands are governed by the United Kingdom, whose sovereignty over the islands is disputed by Argentina.
South Georgia and the South Sandwich Islands may be associate
A microclimate is a local set of atmospheric conditions that differ from those in the surrounding areas with a slight difference but sometimes with a substantial one. The term may refer to areas as small as a few square meters or square feet or as large as many square kilometers or square miles; because climate is statistical, which implies spatial and temporal variation of the mean values of the describing parameters, within a region there can occur and persist over time sets of statistically distinct conditions, that is, microclimates. Microclimates can be found in most places. Microclimates exist, for example, near bodies of water which may cool the local atmosphere, or in heavy urban areas where brick and asphalt absorb the sun's energy, heat up, re-radiate that heat to the ambient air: the resulting urban heat island is a kind of microclimate. Another contributing factor of microclimate is the aspect of an area. South-facing slopes in the Northern Hemisphere and north-facing slopes in the Southern Hemisphere are exposed to more direct sunlight than opposite slopes and are therefore warmer for longer periods of time, giving the slope a warmer microclimate than the areas around the slope.
The lowest area of a glen may sometimes frost sooner or harder than a nearby spot uphill, because cold air sinks, a drying breeze may not reach the lowest bottom, humidity lingers and precipitates freezes. The terminology "micro-climate" first appeared in the 1950s in publications such as Climates in Miniature: A Study of Micro-Climate Environment; the area in a developed industrial park may vary from a wooded park nearby, as natural flora in parks absorb light and heat in leaves that a building roof or parking lot just radiates back into the air. Advocates of solar energy argue that widespread use of solar collection can mitigate overheating of urban environments by absorbing sunlight and putting it to work instead of heating the foreign surface objects. A microclimate can offer an opportunity as a small growing region for crops that cannot thrive in the broader area. Microclimates can be used to the advantage of gardeners who choose and position their plants. Cities raise the average temperature by zoning, a sheltered position can reduce the severity of winter.
Roof gardening, exposes plants to more extreme temperatures in both summer and winter. In an urban area, tall buildings create their own microclimate, both by overshadowing large areas and by channeling strong winds to ground level. Wind effects around tall buildings are assessed as part of a microclimate study. Microclimates can refer to purpose-made environments, such as those in a room or other enclosure. Microclimates are created and maintained in museum display and storage environments; this can be done using passive methods, such as silica gel, or with active microclimate control devices. If the inland areas have a humid continental climate, the coastal areas stay much milder during winter months, in contrast to the hotter summers; this is the case further north on the American west coast, such as in British Columbia, where Vancouver has an oceanic wet winter with rare frosts, but inland areas that average several degrees warmer in summer have cold and snowy winters. The type of soil found in an area can affect microclimates.
For example, soils heavy in clay can act like pavement. On the other hand, if soil has many air pockets the heat could be trapped underneath the topsoil, resulting in the increased possibility of frost at ground level. Two main parameters to define a microclimate within a certain area are humidity. A source of a drop in temperature and/or humidity can be attributed to different sources or influences. Microclimate is shaped by a conglomerate of different influences and is a subject of microscale meteorology; the well known examples of cold air pool effect are Gstettneralm Sinkhole in Austria and Peter Sinks in the US. The main criterion on the wind speed v in order to create a warm air flow penetration into a CAP is the following: F r = v N h ≥ F r c, where F r is the Froude number, N --- the Brunt–Väisälä frequency, h --- depth of the valley, F r c --- Froude number at the threshold wind speed; the presence of permafrost close to the surface in a crater creates a unique microclimate environment.
As similar as lava tubes can be to caves which are not formed due to volcanic activity the microclimate within the former is different due to dominant presence of basalt. Lava tubes and basaltic caves are important astrobiological targets on Mars; as pointed out by Rudolf Geiger in his book not only climate influences the living plant but the opposite effect of the interaction of plants on their environment can take place, is known as plant climate. Artificial reservoirs as well as natural ones create microclimates and influence the macroscopic climate as well. Northern California above the Bay Area is well known for microclimates with significant differences of temperatures; the coastline averages between 17 and 1
Pterophyllum is a small genus of freshwater fish from the family Cichlidae known to most aquarists as angelfish. All Pterophyllum species originate from the Amazon Basin, Orinoco Basin and various rivers in the Guiana Shield in tropical South America; the three species of Pterophyllum are unusually shaped for cichlids being laterally compressed, with round bodies and elongated triangular dorsal and anal fins. This body shape allows them to hide among roots and plants on a vertical surface. Occurring angelfish are striped longitudinally, colouration which provides additional camouflage. Angelfish prey on small fish and macroinvertebrates. All Pterophyllum species form monogamous pairs. Eggs are laid on a submerged log or a flattened leaf; as is the case for other cichlids, brood care is developed. Pterophyllum should not be confused with marine angelfish, perciform fish found on shallow ocean reefs; the recognized species in this genus are: Pterophyllum altum Pellegrin, 1903 Pterophyllum leopoldi Pterophyllum scalare The freshwater angelfish was described in 1824 by F. Schultze.
Pterophyllum is derived from phyllon. In 1906, J. Pellegrin described P. altum. In 1963, P. leopoldi was described by J. P. Gosse. Undescribed species may still exist in the Amazon Basin. New species of fish are discovered with increasing frequency, like P. scalare and P. leopoldi, the differences may be subtle. Scientific notations describe the P. leopoldi as having 29–35 scales in a lateral row and straight predorsal contour, whereas, P. scalare is described as having 35–45 scales in a lateral row and a notched predorsal contour. P. leopoldi shows the same coloration as P. scalare, but a faint stripe shows between the eye stripe and the first complete body stripe and a third incomplete body stripe exists between the two main body stripes that extends three-fourths the length of the body. P. scalare's body does not show the stripe between the eye stripe and first complete body stripe at all, the third stripe between the two main body stripes extends downward more than a half inch, if present.
P. leopoldi fry develop three to eight body stripes, with all but one to five fading away as they mature, whereas P. scalare only has two in true wild form throughout life. Angelfish were bred in captivity for at least 30 years prior to P. leopoldi being described. Angelfish are one of the most kept freshwater aquarium fish, as well as the most kept cichlid, they are prized for their unique shape and behavior. It was not until the late 1920s to early 1930s that the angelfish was bred in captivity in the United States; the most kept species in the aquarium is Pterophyllum scalare. Most of the individuals in the aquarium trade are captive-bred. Sometimes, captive-bred Pterophyllum altum is available. Pterophyllum leopoldi is the hardest to find in the trade. Angelfish are kept in a warm aquarium, ideally around 80 °F. Though angelfish are members of the cichlid family, they are peaceful when not mating. P. scalare is easy to breed in the aquarium, although one of the results of generations of inbreeding is that many breeds have completely lost their rearing instincts, resulting in the tendency of the parents to eat their young.
In addition, it is difficult to identify the sex of any individual until it is nearly ready to breed. Angelfish pairs form long-term relationships where each individual will protect the other from threats and potential suitors. Upon the death or removal of one of the mated pair, breeders have experienced the total refusal of the remaining mate to pair up with any other angelfish and breed with subsequent mates. Depending upon aquarium conditions, P. scalare reaches sexual maturity at the age of six to 12 months or more. In situations where the eggs are removed from the aquarium after spawning, the pair is capable of spawning every seven to 10 days. Around the age of three years, spawning frequency decreases and ceases; when the pair is ready to spawn, they choose an appropriate medium upon which to lay the eggs, spend one to two days picking off detritus and algae from the surface. This medium may be a broad-leaf plant in the aquarium, a flat surface such as a piece of slate placed vertically in the aquarium, a length of pipe, or the glass sides of the aquarium.
The female deposits a line of eggs on the spawning substrate, followed by the male, which fertilizes the eggs. This process is repeated until a total of 100 to more than 1,200 eggs are laid, depending on the size and health of the female fish; as both parents care for the offspring throughout development, the pair takes turns maintaining a high rate of water circulation around the eggs by swimming close to the eggs and fanning them with their pectoral fins. In a few days, the eggs hatch and the fry remain attached to the spawning substrate. During this period, the fry survive by consuming the remains of their yolk sacs. At one week, the fry become free-swimming. Successful parents keep close watch on the eggs until then. At the free-swimming stage, the fry can be fed suitably sized live food. P. altum is notably difficult to breed in an aquarium environment. In pet stores, the freshwater angelfish is placed in the semiaggressive category; some tetras and barbs are compatible with angelfish, but ones small enough to fit in the mouth of the angelfish may be eaten.
Generous portions of food should be available so the angelfish do not get hungry and turn on their tank mates. Most stra
A wildlife corridor, habitat corridor, or green corridor is an area of habitat connecting wildlife populations separated by human activities or structures. This allows an exchange of individuals between populations, which may help prevent the negative effects of inbreeding and reduced genetic diversity that occur within isolated populations. Corridors may help facilitate the re-establishment of populations that have been reduced or eliminated due to random events; this may moderate some of the worst effects of habitat fragmentation, wherein urbanization can split up habitat areas, causing animals to lose both their natural habitat and the ability to move between regions to use all of the resources they need to survive. Habitat fragmentation due to human development is an ever-increasing threat to biodiversity, habitat corridors are a possible mitigation; the main goal of implementing habitat corridors is to increase biodiversity. When areas of land are broken up by human interference, population numbers become unstable and many animal and plant species become endangered.
By re-connecting the fragments, the population fluctuations can decrease dramatically. Corridors can contribute to three factors that stabilize a population: Colonization—animals are able to move and occupy new areas when food sources or other natural resources are lacking in their core habitat. Migration—species that relocate seasonally can do so more safely and when it does not interfere with human development barriers. Interbreeding—animals can find new mates in neighboring regions so that genetic diversity can increase and thus have a positive impact on the overall population. Rosenberg et.al. were among the first to define what constitutes a wildlife corridor. The definitions of "biological corridor" had, in the early years of studying corridors, been "vague and inconsistent, they confound form and function" Rosenberg et.al. Developed a conceptual model that emphasized the role of a wildlife corridor as a facilitator of movement, not restricted by requirements of native vegetation or intermediate target patches of habitat.
Their definition required that movement to a target patch via the corridor be greater that if the corridor were absent. Although corridors had been implemented with the assumption that they would increase biodiversity, not enough research had been done to come to a solid conclusion; the case for corridors has been built much less on empirical evidence. Tewksbury et. al. claimed that the early controversies had arisen because most studies had been limited in that they had a narrow taxonomic focus and, that if corridors facilitate animal movement, they should have strong indirect effects on plant populations due to increased pollen and seed by animals. Results of their 2002 experiment provided a large-scale experimental demonstration that habitat corridors facilitate movement of disparate taxa between otherwise isolated patches after controlling for area effects. Another factor that needs to be taken into account is; some species have reacted more positively to corridors than others. A habitat corridor could be considered as a possible solution in an area where the destruction of a natural area has affected its native species.
Development such as roads and farms can interrupt plants and animals in the region being destroyed. Furthermore, natural disasters such as wildfires and floods can leave animals with no choice but to evacuate. If the habitat is not connected to a safer one, it will lead to death. A remaining portion of natural habitat is called a remnant, such portions need to be connected because when migration decreases, extinction increases. Corridors can be made in two distinct areas -- land. Water corridors are called riparian ribbons and come in the form of rivers and streams. Land corridors come on a scale as large as wooded strips connecting larger woodland areas. However, they can be as simple as a line of shrubs along a sidewalk; such areas can facilitate the movement of small animals birds, from tree to tree, until they find a safe habitat to nest in. Not only do minimal corridors aid in the movement of animals, they are aesthetically pleasing, which can sometimes encourage the community to accept and support them.
Species can be categorized in one of two groups. Passage users occupy corridors for brief periods of time; these animals use corridors for such events as seasonal migration, dispersal of a juvenile, or moving between parts of a large home range. Large herbivores, medium to large carnivores, migratory species are passage users. One common misconception is that the corridor only needs to be wide enough for the passage users to get through. However, the corridor still must be wide enough to be safe and encourage the animals to use it though they do not live out their entire lives in it. Corridor dwellers can occupy the passage anywhere from several days to several years. Species such as plants, amphibians, birds and small mammals can spend their entire lives in linear habitats. In this case, the corridor must include everything that a species needs to live and breed, such as soil for germination, burrowing areas, multiple other breeding adults. Habitat corridors can be categorized according to their width.
The wider the corridor, the more use it will get from species. However, the width-length ratio, as well as d
Ecology is the branch of biology which studies the interactions among organisms and their environment. Objects of study include interactions of organisms that include biotic and abiotic components of their environment. Topics of interest include the biodiversity, distribution and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, the non-living components of their environment. Ecosystem processes, such as primary production, nutrient cycling, niche construction, regulate the flux of energy and matter through an environment; these processes are sustained by organisms with specific life history traits. Biodiversity means the varieties of species and ecosystems, enhances certain ecosystem services. Ecology is not synonymous with natural history, or environmental science, it overlaps with the related sciences of evolutionary biology and ethology. An important focus for ecologists is to improve the understanding of how biodiversity affects ecological function.
Ecologists seek to explain: Life processes and adaptations The movement of materials and energy through living communities The successional development of ecosystems The abundance and distribution of organisms and biodiversity in the context of the environment. Ecology has practical applications in conservation biology, wetland management, natural resource management, city planning, community health, economics and applied science, human social interaction. For example, the Circles of Sustainability approach treats ecology as more than the environment'out there', it is not treated as separate from humans. Organisms and resources compose ecosystems which, in turn, maintain biophysical feedback mechanisms that moderate processes acting on living and non-living components of the planet. Ecosystems sustain life-supporting functions and produce natural capital like biomass production, the regulation of climate, global biogeochemical cycles, water filtration, soil formation, erosion control, flood protection, many other natural features of scientific, economic, or intrinsic value.
The word "ecology" was coined in 1866 by the German scientist Ernst Haeckel. Ecological thought is derivative of established currents in philosophy from ethics and politics. Ancient Greek philosophers such as Hippocrates and Aristotle laid the foundations of ecology in their studies on natural history. Modern ecology became a much more rigorous science in the late 19th century. Evolutionary concepts relating to adaptation and natural selection became the cornerstones of modern ecological theory; the scope of ecology contains a wide array of interacting levels of organization spanning micro-level to a planetary scale phenomena. Ecosystems, for example, contain interacting life forms. Ecosystems are dynamic, they do not always follow a linear successional path, but they are always changing and sometimes so that it can take thousands of years for ecological processes to bring about certain successional stages of a forest. An ecosystem's area can vary from tiny to vast. A single tree is of little consequence to the classification of a forest ecosystem, but critically relevant to organisms living in and on it.
Several generations of an aphid population can exist over the lifespan of a single leaf. Each of those aphids, in turn, support diverse bacterial communities; the nature of connections in ecological communities cannot be explained by knowing the details of each species in isolation, because the emergent pattern is neither revealed nor predicted until the ecosystem is studied as an integrated whole. Some ecological principles, however, do exhibit collective properties where the sum of the components explain the properties of the whole, such as birth rates of a population being equal to the sum of individual births over a designated time frame; the main subdisciplines of ecology, population ecology and ecosystem ecology, exhibit a difference not only of scale, but of two contrasting paradigms in the field. The former focus on organisms distribution and abundance, while the focus on materials and energy fluxes; the scale of ecological dynamics can operate like a closed system, such as aphids migrating on a single tree, while at the same time remain open with regard to broader scale influences, such as atmosphere or climate.
Hence, ecologists classify ecosystems hierarchically by analyzing data collected from finer scale units, such as vegetation associations and soil types, integrate this information to identify emergent patterns of uniform organization and processes that operate on local to regional and chronological scales. To structure the study of ecology into a conceptually manageable framework, the biological world is organized into a nested hierarchy, ranging in scale from genes, to cells, to tissues, to organs, to organisms, to species, to populations, to communities, to ecosystems, to biomes, up to the level of the biosphere; this framework exhibits non-linear behaviors.