вторник, 30 июля 2019 г.
An ecosystem as a community Essay
Introduction An ecosystem is a community of living organisms (plants, animals and microbes) in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces (although some scientists say that the entire planet is an ecosystem). Energy, water, nitrogen and soil minerals are other essential abiotic components of an ecosystem. The energy that flows through ecosystems is obtained primarily from the sun. It generally enters the system through photosynthesis, a process that also captures carbonfrom the atmosphere. 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 both by external and internal factors. External factors such as climate, the parent material which forms the soil and topography, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. Other external factors include time and potential biota. Ecosystems are dynamic entitiesÃ¢â¬âinvariably, 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 have very different characteristics simply because they contain different species. Theintroduction of non-native species can cause substantial shifts in ecosystem function. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops. While the resource inputs are generally controlled by external processes like climate and parent material, theÃ availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other internal factors include disturbance, succession and the types of species present. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Biodiversity affects ecosystem function, as do the processes of disturbance and succession. Ecosystems provide a variety of goods and services upon which people depend; the principles of ecosystem management suggest that rather than managing individual species,natural resources should be managed at the level of the ecosystem itself. Classifying ecosystems into ecologically homogeneous units is an important step towards effective ecosystem management, but there is no single, agreed-upon way to do this. Classification Classifying ecosystems into ecologically homogeneous units is an important step towards effective ecosystem management. A variety of systems exist, based on vegetation cover, remote sensing, and bioclimatic classification systems. American geographer Robert Bailey defines a hierarchy of ecosystem units ranging from microecosystems (individual homogeneous sites, on the order of 10 square kilometres (4 sq mi) in area), through mesoecosystems (landscape mosaics, on the order of 1,000 square kilometres (400 sq mi)) to macroecosystems (ecoregions, on the order of 100,000 square kilometres (40,000 sq mi)). Bailey outlined five different methods for identifying ecosystems: gestalt (Ã¢â¬Å"a whole that is not derived through considerable of its partsÃ¢â¬ ), in which regions are recognized and boundaries drawn intuitively; a map overlay system where different layers like geology, landforms and soil types are overlain to identify ecosystems; multivariate clustering of site attrib utes; digital image processing of remotely sensed data grouping areas based on their appearance or other spectral properties; or by a Ã¢â¬Å"controlling factors methodÃ¢â¬ where a subset of factors (like soils, climate, vegetation physiognomy or the distribution of plant or animal species) are selected from a large array of possible ones are used to delineate ecosystems. In contrast withÃ BaileyÃ¢â¬â¢s methodology, Puerto Rico ecologist Ariel Lugo and coauthors identified ten characteristics of an effective classification system: that it be based on georeferenced, quantitative data; that it should minimize subjectivity and explicitly identify criteria and assumptions; that it should be structured around the factors that drive ecosystem processes; that it should reflect the hierarchical nature of ecosystems; that it should be flexible enough to conform to the various scales at which ecosystem management operates; that it should be tied to reliable measures of climate so that it can Ã¢â¬Å"anticipat[e] global climate change; that it be applicable worldwide; that it should be validated against independent data; that it take into account the sometimes complex relationship between climate, vegetation and ecosystem functioning; and that it should be able to adapt and improve as new data become availableÃ¢â¬ . Types Aquatic ecosystem An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems andfreshwater ecosystems. Marine ecosystems: cover approximately 71% of the EarthÃ¢â¬â¢s surface and contain approximately 97% of the planetÃ¢â¬â¢s water. They generate 32% of the worldÃ¢â¬â¢s net primary production. They are distinguished from freshwater ecosystems by the presence of dissolved compounds, especially salts, in the water. Approximately 85% of the dissolved materials in seawater are sodium and chlorine. Seawater has an average salinity of 35 parts per thousand (ppt) of water. Actual salinity varies among different marine ecosystems. Large marine ecosystems: (LMEs) are regions of the worldÃ¢â¬â¢s oceans, encompassing coastal areas from river basins and estuaries to the seaward boundaries of continental shelves and the outer margins of the major ocean current systems. They are relatively large regions on the order of 200,000 kmÃ ² or greater, characterized by distinct bathymetry, hydrography, productivity, and trophically dependent populations. The system of LMEs has been developed by the US National Oceanic and AtmosphericÃ Administration (NOAA) to identify areas of the oceans for conservation purposes. The objective is to use the LME concept as a tool for enabling ecosystem-based management to provide a collaborative approach to management of resources within ecologically-bounded transnational areas. This will be done in an international context and consistent with customary international law as reflected in 1982 UN Convention on the Law of the Sea. LME-based conservation is based on recognition that the worldÃ¢â¬â¢s coastal ocean waters are degraded by unsustainable fishing practices, habitat degradation, eutrophication, toxic pollution, aerosol contamination, and emerging diseases, and that positive actions to mitigate these threats require coordinated actions by governments and civil society to recover depleted fish populations, restore degraded habitats and reduce coastal pollution. Although the LMEs cover only the continental margins and not the deep oceans and oceanic islands, the 64 LMEs produce 95% of the worldÃ¢â¬â¢s annual marine fishery biomassyields. Most of the global ocean pollution, overexploitation, and coastal habitat alteration occur within their waters. NOAA has conducted studies of principal driving forces affecting changes in biomass yields for 33 of t he 64 LMEs, which have been peer-reviewed and published in ten volumes. Freshwater ecosystems: are a subset of EarthÃ¢â¬â¢s aquatic ecosystems. They include lakes and ponds, rivers, streams and springs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, and vegetation. Freshwater ecosystems can be divided into lentic ecosystems (still water) and lotic ecosystems (flowing water). Limnology (and its branch freshwater biology) is a study about freshwater ecosystems. It is a part of hydrobiology. Original efforts to understand and monitor freshwater ecosystems were spurred on by threats to human health (ex. Cholera outbreaks due to sewage contamination). Early monitoring focussed on chemical indicators, then bacteria, and finally algae, fungi and protozoa. A new type of monitoring involves differing groups of organisms (macroinvertebrates, macrophytes and fish) and the stream conditions associated with them. Current biomonitering techniques focus mainly on community structure or biochemical oxygen demand. ResponsesÃ are measured by behavioural changes, altered rates of growth, reproduction or mortality. Macroinvertebrates are most often used in these models because of well known taxonomy, ease of collection, sensitivity to a range of stressors, and their overall value to the ecosystem. Most of these measurements are difficult to extrapolate on a large scale however. The use of reference sites is common when assessing what a healthy freshwater ecosystem should Ã¢â¬Å"look likeÃ¢â¬ . Reference sites are easier to reconstruct in standing water than moving water. Preserved indicators such as diatom valves, macrophyte pollen, insect chitin and fish scales can be used to establish a reference ecosystem representative of a time before lar ge scale human disturbance. Common chemical stresses on freshwater ecosystem health include acidification, eutrophication and copper and pesticide contamination. Lake ecosystems :The ecosystem of a lake includes biotic (living) plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions. Lake ecosystems are a prime examples of lentic ecosystems. Lentic refers to standing or relatively still water, from the Latin lentus, which means sluggish. Lentic waters range from ponds to lakes to wetlands, and much of this article applies to lentic ecosystems in general. Lentic ecosystems can be compared withlotic ecosystems, which involve flowing terrestrial waters such as rivers and streams. Together, these two fields form the more general study area of freshwater or aquatic ecology. Lentic systems are diverse, ranging from a small, temporary rainwater pool a few inches deep to Lake Baikal, which has a maximum depth of 1740 m. The general distinction between pools/ponds and lakes is vague, but Brown states that ponds and pools have their entire bottom surfaces exposed to light, while lakes do not. In addition, some lakes become seasonally stratified (discussed in more detail below.) Ponds and pools have two regions: the pelagic open water zone, and the benthic zone, which comprises the bottom and shore regions. Since lakes have deep bottom regions not exposed to light, these systems have an additional zone, the profundal. These three areas can have very different abiotic conditions and, hence, host species that are specifically adapted to live there. River ecosystem The ecosystem of a river is the river viewed as a system operating in its natural environment, and includes biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions. River ecosystems are prime examples of lotic ecosystems. Lotic refers to flowing water, from the Latin lotus, washed. Lotic waters range from springs only a few centimeters wide to major rivers kilometers in width. Much of this article applies to lotic ecosystems in general, including related lotic systems such as streams and springs. Lotic ecosystems can be contrasted with lentic ecosystems, which involve relatively still terrestrial waters such as lakes and ponds. Together, these two fields form the more general study area of freshwater or aquatic ecology. The following unifying characteristics make the ecology of running waters unique from that of other aquatic habitats. Flow is unidirectional. There is a state of continuous physical change. There is a high degree of spatial and temporal heterogeneity at all scales (microhabitats). Variability between lotic systems is quite high.Ã The biota is specialized to live with flow conditions. Wetland ECOSYSTEM A wetland is a land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem. Primarily, the factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetationthat is adapted to its unique soil conditions. Wetlands consist primarily of hydric soil, which supports aquatic plants. The water found in wetlands can be saltwater, freshwater, or brackish. Main wetland types include swamps, marshes, bogs and fens.Sub-types include mangrove, carr, pocosin, and varzea. Wetlands play a number of roles in the environment, principally water purification, flood control, and shoreline stability. Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant andÃ animal life. Wetlands occur naturally on every continent except Antarctica. They can also be constructed artificially as a water management tool, which may play a role in the developing field of water-sensitive urban design. The largest wetlands in the world include the Amazon River basin and the West Siberian Plain. Another large wetland is the Pantanal, which straddles Brazil, Bolivia, and Paraguay in South America. The UN Millennium Ecosystem Assessment determined that environmental degradation is more prominent within wetland systems than any other ecosystem on Earth. International conservation efforts are being used in conjunction with the development of rapid assessment tools to inform people about wetland issues. Terrestrial ecosystem A terrestrial ecosystem is an ecosystem found only on landforms. Six primary terrestrial ecosystems exist: tundra, taiga, temperate deciduous forest, tropical rain forest,grassland and desert. A community of organisms and their environment that occurs on the land masses of continents and islands. Terrestrial ecosystems are distinguished from aquatic ecosystems by the lower availability of water and the consequent importance of water as a limiting factor. Terrestrial ecosystems are characterized by greater temperature fluctuations on both a diurnal and seasonal basis than occur in aquatic ecosystems in similar climates. The availability of light is greater in terrestrial ecosystems than in aquatic ecosystems because the atmosphere is more transparent in land than in water. Gases are more available in terrestrial ecosystems than in aquatic ecosystems. Those gases include carbon dioxide that serves as a substrate for photosynthesis, oxygen that serves as a substrate in aerobic respiration, and nitrogen that serves as a substrate for nitrogen fixation. Terrestrial environments are segmented into a subterranean portion from which most water and ions are obtained, and an atmospheric portion from which gases are obtained and where the physical energy of light is transformed into the organic energy of carbon-carbon bonds through the process of photosynthesis. Terrestrial ecosystems occupy 55,660,000 mi2 (144,150,000 km2), or 28.2%, of EarthÃ¢â¬â¢s surface. Although they are comparatively recent in the history of life (the first terrestrial organisms appeared in the Silurian Period, about 425 million years ago) andÃ occupy a much smaller portion of EarthÃ¢â¬â¢s surface than marine ecosystems, terrestrial ecosystems have been a major site of adaptive radiation of both plants and animals. Major plant taxa in terrestrial ecosystems are members of the division Magnoliophyta (flowering plants), of which there are about 275,000 species, and the division Pinophyta (conifers), of which there are about 500 species. Members of the division Bryophyta (mosses and liverworts), of which there are about 24,000 species, are also important in some terrestrial ecosystems. Major animal taxa in terrestrial ecosystems include the classes Insecta (insects) with about 900,000 species, Aves (birds) with 8500 species, and Mammalia (mammals) with approximately 4100 species. Organisms in terrestrial ecosystems have adaptations that allow them to obtain water when the entire body is no longer bathed in that fluid, means of transporting the water from limited sites of acquisition to the rest of the body, and means of preventing the evaporation of water from body surfaces. They also have traits that provide body support in the atmosphere, a much less buoyant medium than water, and other traits t hat render them capable of withstanding the extremes of temperature, wind, and humidity that characterize terrestrial ecosystems. Finally, the organisms in terrestrial ecosystems have evolved many methods of transporting gametes in environments where fluid flow is much less effective as a transport medium. The organisms in terrestrial ecosystems are integrated into a functional unit by specific, dynamic relationships due to the coupled processes of energy and chemical flow. Those relationships can be summarized by schematic diagrams of trophic webs, which place organisms according to their feeding relationships. The base of the food web is occupied by green plants, which are the only organisms capable of utilizing the energy of the Sun and inorganic nutrients obtained from the soil to produce organic molecules. Terrestrial food webs can be broken into two segments based on the status of the plant material that enters them. Grazing food webs are associated with the consumption of living plant material by herbivores. Detritus food webs are associated with the consumption of dead plant material by detritivores. Th e relative importance of those two types of food webs varies considerably in different types of terrestrial ecosystems. Grazing food webs are more important in grasslands, where over half of net primary productivity may be consumed by herbivores. Detritus food webs are more important in forests, where lessÃ than 5% of net primary productivity may be consumed by herbivores. There is one type of extensive terrestrial ecosystem due solely to human activities and eight types that are natural ecosystems. Those natural ecosystems reflect the variation of precipitation and temperature over EarthÃ¢â¬â¢s surface. The smallest land areas are occupied by tundra and temperate grassland ecosystems, and the largest land area is occupied by tropical forest. The most productive ecosystems are temperate and tropical forests, and the least productive are deserts and tundras. Cultivated lands, which together with grasslands and savannas utilized for grazing are referred to as agroecosystems, are of intermediate extent and productivity. Because of both their areal extent and their high average productivity, tropical forests are the most productive of all terrestrial ecosystems, contributing 45% of total estimated net primary productivity on land. CAUSES OF DESTRUCTION The degradation of ecosystems is an environmental problem that diminishes the capacity of species to survive. This degradation occurs in different ways and is manifested in a reduction in the richness of the ecosystems as well as their biological diversity, and in the goods and services they can offer, thereby affecting indigenous and/or migratory species. The degradation of ecosystems due to overexploitation of their resources, though serving a short-term economic goal, has had direct negative effects on social welfare in the medium and long terms. As long as the ecosystem is not degraded, it represents a source of wealth for society, hence the importance of keeping it in good condition. One of the main causes that contributes to the degradation of ecosystems is the deforestation due to the advance of the agriculture frontier and inappropriate forest exploitation. More lands are deforested for commercial agriculture and live-stock rearing, and due to overexploitation of forest for wood and energy. In Nicaragua deforestation rates reach over 150,000 hectares per year and in Costa Rica over 18,500 hectares per year. At a lower scale, another problem is the uncontrolled fires used to prepare land for agricultural activities or to remove forest for the development of stock rearing areas. This practice eliminates the organic covering of the land, making it more susceptible to erosion by bothÃ wind and water. In addition, the fires cause health problems and detract from the aesthetic value of the landscape. Accidental or natural fires are another case in point. They affect areas of natural forest. In the Upala and Los Chiles cantons, in Costa Rica, some 10,000 hectares were burned between 1998 and 1999. This problem is even more serious in the Nicaraguan territory of the basin. Equipment is lacking and communities need to be organized to control t hese fires as one of the main barriers to the burning of large areas. The construction of roads without proper drainage measures or in territories subject to penetration and settlement are high-stress factors for ecosystems, especially those which are highly fragile as a result of their weather conditions and the nature of their soil and water. Mining and the extraction of construction materials without taking measures to cushion the impact cause drastic changes in the natural landscape while degrading its valuable ecosystems. Wetlands are very fragile ecosystems that are being severely affected, causing a reduction in the number and diversity of the species of terrestrial flora, birds, reptiles, mammals, fish, and crustaceans. This problem results from excessive exploitation of wildlife species either to feed the population, to trade their furs, or to trade live species, and from sedimentation, which causes changes in water quality, thereby significantly affecting the reproduction of aquatic species that live and/or reproduce in the wetlands. The SJRB wetlands are very valuable ecosystems, which regulate the hydrological cycle and provide food and shelter for hundreds of species, including large quantities of migratory birds. One major cause of the deterioration of this ecosystem is the draining of wide areas of wetlands to give access to agricultural zones or human settlements. Aerial photographs of the CaÃ ±o Negro sector show how the pools of water have diminished over time, due in part to the drainage of wetlands for agricultural purposes and to the sedimentation occurring in recent years in the basin. Owing to the deterioration of these areas and the pressure of the neighboring communities on the use of the natural resources of the wetlands, it is necessary to draw up management plans to outline the socioeconomic characteristics of users and guidelines for usage, since people are highly dependent on these resources for their survival. A large portion of the ecological problems of the wetlands is due to ignorance of their benefits. The use of inappropriate fishing techniques endangers theÃ existence of certain species, altering the food chain of aquatic fauna and consequently deteriorating the aquatic ecosystems. This is the case of the bull shark that is now hard to find in Lake Nicaragua or in the San Juan River. In some cases, the introduction of exotic species endangers the existence of indigenous species with a high cultural value. Such is the case of the guapote, whose numbers are being reduced by the introduction of tilapias. The deterioration of ecosystems is exacerbated by the lack of an institutional presence in the territory, be it for technical or economic reasons, or a combination of both. As a result, laws on the regulation and control of natural resource use are not enforced. The participation of civil society in controlling the use and exploitation of natural resources is limited and, in many cases, very timid or markedly apathetic. One aspect that has not been evaluated in the degradation of the ecosystems is the incidence of different phenomena on these systems. The geographic location of the SJRB and the various geographic accidents encountered there render it susceptible to the impact of various events of this kind. In the SJRB there are a number of active volcanoes, which spew gas and ash causing damage to the plant life, the soil, polluting water bodies, and causing severe damage to entire populations. These volcanoes include the Masaya, the Maderas, and the IrazÃ º. Another natural phenomenon in the SJRB is landslides which, though located in specific areas, cause damage to the ecosystems, the soil, pollute water bodies, damage infrastructure and entire settlements. The Maderas volcano on the island Ometepe is a case in point. Similarly, during the last century, the SJRB has suffered the destructive effects of at least three hurricanes which, with their heavy rainfall, cause flooding damaging ecosystems, eroding soil, diverting river courses, causing severe damage to infrastructure and entire populations, resulting in the loss of human lives. Other natural phenomena that have caused damage to the ecosystems of the SJRB are the droughts that have occurred as a result of the El NiÃ ±o and seismic activity, which have changed river courses, particularly in the case of the Tipitapa River that provided a permanent connection between the Managua and Nicaragua lakes. As a result of an earthquake during the last century, the riverbed rose in a certain sector cutting off the existing connection between the two lakes. The degradation of the ecosystems makes the economic and social infrastructure of the SJRB more vulnerable andÃ increases the potential impact on the population. This vulnerability is reflected in shorter periods between the occurrence of floods or droughts and the soil becomes more unstable. Possible solutions to the problem of deterioration of the ecosystems include developing formal and informal environmental education programs to make farmers more aware of their actions; increasing enforcement of the existing l egislation; promoting proper natural resource management; and promoting the organization of grassroots groups to control burning from the outset. To prevent or mitigate the damage caused by extreme conditions, such as flooding and droughts and other effects of natural phenomena, it is necessary to set up and early warning system about possible swelling of water bodies and to monitor hydrometeorological behavior. It is also necessary to set up a seismographic network to monitor the behavior of volcanoes and tectonic faults. Similarly, social organization is necessary to design and test emergency plans for natural phenomena, to reduce the damage they cause. Institutions responsible for the control and regulation of natural resource use must be strengthened, both technically and economically, and be given the means for their mobilization. This would enable them to have a real presence in the territory. It is also necessary to create mechanisms for enforcing the current legislation. Conservation practices to save ecosystem Environmental protection is a practice of protecting the natural environment on individual, organizational or governmental levels, for the benefit of both the natural environment and humans. Due to the pressures of population and technology, the biophysical environment is being degraded, sometimes permanently. This has been recognized, and governments have begun placing restraints on activities that cause environmental degradation. Since the 1960s, activity of environmental movements has created awareness of the various environmental issues. There is no agreement on the extent of the environmental impact of human activity, and protection measures are occasionally criticized. Academic institutions now offer courses, such as environmental studies, environmental management and environmental engineering, that teach the history and methods of environment protection. Protection of the environment is needed due to various humanÃ activities. Waste production, air pollution, and loss of biodiversity (resulting from the introduction of invasive species and species extinction) are some of the issues related to environmental protection. Environmental protection is influenced by three interwoven factors: environmental legislation, ethics and education. Each of these factors plays its part in influencing national-level environmental decisions and personal-level environmental values and behaviors. For environmental protection to become a reality, it is important for societies to develop each of these areas that, together, will inform and drive environmental decisions. How to Save Our Ecosystem Instructions Educate yourself about your local environment. Starting small and learning about the plants and animals in your immediate surroundings will give you an appreciation for the enormous variety of ecosystems on our earth. It will also help you understand how you fit into your natural surroundings and get you thinking about the effects of your actions. When you flush the toilet, where does your water go? When you wash the car and soap runs off into the street, what does that soap go on to affect? What animals do you disturb by replacing native vegetation with nonnative landscaping? Asking yourself these questions is a one of the first steps to reducing your carbon footprint. 2Ã Find an activist group in your area with a cause you support. It can be a local issue, such as preserving open space in your community, or a more widespread issue, like passing legislation that requires cars to produce fewer greenhouse gas emissions. Being part of a group allows you to meet like-minded people and work toward a common environmental goal. Sponsored Links Homeworks for free We answer 1000 questions daily Free and fast brainly.in 3Consider the implications of your consumerism. Everything you buy has a product life cycle, or a history of how it was produced using what materials. When possible, reduce the impact of your purchase by buying products that are made locally and/or are manufactured from recycled materials. 4Ã Eat local, organic food. Local food travels less distance from farm to your table, which means that it has a lower carbon footprint, is fresher, and supports your communityÃ¢â¬â¢s farmers. Organic food is produced without the use of chemical pesticides or fertilizers, and without genetically modified crops. Chemical pesticides and fertilizers can get into the natural environment and harm existing plants and animals; genetically modified crops reduce biodiversity by encouraging a monoculture farm. 5Ã Travel wisely to decrease your carbon footprint. Use alternative methods of transportation whenever feasibleÃ¢â¬âwalk to the store, ride your bike to work, take public transportation downtown. When you do drive, accelerate and decelerate gradually to conserve gas. Also, make sure that your tires are properly inflated and that the emissions system on your vehicle is well maintained.