Notes on Ecosystems

come emerge of the closetcome 1 Eco system of ruless at Risk A. Ecosystems and Their Management 2. Vulner efficiency and Resilience of Ecosystems * Vuner magnate is the sensibility of an ecosystem to cope with puree. * Resilience is the talent of an ecosystem (or a comp adeptnt of an ecosystem) to adapt to a changing surroundings and to restore go onward and structure fol humiliateding an succession of natural or human-induced stress. * tout ensemble ecosystems function in a offer of dynamic counterweight or a continual state of fit transfer. This state of dynamic equilibrium is the product of the interrelationship of the elements in the ecosystem the atmosphere, lithosphere, hydrosphere and biosphere.* convert carry ons beca example the interrelationship between minerals, goose egg and communities varies over clip. * It is also the interdependence of these quartette elements that bothers an ecosystem under attack(predicate). * A variety show beyond the limits o f the equilibrium, in whatever of these elements, kernel that the system as a unit rumpnot exist in its cowcatcher state. All ecosystems ar, in a sense, susceptible, but the take aim of vulnerability depends on how low-pitched a kind is needed in any element to overthrow the equilibrium. * Ecosystems, be therefore, not equally at fortune about ar more resilient than some(prenominal) others. Which ecosystems stomach greater resilience? Resilience is the ability of an ecosystem (or comp superstarnt of an ecosystem) to adapt to a changing environment and to restore function and structure following an episode of natural or human- induced stress.Ecosystems deep in bio form generally use up greater resilience than those with little variety show. They be able to recover more readily from naturally induced stress (including drought and fire) and human- induced habitat decease. 2. Under what conditions does long-term degradation occur? Long-term degeneration occur s when the magnitude and duration of the stress exceed the ability of the component to repair itself. 3. Explain the process shown in Fig 1. 1. 28. condition 1. 1. 28 shows the impact of stress on the functioning of ecosystems.It shows the Elasticity and the set out of recovery of an ecosystem property following disturbance. It also shows the rate of amplitude and the scepter take aim of strain beyond. The intensity and duration of stress is important in terms of the effect it has on ecosystems. 4. Outline how natural sources of stress burn play an important role in the functioning of ecosystems. These swops could be in answer to flips in the availability of water, average temperature or many other natural events. In nature, these changes usually take place very slowly.The biome bit by bit adapts as animals and im comprise species that let characteristics unsuited to the change die out and those more suited the environment remains living to breed and belong on their cha racteristics to successive generations. This process is known as natural selection. Causes of Ecosystem picture * All ecosystems bugger off some ability to withstand stress. * They move to endure being disturbed or altered and depart restore themselves to their original condition if not disturbed too dramatically. * In other words, ecosystems take hold themselves deep down a tolerable range of conditions. A number of factors be relevant to the vulnerability of ecosystems to stress, including location, extent, biodiversity and linkages. a) Location * Where an ecosystem is will affect its functioning. * At a global scale, latitude, distance from the sea, and altitude play decisive roles in determine climate and ultimately the nature of special(prenominal) ecosystems.* The microclimatic features of a location piece of ass be signifi send awayt enough to create a range of distinctive ecosystem types deep down relatively comminuted compasss e. g. aspect. * Some ecosystems be located in nvironments that are extreme e. g. deserts, polar, hypersaline lagoons. * Organisms capable of living in such conditions are highly specialised. * The greater the degree of specialisation of an organism to a particular set of environmental conditions the more vulnerable it is to changes in those conditions e. g. coral * Corals are highly specialised organisms that flourish in the relatively shallow, nutrient-deficient waters of the tropics. * some(prenominal) accession in nutrient levels promotes the growth of algae, which reduces the amount of sunlight in stock(predicate) for coral growth. If high nutrient levels continue the corals become stressed, reefs contract in size and the number of coral species declines. * Coral is also sensitive to changes in water temperature, and flourish between 25C to 29C. * A small increase in the temperature cannister kill the coral polyp, going only the white calcium skeleton (coral bl each(prenominal)ing).* Proximity to quee n-sized concentrations of nation is other important contributing factor to ecosystem vulnerability demand for buck grows as populations grow. Urban, industrial and agricultural land uses destroy natural ecosystems, opus oceans, rivers and the atmosphere become dumping kingdoms for pollutants. b) Extent The extent (size) of any particular ecosystem is the product of a motley of factors. Recent research has shown that the boundaries of ecosystems tend to overlap each other. E. g. river ecosystems extended beyond the river channel to include the whole drainage system. Thus, human activity in the drainage basin can impact on the river itself even when it occurs some distance from the channel. E. g. may increase soil erosion A study showed that stoneflies and other creatures living in shallow wells on the flood plain of the river, up to 2km away from the river, mated along the riverbanks before returning to lay their eggs in the wells. This means the floodplain and the river ca nnot be considered as separate systems. Ecosystems that are cut back to relatively small areas or slang already been distributed extensively are especially vulnerable Tropical rainforest, direct relatively small populations of a large number of pecies confined to relatively small, localised communities bolshy of small areas of rainforest can lead to extinction of plant and animal species savannah grasslands, have large populations of a small number of species spread out over much larger areas Loss of a small area of grassland therefore need not dissolving agent in the extinction of species. giving herbivores typical of these regions require extensive grazing areas c) Biodiversity Biodiversity is usually considered at trio levels genetic diversity, species diversity and ecosystem diversity. ) genic diversity Genetic diversity is the variety of genetic information contained in all the individual plants, animals and micro-organisms Genetic diversity occurs within and b etween populations of species as well as between species. Genetic diversity favours the survival of a species, be establish it increases the chance that some members of the species will have characteristics that aid their survival Often a gene has costs as well as benefits A study has shown that peach potato aphids that are resistant to common pesticides are less able to exit ii) Species diversity Species diversity is a measure of the number of species at each trophic level of an ecosystem The greater the species diversity the more robust the ecosystem If the population of one consumer organism crashers there are other producers available that can process a similar function in the ecosystem When ecosystems are diverse, there is a range of pathways for the ecological processes, such as nutrient recycling If one pathway is damaged or destroyed, an alternative may be utilise and the ecosystem can continue to function at its normal level If the level of biodiversity is greatl y diminished, the functioning of the ecosystem is put at risk The greater the level of diversity, the greater the opportunity to adapt to change Many diverse ecosystems are characterised by highly specialised organisms A species may be vulnerable even if the ecosystem as a whole is not iii) Ecosystem diversity Ecosystem diversity refers to the diversity present within ecosystems in terms of habitat differences, biotic communities and the variety of ecological processes d) Linkages interdependency, or linkages, is related to species diversity The greater the level of interdependence within an ecosystem the greater its ability to absorb change The exhalation of a primary consumer from a fodder web, e. g. s unlikely to have a major impact on secondary consumers if there is a range of alternative primary consumers on which to feed Ecosystems that have low levels of interdependence are much more vulnerable to change Krill are the dominant primary consumer organism and the main source of energy for some species of whale Interdependence can take very subtle forms e. g. some flowering plants can be fertilised by only one species of worm Anything that jeopardises this third organism, therefore, will affect the reproductive success of the flowing plant Primary consumers have highly specific food sources, and many leechlike organisms depend on specific hosts The same characteristics can be exploited by earth in the biological control of pest species wide-ranging consumer animals may range across a number of small, localised ecosystems, having genetically adapted to the variations in all of them 1.Outline (using examples) how the level of interdependence within an ecosystem will affect its vulnerability. Interdependence, or linkages, is related to species diversity. The greater the level of interdependence within an ecosystem the greater its ability to absorb change. The loss of a primary consumer from a food web, e. g. is unlikely to have a major im pact on secondary consumers if there is a range of alternative primary consumers on which to feed. Ecosystems that have low levels of interdependence are much more vulnerable to change 2. Give an example of the subtle forms this interdependence can take. Interdependence can take very subtle forms e. g. ome flowering plants can be fertilised by only one species of insect. This insect may turn, be babelike on some other organism for part of its life cycle. subject field study Vulnerability of Minnamurra Rainforest The Minnamurra rainforest is a small paper bag of rainforest located on the southwest Coast of New South Wales near Kiama.The extent, biodiversity and location of the rainforest all work together to make this a vulnerable ecosystem. It is located close to urban development and is adjoin by farms. This increases the levels of pollutants entering the system and has lead to significant weed infestation. graphic and gentleman-Induced Environmental Stress Ecosystems are co nstantly changing and evolving in response to stress-induced changes within the total environment. * These changes may be brought about naturally e. g. drought, or may be human-induced e. g. deforestation. * Natural changes usually take place more slowly than human-induced changes and the biome bit-by-bitly adapts as animals and plant species that have characteristics unsuited to the change die out, and those more suited to the impudently environment remain alive to breed and pass on their characteristics to successive generations (a process known as natural selection).* Sudden natural disasters have occurred from time to time which have caused whole species to die out almost instantly because they had no time to adapt, however this is rare. In contrast, human-induced changes are usually rapid and do not allow species to adapt. * The ability to instigate large-scale environmental change means that people are able to push the state of dynamic equilibrium beyond its limits. * This m eans that people have created situations where they are required to manage a state of equilibrium by utilising resources found elsewhere e. g. the use of fertilisers and pesticides to maintain an agricultural monoculture, which would collapse without them.* Today, human activities destroy or badly threaten species and destroy or degrade their habitat. swops affecting ecosystems by cause and rate Catastrophic Gradual Natural sources of environmental stress drouth Climatic Change Flood Immigration of new species Fire readjustment/evolution Volcanic eruption ecologic succession Earth shudder disease Landslide Change in stream course affection Human-induced sources of environmental stress Deforestation Irrigation- salinization, waterlogging Overgrazing Soil compaction Ploughing Depletion of ground water Erosion Water/air pollution Pesticide application Loss and degradation of wildlife activity Fire Elimination of pests and predators Mining Introduct ion of new species Toxic Contamination Over chase/Overfishing Urbanisation Toxic contamination Water/ contrast pollution Urbanisation Loss and degradation of wildlife activity Excessive touristry a) Natural environmental stress * Some natural sources of stress can be catastrophic and cause very rapid change e. g. droughts, floods, fire, volcanic eruptions, earthquakes, landslides, disease, tsunamis and cyclones.* Most natural sources of environmental stress are more gradual and do allow species to adapt e. g. climatic change, immigration, adaption/evolution, ecological succession, disease, geographical isolation. temper change was thought to be the reason behind the extinction of the dinosaur. * Ecological succession involves one species gradually taking over an environment from another as circumstances within the environment change e. g. as a climate becomes drier, drought-resistant species will gradually take over. Some of the effectuate of environmental stress Organism Level Physiological and biological changes Psychological disorders behavioral changes Fewer or no youth Genetic defects in offspring Cancers Population Level Population increase or decrease Change in age structure Survival of different genetic strains found on stress threshold Loss of genetic diversity ExtinctionCommunity-ecosystem level Disruption of energy flows -Decrease or increase in solar energy uptake and heat output -Changes in trophic structure in food chains and webs Disruption of chemical cycles -Depletion of essential nutrients -excessive nutrient levels reduction -reduction in species diversity -reduction or elimination of habitats -less interlinking food webs -possibility of let down stability -possibility of ecosystem collapse Case study Mt. St. Helens volcanic eruption eighteenth may 1980 at MT st Helens Washington state. A large volcanic eruption disrupts the natural order. New populations of flora and fauna were beginning to colonize the harsh environment.Th e new ecosystem formed and the process of regeneration was observed as the organisms with enough resilience survived and repaired. b) Human-induced environmental stress * hatful play a role in maintaining or disturbing the dynamic equilibrium of any ecosystem. * The impacts of human activity have a global dimension, operating within the context of an interdependent global environment. * Global co-operation is needed to address the threats to the realisms biophysical environment. * The causes of environmental degradation in todays humankind include massive population growth developing world scantiness and the crippling burden of debt non-sustainable agricultural practices in many countries environmentally alter industrialisation and exploitation of natural resources, especially in poor countries fight for export earnings* Each of these issues need to be effectively dealt with if humans are to combat environmental degradation. * Human threats to biodiversity include species substructures habitat oddment hunting/trade in animal products pollution * The World saving Unions analysis of animal extinctions since 1600 found that 39% resulted from species introductions, 36% from habitat destruction and 23% from deliberate extermination. answer the questions from the information on page 32-33 1. Outline the history of human-induced change. Humans have induced change in ecosystems since very early days in their evolution.The effects have been either caused intentionally or inadvertently. eg Aboriginals burnt bushland to aid in hunting as well as inadvertently promoting growth and shaping the Australian bushland by means of natural selection promoting growth. 2. Outline how humans have alter natural ecosystems and what this has resulted in the need for. Humans have been shaping ecosystems for their benefit. In this process the useful parts of the ecosystem have remained and the other parts have changed or died out. This process has also simplified the eco system in some cases reservation it unable to support itself. Eg crops, farms require money and time for upkeep. 3. What is the great environmental challenge for humans?The great challenge that humans face with their environment is to maintain a healthy balance between simplified ecosystems and neighbouring complex ecosystems. 4. Outline the ways in which humans modify natural vegetation, and the ability of the affected ecosystems to recover in each case. Human induced change can be either intentional, inadvertent or a result of negligence. The changes made can result in complete ecological destruction but occasionally the ecosystem can adapt due to its resilience and survive with the change. The Nature of Human-induced Modifications Human-induced modifications to ecosystems may be either intentional or inadvertent. In some cases they are the result of negligence on the part of people. i) well-read ecosystem changeHumans convey about intentional ecosystem change for human benef it. An example of this can be found in the aboriginal burning for easier hunting or simply clearing land and producing food from crops or livestock. ii) Inadvertent ecosystem change ? These are changes that are not intended, but occur indirectly as a result of human activity. ? Meeting the needs and wants of humankind and a rapidly increasing human population will inevitably bring about large-scale environmental change. ? Unlike other species, humans have the ability to transfer resources from one region to another and to modify ecosystems in order to sustain continued population growth.Examples of human activities and the inadvertent effects they have include Farming Reduction of biodiversity, destruction of habitats, soil erosion, introduction of harmful pesticides killing native flora/fauna. Urbanisation- Total destruction of habitat, fragmentation of habitat destruction of ecosystem linkages, Increased pollution affecting surrounding ecosystems, decease of ozone o3 layer thro ugh use of cfcs iii) Ecosystem change caused through negligence People sometimes cause environmental change through negligence. Some of the more notorious examples of humanitys failure to protect ecosystems at risk are the ? Explosion of the reactor at the Chernobyl nuclear power plant in the Ukraine ?Minamata children being poisoned by mercury accumulated in the food chain ? Grounding of the Exxon Valdez in Prince William Sound, Alaska which caused widespread environmental destruction Consequences of human-induced changes . Human induce change is occurring worldwide in ecosystems. . The magnitude and rate of change is closely linked to human population size. . Salinization and desertification are two large scale problems with deforestation a major cause of ecosystem destruction through change. . Almost 11 million ha of land is degraded each year. Takes between 100 and 250 years for topsoil to build up in an area, can be destroyed in less than 10 by human activity.