Notes on Ecosystems

stem 1 Ecosystems at Risk A. Ecosystems and Their Management 2. vulner strength and resilience of Ecosystems * Vuner capability is the sensitivity of an ecosystem to cope with stress. * Resilience is the ability of an ecosystem (or a comp whiznt of an ecosystem) to adapt to a changing environs and to restore bit and mental synthesis adjacent an episode of inherent or clement-induced stress. * All ecosystems work in a state of dynamic sense of remainder or a continual state of equilibrise qualify. This state of dynamic equilibrium is the product of the interrelationship of the elements in the ecosystem the atmosphere, lithosphere, hydrosphere and biosphere.* Change conks be ca-ca the interrelationship amongst minerals, efficacy and communities varies oer cartridge holder. * It is similarly the mutualness of these four elements that makes an ecosystem susceptible. * A alternate beyond the limits of the equilibrium, in either of these elements, meaning that the system as a whole discharge non go in its original state. All ecosystems be, in a sense, under fire(predicate), but the direct of pic depends on how depressed a motley is needed in any element to upset the equilibrium. * Ecosystems, ar therefore, non as at risk most atomic number 18 to a strikinger extent resilient than early(a)s. Which ecosystems spend a penny greater resilience? Resilience is the ability of an ecosystem (or component of an ecosystem) to adapt to a changing environment and to restore function and structure followers an episode of ingrained or forgiving- induced stress.Ecosystems siz sufficient in bio miscellany gener totally(prenominal)y have greater resilience than those with little motley. They are able to recover more readily from course induced stress (including dr awayh and fire) and homosexual- induced habitat goal. 2. Under what agrees does long-term adulteration occur? Long-term degeneration occurs when the order and success ion of the stress exceed the ability of the component to desexualize itself. 3. Explain the process shown in Fig 1. 1. 28. take in 1. 1. 28 shows the impact of stress on the procedure of ecosystems.It shows the Elasticity and the rate of recovery of an ecosystem property avocation disturbance. It withal shows the rate of amplitude and the threshold level of strain beyond. The intensity and duration of stress is historic in terms of the effect it has on ecosystems. 4. precis how inborn sources of stress pot play an alpha social occasion in the functioning of ecosystems. These dislodges could be in response to transfigures in the availability of water, average temperature or numerous another(prenominal) natural events. In temper, these changes usually take place very slowly.The biome little by little adapts as animals and plant species that have characteristics unsuited to the change become out and those more suited the environment corpse alive to breed and pass on their characteristics to incidental generations. This process is known as natural selection. Causes of Ecosystem photograph * All ecosystems have some ability to give stress. * They tend to resist being disturbed or altered and will restore themselves to their original condition if not disturbed too dramatically. * In other words, ecosystems brinytain themselves indoors a tolerable grasp of conditions. A calculate of factors are relevant to the vulnerability of ecosystems to stress, including location, extent, bio sort and linkages. a) Location * Where an ecosystem is will allude its functioning. * At a global shell, latitude, blank space from the sea, and altitude play fateful roles in determining temper and ultimately the nature of picky ecosystems.* The microclimatic features of a location rouse be epochal enough to create a take to the woods of distinctive ecosystem types inwardly relatively humble areas e. g. aspect. * whatsoever ecosystems are located in nvir onments that are thoroughgoing e. g. deserts, polar, hypersaline lagoons. * Organisms capable of living in such conditions are extremely specialised. * The greater the degree of specialisation of an being to a take upicular set of environmental conditions the more vulnerable it is to changes in those conditions e. g. red coral * Corals are heightsly specialised organisms that flourish in the relatively school, nutrient-deficient wet of the tropics. * Any growth in nutrient levels promotes the development of algae, which reduces the amount of sunlight available 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 throw out kill the coral polyp, leaving further the white calcium flesh (coral bleaching).* Proximity to largish concentrations of people is an other authorized contributing factor to ecosystem vulnerability demand for tear grows as tribes grow. Urban, industrial and art slight land uses pulverise natural ecosystems, while oceans, rivers and the atmosphere become toss grounds for pollutants. b) Extent The extent (size) of any particular ecosystem is the product of a compartmentalization of factors. Recent explore has shown that the boundaries of ecosystems tend to overlap each other. E. g. river ecosystems extended beyond the river channel to acknowledge the whole drainage system. Thus, world activity in the drainage basin can impact on the river itself even when it occurs some distance from the channel. E. g. whitethorn increase soil erosion A composition 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 go to lay their eggs in the wells. This means the flood plain and the river cannot be cons idered as separate systems. Ecosystems that are restrict to relatively small areas or have already been distributed extensively are curiously vulnerable equatorial rainforest, have relatively small populations of a galactic number of pecies confined to relatively small, localised communities personnel casualty of small areas of rainforest can lead to extinction of plant and animal species Savanna 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 dissolvent in the extinction of species. cock-a-hoop herbivores normal of these regions require extensive grazing areas c) Bio revolution Bio diversity is usually considered at three levels genetic diversity, species diversity and ecosystem diversity. ) Genetic diversity Genetic diversity is the variety of genetic cultivation contained in all the individual plants, animals and micro-organisms Genetic diversity occurs at bot tom and between populations of species as well as between species. Genetic diversity favours the survival of a species, because it increases the chance that some members of the species will have characteristics that precaution their survival Often a gene has cost as well as benefits A study has shown that peach potato aphids that are resistant to cat valium pesticides are less able to function 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 fulfil a similar function in the ecosystem When ecosystems are diverse, there is a range of pathways for the ecologic processes, such as nutrient recycling If one pathway is damaged or destroyed, an utility(a) may be used and the ecosystem can continue to function at its normal level If the level of biodivers ity is greatly 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 passing 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) Linkagesmutualness, or linkages, is related to species diversity The greater the level of mutualness within an ecosystem the greater its ability to absorb change The qualifying of a immemorial consumer from a food web, e. g. s flimsy to have a major impact on alternative consumers if there is a range of alternative base 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 clear-sighted forms e. g. some flowering plants can be fertilised by wholly one species of insect Anything that jeopardises this third organism, therefore, will postulate the reproductive success of the flowing plant unproblematic consumers have highly specific food sources, and many parasitic organisms depend on specific hosts The comparable characteristics can be exploited by globe in the biological control of pest species Large consumer animals may range across a number of small, localised ecosystems, having genetically adapted to the variations in all of them 1. system (using physical exercises) 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 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 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 leechlike on some other organism for part of its life cycle. Case study Vulnerability of Minnamurra rainforest The Minnamurra rainforest is a small pocket of rainforest located on the South Coast of wise 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 touch by farms. This increases the levels of pollutants entering the system and has lead to significant weed infestation. Natural and sympathetic-Induced Environmental Stre ss Ecosystems are constantly 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 gradually adapts as animals and plant species that have characteristics unsuited to the change die out, and those more suited to the new 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 closely 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 means that people have created situations where they are inseparable to maintain 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 in earnest threaten species and destroy or degrade their habitat. Changes touching ecosystems by cause and rate Catastrophic dilatory Natural sources of environmental stress Drought climatic Change Flood Immigration of new species send away Adaptation/evolution Volcanic boot bionomic succession Earth Quake disease landslip Change in stream course unhealthiness Human-induced sources of environmental stress Deforestation Irrigation- salinization, waterlogging Overgrazing Soil contraction Ploughing Depletion of ground water Erosion piss/air pollution Pesticide application Loss and adulteration of wildlife activity Fire Elimination of pests and predators Mining origin of new species poisonous Contamination Overhunting/Overfishing urbanization Toxic contamination Water/Air 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.* to the highest degree 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. Climate change was design to be the reason behind the extinction of the dinosaur. * bionomic 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 mak e of environmental stress Organism Level physiologic and biological changes Psychological disorders Behavioural changes Fewer or no payoff Genetic defects in offspring Cancers Population Level Population increase or decrease Change in age structure Survival of different genetic strains based on stress threshold Loss of genetic diversity ExtinctionCommunity-ecosystem level Disruption of energy flows -Decrease or increase in solar energy uptake and rouse output -Changes in trophic structure in food chains and webs Disruption of chemical cycles -Depletion of essential nutrients -excessive nutrient levels Simplification -reduction in species diversity -reduction or elimination of habitats -less heterogeneous food webs -possibility of lowered perceptual constancy -possibility of ecosystem collapse Case study Mt. St. Helens volcanic eruption 18th may 1980 at MT st Helens cap state. A large volcanic eruption disrupts the natural order. New populations of flora and fauna were beginning to annex the harsh environment.The new ecosystem formed and the process of variety was observed as the organisms with enough resilience survived and repaired. b) Human-induced environmental stress * large number 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 dependent global environment. * Global co-operation is needed to address the threats to the realnesss biophysical environment. * The causes of environmental degradation in todays world include massive population growth developing world poverty and the incapacitating burden of debt non-sustainable agricultural practices in many countries environmentally damaging industrialisation and exploitation of natural resources, especially in poor countries struggling for export cyberspace* Each of these issues need to be effectively dealt with if adult male are to combat environmental degradation. * H uman threats to biodiversity include species introductions habitat dying hunting/trade in animal products pollution * The World Conservation legal jointures analysis of animal extinctions since 1600 found that 39% resulted from species introductions, 36% from habitat destruction and 23% from reach extermination. answer the questions from the information on page 32-33 1. limn 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 designedly or inadvertently. eg Aboriginals burnt bushland to aid in hunting as well as inadvertently promoting growth and formative the Australian bushland finished natural selection promoting growth. 2. Outline how humans have simplified 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 change d or died out. This process has also simplified the ecosystem in some cases making it otiose to support itself. Eg crops, farms require money and time for upkeep. 3. What is the great environmental dispute 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 interchange 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 now and again 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) Intentional ecosystem changeHumans conduct about intentional ecosystem change for human benefit. An example of this can be found in the old burning for easier hunting or simply modify 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 chop-chop increasing human population will inevitably bring about large-scale environmental change. ? contrasted other species, humans have the ability to air 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 cultivation Reduction of biodiversity, destruction of habitats, soil erosion, introduction of pernicious pesticides killing native flora/fauna. Urbanisation- Total destruction of habitat, fragmentation of habitat destruction of ecosystem linkages, Increased pollution a ffecting surrounding ecosystems, Destruction of ozone o3 layer with 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 king plant in the Ukraine ?Minamata children being poisoned by hectogram accumulated in the food chain ? initiation 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 degree centigrade and 250 years for topsoil to build up in an area, can be destroyed in less than 10 by human activity.