Ecosystems at risks full course notes PDF

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Ecosystems at risks full course notes, include all sub topics and necessary statistics for assessments and essays...

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Ecosystems at risk course notes Ecosystems and their management Biophysical interactions which lead to diverse ecosystems and their management o Ecosystem – The dynamic complex of plant, animal and micro-organism communities and their non-living environment as a functional unit, with each component having an interdependent relationship o Classified as either aquatic or terrestrial – these are known as biomes. There are no edges where one ecosystem ends, or another begins – these blended borders are known as ecotones o Productivity – the amount of biomass per square metre of land or the energy flows in nutrient cycling. o The functioning of ecosystems is based on the changes in the biophysical environment: The atmosphere o The main source of the climatic factors that impact an ecosystem functioning. Temperature and the amount of rainfall determine that nature of elements within the ecosystem and the speed at which they function. The climates created by the atmosphere are diverse, and the creation of the warm moist environment is the reason why they are so dynamic. These conditions accelerate the rate of plant growth, the decay of dead material and the take up of nutrients. The Hydrosphere o The Hydrosphere is closely linked with the atmosphere as it determines the nature of the water cycle in a particular area. In tropical rainforests, large volumes of rainfall occur within relatively short spaces of time. This provides an environment conductive to the maintenance of the high levels of biodiversity. The lithosphere o The lithosphere determines that nature of soils and provides habitats for many of the decomposer organisms that recycle the minerals essential to the plants that form the basis of the food web. The lithosphere stores nutrients and water which are available for plants to use. What the soil can hold determines the nature of the ecosystem. Landforms also affect ecosystems. Small variations in elevation can result in marked differences in plant communities. The Biosphere o The biosphere is the domain on or near the earth’s surface where the environmental conditions enable solar energy to produce the chemical changes necessary for life. It comprises all living and dead organisms found near the earth’s surface. These exist in parts of the atmosphere, biosphere, and hydrosphere.

Bioaccumulation Bio accumulation is the process where toxic chemicals are concentrated as successively higher tropic levels within the food chain. The accumulation and amplification of toxic substances in an organism can kill it directly, reduce its ability to reproduce or weaken it to a point where it is vulnerable to disease, parasites and predators. Because this is mainly an issue in the higher trophic levels, its effect the populations of those in lower levels in that they are more likely to populate quickly and this reduces organisms in the levels below in that, populations decrease. Vulnerability and resilience of ecosystems Ecosystems exist in a state of dynamic equilibrium. Changes occur as a constant part of the natural processes that maintain the balance between abiotic and biotic elements on natural ecosystems. The state of dynamic equilibrium is a result of the constant changing interrelationships between the biosphere, lithosphere, hydrosphere and atmosphere. The ability of ecosystems to deal with disturbances or alterations to the flow of air, energy, water and nutrients and return to equilibrium is determine by their resilience – (the ability of an ecosystem to adapt to changes and restore structure and function after a disturbance)

Causes of ecosystem vulnerability Location: Affects an ecosystem functioning. At as global scale, scale, latitude, distance from sea, and altitude play decisive roles in determining climate and ultimately the nature of ecosystems. Extent The extent (size) of any ecosystem is the product of a variety of factors. Ecosystems that are restricted to relatively small areas or have already been disrupted extensively are especially vulnerable. Biodiversity Genetic diversity favours the survival of a species because it increases the chance that some members of the species will have characteristics that will aid their survival if the population is subject to stress. Many diverse ecosystems are characterised by highly specialised organisms. However, a species may be vulnerable even if the ecosystem is not. Linkages Independence or linkages is related to species diversity. The greater the level of independence within an ecosystem, the greater its ability to absorb change. Signs of ecosystems at risk - Drop in primary activity - Contaminants - Decline in species diversity - Larger populations of insect pests or disease organisms - Increased nutrient losses

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Decline or extinction of indicator species (species that serve as a warning that a community or ecosystem is being damaged). Concepts related to resilience in ecosystems: - Elasticity: The rate of recovery of an ecosystem property following disturbance. - Amplitude: Refers to the threshold level of strain beyond which return to the original state no longer occurs. - Malleability: Is the difference between the ecosystem’s fin al recovery level and the prestress level; the greater the difference, the less resilient is the ecosystem.

Impacts due to natural stress There are 2 types of causes of natural stress: Catastrophic and Gradual

Effects of environmental stress: - psychological disorders - genetic defects in offspring - fewer or no offspring - biological changes - loss of diversity and adaptability - extinction - disruption of energy flows - disruption of chemical cycles - behavioural changes - simplification For example: Mt St Helens eruption - cleared 380 square kms of land, killed countless animals, 100 people, destroyed coniferous forests - Resilience  gophers burrowing in ash bringing up old topsoil  Lupin’s bacteria released nitrogen for all plants to use

Birds and animals transported nutrients in their droppings. Human threats to biodiversity include: Intentional Ecosystem Change In many instances, human induced ecosystem change is the unintended consequences of human activity. Such changes often stem from inadequate or incomplete knowledge of ecosystems functioning. E.g. the aboriginals used firesticks to manage the environment, but they were unaware of the long term effects. Inadvertent Ecosystem Change Meeting the needs of mankind and a rapidly increasing human population, will inevitably bring about large-scale environmental change. In the natural world, the explosion of a population in any part of the biosphere is compensated for by an adjustment somewhere else in the biosphere. E.g. an excess of grasshoppers means the plants they eat are placed under stress and die. Change Caused through Negligence People sometime cause change through negligence. Some of the more notorious examples of humanities failure to protect ecosystems at risk are: o Minamata children being poisoned by mercury accumulated in the food chain. Natural stress o Natural selection and evolution is the response which organisms have to gradual changes over millions of years. Natural disasters and events (cyclones, the ice age, fires, volcanoes etc) have caused ecosystems to evolve and adapt to ensure survival. Human induced stress o Large scale environmental change causes ecosystems to be disturbed – many of these ecosystems cannot cope with the changes and are thus negatively impacted. Human threats to biodiversity include: o Introduced species – deliberately or accidentally. Exotic species can wipe out native ones by predatory competition diminishing food supply. This disrupts the flow of energy and effects the entire food chain o Habitat destruction – major threat to biodiversity; deprives native species of habitat and food supply, impacting the species diversity and nutrients available o Hunting – uncontrolled exploitation of animals has destroyed some species; this effects the food chain and species population o Pollution – a threat to aquatic and terrestrial ecosystems as it can alter the salinity, turbidity, nutrients available, precipitation and runoff, disrupting biodiversity and efficiency of nutrient flows

The importance of ecosystem management and protection -

HUMIN factors

Heritage Value - Heritage value is the cultural, historic, environmental, and scientific significance of the place. Ecosystems can be the sites of important historical or cultural events or be places of important scientific research. Some environments possess so much heritage value that they are listed as national heritage or world heritage sites. The maintenance of genetic diversity o Ecosystems rich in diversity have greater resilience and can recover more easily from stress. If diversity is diminished, so is its ability for recovery o The diverse range of species means that there is almost an infinite number of combinations for a species to inherit – this allows for adaptation and change, making the ecosystem less vulnerable Utility value o All components of an ecosystem have existing or potential utility value – its usefulness to humans. Our own ability to cope with changes in an ecosystem are the result of humans utilising the environment around them; and being able to transform parts of the environment into valuable resources which aid the impacts of change. o Humans tap into the diversity of ecosystems and utilise their resources as required by change. The loss of a species also is the loss of its potential utility in the form of food, medicine, fibres, and chemicals. o E.g. – corkwood species has medicinal value; the cycasin plant is used for motion sickness o Option value is the cost of keeping the ecosystem in its natural state compared to exploiting it (opportunity cost). o Exploiting utility value will affect future generations and therefore needs management to reduce degradation Intrinsic value o Ecosystems have the right to exist regardless of their utility value o The biophysical environment can provide many with spiritual, aesthetic (increasingly valued due to rapid urbanisation) and functional needs of people. The environment can provide inspiration, which is the basis of wellbeing for some people, providing a reminder that humans are interdependent with the environment. o Intrinsic value is important to consider as a reason to protect ecosystems as many activities like photography, hiking and birdwatching revolve around the beauty of the environment – not to mention the intrinsic spiritual and religious links which people hold with the biophysical environment (Aboriginal spirituality) o Taking intrinsic value to the extreme means that there would be no alteration or human interaction with the environment. This, whilst a difficult task, would assist the long-term survival and preservation of a particular environment.

Need for Natural Change to Occur - The need for natural change to occur is like that of genetic diversity. Ecosystems need to be able to change and grow over time through the process of natural selection. Environments also help to maintain the Earth’s dynamic equilibrium, which is the state of balance Evaluation of traditional and contemporary management strategies. Approaches to ecosystem management can be classified under four headings: - Preservation: where the habitat and species is totally protected from human activity of any kind. - Conservation: where there is limited impact on ecosystems through sustainable use of resources. - Utilisation: where ecosystems are modified by humans for sustainable use, such as commercial agriculture. - Exploitation: where ecosystem resources are exploited regardless of the consequences. The end results is species extinction, ecosystem destruction and reduction and possible ecosystem collapse. Philosophies of ecosystem management/management approaches 1. Environmental imperialism: Resources are exploited without regard for possible ecological consequences. Operates in developing countries. 2. Utilitarianism: Where the natural resources are used, and the natural ecosystem replaces by a human-modified environment that provides a sustainable yield. 3. Stewardship: Ecological resources are sustainably used with no ling term damage. 4. Romanticism: Encourages resource use that is not damaging or exploitative. 5. Radical environmentalism: Ecosystem quarantined from any human activity. Human access is prohibited. Contemporary management strategies - PUCE Strategies Preservation -

protection in its’ existing form prevention of all human activities in the area being protected e.g. some parts of national parks

Utilisation -

Resources used irrespective of the ecological consequences > destruction or reduction in size. Replacement of an ecosystem with human made environment e.g. commercial agriculture. Coincides with exploitation if taken too far.

Conservation - Active resource management + planned use of natural resources in effort to minimise waste and environmental damage. - Activity has little impact on ecosystems e.g. national parks camping areas.

Exploitation -

In conjunction with sustainable development and stewardship. Uncontrolled, excessive use of natural resources without the intention to maintain it.

Evaluative Terms - BIPI Criteria Intragenerational Equity: - The ability for the current generations to benefit from the ecosystem Intergenerational Equity - The ability for future generations to benefit from the ecosystem. Precautionary Approach: - This helps to ecosystem to survive into the future and be resilient against threats Biological diversity: - The maintenance of a functioning ecosystem and biological diversity Stockton Bight Sand Dunes – Case Study ***(more concise notes: http://mrstevennewman.com/geo/Stockton/Home/index.html ) Notes below taken from other students Spatial patterns and dimensions – location, latitude, size, shape, and continuity o

o o o o o o

Located: the mid-point of the NSW coast, 165 kilometres north of Sydney, extends approximately 31.8 kilometres from Stockton in the SW to Birubi Point (near Anna Bay) in the NE Latitude: 32°50’S to 151°53’E Size: 4200 hectares; 1800 of which are forest, 32km of sand dunes 78km2 Shape: Bight shape Continuity: Formed initially in the Pleistocene period (2million years -10000 years ago); top layers of dunes from the Holocene period (11000 years old) Altitude: averages 15-20m above sea level, larger dunes are 30-40m, low lying areas in between are known as swales which might have wetlands in them Extent: area 78km2 length 31.8km width 3.5km at the widest point; average 2-3km depth 30m

Biophysical interactions o formed by interactions of the four spheres in a cycle known as the accretion cycle. o Accretion is a complex process where the spheres create, build up, store and remove sand in the dune system in a constant cycle.

o Begins by sea erosion and deposition  transported  deposited  stored by vegetation  destructive waves take sand back and is then deposited by constructive waves

Weather and climate o o

Wind, temperature, and rain play a role in sand dune formation, also helps vegetation to grow which stabilises dunes Wind – shapes, dries, moves, and weathers sand, prevailing winds from the beach is what forms the sand dunes on the coast (75% of the wind is on shore prevailing winds from the SE). Aeolian transport contributes to the erosion of sand particles and moves sand in the

o o

accretion cycle – sand bigger than 1cm in diameter is too big to move. Air can cause sand to bounce and collide at an average angle of 10-16 degrees. Temperature – affects the drying of sand dunes. Temperature between 21-27 degrees (winter 10-15). Helps plant growth and therefore dune stabilisation Precipitation – determines sand moisture and helps plant growth, wet sand helps stick more sand for storage in the accretion cycle. Closeness to the sea allows for even rain spread. JanJune is the wet season 1000mm(N) to 1300mm(E). fluctuation in sand wetness allows for the accretion cycle to continue

Biogeographical processes Colonisation – first organisms to inhabit the land Succession – sequence of organisms which succeed each other until climax community. o o o o o

Most dune vegetation was deposited by storms on berms or sand ridges, trapped by sand drying around them. Sea birds, seaweed brings passengers to feed on plants, birds bring nitrates in their droppings which are good plant foods. Plants stop tumbleweeds containing seeds. Tiny dunes formed by plants will trap more sand around them and form a larger dune (plants like spinifex, pigface and goats foot) Time, isolation and no interference mean that the primary dune can be formed which means more stabilisation and a dune system can form Over time SE winds, sand and spinifex grass form a ridge creating a natural wall of defence, accasias and banksias form in the swale which hides behind.

Vegetation o o o o

Incipient dune – primary vegetation zone, plants with deep strong forms Foredune - secondary vegetation zone, banksias form Hind dune – tertiary vegetation zone, trees dominate, characterised by organic matter (humus) Vegetation acts as a wind barrier to stabilise dunes; incipient is 1st wall of defence, secondary, then foredune

Adjustments to natural stress o

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Storm damage – heavy rain, strong winds and powerful waves cause structural damage such as blowouts where breaches in sand dunes where wind blows sand into the secondary and tertiary vegetation. Adapts to this by vegetation succession. Blowouts in Stockton include the tongue (5.5km x 1.9km wide) and the bowl (from careless land use). o Washouts also occur from destructive waves which breach the foredune area, so powerful that they move above the swash zone to incipient and foredune area. These waves erode sand and weaken the vegetation. Dunes adapt to this as wash overs are a part of the accretion cycle which is restored by deposition and vegetation. In 1974 the NSW coast was battered by storms with swells 17m high and 165km/h wind which caused massive wash overs which flattened the dunes, but the accretion cycle fixed it Bushfires – occur in tertiary and secondary dunes, linked to lightning. Vegetation has adapted to this by: o Propagation – fires can be the catalyst for seeds to propagate (open) and cause new growth post-bushfire e.g. Banksia and wattle plants o New growth is also encouraged e.g. Eucalypt o Inputs in nutrient cycling – bushfires encourage chemical reactions that convert complex chemicals into simple ones which organisms can consume

The nature and rate of change which affects ecosystem functioning Natural change o o

o

Accretion cycle and natural stress – rapid changes have slower replenishment, but dunes have adapted to such changes Wind – wind blowing sand has the most significant change as it reshapes dunes and the topography regularly. At Stockton bight, wind continuously blows beyond the limits into tertiary vegetation making it a mobile transgressive dune system Sea levels – significant changes between ice ages, the rise and fall of sea levels and temperature change the geomorphic vegetation zones. The Stockton dunes are made up of layers of ancient dune ecosystems which are millions of years old. 100m years ago, sea levels were 200m higher, the fall of sea levels saw sand deposited and layered. The current layer has developed over the last 10 000 years (Holocene period) and the last ice age meant the swash zone was further out to sea. The different temperatures and water levels meant that the vegetation has varied over time.

Human change o

Humans have contributed significantly to the change of coastal sand dunes ecosystems. Human activities like cattle, developments, 4wd, introduced species & sea walls have changed the lithosphere and topography of Stockton. Human impacts have caused rapid change, altering adaptability and decreasing biodiversity.

Human impacts Positive o o

From aboriginal (wo...