Issues of Ecosystem

Issues of Ecosystems

Introduction

Ecology à the study of organisms and their relationship to one another and their surroundings. It includes biotic and abiotic.

Ecosystem à An identifiable system of interdependent relationships between living organisms and their biophysical environment.

The ecosphere à The ecosystem of the planet, the totality of all ecosystems.

The components of the ecosphere:

Ecosphere

Ecosystems

Communities-Several populations interacting within a particular habitat

Populations-A group of organisms living in the same area

Organisms

Classifying ecosystems

Ecosystems can be classified by:

Climate à eg desert, polar and alpine ecosystems

Vegetation à eg tundra, tropical rainforests, grasslands, forests

Physical features à mountains, coral reefs, islands and lakes

Also can be classified as:

Terrestrial à land based eg deserts, forests, grasslands

Aquatic à water based à lakes, ponds, wetlands,

• Biophysical interactions which lead to diverse ecosystems and their functioning

Ecosystems are characterised by the complex interactions between the abiotic and biotic environments. The various interactions produce a wide diversity of ecosystems across the world.

This involves a number of major systems:

• Atmosphere -

-The atmosphere brings about changes to the climate of ecosystems, particularly rainfall and temperature which impacts on their functioning.

-The atmosphere is the ecosystems source of nutrients such as carbon dioxide and oxygen

-The atmosphere can either slow down or accelerate an ecosystems functioning.

• The hydrosphere

-The hydrosphere is closely linked to the atmosphere, which is responsible for the water cycle in a particular area à eg the climate that is the temperature and the amount of rainfall emanating from the atmosphere results in the slow functioning of polar ecosystems.

· The lithosphere

-Determines the nature of the soil in an ecosystem

-Climatic factors also affect the role soil plays in an ecosystem à eg the Perma frost soils of the tundra ecosystem, due to the cold weather the soil remains frozen all year round.

-It provides habitats for many of the decomposer organisms

-Stores minerals and water for plant usage

· The biosphere

-The environmental conditions of the biosphere enable solar energy to produce he chemical changes necessary for life.

-Population dynamics-explosions and crashes in populations influence species interactions

-Life cycles influence food chain relationships

-Migration behaviour patterns of birds and animals influence such things as vegetation patterns, seed dispersal and cross-pollination.

-The biosphere consists of two types of organisms:

Autotrophs à those that manufacture their own food à these organisms are at the beginning of an ecosystem’s functioning,

Heterotrophic à organisms that cannot manufacture their own food (Consumers)

Producers à make their own food from substances obtained from their environment. They convert energy into food through:

-Photosynthesis –Chemosynthesis

Consumers à obtain nutrients from feeding on producers or other consumers.

Consumers are classified according to their food sources:

-Primary consumers à feed directly from producers

-Secondary consumers à feed only on consumers

- Decomposers à feed off dead organisms and their waste products

Bioaccumulation à non-biodegradable toxic substances being released into the environment and accumulating in organisms at the highest level of the food chain particularly

Effects: Bioaccumulation in an organism can kill it directly, reduce its ability to reproduce, or weaken it to a point where it is vulnerable to diseases, parasites and predators.

· The technosphere

- Human intervention resulting in changes to the biophysical environments and thus ecosystems, eg contemporary land management practices eg pesticides.

Biodiversity

Def: Biodiversity is the variety of living things that are best suited to survive the conditions currently existing on earth.

Biodiversity includes 3 things:

-Genetic diversity à variations in the genetics of individual species

-Species diversity à the variety of species in different habitats

-Ecological diversity à the variety of biological communities that interact with each other and their non-living environment.

· Vulnerability and resilience of ecosystems

General points on Resilience:

Def: Resilience is the ability of an ecosystem to adapt to changes in its environment and to restore function and structure after an episode of natural or human induced stress.

· Ecosystems exist in a state of dynamic equilibrium. The state of dynamic equilibrium is a result of constantly changing interrelationships between the 4 spheres.

Ecosystems need to be able to bounce back after stress so this equilibrium is maintained.

· The more resilient a species is, the less vulnerable it is to changes in its ecosystem.

• Ecosystems rich in biodiversity generally have greater resilience that those with little biodiversity à more living things to support it.

• An ecosystem, which is under stress as a result of human or natural, factors which decrease in its resilience. Ecosystems are always changing and evolving in response to stress induced changes within the total environment.

3 important concepts related to resilience in ecosystems:

-Elasticity à the rate of recovery of an ecosystem after stress

-Malleability à the difference between the final recovery level and the level pre-stress period

-Amplitude à the threshold level of change that prevents an ecosystem from recovering to its original level

Vulnerability

· The fact that all ecosystems are interdependent makes them vulnerable (susceptible).

· The ability of ecosystems to deal with disturbances or alterations and return to equilibrium depends on their resilience.

There are several factors that influence (cause) the vulnerability of ecosystems:

Location Extent Biodiversity Interdependent

Location

The location of ecosystems plays a large role in determining their vulnerability.

The more specialised a population is, the more vulnerable it is likely to be to changes in environmental conditions. Eg coral which flourish in shallow, nutrient deficient waters of the tropics.

Extent

The extent of a particular ecosystem depends on many factors, the most important being climate.

Ecosystems that are restricted to relatively small areas or have already been subject to extensive disturbance are especially vulnerable.

Eg tropical rainforests are confined to localised communities; therefore the loss of even a small area can lead to the extinction of plants and animals.

Biodiversity ( genetic, species and ecological)

The greater species in an ecosystem the less vulnerable it is. If one organism crashes, there are others available to fulfil the specific function. Biodiversity is like an insurance policy against disaster.

Genetic diversity increases the chance that some members of a particular species will have characteristics that aid their survival if they are subject to stress.

Interdependence

Ecosystems with a high degree of interdependence have a greater ability to cope with change. For example the loss of a primary consumer from the food web is unlikely to have a major impact on secondary consumers if there is a range of alternative primary consumers on which to feed.

Ecosystems have low levels of interdependence are more vulnerable to change.

· Impacts due to natural stress

• Naturally induced changes to ecosystems can either be Catastrophic (Instant) or Gradual

• Catastrophic natural sources of stress on ecosystems include:

- Natural disasters à such as droughts, floods, volcanic eruptions, earthquakes, land slides, fires

-Changes in stream course

• Gradual changes include:

-Climatic change

-Adaptation/evolution

-Disease

- Ecological succession à process where different communities replace existing communities of plants and animal species over time.

An example of a natural stress à The Mount St Helens Eruption à the resilience of this ecosystem was high as it was able to revamp itself and adapt to considerable changes à within a few years scientists observed that native flora and fauna were beginning to regenerate.

Such considerable alterations to ecosystems have also been able to be utilised for the better. Eg the roots and decaying leaves and stems of the vegetation provided organic material needed to convert volcanic grit into sustaining soil.

Stress Dependent Organisms à some organisms’ reply on stress to stimulate certain cycles or growth phases. Eg many plants in Australia are reliant on fires to initiate the regermination of seeds.

• Impacts due to human-induced modifications

Humans have been interacting and modifying ecosystems since the beginning of time, however the impact of human-induced modifications to ecosystems have increased due to:

-Speed of changes à the speed at which humans change ecosystems has never been greater.

-Scale of changes à humans are now capable of greater scale ecosystem change than ever before, extending to a global level.

-Technology à to implement large-scale changes to ecosystems efficiently is accelerating.

-Population explosion à the earth’s human population is continuing to grow, placing even greater pressure on ecosystems .

Examples of human induced changes to ecosystems

Examples of human activities, which bring inadvertent effects to ecosystems.

Farming à Leads to a reduction of biodiversity

• Destruction of habitats and ecosystem linkages
• Soil erosion
• Irrigation disrupts the hydrological cycle
• Pesticides and fertilisers:

-Affect nitrate and phosphate levels à poisoning or organisms and algae growth.

- Pesticides also cause pest populations to become stronger as they develop resistance to pesticides and herbicides.

Grazing à

Mining à - Removal of lithosphere and total ecosystem + total ecosystem destruction especially with open or strip cut mining.

- Interference with the hydrological cycle.

Rain forest clearing and logging à total habitat destruction

- Loss of biodiversity à increases the vulnerability

- Soil erosion à removes the shallow topsoil and making regeneration a long process.

Urbanisation à total destruction of habitats

- Pollution of atmosphere and hydrosphere

- Increased run off from hard surfaces.

Introduction of alien species à 2nd most potent threat to ecosystems à these foreign species can have devastating impacts on ecosystems as they usually have no predators. Accelerate the extinction of native species.

Eg foxed were deliberately released into Tasmania in 2001=act of ecoterrorism.

Cane toads à introduced into Australia to control beetles that were destroying sugarcane crops à they failed to control the cane beetles, and became a major pest themselves. Cane toads can harm native wildlife by eating small animals and poisoning larger predators that try to eat them Cane toads may also eat native animals, with a heavy impact on some species, particularly those that are already threatened.

Ecosystems change caused by negligence à humanity’s failure to protect ecosystems eg explosion at Chernobyl nuclear power plant in Ukraine.

Intentional Ecosystem change

• In most cases, human-induced ecosystem change is the unintended consequences of human activities.

• Often changes eventuate from an inadequate knowledge of ecosystem functioning.

• Some modifications are intentional, but result in unintended consequences in the long term.

Eg aboriginal Australians burnt the bush intentionally to clear away undergrowth and aid hunting.

Iraq-Kuwait war (1991)-purposely dumped water into the sea as a defence mechanism.

Unintential ecosystem change

• Meeting the needs of the technosphere and a rapidly growing human population will inevitably bring about large-scale environmental damage/change.

• Humans have the ability to transfer resources from one area to another and to modify ecosystems in order to sustain continued population growth à but such modifications often continue to lead to inadvertent changes to ecoystems.

• Energy flows

Producers, consumers and decomposers form a chain that facilitates the flow of energy from the sun, through plants; to various kinds of animals within an ecosystem à all species are dependent on each other for survival

Food chains facilitate the recycling of nutrients from producers, consumers and decomposers back to the producers.

N.B à Therefore all organisms rely on each other for support in an ecosystem. If species are extinct (due to human induced modifications) à essential energy is not transferred to some organisms and recycled.

• Nutrient Cycling

Ecosystems have several nutrient cycles operating in them. These cycles continuously move the elements and compounds from the abiotic to the biotic environment and back à eg carbon cycle, nitrogen cycle, oxygen cycle (essential for the proper functioning of ecosystems)

Human induced changes to nutrient cycles:

-Salinity

-Soil erosion

-Air pollution

-Chemical spills

-Removal of crops and animals for human use

-Rainforest clearing and logging

• The importance of ecosystem management and protection:

Reasons for managing and protecting ecosystems:

• Maintaining genetic diversity

- Ecosystems rich in diversity generally have a greater resilience. As a result they are able to recover quickly from naturally induced stress eg droughts, fire.

-The vast numbers of species that inhabit the earth represent a huge genetic “database” off successful survival strategies.

- Survivors of stress pass these traits on to subsequent generations.

-Loss of genetic diversity à the opportunity cost of an expanding technosphere.

-Biodiversity is an untapped source à we do not know what species may be useful to humans in the future as a source of food, medicine and other human needs.

• Utility Value

-All living and non-living components of the earth’s ecosphere have either an existing or potential utility value à Usefulness.

-Biodiversity within ecosystems provides genetic material, which can be used as human needs change.

-The loss of species denies humanity a possible source of food, medicine, chemicals, fibres and other materials.

Eg plants, microorganisms and animals provide us with many medicines used to cure disease.

-Components of various ecosystems play a vital role in protecting catchments, purifying water, regulating temperature, recycling nutrients and re-generating soil.

There are two worldviews, which reflect the utility value of ecosystems:

An anthropomorphic view à People are the key and the environment had to live around peoples needs. First comes people then the environment.

Eg we are concerned about soil degradation because it affects agricultural production and water quality, however we still continue to degrade the soil through our agricultural practices because we need it for farming à Profit.

Ecocentric View à Our lives revolve around the environment.

Eg each species has en inherent right to exist or at least to struggle to do so equal to others.

• Intrinsic/ethical Value

-This is that ecosystems have a right to exist regardless of their utility value.

-There are three interconnected types of intrinsic value:

1) Existence - à simply the fact that ecosystems exist means they are valuable. Ecosystems need to be preserved for future generations regardless of their present or future uses.

2) Spiritual and philosophical à this value can be most strongly seen in the links the indigenous peoples possess with the biophysical environment. Indigenous people believe that it is part of their identity, they have an inextricable connection which they derive spiritual strength from their relationship with the environment à Ecocentric worldview.

Many religions have similar views.

3) Aesthetic à the appreciation of the beauty of ecosystems brings satisfaction and enjoyment to people. The beautiful landscapes, plant and animal species etc.

• Heritage Value

-Natural heritage à Natural features which are of outstanding universal value either cultural or natural value.

-In Australia world heritage listed sites include The Great Barrier Reef, The 3 sisters and Lord Howe Island, Tasmanian Wilderness etc.

• The need to allow natural change to proceed

-Ecosystems are valuable because they allow natural change to proceed à they are the net result of millions of years of evolutionary changes in response to environmental changes.

-Ecosystems will continue to play an important role in the evolution of new life forms on the planet à therefore natural change needed to proceed so that the balance is maintained.

-Ecosystems provide many invaluable eco-services naturally such as pollination, insect control, flood control, pest control, and climate control.

- If natural change is not allowed to proceed because of human interference on a large-scale à end result will be less biodiversity, simplified ecosystems and fewer resources for the future.

Therefore the protection and management of ecosystems allows natural change to proceed through:

-Environmental boundaries

-Buffer zones

-Representative diversity

-Ensuring that the area is large enough to function properly