Ecosystem Changes and Conservation Strategies for Biodiversity 7

Define habitats.

environments in which a species normally lives

What results in habitat destruction?

• rise in human population + increased demands on resources

• increased pressure on land use for human activities

  • e.g. manufacturing, agriculture, forestry, mining, urbanisation

What are the effects of habitat loss?

• reduced species richness

• species are vulnerable to extinction, threatening biodiversity

• e.g. tree clearing for WA’s timber mills

What is urbanisation?

• the extreme modification of an ecosystem by humans to support a human population of gradually increasing density

  • happens as more and more people migrate to cities from rural areas

What are the effects of urbanisation?

• urban ecosystems are dominated by people and have heavily reduced biodiversity, with little recycling of matter occurring between the community and non-living surroundings

• there is an increased output of gaseous and material wastes into the atmosphere and environment due to the additional inputs of energy and matter needed from other ecosystems to maintain modern standards of living

  • e.g. increased gaseous outputs into the atmosphere, due to combustion from vehicles and burning fossil fuels

• urbanisation can cause rapid changes of large magnitude to an ecosystem and even though new species may potentially move into an urban area, it often leads to a permanent change in the ecosystem

What is agriculture?

agriculture includes cultivating soil, growing crops, raising animals, preparation of plant and animal products

What are the effects of agriculture?

• more than 20% of Australia's forests have been cleared for crops & grazing since 1750, with nearly 90% of vegetation loss in more fertile regions

• agriculture has resulted in the loss of habitats

What is habitat fragmentation?

• occurs when some parts of a habitat are separated into isolated sections (to build roads, agriculture, residential, etc)

• isolates groups of organisms that were once part of a larger population due to physical barriers (e.g. roads, infrastructure)

What are the effects of habitat fragmentation?

• the smaller subpopulations cannot interbreed and therefore cannot share genetic biodiversity, decreasing population resilience to adapt/survive

  • leads to reduced genetic diversity within each population, causing organisms to be more prone to diseases and adverse conditions can increase chances of species becoming extinct

• e.g. the fire of Carnaby’s cockatoo in the Perth and Peel regions will continue to be affected by the growth of the greater Perth metropolitan area

What is a genetic conservation strategy?

• a conservation method that preserves the genetics of endangered species

• gene banks are a modern and important genetic strategy used for agricultural insurance

What are seed banks and how is it considered a genetic conservation strategy?

• a reservoir for plant genetic material especially for species threatened with extinction

• if a population/species did become extinct, seeds from the seed bank can be accessed to reintroduce an extinct species back to its habitat

  • seeds are collected, cleaned and dried under controlled conditions

  • stored in freezers at -18C, having the potential to live for decades

  • WA Seed Centre, Kings Park

What is an environmental conservation strategy and how does it help the environment?

• revegetation/regeneration of land and bush corridors to reconnect isolated habitats can be an effective way of returning habitat to populations and enabling subpopulations to interbreed

• Gondwana Link - reconnect bushland in the south-west of Australia since 2002

• habitats were cleared for farming, roads, homes so some landowners are now working collaboratively with scientists and farmers to restore significant areas of land, with the aim of re-establishing ecosystem resilience

• when farmland is restored to bush, animals can once again move freely between populations, maintaining and increasing biodiversity

What are management conservation strategy?

• management conservation strategy rely on controlling aspects of the environment for conservation purposes, usually meaning there is a guide/set of rules governing human activities (e.g. harvesting, research, use of certain species), minimizing the negative impacts of human activity

• promote community awareness in understanding conservations actions and communicate with decision makers to increase their understanding of conservation

• conduct research into areas such as:

  • population demographics

  • health movements

  • feeding, roosting behaviour

  • modeling of climate change

Give an example of a management conservative strategy.

• e.g. national recovery plan for Carnaby’s cockatoo

  • protection of habitats, including feeding, breeding and non-breeding habitats

  • monitor nest hollows and non-breeding factors (roost sites, feeding habitat) and using citizen science to count population numbers( the great cocky count)

  • monitoring and managing effects of car collisions, shooting, poaching and illegal habitat destruction

Describe the captive-breeding programs at Perth Zoo.

• endangered species are selected for captive-breeding programs

• ideal amount of food, water, shelter is given with no competitors, predators or parasites

• animals live in their own enclosures with the availability of reproducing mates

• population increase, species develops resilience

• once the population is established, they are released into their habitat, saving species from extinction

What is land and soil degradation?

• hard hooves of introduced domestic animals compact soil when they graze, damaging the soil, creating opportunities for invasive, shallow-rooted plants to grow at the expense of deep-rooted native grasses

• with significantly reduced tree cover and an increase in shallow-rooted grasses, the topsoil becomes more exposed to the effects of abiotic factors (e.g. wind, rain → increased soil erosion)

• soil is a non-renewable resource, so soil loss by wind/water leads to production loss by farmers and death of organisms in ecosystems

• past land clearance practices, the move to shallow-rooted pastoral grasses and the overuse of fertilisers that have affected soil organisms have all place enormous pressures on the structure of the soil and the ability of the land to hold its topsoil

What helps land and soil degradation?

• regenerative agriculture (e.g. preserving ground cover and soil stability) has lead to:

  • healthier nutrient recycling

  • increased biodiversity

  • more stable and resilient ecosystems

What is dry land salinity?

• the process of salts normally found under the surface of soil being transported to the soil surface by a rising water table

• occurs when deep-rooted natural vegetation is replaced with shallow-rooted crops that require irrigation

  • deep-rooted trees helps to keep the water table stable by transporting water from the roots, through their stems and out of their leaves, by evaporation into the atmosphere

  • when deep-rooted native perennial species are removed, they no longer use water from the water table and it starts to rise to the surface, dissolving salt from surrounding soil as it rises

  • when it reaches the surface, the water evaporates due to the dry climate, leaving behind the salt

What is 1 method to avoid dry land salinity?

• to plant rows of short-rooted crops adjacent to rows of deep-rooted trees, preventing the water table from rising and stops the salty water from entering the topsoil

• it reduces the amount of a crop that can be plants, but it ensures the land will remain fertile in the long term

What are introduced species and how do they become invasive?

• introduced species - species that humans have intentionally/unintentionally moved from their native location to a new ecological region

  • new environment lacks natural predators, parasites and pathogens, meaning their growth is not limited, allowing them to out-compete native species, potentially casing extinction to native species

  • become invasive if they manage to establish populations in new areas

Describe the invasive species of European rabbits and cane toads.

• European Rabbits

  • selective grazers (selectively eat the seeds of native species)

  • compete with native animals for limited resources

  • sustain other invasive predators

• cane toad

  • introduced to Australia to help control cane beetle populations that were damaging the sugarcane industry

  • kill native animals with their toxins (present at all stages of their life cycle) that are excreted from glands around their neck

What is the chemical control for invasive species?

• a pesticide/poison used to control the population of an invasive species

• quick and effective method but chemical pesticides can be damaging in to the environment and costly

• 1080 poison baits target feral pigs, rabbits, foxes

  • it is a biodegradable and does not harm the environment

• 1080 poison could be costly and could harm domestic pets if consumed

What is the biological control for invasive species?

• when a species is used to control the population of a pest species

• field trials will be conducted in an isolated area to discover any unexpected effects before wide release, especially to check the risk of the biological control species becoming a pest itself

• to be released more widely, the biological control species must:

  • only target the pest species and not impact on other populations

  • decrease in number as the pest species decreases in number

  • not compete with native species for a resource

  • be reproductively self-sustaining in the new environment

What are the 4 different types of biological control species?

1. General Predators

• a species that consumes a great variety of pest species

• e.g. ladybirds target aphids, caterpillars, mites and small beetles

2. Specialized Predators

• species that target one pest species at all life stages

• e.g. dragonflies target a species of mosquito

• e.g. Paterson’s Curse

  • invasive weed with purple flowers

  • contains a toxin that harms livestock that consume it, causing liver damage

  • crown weevil, root weevil, flea beetle and pollen beetle are used to control the weed

3. Parasites

• species that lay their eggs in the bodies of hosts and when the eggs hatch, the larvae feed on the body of the host, causing the host’s death

• e.g. parasitic wasp laying eggs in a caterpillar

4. Microbial Disease

• caused by bacteria, fungi and viruses that target particular species and cause death through illness

• e.g. myxomatosis virus to control rabbit populations

What is the physical control of culling?

• under strict regulations, invasive organisms are culled (a license is required)

• Australian red and grey kangaroos overgraze, destroying many native vegetation and outcompeting other native species for resources so they are culled for human consumption in Australia or are exported

What is overharvesting?

• harvesting a species at a rate that exceeds the replenishing rate of the population

• organisms that have low reproductive rates are especially vulnerable to overharvesting

  • because the the sum of new individuals from births and immigration does not exceed the total individuals lost to death plus emigration

• e.g. commercial fishing has driven some species almost to extinction

What is the effects of over-harvesting?

• food web will collapse if it is a keystone species is being over-harvested

• increased competition between species for food

• decreased nutrient composition in soil due to decreased waste & decomposition

• increased soil compaction (e.g. if burrowing species are over-harvested)

What is by-catch and bottom-trawling?

• by-catch - the unwanted fish and other marine creatures trapped by commercial fishing nets during fishing

  • as populations of commercial fish decrease, there are fewer fish reaching reproductive age to sustain population growth

  • scientists and commercial fishers are trying to develop nets with meshes that will allow undersized fish to escape unharmed

• bottom trawling - method of fishing that involves dragging heavy weighted nets across the sea floor, in an effort to catch large amounts of fish

  • deep sea fish species are targeted globally by bottom trawling and it also removes vast amounts of non-target species, including habitat forming deep-sea corals and sponges

What are ways to create and monitor protected areas to help sustainable fishing?

• using less destructive fishing methods and managing vulnerable areas are 2 measures that can help to protect lower ocean ecosystems

• fishing sustainably reduces the size of a population but does not reduce biodiversity, preventing the complete depletion of marine ecosystems

• in WA, recreational fishing licenses and fishing seasons are compulsory and are used to control fishing levels

• prohibiting bottom-trawling in vulnerable marine areas (near shores)

• continuous monitoring of fish stocks over time to develop effective management strategies for conservation and to sustain commercial fishing

What is eutrophication?

• process that occurs when excess nutrients, particularly nitrogen and phosphorus, enter a body of water and become highly concentrated, leading to excess growth of organisms (e.g. algae)

1. fertilizers compounds are usually rich in nitrogen and phosphors, which are nutrients for algae, and are used on nutrient-poor farmland, parks and gardens

2. when fertilizer dissolves in rainwater or excess irrigation water, known as run-off, it can flow into local water bodies and cause algal blooms, which is a rapid increase in the population of algae/other micro-organisms at the surface of a water body that blocks sunlight from entering, killing autotrophs that live under the surface

3. excess nitrogen and phosphorus not absorbed by roots are often leached from the soil by run-off and may enter the water table

4. eventually, the algae will die and are decomposed by bacteria

5. as bacteria consume the dead algae, they use large amounts of oxygen from the water, which depletes oxygen levels, causing water to become hypoxic (low in O2) and possibly anoxic (completely devoid of O2), causing aquatic organisms to die

What is biomagnification? Give examples.

• occurs when successively higher concentrations of non-biodegradable chemicals build up in the tissues of organisms in the higher trophic levels of a food chain

• organisms acquire toxins, along with nutrients and water, from the many toxic chemicals released into the environment by human activities

  • while some toxins are excreted, others are stored in tissue because the organism is unable to excrete/metabolize them

• when these organisms are consumed, the chemical accumulates in the next trophic level, becoming more concentrated

  • this repeats for each trophic level and as it goes higher, organisms consume relatively large amounts compared to the level below, leading to increasing concentrations of the chemical

• DDT was used widely in the 1900s to kill mosquitoes but through biomagnification, it has led to serious health effects in many organisms

What are greenhouse gases and how are they released? Give examples.

• gases that trap heat

• released from natural sources (e.g. living things, volcanoes, fires) and industrial processes

• greenhouse gases released by natural sources:

  • carbon dioxide

  • nitrous oxide

  • water vapour

  • methane

What is the natural greenhouse effect?

• the insulating effect of greenhouse gasses in the atmosphere that traps heat in the Earth’s atmosphere, keeping the Earth warm

• essential for maintaining warm temperatures for humans and other organisms to survive on Earth

What is the enhanced greenhouse effect?

• when the concentration of greenhouse gases have increased and too much heat is being re-emitted into the Earth’s atmosphere

• it is the main cause of rising global temperatures, leading to global warming

  • e.g. melting of glaciers and polar ice sheets

  • rise in sea levels

• due to human activities such as:

  • burning fossil fuels

  • agriculture

  • deforestation

How has burning fossil fuels increased the greenhouse effect and contributed to global warming?

• fossil fuels are formed from fossilised living things, usually in sedimentary rock, over millions of years

• burned for fuel and food to meet human demands, which increases as the population increases

• burning fossil fuels release large amounts of greenhouse gases into the atmosphere, causing more heat to be trapped in the Earth’s atmosphere

  • thus further warming the Earth’s surface, contributing to global warming

How has deforestation increased the greenhouse effect and contributed to global warming?

• permanent removal of standing forests and can lead to significant carbon dioxide emissions

• forests are cut/burned for human benefit, to clear land for agriculture and to make various products

• deforestation removes vegetation, reducing the amount of carbon dioxide being converted into oxygen via photosynthesis, leading to the accumulation of carbon dioxide, trapping more heat in the atmosphere

  • therefore further warming the earth’s surface, contributing to global warming

How has agriculture increased the greenhouse effect and contributed to global warming?

• the farming of livestock increases the release of methane, a greenhouse gas into the atmosphere, leading to more heat being trapped in the Earth’s atmosphere

• this further warms the Earth’s surface, contributing to global warming