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Biology 3A Biodiversity

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Presentation on theme: "Biology 3A Biodiversity"— Presentation transcript:

1 Biology 3A Biodiversity

2 Biodiversity ecosystem biodiversity – a range of different habitats and complex ecosystems are available around the world or within an area species biodiversity – different species exist within each ecosystem genetic biodiversity – variations exist within a species within an ecosystem

3 Diversity and change Ecosystems change – Abiotic factors may vary –
eg light, water, temperature, salinity, tides These may vary cyclically eg day/night; monthly, seasonally, over longer periods, or catastrophically (eg fire, flood, volcanic eruption, ice age, etc) Biotic factors may vary – Numbers of Producers Prey species (1st order consumers) Predators (high order consumers)

4 Everything in an ecosystem is linked
A change in one factor can lead to changes in other factors – domino effect eg decreased rainfall  decrease in vegetation  decrease in herbivores (prey species)  decrease in predators eg removal of predators (hunting or biomagnification)  increase prey species (plague)  decrease vegetation  decrease in herbivores due to no food Key species a species whose removal negatively affects an entire ecosystem eg otters in kelp forests – when hunted to extinction, sea urchin numbers increased so much that they destroyed the kelp  decrease in the other species depending on kelp for food or shelter

5 Changes in ecosystems - water
Damschanges distribution of populations in ecosystems – can get animals accumulating around dams  over grazing near the water source; loss of original ecosystem in flooded area Presence of bores  lowers water table; increases number of animals around bore  over grazing near the water source Tailing dams  kills wildlife that tries to use it as water Removing water for human use  lowers amount of water in river/streams eg Murray  not enough water to maintain ecosystem Filling in wetlands  destroys ecosystem; loss of habitat for migrating birds; damage to neighbouring ecosystems as wetlands act as filters to remove pollutants and excess nutrients

6 Changes in ecosystems - clearing
Loss of trees  loss of habitat & nesting places as well as the following Loss of topsoil  (= erosion) loss of fertility  decreased producers  decreased biomass in the whole ecosystem Rise of water table  water logging in low lying areas, increased soil salinity as salts are brought up with the water Increased soil salinity  loss of fertility  decreased producers  decreased biomass in the whole ecosystem Increased water salinity  loss of fertility  decreased producers  decreased biomass in the whole ecosystem; poisoning of consumers, loss of aquatic life

7 Changes in ecosystems – climate change
Climate change  changes in temperature, rainfall & humidity – also affects water availability Increased temperature  increased water loss  higher water needs; may cause death of organisms if temperature too high; rising sea levels (thermal expansion of water) and melting of glaciers and polar icecaps may also impact on ecosystems Decreased rainfall  reduced water availability  decreased biomass (less plants  less animals) Reduced water table  dries out seasonal water sources (eg swamps, small creeks) and cave systems, less water  decreased biomass (less plants  less animals) Change in seasons  organisms may not be able to find enough food to survive & raise offspring eg birds breed as light levels change, insects breed as temperature rises

8 Changes in ecosystems -agriculture
Farming  agricultural practices include Monoculture  presence of only one species in the crop, decreases biodiversity, encourages population explosions or plagues of pest species eg mice, locusts, in the long term reduces soil fertility Killing insects (eg pesticides)  disrupts ecosystems by destroying food source of higher order species (eg owls, wattle birds); can lead to ecological magnification Loss of dead/decaying matter  loss of fertility, loss of decomposers  soil problems  reduction in producers  reduction in consumers Fertilisers  chemical poisoning of plants or animals (eg high phosphate fertilisers kill many native trees; run-off into rivers can cause eutrophication (algal blooms)

9 Changes in ecosystems – human interference
Human presence  disrupts ecosystems in many ways including: Loss of predators  removal of predators (sg spiders, wolves) can lead to population explosions of prey species Introduction of new carnivore  eg foxes, cats, dogs  loss of native wildlife Introduction of new herbivore  eg rabbit, sheep, may out-compete natives  loss of native species; may cause over grazing as no native predators erosion Introduction of new producer  eg brambles, prickly pear, may out compete natives (as often not edible to consumers)  loss of native plant and animal species (now not enough food for them); aquatic plants eg duckweed may block rivers

10 Succession Succession change in an ecosystem over time as organisms change the abiotic features (eg soil, humidity) so it becomes more suitable for other organisms to survive Colonisers hardy organisms that first invade an area and establish themselves. They must be able to cope with harsh conditions eg no soil, low soil fertility, salinity, low humidity, etc Climax community final community. This is the most diverse and stable, and usually consists of forest

11 Primary succession Occurs when the soil is totally destroyed or absent, or extremely infertile, organisms must invade from neighbouring ecosystems eg after a volcanic eruption, a glacier retreats or at the beach

12 Secondary succession Occurs when a disruption occurs that kills organisms, but the soil remains relatively fertile, organisms may still survive or seeds may still be present eg after a fire, clearing or logging, abandoned land

13 Effects of increased human population
Settlement patterns More people living in cities, cities become larger. Resource use: Energy Water Food Increases – leading to scarcity in fuel, water & food supply  more land cleared for farming, increased use of pesticides & fertilizers The environment: Desertification Eutrophication Pollution Biodiversity More land is cleared for farming  desertification More fertilizers are used  eutrophication More people  more pollution (sewage, combustion, industrial pollution) Changes in species as some native species are removed and others added (introduced species)

14 Introduction of new species
Examples of introduced species Reasons for introduction Effects of introduction Fox For hunting Predation of native species Cat, dog Escaped from houses, dumped Rabbits Brought in as food source Competition for feed, overgrazing & burrows cause erosion Goats, sheep, cattle, horses, camels, water buffalo Escaped from farms, dumped Competition for feed, overgrazing causes erosion, hooves damage river banks Carp Escaped, dumped Competition for food sources, predation, reduces native species Cane toad Brought in to control cane beetle Corellas, cockatoos Compete for resources – especially nesting sites Prickly pear, brambles, arum lilies Competition, reduces native species Duckweed, water hyacinth Chokes water ways

15 Removal of organisms Examples of removed organisms Reasons for removal
Effects of removal Wolf, puma Removal of predators so there would be more deer to hunt Overpopulation of deer, ate out the food supply, ecosystem destruction Tasmanian tiger Hunted to extinction (thought to be danger to livestock) Extinct native species Trees Clearing for mining, farming, housing Salinity, erosion, loss of habitat for native species Hollow logs & dead wood Firewood, aesthetics, clearing for mining, farming, housing No nesting sites for native birds, especially cockatoos Wetland organisms Filling in for housing or landfill Salinity, erosion, loss of habitat, downstream pollution Elephant, rhino, orang utan, etc Poaching for tusks, horns, fur, pet trade Disrupts ecosystems, threat of extinction for some hunted species

16 Pollution Examples of pollution Causes of pollution
Effects of pollution Carbon dioxide Combustion –eg cars, factories, etc Greenhouse gas  global warming Carbon monoxide Poison Nitrogen dioxide, sulfur dioxide Factories, mining Combines with water in the air to produce nitric & sulfuric acid  acid rain Methane Ruminants (eg sheep & cattle), rotting garbage (land fill) Green house gas global warming Fertilizers Farming, gardens Algal bloom (eutrophication) Pesticides Farming, urban spraying Ecological magnification Heavy metals eg mercury, lead, cadmium Poisons Sewage Human waste Algal blooms, disease

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