Biology 3A Biodiversity. Biodiversity ecosystem biodiversity – a range of different habitats and complex ecosystems are available around the world or.

Biology 3A Biodiversity

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

Diversity and change

Ecosystems change –Abiotic factors may vary – eg light, water, temperature, salinity, tidesThese 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)

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

Changes in ecosystems - water

• Damschanges 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

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

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

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)

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

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

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

http://www.micro.utexas.edu/courses/levin/bio304/ecosystems/ecology.html

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

http://www.scienceclarified.com/Sp-Th/Succession.html

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)

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 Predation of native species

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

Predation of native species

Corellas, cockatoos Escaped, dumped Compete for resources – especially nesting sites

Prickly pear, brambles, arum lilies

Escaped, dumped Competition, reduces native species

Duckweed, water hyacinth

Escaped, dumped Chokes water ways

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

Pollution

Examples of pollution Causes of pollution Effects of pollution

Carbon dioxide Combustion –eg cars, factories, etc

Greenhouse gas global warming

Carbon monoxide Combustion –eg cars, factories, etc

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

Factories, mining Poisons

Sewage Human waste Algal blooms, disease