Human Activity

Question 1

Ecological succession

Answer 1

Ecological succession is a process of change in a community with time
Ecological succession can affect biotic and abiotic interactions in the community, which in turn can affect the species present and their population size

Question 2

Succession

Answer 2

Communities change progressively over time, with one community being replaced by the next in the process of succession

Question 3

Succession steps

Answer 3

1. Pioneer plants colonise (lichens)
2. Soil formation
3. The early colonising plants have characterised that make them successful
4. A new community forms
5. As the succession process slowly continues, biodiversity increases

Question 4

Primary succession

Answer 4

Is the colonisation of new sites by communities
Occurs on bare sites that have no organisms inhabiting the affected area
E.g. bare rock or areas with no soil
E.g. new sites are formed when volcanic eruptions form new rock or lacier retreat to expose bare rock
- Starts with the arrival of living things such as lichens that do not need soil to survive (Called pioneer species)
- Acid produced by the lichens attack and weather the rock surface.
- This creates the attract of soil to form in rock cracks. Mosses start to establish themselves
- As lichens and mosses die, it thickens the soil and adds nutrients
- Bacteria, fungi and simple invertebrate animals move in. A simple community now exists
- as ore soil and nutrients are added to the environment, more complex organisms form grasses to ferns to shrubs start to establish themselves
- taller plants add shade and root systems increase weathering processes
- me animals immigrate into the community from insects to smaller herbivores then carnivores

Question 5

Secondary succession

Answer 5

Begin in a place that already has soil and was once the home of living organisms
Takes place on existing soil
Occurs after catastrophic events (like fire, cyclones or tsunamis) wipe out all life on the clearing land (a farmer clearing a field or deforestation)
With the soil still present and possibly also some root systems and seeds still in the soil, the community comes back faster
Grasses and annual plants appear first, followed by some shrubs and bushes and then trees
Animals gradually immigrate form the invertebrates to insects to herbivores to carnivores

Question 6

Climax community

Answer 6

Are a stable group of plants and animals that is the end result of the succession process
Little or no succession takes pace in the community
Slow-growing, long-lived species (K-selected species)
Does not always mean big trees
- grasses in prairies
- cacti in deserts

Question 7

Unstable community

Answer 7

Going through succession, especially after unpredictable events. Population explosions of colonisers often occur
Exploited by r-selected species

Question 8

Stable communities

Answer 8

Exist close to carrying capacity at relative equilibrium. Can be a climax community
Many K-selected species exist within

Question 9

Fire - a dynamic factor

Answer 9

All ecosystem change over time
Fire is neither innately good or bad, it is just an agent of change

Question 10

Roles of fire in ecosystems

Answer 10

Reduces probability of catastrophic fire
Nutrient input into soil
Control of insect pests and disease
Maintains species diversity

Question 11

Reduces probability of catastrophic fire

Answer 11

• Fire intensity depends on fuel load and weather
• In many forest types the fire regime ( the historical frequency and intensity of fire natural fires) reduces fuels
• Means that future fires low to moderate intensity instead of catastrophic

Question 12

Nutrient input into soils

Answer 12

• soil nutrients are usually tied up in organic matter. These are released after fire, increasing availability to plants and soil microorganisms
• fewer leaves left to catch rain and plants using water will allow moisture to reach the soil
• blackened soil and greater exposure to sunlight, wind and evaporation, however, will work in the other way to dry the soil
• the fire may have created an impermeable crust at the soil surface, if organisms matter on the ground was heated by he fire into a waxy residue. May lead to increased soil erosion through surface runoff-off
• ash and charcoal provided added nutrients back to soil

Question 13

Control of insects pests and disease

Answer 13

Some insects populations are apparently controlled by fire
High temperatures and make smoke directly kill adults, larvae and eggs
Reduced tree density decreases susceptibility to infect attach and disease (density-dependent factors)
Some insect pests can also invade after fire, feeding off the dead materials

Question 14

Maintains species diversity
Effect on vegetation i classified according to their response to fire

Answer 14

Fire-intolerant plants - highly flammable and completely destroyed
Fire-tolerant plants - able o withstand some forms of fire and grow despite some damage
Fire resistant plants - suffer little damage

Question 15

Maintains species diversity
Many different effects on fire on plants

Answer 15

• negative - individual death
• positive - altered surface light/ conditions releases canopy seeds or stimulates germination of seeds
• increased - situated seed dispersal distanced, flowering, productivity and seed establishment
  Some plants have back up protection from fire, so that they are capable of regeneration afterwards
  Epicormic buds - dormant buds tat only grow after leafy tissue is destroyed
  Lignotubers - woody tuber at the roots (safe form the fire damage) that stores water and food to support regrowth
  Most animal species respond predictable to the passage of fire, although the responses vary among species. Some flee, seek refuge, or rescue young. Other species are attracted to burning areas (forage during fires or red on charcoal and ash after fires)

Question 16

Maintains species diversity
Vertebrates

Answer 16

• mortality - related to size of fire and rate of speed
• loss of nesting sites and young but…
• cavity nesters and insect foragers love dead trees
• immediate increases in food sources for predators

Question 17

Maintains species diversity
Invertebrates

Answer 17

• mortality - high in burn area for life stages in litter or on plants
• rapid invasion by some species may follow burn
• after a fire, the species composition changes to early successional animals
• birds - some prefer more open conditions, periodic fires recreate scrub habitats
• large mammals - some benefits from flush or new growth
• small mammals - increased seed production important for food

Question 18

Human impact on resources

Answer 18

• human impact on the natural world has increases dramatically as the scope and intensity of human activity have increased
• unresolved problems include the loss tropical forests, the build up of greenhouse gases and the loss of biodiversity
• the impact of humans on the global environment is the result of resource use, rapid population growth, large population size and disproportionate distribution of resources

Question 19

Global issues

Answer 19

• threats to biodiversity from all sources are quickly reaching a critical level. Current extinction rates are 100 to 1000 times higher than pre-human levels
• aquatic environments such as coral reefs and freshwater habitats in lakes, rivers and wetlands are all at risk of degradation (deterioration of the ecosystem through the depletion of its natural resources)

Question 20

Habitat destruction
Human impact on ecosystems

Answer 20

• deforestation worldwide is a huge issue
• salinity - removal of natural vegetation which causes the underground water table to rise
  This pushes the salt to the surface. Greatly reduces biodiversity and can make the all completely uninhabitable
• fragmentation - when once continuous habitats become separated form one anther
  Small habitats can only suppress small population making organisms more vulnerable to extinction

Question 21

Introduced species
Human impact on ecosystems

Answer 21

• species can be introduced unknowingly (in the post, on shoes or other organisms) or deliberately
• they pose a major threat to ecosystems, as they often have no natural predators and compete with native species for resources
• goats, pigs, wheat, other cereal crop, foxes, black rats, camels, cats and dogs are all introduced species to Australia. Some have become pests, out competing the native organisms
• often species are deliberately introduced as a biological control agent
• however, some bio-control agents may even become pests themselves. The cane toad was introduced to Austria o control grey cane beetles and is now a major threat to native wildlife

Question 22

Agriculture
Human impact on cecosystems

Answer 22

• nature maintains biodiversity through the natural process of succession. Agriculture greatly alters this
• monoculture - where one species of organism is grown (e.g. a wheat of organisms is grown (e.g. a wheat field)). Monoculture requires large amount of fertilisers and pesticides
• intensive (industrialised) agriculture uses large amount of fossil fuels fuel energy, water, fertilisers and pesticides to increase he net production (crop yield)

Question 23

European settlement and urbanisation
Human impact on ecosystems

Answer 23

• the first inhabitants of Australia - aboriginal and Torres Strait Islanders have lived off most of the land from at least 40,000 years ago
• they altered the natural environment of Australia through fire regimes, which increased the prevalence of fire tolerant species
• hunting by the first Australians also saw the extinction of megafauna (elephant sized wombats and 6m long goanna)
• with the arrival of Europeans to Australia the greatest change in natural environments occurred
• extensive land clearing from farming, irrigation & damming water supplied and urbanisation began
• even as early as in the 1850s, it was noted that plant species were disappearing, erosion was evident and print water supplies were vanishing in Australia
• urbanisation - is a pollution shift from rural to urban areas or the gradual increase in the proportion of people living in urban areas
• urban ecosystems use a large amount of natural resources, most of high are not found there and have to be brought into the urban environment. They also produce a large amount of water (rubbish, air and water pollution)

Question 24

Water flow and Eutrophication
Human impact on ecosystems

Answer 24

Human requirements for water have resulted in:
- irrigation - channels water to where it is needed, meaning it alters the natural flow and removes vegetation
- construction dams and reservoirs to store water for our use. Can result in downstream ecosystems being starved for water and shut off
- degradation of urban waterways and streams by pollution and stormwater drains
- Eutrophication is a term describing the enrichment of waters with nutrients. It often results in excessive growth of weed and algae
- miscroorganism decompose the organism matter in the polluted water and their activity increases the uptake of dissolved oxygen
- this reduces the amount of dissolved oxygen available to their aquatic organism and may subsequently cause their death

Question 25

Fishing
Human impact on ecosystems

Answer 25

• overfishing also threatens the whole ecosystem, not just the one species
• removal of one organism in the food web can result in loss of biodiversity or collapse
• off the coast of NSW, the has been an 80% decline in the population of sharks, stink rays and skates between 1996-1997. Worldwide, 1/3 of the sharks, sting rays and skates are threatened with extinction

Question 26

Biomagnification

Answer 26

• biomagnification (also called bioaccumulation) occurs when highly persistent pesticides, which cannot be metabolised or excreted, are stores and accumulated in fatty tissues of organisms
• there is a progressive concentration of the pesticides with increasing trophic level
• high-order consumers are at greater risk because they eat a large number of lower-order consumers
• e.g. DDT is an organochloride that was used as an insecticide by banned in the US in 1972. Some countries still use it to control mosquitoes that spread malaria
• substances with biomagnification include many pesticides, heavy metal like mercury, radioactive isotopes and any industrial chemicals

Question 27

Climate change

Answer 27

• The Earths atmosphere comprises a mixture of gases including nitrogen, oxygen and water vapour
• Also prevent are small quantities of carbon dioxide, methane, and a number of ‘trace’ gases
• Global warming is a term generally used to describe the gradual increase in the average global temperature of the earth due to the increased level of ‘greenhouse gases’
• Much of this heat is absorbed be greenhouse gases, which in turn sen the heat back to the surface, to other greenhouse gas molecules, or out of space. Though only 1% of atmospheric gases are greenhouse gases, they are extremely powerful heat trappers
• Greenhouse gases include carbon dioxide, nitrous oxide, methane and CFCs
• By burning fossil fuels faster an faster, humans are effectively pilling on more blankets, heating the planet so munch and so quickly that its hard for environment and human societies to adapt
• Climate change refers to long-term shifts in temperatures and weather patterns, mainly caused by human activities, especially the burning of fossil fuels
• Coastal resources - the sea level is expected to rise by 50cm by the year 2100. This is the result of thermal expansion in the ocean (water expanding as it warms) and by the same melting of non-polar ice
• Forests - higher temperatures and rainfall changes could increase the susceptibility of forests to fire, disease and insect damage. A richer CO2, atmosphere will reduce transpiration in plants

Question 28

Climate change =

Answer 28

• CFCs = chlorofluorocarbons
• Refrigerant - destroys ozone
• Ozone layer - blocks much of the harmful UV radiation

Question 29

Climate change
Effect on global warming

Answer 29

• weather patterns - under a warmer climate regime, regional changes in weather patterns such as El Niño an La Niña are likely. Changes in the intensity and frequency extremes weather conditions (storms and droughts) are also expected
• water resources - increased evaporation rates and changes in air fall are predicted to affect the availability of water for irrigation, drinking, industrial use and hydroelectric power generation
• health - high temperatures over longer periods may result in distribution shifts and crate heat-tress or mortality in susceptible organisms. Climate changes may reduce new breeding sits or pests e.g. mosquitoes, shifting the range of infectious diseases
• agriculture - climate change may affect the viability of stable crops, such as rice, in some regions, particularly the developing countries

Question 30

Pollution

Answer 30

• besides air pollution being the abortive cause of climate change around the world, it ca also impact in other ways
• water pollution is another added problem for the world’s water supplies
• water pollution occurs as a result of contamination from sources ranging form urban and industrial to agriculture
• some forms of pollution simply alter the physical state of the water, such as its temperature, pH, or turbidity (clarity), but others involve the addition of potential harmful substances
• raw or partially treated sewage is a common water pollutant
• sewage pollution results from the disposal of household and industrial wastes into rivers, lakes, and seas. Most communities apply some treatment to raw sewage prior to discharge from point sources, but even treated sewage can be high in nutrients
• sewage is a source of pathogens (disease-causing agents). During floods, human waste mix with drinking water and increase the risk of water-borne diseases such as cholera

Question 31

Pollutants may enter via
Pollution

Answer 31

• non-point sources where pollutants, such as agrichemicals, enter water bodies over large eras via ground-water and runoff
• singe or post sources where pollutants have been discharges into the environment through pipes, sewers, or ditches from specific sites

Question 32

Conservation

Answer 32

• is the ethical use, location and protection of resources
• its primary focus is upon maintaining the health of the natural world, it fisheries, habitats, and biological diversity
• secondary focus is on material conservation, including non-renewable recurves such as metals, minerals and fossil fuels, and energy conservation which its important to protect the natural world
• conservationists are those who follow the conservation ethics and,especially, those who advocate or work toward conservation goals

Question 33

Why conserve

Answer 33

• Ethics - we know what we are doing and is negative effects - is it right to continue this?
• Aesthetics - the natural world is more beautiful than urban centres and roads -should we keep it around?
• Genetic resources - end result of millions of years of evolution is the unique gene combination for disease resistance, chemical production, etc
• Commercial - most of the products we rely on result from the biotic component s of the plant
• Life support - plants reduce the oxygen we need to survive, soil provides the means y growing food, organisms/processes cycle purify the water we need
• Ecosystem support - the interactions of the old are all connected - effect one - effect it all

Question 34

Conservation strategies

Answer 34

• genetic strategies
• environment strategies
• management strategies

Question 35

Genetic strategies

Answer 35

Aims to maintain biodiversity by preserving the current variety in nature and improve the chance of species success through genetics

Question 36

Gene/seed banks

Answer 36

samples of DNA, parts of or whole organisms, and seeds are stored. These are “spare” copies should the species become extinct or a drastic worldwide event occurs. The theory is, they can then re-established
Best known seed banks is the Svalbard Global Seed Vault

Question 37

Captive breeding program

Answer 37

• processes of breeding animals in controlled environments, such as wildlife reserves, zoos, and other conservation facilities
• sometimes the process includes the releases of individual organisms to the wild, when there is sufficient natural habitat to support new individuals or when the threat to the species in the wild is lessened
• captive breeding programs aim to facilitate biodiversity and may save species form extinction
• but may reduce genetic diversity due to interbreeding of organisms. Captive born animals may also lose their natural behavioural skills and not be able to survive returning to the wild

Question 38

Environmental strategies

Answer 38

• environmental conservation (also referred to as ecological restoration) aims to fix and repair the damage that has already been done
• there are many reasons to restore ecosystems
  Some include
• restoring natural capital such as drinkable water on wildlife populations
• reducing climate change
• helping threatened or endangered species
• aesthetic reasons
• moral reasons: we have degraded, and in some cases destroyed, many ecosystems so it fails on us to ‘fix’ them

Question 39

Rehabilitation

Answer 39

• rehabilitation or revegetation involves restoring degraded ecosystems
• normally also involves re-establishing quality top soil and soil nutrients for plants to grow
• quite often grasses are planted and then natural succession is allowed to occur
  In WA, rehabilitation of past mining sites is a big issue. The rehabilitation involves:
• waste dumps being contoured to flatten them out, to further stabilise them against erosion
• dams and leftover ore material usually covered with a layer of clay to prevent future pollution
• landfills are overhead with topsoil, and edge tat in is planted to help consolidate the material
• the open pit is then surrounded with a fence, to prevent access, and is generally eventually fills us with groundwater

Question 40

Feral animal & pest control

Answer 40

Another environmental strategy involves reducing the impact and numbers of feral animal pests
Conservation fencing to keep small feral mammals like foxes and cats is one program being undertaken in Australia
Culling of the program species is also a coon practise. Kangaroo and Koala populations in Australia have been culled to help reduced their numbers and bring a balance back to the ecosystem
Biological control is another way of getting rid of sets, without the use of chemicals
Biological control methods can take the form of introducing general or specialised predators or introduced parasites or diseases
Has the potential to create more problems by disrupting ecosystems
Once common and normally successful example is introducing ladybirds to battle aphids on crops

Question 41

Management strategies

Answer 41

• management strategies is the largest of the three types of conservation strategies
• aims of these strategies are the maintain biodiversity fir the long term, reduce any further damage to the environment and educate the public on the issues
• one of the major management strategies is to have world heritage sites, national/state parks and reserves and protection areas. These places can have restricted access and close monitoring to prevent any degradation

Question 42

World heritage sites

Answer 42

The world heritage site is a place (such as forest, mountain, lake, island, desert, monument, building, complex, or city) this is listed by the UNSECO of special cultural or physical significance. There are 188 natural world heritage sites listed across the Earth

Question 43

National Parks & reserves

Answer 43

The Australia Government manages Commonwealth parks and reserves including areas located on external island territories and within Australian water. Each Australian State and Territory Government also has their own protected area management agencies

Question 44

Australia’s biodiversity strategy

Answer 44

• Australia’s Biodiversity Conservation Strategy 2010-2030 is a guiding framework for conserving our nations biodiversity over the coming decades
• it brings together lots of areas of the community to plan to preserve and improve Australia’s biodiversity

Question 45

Management strategies - farming

Answer 45

• crop rotation is a farm practise where corps with different nutrients demands are cultivated in succession of the same ground in successive years
• its purpose is to maintain soil fertility and reduce pest infestation. This avoids the need for chemical pesticides
• a typical rotation is of three to six years. Legumes (e.g. clover, beans) are important int he rotation as they restore nitrogen to the soil. These alternate with root and cereal crops

Question 46

Management strategies - fisheries

Answer 46

The key feature in fisheries management include -
- development and understanding of the resource before harvesting
- a community to ongoing research into the biology of the fished species
- developing the safeguards necessary for sustainability such as catch limits and fishing seasons
- consideration of human needs and demands

Question 47

Management strategies - climate change

Answer 47

• reducing carbon dioxide emissions is not easy as they are the end-product of fossil fuel combustion, and modern societies are powered by fossil fuels
• the Kyoto Protocol is an international treaty on climate change. It aims to reduce greenhouse gas emissions through the creation of an international market in carbon credits. Unfortunately many countries have not agreed to the second stage of the plan
• in Australia we had the carbon tax introduced in 2012, but was repeated in 2014

Question 48

Management through education

Answer 48

• a huge part of managing biodiversity educating people about it
• companies and communities all have outreached education programs to teach the general public about the strategies and the global benefits of them

Question 49

Species at risk

Answer 49

• conservation of specific species happens when they are identifies as beneath risk. Some of the criteria used to classify a species as at risk include:
• a substantial rate of decline (observed, inferred, or projected)
• a small geographical range that is shrinking or is projected)
• a small population that is either single, or fragmented into isolated sub populations
• a strong probability of extinction within a specified time period, revealed by a quantitative analysis of population viability