Chapter 7 - Ecosystem changes and conservation strategies

what is a sign of a healthy ecosystem

can sustain stress in the form of extreme conditions, such as floods, droughts, invasive species, disease and overexploitation. Usually, resilience is a direct result of having a substantial level of Biodiversity

What is habitat destruction?

Habitat destruction refers to the process of damaging or eliminating environments where species normally live, primarily due to human activities.

What are some human activities that contribute to habitat destruction?

Human activities include urbanization, manufacturing, agriculture, forestry, mining, and fishing.

What is the greatest threat to biodiversity?

Habitat loss is the greatest threat to biodiversity, leading to reduced species richness and increased vulnerability to extinction.

What is urbanization?

Urbanization is the extreme modification of an ecosystem by humans to support a growing human population, often resulting from migration from rural to urban areas.

How does urbanization affect biodiversity?

Urbanization reduces local biodiversity and leads to ecosystems dominated by people, with little recycling of matter between living and non-living components.

What is the impact of urbanization on waste production?

Urbanization increases the output of gaseous and material wastes, which are often disposed of improperly, affecting the atmosphere, land, and water ecosystems.

What are the long-term effects of urbanization on ecosystems?

Urbanization causes rapid, large-magnitude changes to ecosystems, leading to reduced biodiversity and often permanent alterations in the ecosystem structure.

What percentage of Australia’s forests has been cleared for agriculture since European colonization?

More than 20% of Australia’s forests have been cleared for crops and grazing.

What is habitat fragmentation?

Habitat fragmentation occurs when parts of an ecosystem's habitat are separated into isolated sections, often due to human activities like land clearing and urbanization.

How does habitat fragmentation affect populations of organisms?

Habitat fragmentation isolates groups of organisms, preventing smaller subpopulations from interbreeding and sharing genetic biodiversity, which can lead to reduced resilience and local extinction.

What is a seed bank?

A seed bank is a reservoir for plant genetic material, especially for species threatened with extinction. It stores seeds that can be used to reintroduce species to their habitat if they become extinct.

What are gene banks, and why are they important?

Gene banks are used for agricultural insurance to store seeds containing genetic material, preserving genetic diversity and helping species survive future environmental changes.

What is the purpose of revegetation and bush corridors?

Revegetation and bush corridors aim to regenerate land and reconnect isolated habitats, allowing subpopulations to interbreed and restore ecological resilience.

What is the goal of management conservation strategies?

The goal is to control aspects of the environment to maintain or improve the survival of species and minimize negative impacts from human activities.

What are some examples of management strategies for individual species?

An example is introducing rules for seasonal fishing of a fish species being harvested unsustainably.

What actions are included in the national recovery plan for Carnaby’s black cockatoo?

Actions include protecting important habitats, monitoring nest hollows, conducting research, managing threats, promoting community awareness, and communicating with decision-makers.

Why are sheep and some introduced domestic animals detrimental to soil health?

Their hard hooves compact the soil, creating conditions for shallow-rooted invasive plants to thrive while native deep-rooted grasses decline.

What happens to the topsoil when tree cover is reduced and shallow-rooted grasses increase?

The topsoil becomes more exposed to abiotic factors like wind and rain, leading to erosion and soil degradation

How does selective grazing by sheep affect vegetation?

Sheep selectively graze, preferring some plants over others, which gradually changes the composition of the vegetation in the area.

What are the consequences of soil degradation for agriculture?

Soil degradation results in production loss for farmers and can lead to death for plants, animals, and organisms that depend on the soil ecosystem.

What is dryland salinity?

Dryland salinity occurs when salts normally found under the surface of the soil are transported to the soil surface by a rising watertable, making the soil infertile.

What causes the rising watertable that leads to dryland salinity in WA's agricultural areas?

The removal of deep-rooted, perennial vegetation, which normally keeps the watertable stable by using water from deep in the soil, causes the watertable to rise.

How do deep-rooted trees help prevent dryland salinity?

Deep-rooted trees transport water from the watertable through their roots, stems, and leaves, where it evaporates into the atmosphere, preventing the watertable from rising.

What happens when salty water reaches the surface in areas affected by dryland salinity?

The water evaporates due to the dry climate, leaving behind the salt, which makes the soil infertile and prevents crops from growing.

How can farmers reduce dryland salinity?

Farmers can siphon off or pump water from the rising watertable to lower it and prevent salts from reaching the surface.

What is a method used to prevent dryland salinity while still planting crops?

Planting rows of short-rooted crops next to rows of deep-rooted trees prevents the watertable from rising and keeps the land fertile long term.

What are introduced species?

Introduced species are species that humans have intentionally or unintentionally moved from their native location to a new ecological region.

Why do introduced species often thrive in their new location?

In their new location, introduced species lack natural predators, parasites, and pathogens that would typically limit their growth.

What is another term for introduced species?

Introduced species are also known as exotic species.

How has human travel contributed to the spread of introduced species?

The increase in human travel by ship and air has accelerated the rate at which introduced species are spread to new regions.

When do introduced species become invasive species?

Introduced species become invasive species if they manage to establish populations in new areas.

How do feral animals, such as foxes and cats, impact ecosystems in WA?

Feral animals like foxes and cats prey on native species and outcompete them for food and habitat resources, causing significant damage to ecosystems.

Why are cane toads considered a major invasive species in Australia?

Cane toads excrete a deadly toxin, which kills many native species that prey on frogs, such as quolls. They also compete with native species for food, threatening Australia’s biodiversity

How do some decorative plants, such as Gazania, become environmental weeds?

Gazania is sold for its attractive flower but spreads rapidly into nearby ecosystems, replacing native plants and severely altering vegetation structures. It is classified as an environmental weed in South Australia and a potential weed in WA.

What is chemical control in environmental management, and what are its downsides?

Chemical control uses pesticides to quickly eliminate pests but can be ecologically damaging and costly.

What is biological control, and why is it favored by scientists?

Biological control uses one species to manage another species. it is environmentally sustainable and exploits relationships between organisms.

What are the four kinds of biological control agents?

• General predators

• Specialized predators

• Parasites

• Microbial diseases

What is Paterson’s curse, and how has biological control been used to manage it?

Paterson’s curse is a toxic weed harmful to livestock. Insects such as the root weevil, crown weevil, flea beetle, and pollen beetle attack it at various life stages, helping control its spread and reducing its impact on pasture and wool production.

What precautions must be taken before releasing a biological control agent into an ecosystem?

Field trials must be done in isolated areas to prevent ecological disasters. The agent should target only the pest species, reduce with the pest's population, not compete with native species, and be self-sustaining in the environment.

Why are captive-breeding programs important, and what factor influences their success?

Captive-breeding programs are crucial for endangered species like Galaxias and various marsupials. Their success depends on releasing these species into protected areas free of invasive predators, often requiring pest-proof fencing.

Why is culling considered controversial, and why is it practiced?

Culling is controversial because it involves killing species that have exceeded their ecosystem’s carrying capacity. It is practiced to reduce competition for resources.

What is unsustainable use of natural resources, and how does it affect biodiversity?

Unsustainable use of natural resources occurs when resources are used faster than they can naturally replenish, leading to biodiversity loss. Overharvesting, for example, depletes populations faster than they can recover.

What are some threats to biodiversity posed by commercial fishing in Australia?

Commercial fishing depletes fish populations, such as sharks, and disrupts food chains. Penguins and seals now compete with fishers for food. By-catch and abandoned fishing lines also harm marine species like turtles and birds.

What is the impact of by-catch in commercial fishing?

By-catch includes undersized fish, mammals, and reptiles accidentally caught in fishing nets. As populations of valuable fish species decline, fewer fish reach reproductive age, hindering population growth.

Why is bottom trawling destructive to marine ecosystems?

Bottom trawling involves dragging nets across the seafloor, capturing deep-sea species and destroying non-target species like corals and sponges, posing a risk to deep-sea ecosystems.

How can fishing practices become more sustainable?

Using less-destructive fishing methods, managing vulnerable areas, and continuous monitoring of fish stocks and water quality can help sustain marine populations and protect ecosystems.

What is eutrophication?

Eutrophication is the process where excess nutrients, particularly nitrogen and phosphorus, enter a body of water, leading to excessive growth of algae and other organisms.

What causes eutrophication?

Eutrophication is caused by excess nutrients from sources like fertilisers, which enter water bodies through run-off from rain or irrigation.

What are the main nutrients responsible for eutrophication?

Nitrogen and phosphorus are the primary nutrients that cause eutrophication by promoting excessive algal growth.

How do fertilisers contribute to eutrophication?

Fertilisers rich in nitrogen and phosphorus dissolve in rainwater or irrigation water, and the resulting run-off carries these nutrients into local water bodies, leading to algal blooms.

What happens during an algal bloom?

An algal bloom is a rapid increase in algae or micro-organisms that blocks sunlight from reaching underwater autotrophs, causing them to die.

How do algal blooms affect oxygen levels in water bodies?

When algae die, bacteria decompose them, using large amounts of oxygen, which can lead to hypoxic (low oxygen) or anoxic (no oxygen) conditions in the water.

What is the consequence of hypoxic or anoxic water conditions?

Low oxygen levels cannot support the respiration needs of aquatic organisms, leading to the death of fish and other species.

What factors increase the likelihood of algal blooms?

High light levels (from tree removal) and reduced water flow (due to water diversion for irrigation) increase the chances of algal blooms.

What are the effects of toxic algal blooms?

Some algal blooms are toxic, affecting the nervous system of animals and humans, while others may be relatively harmless.

What is biomagnification?

Biomagnification is the process where successively higher concentrations of non-biodegradable chemicals build up in the tissues of organisms at higher trophic levels in a food chain.

How do toxins accumulate in organisms?

Organisms acquire toxins from the environment along with nutrients and water. Some toxins are excreted, but others are stored in tissues, often in fat cells, because they cannot be excreted or metabolized.

What happens when an organism with stored toxins is consumed?

When an organism with stored toxins is consumed, the chemicals accumulate in the next trophic level, becoming more concentrated. This process repeats at each level of the food chain.

Why does biomagnification increase at higher trophic levels?

Each trophic level needs to consume relatively large amounts of matter from the level below, which leads to an increasing concentration of toxins at higher trophic levels.

What are some dangers animals face from ingesting plastic?

Ingested plastic can cause stomach or intestinal blockages or injuries from sharp pieces, leading to death.

What is the difference between climate and weather?

Weather refers to atmospheric conditions in an area over a short time (usually 2–3 days), while climate is the long-term average of weather conditions over a much longer period.

What is climate change?

Climate change is a significant change in the global climate identified by changes in average and variability of features like temperature and precipitation, lasting typically decades or longer.

How do scientists find evidence for climate change?

Scientists compare past and present climates by analyzing samples from ancient ice cores, which contain bubbles of gas that reveal data about past carbon dioxide levels and temperature.

What do the layers of ice in an ice core represent?

The layers of ice represent different time periods, with lower layers corresponding to earlier times. Scientists can measure variables in each layer to track changes over relative time.

Why do many scientists believe recent increases in carbon dioxide are significant?

Many scientists hypothesize that the rapid increase in atmospheric carbon dioxide is causing relatively rapid climate change and impacting biodiversity, differing from past increases that occurred over thousands of years.

What are greenhouse gases?

Greenhouse gases are gases that trap heat in Earth’s atmosphere, including carbon dioxide, nitrous oxide, water vapor, methane, and industrial gases like perfluorocarbons and hydrofluorocarbons.

What is the natural greenhouse effect?

The natural greenhouse effect maintains Earth’s average global temperature within a range suitable for life by trapping some of the heat that is re-emitted from incoming solar radiation.

What is the enhanced greenhouse effect?
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The enhanced greenhouse effect occurs when increased concentrations of greenhouse gases from human activities trap too much heat, leading to rising average global temperatures.

What are fossil fuels, and what do they produce when burned?

Fossil fuels (coal, oil, natural gas) are formed from fossilized living things and produce carbon dioxide when burned.

What is one alternative energy source that emits less greenhouse gas?

Wind energy is an alternative energy source that emits significantly less greenhouse gas.

What is deforestation, and how does it impact carbon dioxide levels?

Deforestation is the permanent removal of forests, which can lead to significant carbon dioxide emissions as forests normally act as carbon sinks.

How do intense wildfires affect carbon storage in forests?

Intense wildfires can remove forests and release carbon into the atmosphere, turning carbon sinks into carbon sources.

What role does agriculture play in greenhouse gas emissions?

Agriculture contributes to greenhouse gas emissions by producing methane and nitrous oxide, accounting for 14% of WA’s emissions.

What is carbon farming?

Carbon farming includes practices that reduce greenhouse gas emissions and increase carbon storage in vegetation and soils, such as changing tillage practices, revegetation, and adjusting fire management.

What are the benefits of carbon farming for farmers?

Farmers benefit by reducing contributions to climate change, decreasing soil erosion, and improving soil structure and fertility.

What are some observable factors related to climate change?

Changes in long-term weather variables, shifting wind and precipitation patterns, and increased frequency of extreme weather events (droughts, floods, storms).

How is climate change affecting glaciers and polar ice sheets?

Climate change is causing increased melting of glaciers and polar ice sheets, resulting in a gradual rise in sea levels.

How does climate change affect plants and animals?

Climate change affects the timing of seasonal events (e.g., flowering, pollination), impacting plant and animal life cycles.

What are some consequences of changing abiotic and biotic factors in ecosystems?

Changing factors can lead to unsuitable habitats, insufficient food, and require fast migration for some species, affecting their survival.

What is the result of losing individuals and species due to climate change?

The decline in individuals and species leads to a decrease in biodiversity and reduced resilience of ecosystems.