Effects of human activities on habitats and their ecosystems

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Slide 11

Human activities such as use of motor cars and the emissions caused by industries pollute the atmosphere. This leads to a reduction in the quality of the air that is available for organisms to breathe, and climate change as many of the gases released are greenhouse gases. In addition, the mixing of acidic pollutants with rain causes acid rain.

(click) Acid rain does a lot of damage to habitats. It damages and kills trees, and can damage the leaves of other plants. This reduces the ability of plants to photosynthesise, so there is less food available for plants and animals in the habitat. Acid rain can also make soils infertile and change the chemistry of our waterways.
Thus, it can harm fish and other animals. Acid rain destroys habitats and leads to a reduction in biodiversity.

Slide 12

The ozone layer is part of the atmosphere that protects the Earth from the Sun’s ultraviolet rays. Industrial and household chemical pollutants can cause the ozone layer to thin substantially. There is substantial thinning of the ozone layer over Australia, and dramatic thinning of the ozone layer over Antarctica during the spring. The thinning over Antarctica is sometimes referred to as a ‘hole’ in the ozone layer. The dark blue area on the picture shows the hole in the Ozone layer over Antarctica in September, 2000. The consequence of thinning of the ozone layer is an increase in the amount of ultraviolet light from the Sun that can penetrate our atmosphere. This is a bad thing for plants and animals as it can lead to skin cancers and other damage to flora fauna.

(click) Although ozone is a good thing high up in the stratosphere, it is actually toxic. When air pollutants such as ozone are found close to the ground, they can damage the lungs of animals, making it difficult to breathe. They can also make it difficult for plants to breathe. These gases block the openings in the leaves of plants through which they absorb carbon dioxide. The absorption of carbon dioxide is necessary for the plant to produce energy through photosynthesis. So, plant growth is stunted and plants can die as a result.

Slide 13

Human activities such as farming and industry increase the release of greenhouse gases such as carbon dioxide and methane into the atmosphere. This leads to global warming and climate change, which changes and damages the habitats that plants and animals live in.

(click) The habitats for animals and plants in the polar regions are being reduced as the polar ice caps melt. This also leads to a reduction in the available food sources and shelter for these plants and animals.

(click) Climate change leads to the warming of the ocean waters and rising sea levels. This is particularly devastating for animals that live in shallow water habitats such as the great barrier reef. There, coral diseases such as coral bleaching are killing the reef, and destroying the habitat of many tiny aquatic animals.

(click) Global warming also leads to climate change in other areas. Areas that have previously been deserts experience increased rainfall and become wet environments. Rainforests become dry. These changes in the habitat of various species make them less suitable, leading to a lack of food, illness and death of organisms, and a loss of biodiversity.

Slide 14

Thousands of exotic species have been introduced to Australia from overseas. Such introductions may have been accidental, such as the import of the rat, but others have been deliberate. Plants have been introduced to provide food or for aesthetic value.

Animals have been introduced for sport, food or to control other pests.

(click) Not all of these introductions have been harmful, but some species have become invasive.

(click) Invasive species can devastate habitats in a number of different ways.
Feral animals such as rabbits, goats, cattle, buffalos, pigs, donkeys and camels intensively graze, stripping the soil of vegetation. The hooves of many of these animals compact the soil and make it difficult for native vegetation to grow. This reduces the quality of our soils and increases soil erosion.

(click) Many introduced animals hunt native animals. For example, feral foxes and cats hunt and kill many native birds and animals. The plague minnow and European carp prey on eggs and attack the tadpoles of native frogs.

(click) Introduced plant and animal species compete with native species for resources and shelter. Feral rabbits can kick native bilbies and bandicoots out of their burrows. Invasive fish compete with native fish for food and habitat, and often uproot aquatic vegetation, and disturb sediments. Weeds such as lantana rapidly take over disturbed sites, competing with native plants for space, nutrients and sunrise, choking them out.

(click) Imported plants and animals also carry diseases and pests that are not native to Australia. For example, viral beak and feather disease can devastate small populations of endangered birds such as some species of parrots. Introduced species of fish can introduce diseases and parasites to native fish stocks.

(click) Finally, invasive species can harm native species by poisoning them. For example, cane toads excrete poison through their skin which can kill native predators, and all parts of lantana are poisonous.

Slide 15

Humans have a tendency to overexploit their resources, particularly as populations increase. Over exploitation of natural resources can have significant impacts on the environment. These include the loss of habitats for animal and plant life caused by overexploiting timber, vegetation and mineral resources through open cut mining. Overhunting of particular species can lead to a lack of biodiversity, and can disrupt food chains. It can also lead to a loss of food sources. For example, overfishing for cod in the northern atlantic ocean in the 1970s and 80s depleted fish stocks. They have taken a long time to recover.. Methods for extracting natural resources can cause the pollution of our water ways. Other consequences include increased soil erosion due to overexploitation of vegetation, and land clearance. This also gives rise to deforestation and desertification. Other natural resources such as minerals, metals and fossil fuels can be depleted if they are used too rapidly.

Slide 16

In this presentation, we’ve seen a number of devastating impacts that humans can have on habitats. Some of these include a reduction in biodiversity, a loss of habitat and food sources, disruption of ecosystems, a reduction of air and water quality, soil erosion, deforestation and desertification, increased exposure to harmful ultraviolet light and the introduction of toxins and diseases to the plants and animals that live in habitats.

This presentation has given you an introduction to the ways in which humans have affected habitats. Why don’t you do some research on your own and see if you can come up with other ways in which humans have impacted different habitats? Once we have identified the ways in which we affect habitats, we can start thinking about ways in which we can minimise our impact on the environment and take steps to solve the problems we cause.