4- human impacts on ecosystems

Define global warming.

A term used to describe a gradual increase in the average temperature of the Earth’s atmosphere and surface.

What is the evidence of climate change?

• Records of carbon dioxide levels- increasing levels of CO² in the atmosphere are believed to contribute towards climate change as CO² is a greenhouse gas and is involved in the greenhouse effect.

• Temperature records- which enable analysis of changes in temperature.

• Pollen in peat bogs- pollen grains are preserved in peat bods and analysis of samples of pollen can give us an idea of what kind of plants were present at the time when the peat was being formed.

• Dendrochronology- the study of tree rings as the size of tree rings is affected by temperature.

Define the greenhouse effect.

The process by which infrared radiation from the sun is trapped by gases such as carbon dioxide and methane, thus leading to an increase in the temperature of the Earth’s surface and atmosphere.

The effects of climate change including changing rainfall patterns and changes in seasonal cycles which in turn lead to:

• Changes in distribution of species -species would move to cooler areas. This could potentially lead to the extinction of some species due to competition.

• Changes to development -sex of many reptiles is determined by temperature, therefore an increase in temperature would affect the sex ratio of certain species thus potentially leading to extinction.

• Disrupted life cycles

The international union for conservation of nature draws up a Red List of Threatened Species annually, what can threatened by further broken down into?

Vulnerable, endangered and critically endangered.

What does CITES stand for and what does it do?

Convention on International Trade in Endangered Species of Wild Fauna/Flora.

It regulates the trade of living organisms and their products by classifying them into three appendices depending on the level of threat to the organism, guided by the Red List.

CITES has had some success at conserving biodiversity. However, its successes are limited because it:

Deals exclusively with trade, many countries haven’t signed up, there is no legal obligation to abide by the rules (only trade sanctions can be used) and commercial interests often override scientific evidence.

What does conservation do?

Works to maintain or increase the biodiversity within a particular habitat by allowing sustainable use of natural resources.

What is preservation?

Serves to maintain the biodiversity levels and the habitat intact by minimising the effect of human activities on the particular habitat.

Name a direct and indirect impact of human activities on ecosystems.

Direct- deforestation

Indirect- climate change

How do human activities cause habitat loss and what does it do?

Deforestation for agriculture, logging for timber, and urbanisation.

Causes species to lose their habitats leading to some species extinction.

How do human activities cause pollution and what does it do?

Both chemical and physical pollution disrupts ecosystems e.g. air pollution, water pollution and soil contamination.

Air pollution- can cause acid rain, harming aquatic and terrestrial ecosystems.

Water pollution- through dumping of waste and chemicals, has devastating impacts on biodiversity in aquatic ecosystems.

How has human activities cause climate change and what does it do?

Human activities release greenhouse gases e.g. CO2 and methane into the atmosphere.

Impacts ecosystems by causing shifts in species distribution, changes in population sizes and alterations in the timing of biological activities.

How do human activities exploit species and what does it do?

Humans overhunt, overfish and the wildlife trade are examples of species exploitation that can disrupt ecosystems.

Overexploitation can lead to a decrease in biodiversity and can cause species to be close to or reach extinction.

How do human activities cause invasive species and what does it do?

Humans often unintentionally introduce a non-native species into new ecosystems.

These invasive species can outcompete native species for resources and disrupt local ecosystems.

How do human activities cause the fragmentation of habitats and what does it do?

Human activities often result in habitat fragmentation, which can lead to isolated populations, reductions in species diversity and changes in species behaviour and genetics.

Roads, agriculture and urbanisation are common causes of habitat fragmentation.

What are strategies which can be used to help mitigate human impact on ecosystems?

Conservation efforts, restoration of damaged ecosystems, sustainable agriculture and fishing practises and regulations to control pollution and habitat destruction.

How can we reduce the CO² levels in the atmosphere (which helps to reduce global warming)?

• Growing plants to use as fuel as biofuels which are carbon neutral- CO² released by burning the fuel is removed from the atmosphere by the plants it is made from (by photosynthesis).

• Reforestation to increase the rate at which carbon dioxide is removed.