UNIT 3 Student Notes. 3.1 How Changes Occur Naturally in Ecosystems

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1 UNIT 3 Student Notes 3.1 How Changes Occur Naturally in Ecosystems Introduction When an organism is born, it belongs to a species, but it also is born with characteristics. Like humans with coloured eyes and heights. Sometimes, these unique characteristics give that individual an within their niche. ie, a salmon with a slightly larger tail may be able to swim a little faster or a little farther in a river. Natural selection is the process where individuals with advantages are and pass along their traits. Those with characteristics have chance to reproduce and pass along their traits. Ie. A salmon with a smaller tail may never have a chance to spawn because it can t swim to the correct location. How Organisms Adapt The, off the coast of Ecuador, are perhaps the most famous example of natural selection. Many species on these islands are to each other, and also to species on the South American continent. o There are thirteen species of finch on the islands. o Each is descended from a finch species from the mainland. o Each species has that allows them to thrive in their own niche, and not compete with other finches for resources. is the term for this type of natural selection.

2 Many different species appear from one original species. Galapagos finches Primary Succession refers to the changes in the biotic characteristics in an area over time. Over time, the life in an area changes There are two types of ecological succession. 1. Primary succession - begins with nothing but Where glaciers scrape away dirt, or a volcano erupts Wind carries spores of lichens and organisms that can survive and eventually, combined with the weathering of rock, The first organisms to survive and reproduce are. o Pioneer species alter the abiotic and biotic environment in some way. o Soil improves, plants are able to grow, animals begin to appear. Primary succession occurs in this way in all parts of the world. This stage can last for hundreds of years, until a mature community eventually forms.

3 Secondary Succession 2. Secondary succession - after a major disturbance in an area and once had living organisms. are the most common reason for secondary succession. The soil remains for plant growth, and contains seeds, micro-organisms, earthworms and insects. Secondary succession is much more rapid than primary succession. o There is already soil, seeds and insects, so. Mature communities are very, and can appear to be unchanging over long periods of time. These are also known as, but mature correctly implies that there are still changes occurring, albeit more slowly. How Natural Events Affect Ecosystems Many disturbances can affect mature communities. 1. Water is not contained within natural or artificial barriers. Generally occurs in locations where water levels can change rapidly. It can result in as well as the spread of pollutants and harmful bacteria associated with wastes. Climate change and global warming may be incidents of flooding.

4 A tsunami occurs when huge waves, from large earthquakes or volcanic eruptions, floods coastal areas. 2. Occurs when an area receives a lower than average amount of rainfall over a very long period of time. Prolonged drought can have severe effects on organisms. 3. Many insects play important roles in their ecosystems. Even insects that appear destructive, such as the mountain pine beetle, actually play a role in the renewal of the forest. o The beetles even have a with a species of fungus that inhibits the trees ability to use resin for protection. However, when normal conditions are, infestations can occur. o Trees can be stressed from overcrowding, drought or animal grazing, and do not resist the insects as effectively. A warmer climate, and lack of forest fires, allows the insects to spread much more effectively than in the past. Not only are the trees affected, but so is the entire forest ecosystem, as well as any human industries relying on the forest. 3.2 How Humans Influence Ecosystems Introduction are special ecosystems that contain completely waterlogged soil for long periods of time. Not only do wetlands contain, but they also filter many impurities out of the water that slowly flows through them. o For this reason, they are sometimes called the kidneys of the Earth. Because they hold large amounts of water, they can help flooding.

5 Human encroachment has caused many BC wetlands to disappear. In the past 100 years: Up to of the wetlands in the lower Fraser Valley have been lost. Up to of the wetlands in the South Okanagan have been lost. Wetlands are vital ecological features in British Columbia. Understanding Sustainability is a word that is used often, and can be defined in more than one way: The ability for an ecosystem to sustain ecological processes. o These processes enable biodiversity and keep the ecosystem healthy. People using an ecosystem to meet their needs today without reducing the function or health of the ecosystem in the future. o Sustainable practices, healthy ecosystems. o Economic opportunity, biodiversity and ecosystem health are all possible. Effects of Land & Resource Use refers to how humans use land around us for urban development, agriculture, industry, mining and forestry. All of the land around us, even in cities, was once a part of an ecosystem. refers to the ways we obtain and use naturally occurring materials. Most products you use every day involve the use of some natural resources in their production. If the land and resources are not used directly, they are often processed and exported to other places for use. Habitat Loss The use of land and resources have seen humans encroach on natural ecosystems very aggressively in the past 150 years. As a result of this expansion, habitats have been. refers to to loss of habitats due to human activities.

6 Name: is the splitting of large habitats into many smaller ones, resulting in disrupted natural activities for plants and animals. Habitat loss (top left) and habitat fragmentation (bottom left) reveal the effects of human activities on ecosystems. Effects of Deforestation is the clearing or logging of forests for human use. The resulting barren land is never reclaimed or replanted. The agricultural crops that are planted are often one species = o This reduces biodiversity, and leaves the crop vulnerable to pests or disease. o, of many plant species, are more economically and biologically diverse. Deforestation is still occurring in many tropical rainforests. Deforestation results in. o Soil degradation is when moving wind and water and leave bare land behind. o Topsoil, the upper layer of soil, is where most of the nutrients, water and air are found for plant growth.

7 Effects of Agriculture If fields are left exposed during non-planting seasons, water and wind erosion can occur. In areas like southwestern BC, the soil can become. Soil particles are squeezed together and become compacted. o This is due to. There is no room for water or air to enter the soil. Water then the soil instead of. o Loss of water, increased erosion and the addition of farm fertilizers and pesticides to the ecosystem. Aeration, which involves removing small plugs of soil, loosens soils and can reduce run-off. Farm animals, such as these cows, can compact soils. Effects of Resource Exploitation Resource exploitation = resource use Humans depend on resource exploitation for jobs, materials, food, shelter and energy. Exploitation can lead to. o Contamination is the introduction of harmful chemicals or microorganisms into the environment. o Many mining and resource exploitations require efforts. Reclamation attempts to reduce environmental impacts of exploitation, and tries to restore the original (or at least functional) habitats. is the extraction of resources until they are gone. o This can result in extinction, such as with the passenger pigeon.

8 o Food webs can be greatly affected over long periods of time o The overexploited species could be a. Resource Management In Aboriginal cultures, is passed down from generation to generation. This knowledge reveals what were like, and also how the ecosystem and humans. Knowledge is found in stories, songs, cultural beliefs, rituals, community laws and traditional practices. Current ecological restoration and usage guidelines often involve this traditional knowledge from Aboriginal representatives. o Traditions such as the allow for ecological renewal. o Fire suppression, enforced in BC for over 100 years, has led to recent issues like the. 3.3 How Introduced Species Effect Our Ecosystems General Information are plants and animals that naturally inhabit an area. Because of the immigration to North America by many people from other continents over the past 400 years, many new species have been accidentally (and on purpose) here. o These new species of plants and animals are called. o Aka, non-native species, exotic species or alien species. o Many of these species are harmless, or sometimes even beneficial. o, such as Purple Loosestrife, negatively impacts native species, and often reduces biodiversity as a result. The European leaf-feeding beetle (left), and the Purple Loosestrife

9 Impact of Introduced Species Invasive species often take advantage of their new habitat. They may. : while the native species have an established balance, the invasive species can throw off this balance. : if the invasive species is a predator, it may have a huge advantage, as the native species may have no methods to survive. : by weakening certain species, a microorganism invading an ecosystem can drastically alter the entire ecosystem and the niches within it. : some invasive species can change the physical structure of the ecosystem by digging, burrowing, blocking sunlight or changing the chemistry of the ecosystem. Invasive Species in BC American Bullfrog European Starling Eurasian Milfoil Norway Rat Saving an Ecosystem Under Siege It often takes human intervention to save established ecosystems. The Garry Oak Ecosystem Recovery Team (GOERT) is trying to save several areas of the Garry Oak ecosystem in BC.

10 of the original ecosystem has been lost to urban development, and the remaining 5% is threatened by. Scotch broom, English ivy and other plant species are its biggest threats. GOERT has representatives from many groups. The BC government, First Nations, conservationists, scientists and businesses believe this work is critical. Garry Oak forests may be better suited to survive in the future than Douglas fir forests.