Earth Sciences

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Natural Ecosystem Changes: Key terms

Natural Selection: The Process where individuals with advantages are able to produce and pass along their traits to their offspring

Unfavourable Characteristics: The process where individuals have a less chance of reproducing and passing their traits to their offspring

Adaptive Radiation: Describes the change from a common ancestor into a number different species that distribute out to inhabit different niches.

Ecological succession: Refers to the changes in the life in an area changes over time. There are two types: Primary and Secondary

Primary succession: Occurs in areas where no soil exists and is broken down into 4 stages: Pioneer, Early, Mid, and Late.

Pioneer: The first organisms (Lichens or Moss) attach to the rock and are called Pioneer Species. They require almost no soil to grow and adapt to harsh, nutrient-poor conditions and produce mild acids that that slowly decompose the rock (chemical weathering).

Early: These species grow low to the ground, produce many offspring at a quick pace. Have short lives and our recycled through other plants.

Mid: These species are tolerant to the sunlight and only need a limited amounts of nutrients.

Late: Plants that our shade tolerant and require many nutrients

Mature Communities: The process of primary succession that leads to the development of mature community, sometimes called a climax community

Climax Community: May appear unchanged, but there are always changes occurring because of small disturbance.

Secondary Succession: The soil remains for plant growth, contains seeds, micro-organisms, and earthworms/ other insects to return nutrients. Secondary is much faster than primary and only takes decades to recover.

Natural events taking effect:

Natural events can destroy habitats and reduce biodiversity:

Flooding: Results in soil erosion, pollution, and disease. Flooding is when toxins and bacteria from untreated sewage enters drinking water, and is no longer contained in its natural barriers. Occurs in areas with water levels change rapidly. Climate change also increases chances of flooding.

Drought: When an area receives a low amount of of rainfall. Drought leads to death of plants and animals.

Insect Infestation: Insects destroy older and weak trees/wood. A warm climate and lack of forest fires, allows the spread of insects.

Tsunamis: Huge waves, from large earthquakes or volcanic eruptions and floods costal areas. Destroys habitats and salt water gets carries onto shore changing the soil composition.

New Species Affect Ecosystems: Key terms

Native Species: Plants and animals that naturally inhabit an area.

Introduced Species or Foreign Species: Are species that have been artificially introduced into an area by humans.

Invasive Species: Harmful to the environment, can dramatically change the ecosystems. Climate change increases the growth of invasive species and a rapid spread of these species can cause global biodiversity loss.

The impact on introduces species:

Competition: Introduced invasive species which reproduce at rapid speeds. They easily out-compete native species for food and habitat. Example: Carpet burweed from south America competes with rare native plants for habitat.

Predation: Introduced predators can have more pact on the prey population than the native predators. Example: Yellow crazy ants

Disease and Parasites: An invasion of parasites or disease-causing viruses and bacteria can weaken the immune response in native plants and animals. Example: The sea lamprey

Habitat Alteration: Some invasive species can change the physical structure of the ecosystem by digging, burrowing, and blocking sunlight. Example: Wild boars.

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Human Influences on Ecosystems and Sustainability: Key terms

Sustainability: The ability of an ecosystem to undergo ecological processes.

Resource use: Refers to the way we obtain and use resources.

Land use: Refers to the way we use the land around us.

Habitat loss: Refers to the loss of habitat due to human activities.

Habitat Fragmentation: The splitting of large habitats into smaller habitats.

Deforestation: The clearing forests for human uses.

Barren land: The result of deforestation, land that is never reclaimed by species.

Monoculture: Agriculture crops that are planted, this reduces biodiversity and leaves the crops vulnerable to pests and disease.

Polyculture: Plants that are more economically and biologically diverse.

Soil degradation: Another result of Deforestation and is when wind and water erode topsoil and leave bare land behind.

Topsoil: The upper layer of soil, where most of the nutrients are stored, where water and air are found for plant growth.

Effects of agriculture:

Water and wind erosion: If fields are left exposes during the non-planting season, water and wind erosion can occur.

When soil particles are squeezed together, due to farm animals and vehicles. This means that their no room for water air to enter and instead of soaking in the water runs off it. Loss of water increased erosion and farm fertilizer adds pesticides to the ecosystem.

Aeration: Involves removing small plugs of soil, loosens the soil in order to reduce the effect of run-off.

Effects of resource exploitation:

Resource exploitation = Resource use

Exploitation: Can lead to habitat loss, soil degradation, and contamination of water supplies.

Contamination: The introduction of harmful chemicals r micro-organisms into the environment.

Reclamation: Attempts to reduce environmental impacts of exploitation, and tries to restore the functions of the original habitat.

Overexploitation: The extraction of resources until they are gone. This can result in extinction.