Invasive Species Case Study: Starlings

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Questions and Answers

What happens to the layers of a lake during summer stratification?

The surface water cools down, causing sinking in the deeper layers.

The hypolimnion becomes warmer than the epilimnion.

The thermocline acts as a barrier preventing mixing of the layers. (correct)

Oxygen circulates evenly throughout all layers of the lake.

Which of the following factors is NOT a part of biotic potential?

Breeding frequency

Birth potential

Feeding habits (correct)

Length of reproductive life

During which seasonal event do surface waters cool and mix in Canadian lakes?

Spring turnover

Winter stratification

Fall turnover (correct)

Thermal layering

What is the primary function of ice on the surface of lakes during winter?

To insulate the water and limit oxygen exchange. Signup and view all the answers

What is indicated by a reduction in oxygen levels in a lake's hypolimnion during summer?

Stratification leading to isolation from surface oxygen. Signup and view all the answers

What is a primary consequence of introduced species lacking natural predators?

They experience unchecked population growth. Signup and view all the answers

Which species exemplifies the impact of introduced species on native populations?

Starlings Signup and view all the answers

What adaptation do coniferous trees in the Taiga biome have for winter?

They have wax-coated needles. Signup and view all the answers

Which of the following best describes the term 'canopy' in a forest ecosystem?

Uppermost layer of forest vegetation. Signup and view all the answers

How many introduced species have established themselves in Canada, leading to ecological disruptions?

Over 3000 Signup and view all the answers

What best characterizes the forest floor in a taiga forest?

Limited types of plants due to limited sunlight. Signup and view all the answers

Which type of ecosystem would you find in Alberta alongside the taiga biome?

Grassland ecosystem Signup and view all the answers

What is a potential effect of the lack of natural predators for introduced prey species?

Overpopulation and competition for resources. Signup and view all the answers

What is considered an unfavourable abiotic condition for plants?

Too cold or too warm temperature Signup and view all the answers

Which biotic factor can increase competition among fern populations?

An increase in grazing animals Signup and view all the answers

What defines the carrying capacity of an ecosystem?

The maximum number of individuals of a species that can be supported sustainably Signup and view all the answers

How can dry weather affect fern populations?

It reduces germination and can lead to population decline. Signup and view all the answers

What effect do few predators have on the fern population?

They allow for an increase in population growth. Signup and view all the answers

Which of the following is a favourable abiotic factor for plant growth?

Adequate sunlight Signup and view all the answers

What can happen when a population exceeds its carrying capacity?

It may lead to resource depletion and decline. Signup and view all the answers

What is the relationship between moist weather and fern population dynamics?

Moist weather increases germination and allows for population growth. Signup and view all the answers

What is resource partitioning and why is it important for species coexistence?

Species use different resources or strategies to share the same habitat. Signup and view all the answers

Which of the following is NOT a density-independent factor affecting population changes?

Food shortage Signup and view all the answers

What major human activity has contributed to the loss of over 60% of virgin forests in Canada since European settlement?

Deforestation for logging Signup and view all the answers

What is an example of slash-and-burn deforestation?

Burning forests to create agricultural land. Signup and view all the answers

Which of the following activities is a significant human-caused change in ecosystems?

Pollution from industrial waste Signup and view all the answers

How has the extent of forest cover changed since the Industrial Revolution?

Decreased from about 6 billion to 4 billion hectares. Signup and view all the answers

What is the primary environmental impact of clear-cutting?

Soil erosion and loss of habitats. Signup and view all the answers

What ecosystem service do forests provide that helps regulate climate?

Recycling water and carbon dioxide. Signup and view all the answers

What is a positive effect of clear-cutting in forest management?

Eliminates pest infestations Signup and view all the answers

What is a significant negative impact of clear-cutting?

Increases soil erosion Signup and view all the answers

What is the primary effect of fire on ecosystems?

Clears overgrown vegetation Signup and view all the answers

Which type of lake is characterized by being deep, cold, and low in nutrients?

Oligotrophic Lake Signup and view all the answers

How does human activity accelerate the eutrophication process in lakes?

Through runoff of fertilizers Signup and view all the answers

What does replanting monocultures after clear-cutting potentially affect?

Reduces forest stability Signup and view all the answers

What is an example of organic waste pollution in aquatic systems?

Sewage and food processing waste Signup and view all the answers

What is a consequence of underbrush removal after clear-cutting?

Creates a monoculture of trees Signup and view all the answers

Study Notes

Introduced Species and Their Impact

Introduced species often thrive due to the absence of natural predators or diseases, leading to unchecked population growth.
Native species can struggle to compete for vital resources such as food, nesting sites, and space.
Prey species may lack defenses against newly introduced predators.
Case Study: Starlings
- Starlings were introduced to Central Park in the 1890s due to a Shakespeare admirer.
- They rapidly multiplied, becoming one of the most common bird species in North America.
- In Alberta, starlings outcompete mountain bluebirds and swallows for nesting, causing a decline in bluebird numbers.
In Canada, over 3,000 introduced species disrupt natural ecosystems, with exotic species like Canada thistle costing billions for control.

Biomes and Ecosystems

Biomes are large geographical regions defined by specific temperature and precipitation ranges, supporting unique plant and animal communities (e.g., Tundra, Taiga).
Terrestrial ecosystems not covered by water are categorized within biomes; Alberta encompasses taiga and grassland.

Taiga Biome Characteristics

Located in northern regions like Alberta, primarily composed of coniferous trees (spruce, pine, fir).
Tree adaptations include wax-coated needles for winter protection; snow insulates ground, preventing root freezing.
Conifer branches are flexible, facilitating snow shedding.
The canopy layer captures sunlight, influencing forest floor vegetation which mainly contains shade-tolerant plants, such as mosses and ferns.

Seasonal Changes in Canadian Lakes

Lakes stratify in winter, with the coldest water (0°C) on top and densest water (4°C) at the bottom, limiting oxygen exchange.
Spring turnover occurs as ice melts, allowing oxygen to mix throughout the water.
In summer, lakes develop distinct layers: Epilimnion (warm upper), Hypolimnion (cold bottom), and Thermocline (middle layer).
Fall turnover replenishes oxygen as surface water cools and sinks.

Population Dynamics and Limits

Biotic Potential: Refers to the maximum offspring a species could produce with unlimited resources, regulated by:
- Birth potential: Maximum offspring per birth.
- Capacity for survival: Number reaching reproductive age.
- Breeding frequency: How often a species reproduces annually.
- Length of reproductive life: Age at sexual maturity and reproductive duration.
Limiting Factors: Conditions affecting population growth can be classified into abiotic and biotic factors:
- Favorable abiotic factors include adequate light, optimal temperature, and suitable chemical environments.
- Unfavorable abiotic factors encompass poor light conditions, extreme temperatures, and pollution.
- Favorable biotic factors include abundant food supply and low predator effectiveness.
- Unfavorable biotic factors involve insufficient food, high predator presence, and intense competition.

Carrying Capacity and Population Fluctuations

Carrying Capacity: Maximum sustainable population a given ecosystem can support, fluctuating due to biotic and abiotic limiting factors.
Resource partitioning allows species coexistence by utilizing resources in varied ways to avoid competition.

Changes in Ecosystems

Natural changes occur due to biotic and abiotic shifts, while human-caused changes result from activities like deforestation and pollution.

Deforestation

Deforestation has drastically reduced global forest coverage from 6 billion hectares to 4 billion, with 60% loss in Canada's virgin forests since European settlement.
Forests provide vital ecosystem services such as climate regulation, water control, and biodiversity habitat.

Forestry Practices and Their Effects

Types of Deforestation:
- Slash-and-burn: Nutrients are quickly lost, causing long-term soil damage.
- Clear-cutting: Involves complete tree removal, leading to biodiversity loss and increased erosion, though it is cost-effective.
- Selective cutting: Less environmental impact, allowing for regeneration.
Clear-cutting can benefit some wildlife by promoting low vegetation but increases erosion, runoff, and challenges for mature forest-reliant species.

Fire and Aquatic Ecosystems

Fire plays a crucial role in ecosystem maintenance by managing overgrowth and stimulating new growth.
Prescribed burns are employed to promote ecosystem health and prevent uncontrolled wildfires.

Aquatic Ecosystem Types

Oligotrophic Lakes: Deep, cold, nutrient-poor, with clear water, supporting organisms like trout.
Eutrophic Lakes: Shallow, warm, nutrient-rich, often murky, with high levels of plant life.
Eutrophication: Natural progression of lakes towards increased nutrient content; accelerated by human activities that introduce excess nutrients.

Water Pollution

Types of Pollution: Includes organic waste leading to oxygen depletion, and disease-causing organisms from sewage runoff, resulting in waterborne diseases.

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Description

Explore the impact of introduced species, specifically starlings, on native ecosystems. This quiz delves into how the absence of natural predators allows these species to thrive and the challenges native species face in competition for resources. Gain insights into the ecological consequences of such introductions.