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Questions and Answers
What does conspecific negative density dependence (CNDD) help maintain in forest communities?
What does conspecific negative density dependence (CNDD) help maintain in forest communities?
- Growth of dominant species
- Increase in population density
- Reduction of natural enemies
- Species diversity (correct)
According to the Janzen-Connell hypothesis, where are host-specific natural enemies primarily found?
According to the Janzen-Connell hypothesis, where are host-specific natural enemies primarily found?
- Near abundant host plant species (correct)
- In areas with high plant diversity
- Within monoculture plantations
- In areas of low species density
What is a key idea behind the green world hypothesis?
What is a key idea behind the green world hypothesis?
- Herbivores significantly aid plant growth
- Predators help control herbivore populations (correct)
- Predators play no role in ecosystem regulation
- Ecosystems thrive without any trophic interactions
What is defined as the phenomenon where apex predators regulate the population of plants/producers?
What is defined as the phenomenon where apex predators regulate the population of plants/producers?
What role do ecosystem engineers play within an ecosystem?
What role do ecosystem engineers play within an ecosystem?
Which of the following best describes a mutualistic relationship?
Which of the following best describes a mutualistic relationship?
What is the distinction between stress and disturbance in ecological terms?
What is the distinction between stress and disturbance in ecological terms?
What characterizes a mycorrhizal relationship?
What characterizes a mycorrhizal relationship?
What is the primary factor that determines the limits of forests?
What is the primary factor that determines the limits of forests?
What type of mycorrhiza improves the host plant's nitrogen nutrition?
What type of mycorrhiza improves the host plant's nitrogen nutrition?
What does the term 'krummholz' refer to in the context of trees?
What does the term 'krummholz' refer to in the context of trees?
In which environments are endomycorrhizae commonly found?
In which environments are endomycorrhizae commonly found?
Which process refers to a tree reaching a size that increases its chances of surviving to maturity?
Which process refers to a tree reaching a size that increases its chances of surviving to maturity?
What is a crucial aspect of symbiotic relationships?
What is a crucial aspect of symbiotic relationships?
What occurs as a result of adiabatic cooling at higher altitudes?
What occurs as a result of adiabatic cooling at higher altitudes?
In alpine ecosystems, what is typically true about the relationship between plant proximity and stress?
In alpine ecosystems, what is typically true about the relationship between plant proximity and stress?
What are the two main factors that influence the success of tree establishment at treelines?
What are the two main factors that influence the success of tree establishment at treelines?
Which term best describes the transitional zone between forest lines and treelines?
Which term best describes the transitional zone between forest lines and treelines?
What is the main difference between growth and establishment of trees?
What is the main difference between growth and establishment of trees?
What is the role of ectomycorrhizal fungi in relation to root nodules on an alder tree?
What is the role of ectomycorrhizal fungi in relation to root nodules on an alder tree?
What type of succession occurs after a disturbance such as a wildfire?
What type of succession occurs after a disturbance such as a wildfire?
What process describes the breakdown of polymers into smaller molecules?
What process describes the breakdown of polymers into smaller molecules?
How do soil microbes interact with nutrient availability for plants?
How do soil microbes interact with nutrient availability for plants?
What is called when precipitation collects nutrients while moving through the canopy?
What is called when precipitation collects nutrients while moving through the canopy?
What percentage of the global nitrogen budget comes from lightning?
What percentage of the global nitrogen budget comes from lightning?
What characterizes a keystone species in an ecosystem?
What characterizes a keystone species in an ecosystem?
What is the process called when microorganisms convert inorganic nutrients into organic forms?
What is the process called when microorganisms convert inorganic nutrients into organic forms?
What is the main function of mineralization in soil ecosystems?
What is the main function of mineralization in soil ecosystems?
Which of the following statements is true about the common mycorrhizal network?
Which of the following statements is true about the common mycorrhizal network?
Flashcards
Conspecific Negative Density Dependence (CNDD)
Conspecific Negative Density Dependence (CNDD)
An ecological process where a species' growth, survival, and recruitment are negatively impacted by its own local population density.
Janzen-Connell Hypothesis
Janzen-Connell Hypothesis
Host-specific natural enemies are more concentrated where their host plant species occur at high densities.
Green World Hypothesis
Green World Hypothesis
Predators regulate herbivore populations, preventing excessive vegetation consumption, allowing the "green world" to flourish.
Trophic Cascades
Trophic Cascades
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Ecosystem Engineer
Ecosystem Engineer
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Symbiosis
Symbiosis
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Mutualism
Mutualism
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Mycorrhizae
Mycorrhizae
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Endomycorrhizae
Endomycorrhizae
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Ectomycorrhizae
Ectomycorrhizae
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Mycorrhizal Network
Mycorrhizal Network
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Primary Succession
Primary Succession
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Secondary Succession
Secondary Succession
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Nitrogen Fixation
Nitrogen Fixation
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Depolymerization
Depolymerization
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Immobilization
Immobilization
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Mineralization
Mineralization
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Keystone Species
Keystone Species
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Throughfall
Throughfall
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Soil Microbes and Plant Uptake Competition
Soil Microbes and Plant Uptake Competition
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Treeline
Treeline
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Krumholz
Krumholz
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What determines the limits of forests?
What determines the limits of forests?
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Alpine Treeline Ecotone
Alpine Treeline Ecotone
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Factors affecting forest establishment
Factors affecting forest establishment
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Stress
Stress
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Disturbance
Disturbance
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Establishment
Establishment
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Growth
Growth
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Adiabatic Cooling
Adiabatic Cooling
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Study Notes
Exam 2 Review
- Nitrogen Cycling: Review chapter 18 on nitrogen cycling. Extensive material covered in the Tuesday before Thanksgiving lecture.
- Conspecific Negative Density Dependence (CNDD): A process where population density negatively impacts growth, survival, and recruitment of the same species. This can maintain species diversity in an area by allowing other species to replace the common species. Conversely, as population density increases, individual growth, survival, and reproduction of each species within that population decrease.
Janzen-Connell Hypothesis
- Explanation: This hypothesis proposes that natural enemies (pathogens, predators) are concentrated where host plant species are most dense. This leads to reduced survival of seedlings close to parent trees or other conspecifics. Specialist pathogens are key in this negative density dependence, not generalist pathogens.
- Prediction: Stronger density-dependent and distance-dependent effects on plant richness in wetter habitats and the tropics, compared to drier habitats and temperate zones.
Vertebrate Herbivores & Predation
- Green World Hypothesis: Predators regulate consumer (herbivore) populations, preventing overconsumption and maintaining plant abundance in ecosystems. This is a critical counterpoint to the previously held assumption that predators had no major impact on ecosystem regulation and stability.
General Ecological Concepts
- Trophic Cascades: Changes in the abundance of top predators can have cascading effects through the food web, impacting multiple trophic levels.
- Ecosystem Engineers: Organisms that create, modify, or maintain habitats. Beavers, coral, and termites are examples. These organisms significantly impact ecosystem structure and processes.
- Symbiosis: Long-term, close relationships between organisms. Different types exist, including mutualism (both benefit), parasitism (one benefits, one harmed), and commensalism (one benefits, other unaffected). Lichen and bees illustrate examples of mutualism. Dwarf mistletoe is an example of parasitism.
- Mycorrhizae: Symbiotic relationships between fungi and plant roots, greatly increasing nutrient uptake for plants. Endomycorrhizae affect a wide range of plants while ectomycorrhizae are specifically found in agricultural and forest soils, impacting a range of hardwood and conifer species. Fungi derive carbon from plants, while plants receive water and nutrients from fungi.
- Common Mycorrhizal Network: Root systems of multiple plants connected through a network of mycorrhizal fungi.
- Keystone Species: A species disproportionately affects its local ecosystem relative to its abundance. Effects can be significant enough that their removal may be devastating to an ecosystem.
Additional Concepts
- Throughfall: Precipitation that passes through the canopy.
- Stem Flow: Water that flows down plant stems and carries nutrients and organic material.
- Treeline: Edge of forests where trees grow less commonly and density decreases due to harsh environmental conditions, such as low temperature, and dry conditions.
- Krumholz: Short, stunted, and dense trees often found at the alpine treeline.
- Alpine Treeline Ecotone: Transition zone between forest and treeline.
- Dispersal: Ability of plants to reach new habitats.
- Germination: Process of seeds sprouting.
- Establishment: A plant successfully taking root in a new habitat.
- Growth: A plant's expanding size and biomass.
- Stress vs. Disturbance: Stress refers to external constraints on primary productivity while disturbance impacts structure, substrate, and resources available to organisms.
- Growth vs Establishment: Establishment is size- and life stage-related while growth is biomass accumulation.
- Adiabatic Cooling: Temperature decrease with altitude due to decreasing atmospheric pressure.
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Description
Prepare for your biology exam with this comprehensive review of Chapter 18 on nitrogen cycling, and explore the concept of Conspecific Negative Density Dependence (CNDD). Understand how population density affects species growth and diversity, as well as the Janzen-Connell Hypothesis and its implications for plant communities. This quiz will enhance your grasp of these critical ecological concepts.
