Ecology Chapter: Primary Production

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Questions and Answers

What is the definition of primary production?

Total biomass produced by consumers in an ecosystem.

Net production available for consumers per unit area.

Production of organic matter per unit area during a specified period. (correct)

Amount of organic matter consumed by decomposers.

How is net primary production calculated?

Total biomass production divided by area.

Total organic matter consumed by producers.

Gross primary production minus respiration. (correct)

Gross primary production plus respiration.

What does secondary production refer to?

Biomass production by consumers over a period. (correct)

The total organic matter available to consumers.

Biomass production by primary producers.

The amount of energy transferred between trophic levels.

Which statement accurately describes trophic levels?

Trophic levels represent the position in a food web. Signup and view all the answers

What is gross primary production?

The total organic matter produced by producers. Signup and view all the answers

Which statement best describes the relationship between primary and secondary production?

Primary production is the foundation for secondary production. Signup and view all the answers

Which factor affects net primary production?

Temperature and sunlight availability. Signup and view all the answers

What does primary production contribute to an ecosystem?

It replenishes energy stores for all trophic levels. Signup and view all the answers

What is the general trend regarding phytoplankton biomass as noted in the content?

It increased between 2-4 times in some areas. Signup and view all the answers

Which area is noted for having the highest rates of primary production by phytoplankton?

Continental margins and upwelling areas. Signup and view all the answers

What is identified as the main nutrient source in the open ocean?

Vertical mixing. Signup and view all the answers

What is a key finding regarding nutrient limitations in the Baltic Sea?

Nitrogen is identified as the limiting nutrient, not phosphorus. Signup and view all the answers

What environmental factor is noted as blocking nutrient access in tropical regions?

Thermocline. Signup and view all the answers

Which process is primarily responsible for nutrient enrichment in marine environments?

Vertical mixing in the water column. Signup and view all the answers

How does nutrient run-off impact phytoplankton biomass?

It contributes to increased biomass and primary production. Signup and view all the answers

In terms of nutrient availability, where are the lowest rates of primary production observed?

In the open ocean. Signup and view all the answers

What was the primary focus of Simberloff's experiment on mangrove islands?

The relationship between island area and species richness Signup and view all the answers

What occurred to species richness when the area of the islands was reduced?

Species richness decreased with each reduction in area Signup and view all the answers

How much variation in species richness among islands was explained by area, according to the content?

44 to 85% Signup and view all the answers

What happened to species richness on the control island during the experiment?

It increased slightly Signup and view all the answers

What does the content imply about habitat diversity's effect when manipulating island area?

It is difficult to separate habitat diversity from area effects Signup and view all the answers

What percentage of annual primary production do grazers consume in the Serengeti, according to McNaughton?

66% Signup and view all the answers

What is the relationship between rainfall quantity and primary production in the Serengeti?

Positively correlated Signup and view all the answers

What effect does light grazing have on compensatory growth?

Insufficient to produce compensatory growth Signup and view all the answers

At what grazing intensities is compensatory growth found to be highest according to McNaughton?

Intermediate intensities Signup and view all the answers

What happens to primary production in ecosystems with greater secondary production?

It supports higher levels of secondary production Signup and view all the answers

What potential benefit does grazing have on grass species?

It increases their growth rate Signup and view all the answers

What is one consequence of energy transfer from one trophic level to another.

Some energy is lost Signup and view all the answers

Which of the following statements best describes the impact of heavy grazing?

Reduces plants' capacity to recover Signup and view all the answers

What was the time required for recontoured roads to reach a restoration point equal to 30 years?

10 years Signup and view all the answers

After how many years was the soil structure of recontoured roads indistinguishable from undisturbed sites?

10 years Signup and view all the answers

What does MacArthur's definition of geographic ecology focus on?

Patterns of plant and animal life that can be mapped Signup and view all the answers

Which aspect does the content focus on within the vast breadth of geographic ecology?

Island biogeography Signup and view all the answers

What influences biodiversity according to the content?

Large-scale regional historical processes Signup and view all the answers

Which of the following is NOT part of the components mentioned in the study of geographic ecology?

Microbial interactions Signup and view all the answers

What term refers to the study of ecological structure and process at large geographic scales?

Geographic ecology Signup and view all the answers

What aspect of species richness is discussed in the context of geographic ecology?

Latitudinal patterns Signup and view all the answers

What determines the number of species in a given area?

The speciation rate minus the extinction rate Signup and view all the answers

According to the proposed theories, which factor contributes to higher species richness in tropical regions?

Larger areas and uniform temperatures Signup and view all the answers

What does the process of allopatric speciation primarily rely on?

Larger species ranges and geographic isolation Signup and view all the answers

Which statement accurately reflects the impact of continental area on species richness?

Positive relationship exists between continental area and species richness Signup and view all the answers

What does Rosenzweig propose about immigration at large scales?

Immigration can be discounted Signup and view all the answers

What impact do uniform temperatures have on organisms according to the content?

They enable organisms to disperse widely and reduce extinction rates Signup and view all the answers

What is a characteristic of tropical species compared to species in temperate regions?

Tropical species have higher speciation rates Signup and view all the answers

Which of the following is NOT mentioned as a factor affecting species richness?

Habitat destruction Signup and view all the answers

Study Notes

Chapter 18: Primary + Secondary Production

Ecosystem ecologists study the complex interactions of energy, water, and nutrient flows in ecosystems, and how these processes sustain life. This field of study is crucial for understanding the ecological balance and the health of different ecosystems.
Primary production is the process through which new organic matter is created per unit area in an ecosystem over a specified time period. This is a fundamental aspect of the energy flow in ecosystems, as it establishes the basis for food chains and supports all life forms that rely on this organic matter for energy.
- Gross primary production (GPP) refers to the total amount of primary production accomplished by all producers in an ecosystem, including plants, algae, and some bacteria. This metric provides insight into the overall productivity of an ecosystem.
- Net primary production (NPP) is derived from gross primary production by subtracting the energy used for respiration by the producers. This calculation represents the biomass that is available for consumption by herbivores and higher trophic levels, making it an essential component for evaluating the energy available to consumers within the ecosystem.
Secondary production denotes the generation of biomass by consumers within an ecosystem, such as animals and microorganisms that feed on the primary producers. This process is vital for recycling nutrients within the ecosystem and supports higher trophic levels.
Trophic levels categorize the various positions in a food web based on the number of energy transfers from primary producers to consumers. Understanding these levels helps define the structure of ecosystems and the relationships among different organisms.
- Primary producers occupy the first trophic level, where they convert sunlight into organic material through photosynthesis, serving as the foundation for all other trophic levels.
- Primary consumers, which include both herbivores and detritivores, occupy the second trophic level. They obtain energy by consuming primary producers or decomposing organic material, respectively.
- Secondary consumers are positioned at the third trophic level and consist of carnivores that prey on primary consumers. This group further illustrates the flow of energy through the ecosystem.
- Tertiary consumers make up the fourth trophic level, feeding on secondary consumers and highlighting the continuation of energy transfer through the food web.
Terrestrial primary production is often influenced by several limiting factors, including temperature, moisture, and nutrient availability. These factors can significantly impact the productivity levels of different ecosystems.
- The highest rates of primary production are typically observed in warm and moist conditions, which facilitate optimal plant growth and energy capture.
- Actual evapotranspiration, which refers to the amount of water that is evaporated and transpired, has a strong correlation with terrestrial primary production. This relationship emphasizes the importance of water availability in supporting ecosystem productivity.
Soil fertility plays a crucial role in influencing terrestrial primary production by determining the availability of essential nutrients for plant growth.
- Adding nutrients, particularly in nutrient-poor environments such as dry meadows, can lead to significant increases in primary production. This highlights the value of managing soil health and nutrient addition in agricultural and natural ecosystems.
Aquatic primary production is often constrained by the availability of nutrients, mainly phosphorus, which is a critical element for phytoplankton growth in freshwater ecosystems.
- A strong relationship exists between phosphorus levels and phytoplankton biomass, as adequate phosphorus concentrations are essential for supporting the primary producers that form the base of aquatic food webs.

Chapter 20: Succession + Stability

Succession refers to the gradual changes in plant, animal, and microbial communities in a given area after a disturbance or the implementation of a new habitat. Understanding this process is critical for restoration ecology and conservation efforts.
- Primary succession occurs on newly exposed geological substrates, such as volcanic rock or glacial landscapes, where soil has not yet formed. This process begins with pioneer species that are capable of colonizing harsh environments.
- Secondary succession takes place in areas where soil and organic matter remain, such as following a forest fire or other disturbances. This type of succession typically occurs more rapidly due to the existing soil nutrients.
- Pioneer communities consist of the initial organisms, such as lichens and mosses, that colonize disturbed areas. They play a crucial role in modifying the environment, making it more suitable for later successional species.
- Climax communities are the stable, mature communities that develop at the end of a succession process. These communities are relatively stable and persist until they are disrupted by a significant disturbance, which could initiate the process of succession once more.
Ecologist Frederic Clements proposed that succession is a predictable series of events that follows a consistent pattern of species interactions, leading to the development of a climax community.
Conversely, Henry Gleason viewed succession as a more chaotic process, driven primarily by the independent responses of species to their particular environmental conditions, suggesting that variances in local species might lead to differing successional outcomes.
Primary succession studies conducted in locations such as Glacier Bay demonstrated a clear progression in plant diversity over time, though the findings also suggested that the predictability Clements proposed was not entirely supported by empirical data, indicating a more complex reality.
In temperate forests, studies of secondary succession revealed that species richness often increases as succession progresses. This phenomenon suggests that disturbances might promote biodiversity by creating opportunities for various species to establish themselves.
Succession is also observable in rocky intertidal communities, where ecological succession occurs among intertidal boulder communities, illustrating the adaptability of communities in response to environmental changes.
Mechanisms of succession can be explained by three primary models—facilitation, tolerance, and inhibition. These models describe how species interactions can either promote or hinder the establishment and growth of subsequent species during the successional process.

Chapter 22: Geographic Ecology

Geographic ecology delves into understanding the spatial distribution of plant and animal life, and how geographical features influence these patterns across different landscapes.
Island biogeography is a specific subfield that examines the factors affecting species richness on islands, including size and distance from the mainland. These factors are critical in determining how many species can thrive in those isolated environments.
- Research in this area explores the relationships between the area of the island and species richness, as larger islands typically support more species due to greater habitat diversity, alongside the distance from the mainland, which affects immigration and extinction rates.
Latitudinal gradients in species richness show a notable trend: species richness generally increases from the polar regions toward the equator. This pattern can be attributed to a range of factors, including historical climate stability, environmental heterogeneity, higher productivity, and more favorable living conditions found in tropical regions.
The dynamics of historical and regional influences are also critical in shaping species richness and diversity. This includes the impact of evolutionary processes, past climatic conditions, and human activities that may have altered natural habitats.

Chapter 23: Global Ecology

The atmosphere at the Earth's surface primarily consists of clean, dry air made up of nitrogen, oxygen, and argon, alongside lower quantities of carbon dioxide and various trace gases that are essential for life.
The greenhouse effect is a natural phenomenon that warms the Earth's surface. This warming occurs through the absorption and re-emission of infrared radiation by atmospheric gases, thus maintaining temperatures suitable for life.
The El Niño Southern Oscillation (ENSO) constitutes a global climate pattern characterized by periodic warming (El Niño) and cooling (La Niña) of ocean surface temperatures in the Pacific Ocean. These fluctuations have widespread effects on global weather patterns, influencing climate across various regions.
Human activity has significantly altered atmospheric composition over recent decades, leading to increased concentrations of greenhouse gases. This anthropogenic impact has been pivotal in shaping current climate patterns and accelerating global warming, thereby influencing ecological and atmospheric processes on a global scale.

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This quiz covers key concepts related to primary production in ecosystems, including definitions, calculations, and the roles of various trophic levels. It also examines factors affecting primary and secondary production and discusses nutrient dynamics in marine environments. Test your knowledge on phytoplankton biomass and nutrient limitations!