Ecosystems Overview and Examples

Questions and Answers

What role do decomposers play in the cycling of nutrients within an ecosystem?

They store nutrients for future use.

They directly provide energy to primary producers.

They recycle chemical elements back to producers. (correct)

They convert inorganic compounds into organic matter.

What would be the ecological consequence of the cessation of decomposition?

There would be an abundance of detritus and insufficient nutrients for producers. (correct)

Energy transfers would become more efficient and less waste would be produced.

Producers would increase in number due to reduced competition.

Chemical nutrients would continuously build up in the primary producers.

In the nutrient dynamics of an ecosystem, how do nutrients primarily flow back to primary producers?

Via the excretion or death of decomposers. (correct)

From predators transferring nutrients directly to producers.

Through energy transfer as heat.

By direct absorption of atmospheric compounds.

What differentiates energy flow from nutrient cycling in an ecosystem?

Energy exits the ecosystem while nutrients do not. Signup and view all the answers

What ultimately happens to most transfers of nutrients through the food web?

They lead to detritus and are recycled back to producers. Signup and view all the answers

What is the primary source of energy flow in an ecosystem?

Solar energy converted by autotrophs Signup and view all the answers

Which of the following best describes chemical cycling within an ecosystem?

Chemicals are recycled between biotic and abiotic components. Signup and view all the answers

Which components are considered part of an ecosystem?

Living organisms combined with the physical environment. Signup and view all the answers

How do decomposers contribute to an ecosystem's chemical cycling?

By breaking down leaf litter and returning chemicals to the soil. Signup and view all the answers

What process do autotrophs primarily use to obtain energy?

Photosynthesis or chemosynthesis to convert energy Signup and view all the answers

Why are ecosystems often not bounded by discrete boundaries?

Ecosystems are dynamic and regions may share common species and resources. Signup and view all the answers

What is a characteristic feature of energy flow in ecosystems?

Energy enters as sunlight and dissipates as heat. Signup and view all the answers

Which term encompasses the sum of all ecosystems on Earth?

Biosphere Signup and view all the answers

What distinguishes energy flow from chemical cycling in ecosystems?

Energy has a one-way flow, whereas chemicals continuously cycle. Signup and view all the answers

Which statement best describes the first law of thermodynamics as it relates to ecosystems?

The total amount of energy in an ecosystem is constant despite transformations. Signup and view all the answers

What role do decomposers play in the cycling of chemical elements in ecosystems?

They break down organic matter and release nutrients back into the soil. Signup and view all the answers

How does the second law of thermodynamics affect energy transfer in ecosystems?

It implies that each energy transfer results in some loss, usually as heat. Signup and view all the answers

In terms of nutrient cycling, which scenario exemplifies how an ecosystem can gain elements?

Nitrogen fixation contributing to the nutrient input of a forest. Signup and view all the answers

Which describes the primary producers in an ecosystem?

Photosynthetic organisms that convert solar energy into chemical energy. Signup and view all the answers

What is a major outcome of the conservation of mass principle in ecosystems?

Chemical elements can cycle within and across ecosystems indefinitely. Signup and view all the answers

Which trophic level in an ecosystem is primarily composed of autotrophs?

Primary producers. Signup and view all the answers

Why is it critical to monitor the balance of nutrient inputs and outputs in ecosystems?

To determine if a nutrient will limit production within the ecosystem. Signup and view all the answers

What type of organisms are classified as primary consumers in an ecosystem?

Herbivores that feed directly on primary producers. Signup and view all the answers

In what way does human activity often influence ecosystems, according to the discussed principles?

By dramatically altering the balance of nutrient inputs and outputs. Signup and view all the answers

How do prokaryotes and fungi function as decomposers in ecosystems?

They digest organic material and absorb the resulting breakdown products. Signup and view all the answers

Why is it said that ecosystems are open systems?

They can continuously exchange both energy and mass with their environment. Signup and view all the answers

What happens to energy that enters an ecosystem from the sun over time?

It is converted into organic matter and eventually lost as heat. Signup and view all the answers

What primarily determines the ecosystem's energy budget?

The total amount of photosynthetic production Signup and view all the answers

Which group of organisms is responsible for synthesizing organic compounds from chemical energy in ecosystems dominated by chemoautotrophs?

Primary producers Signup and view all the answers

What percentage of visible light that strikes photosynthetic organisms is converted to chemical energy?

Approximately 1% Signup and view all the answers

What role does latitude play in the amount of solar energy absorbed by ecosystems?

It affects the intensity of solar energy striking the Earth. Signup and view all the answers

What is the significance of the organic compounds synthesized by autotrophs in ecosystems?

They establish the initial energy input for food webs. Signup and view all the answers

How does much of the solar radiation that strikes Earth ultimately impact photosynthesis?

It rarely reaches the surface due to atmospheric interference. Signup and view all the answers

What limits the possible photosynthetic output of ecosystems?

The total amount of solar radiation absorbed by the ecosystem Signup and view all the answers

What best describes the sunlight's role in contributing to the energy needs of the Earth's human population?

It is adequate for 19 years of human energy consumption. Signup and view all the answers

What is indicated by an ecosystem functioning as a carbon sink?

The ecosystem gains more carbon than it loses. Signup and view all the answers

What effect does climate warming have on arctic ecosystems according to recent research?

It can convert carbon sinks into carbon sources. Signup and view all the answers

During which years did the entire state of Alaska reportedly release more carbon than it absorbed?

2013 and 2014 Signup and view all the answers

What is a major consequence of an ecosystem losing more carbon than it gains?

It contributes to climate change by releasing additional carbon. Signup and view all the answers

How do outbreaks of an insect population potentially affect the net ecosystem production (NEP) of forest ecosystems?

They can disrupt the balance between carbon gain and loss. Signup and view all the answers

What does net primary production (NPP) represent in an ecosystem?

The amount of new biomass added over time Signup and view all the answers

Which of the following ecosystems is likely to have the highest net primary production (NPP)?

Coral reefs Signup and view all the answers

How is net ecosystem production (NEP) different from net primary production (NPP)?

NEP measures biomass accumulation including heterotrophs' respiration. Signup and view all the answers

What role do nutrients like nitrogen and phosphorus play in aquatic ecosystems?

They limit primary production in most oceans and lakes. Signup and view all the answers

Which statement correctly defines gross primary production (GPP)?

The total energy captured by photosynthetic organisms. Signup and view all the answers

What effect does the depth of light penetration have on primary production?

It limits production to shallow depths in water bodies. Signup and view all the answers

Which of the following ecosystems contributes significantly to the global net primary production despite its size?

Open oceans Signup and view all the answers

What does it mean for an ecosystem to be storing carbon?

It has positive NPP exceeding respiration. Signup and view all the answers

How does the biomass of a forest compare to that of grasslands in terms of NPP?

Grasslands can have higher NPP than forests. Signup and view all the answers

What is a common method for estimating net ecosystem production (NEP)?

Assessing net flux of CO2 in and out of an ecosystem. Signup and view all the answers

What is indicated by the color spectrum on a map of global NPP?

Relative productivity of different ecosystems. Signup and view all the answers

Why is satellite data important for studying primary production?

It allows for observation of large-scale productivity patterns. Signup and view all the answers

In terms of habitat productivity, which feature would you expect to find in estuaries?

High NPP due to nutrient influx. Signup and view all the answers

What is the primary factor that limits plant growth in terrestrial ecosystems globally?

Nitrogen Signup and view all the answers

What effect did the introduction of arctic foxes have on the islands near Alaska?

Conversion of grasslands to tundra Signup and view all the answers

Which ecosystems typically experience low productivity due to extreme temperature and moisture conditions?

Deserts and arctic tundra Signup and view all the answers

What relationship exists between NPP (Net Primary Production) and mean annual precipitation for terrestrial ecosystems?

Increased precipitation is associated with higher NPP. Signup and view all the answers

What role do mycorrhizal associations play in plant nutrient uptake?

They supply phosphorus and other limiting nutrients. Signup and view all the answers

Following the introduction of arctic foxes, what did researchers observe regarding the plant community?

A shift towards slower-growing tundra species. Signup and view all the answers

How did the climate changes between 1982 and 1999 affect NPP in terrestrial ecosystems?

NPP increased significantly, particularly in tropical forests. Signup and view all the answers

What has been the recent trend in NPP gains since 2000?

Total reversal of previous gains due to drought. Signup and view all the answers

What is a significant impact of drought-stress on forests in the American Southwest?

Increased tree mortality and decreased NPP. Signup and view all the answers

What is the primary consequence of adding a nonlimiting nutrient in a nutrient-poor ecosystem?

No significant change in plant production. Signup and view all the answers

What adaptation do many plants have to enhance nutrient uptake from the soil?

Root hairs and specialized anatomical features. Signup and view all the answers

How do changes in climate potentially affect the carbon storage capability of an ecosystem?

Drought can decrease carbon storage by causing tree mortality. Signup and view all the answers

What is the main role of enzymes like phosphatases released by plants into the soil?

To make phosphate more accessible to plants. Signup and view all the answers

What occurs to primary production when an ecosystem transitions from nutrient-poor to nutrient-rich conditions?

Primary production can increase dramatically. Signup and view all the answers

Which nutrient was found to limit phytoplankton growth in the coastal waters off Long Island?

Nitrogen Signup and view all the answers

Why are algal blooms a significant ecological concern?

They lead to the formation of dead zones with low oxygen levels. Signup and view all the answers

What happens in areas of the ocean where upwelling occurs?

There is typically high primary production. Signup and view all the answers

What role does iron play in the Sargasso Sea according to nutrient enrichment experiments?

It is a micrountrient limiting primary production. Signup and view all the answers

Which factors primarily control primary production in terrestrial ecosystems on a larger scale?

Temperature and moisture Signup and view all the answers

Which nutrient was shown to limit cyanobacterial growth in many freshwater lakes?

Phosphorus Signup and view all the answers

What is the consequence of excessive nutrient runoff from farming and sewage disposal into freshwater lakes?

Depletion of oxygen leading to fish kills. Signup and view all the answers

What is typically observed in the biomass of phytoplankton in relation to nitrogen availability in the Sargasso Sea?

Low phytoplankton density due to insufficient iron. Signup and view all the answers

In the context of primary production, what is eutrophication?

An increase in primary production due to nutrient enrichment. Signup and view all the answers

Which of the following represents typical nutrient dynamics in the photic zone?

Nutrient concentrations are low due to rapid uptake and sinking detritus. Signup and view all the answers

What is the primary cause of large marine dead zones according to the discussed research?

Oxygen depletion from aerobic decomposition of algal blooms. Signup and view all the answers

Which experimental condition caused a significant increase in phytoplankton density during the nutrient enrichment study?

Addition of nitrogen only. Signup and view all the answers

Study Notes

Ecosystems Overview

Ecosystems consist of all organisms in a specified area interacting with abiotic factors.
Can range in size from large environments (lakes, forests) to microcosms (spaces under logs, small springs).
Boundaries of ecosystems are not always clear-cut; the biosphere is viewed as a global composite of local ecosystems.

Energy Flow and Chemical Cycling

Energy flows in a one-way direction through ecosystems, while chemicals cycle within them.
Solar energy is converted to chemical energy by autotrophs and passed to heterotrophs via food consumption.
Ecosystems lose heat from energy transformations, but chemicals are reused and recycled.
Decomposers break down organic matter and return nutrients to the soil, feeding back into the ecosystem.

Energy Transformation and Thermodynamics

Ecosystems follow the first law of thermodynamics: energy cannot be created or destroyed, only transformed.
Photosynthetic organisms convert solar energy to chemical energy, with energy losses occurring as heat.
The second law states that energy exchanges increase entropy, meaning energy conversions are inefficient.

Conservation of Mass

Matter follows the law of conservation of mass; it cannot be created or destroyed, only recycled within ecosystems.
Nutrients like carbon and nitrogen circulate through biotic and abiotic components; inputs and outputs determine nutrient availability.
Ecosystems are open systems, absorbing energy and matter while releasing waste products.

Trophic Levels in Ecosystems

Species are categorized into trophic levels based on feeding relationships, with primary producers (autotrophs) at the base.
Common autotrophs include plants, algae, and photosynthetic prokaryotes; chemosynthetic prokaryotes serve as primary producers in extreme environments.
Heterotrophs, or consumers, depend on autotrophs for energy; they include primary consumers (herbivores) and secondary consumers (carnivores).

Role of Decomposers

Decomposers break down detritus (nonliving organic material) to recycle nutrients back into the ecosystem.
Primary decomposers include prokaryotes and fungi, which digest organic material and make nutrients available to primary producers.
Without decomposition, accumulated detritus would exhaust vital nutrients necessary for life, halting ecosystem functioning.

Energy and Nutrient Dynamics

Energy enters an ecosystem from the sun, flows through trophic levels, and ultimately exits as heat, while nutrients cycle through the ecosystem.
The interconnectedness of energy flow and nutrient cycling is essential for ecosystem sustainability and productivity.

Energy Transfer in Ecosystems

Energy transfer is fundamental to all biological interactions and is key to understanding ecosystem dynamics.
Primary production in ecosystems refers to the conversion of light energy into chemical energy by autotrophs, creating organic compounds.
Chemoautotrophic ecosystems derive energy from chemical sources, creating organic compounds through microbial processes.

Ecosystem Energy Budgets

Autotrophs, by converting light energy, set the energy budget for the entire ecosystem.
Primary producers' photosynthetic production essentially determines the available energy for consumers.
Earth receives enough solar energy daily to fulfill human energy needs for 19 years (at 2013 consumption levels).

Global Energy Budget

Solar energy absorption varies by latitude; tropical regions receive the highest energy input.
A significant portion of solar radiation (about half) is absorbed or reflected by the atmosphere, limiting photosynthesis.
A small fraction of sunlight reaching Earth is utilized in photosynthesis, converting about 1% of visible light to chemical energy.
Primary producers collectively create a large amount of organic material annually.

Gross and Net Production

Gross Primary Production (GPP) is the total energy converted to organic molecules by primary producers.
Net Primary Production (NPP) accounts for energy used in respiration by autotrophs, typically averaging around 50% of GPP.
NPP represents the energy stored for consumers and can be quantified in energy or biomass per area over time.

Variability in NPP

Different ecosystems exhibit varying NPP levels, with tropical rainforests being highly productive.
Estuaries and coral reefs have high NPP but cover less area than tropical rainforests.
Oceans have lower individual productivity but contribute significantly to global NPP due to vast size.

Primary Production in Aquatic Ecosystems

Light penetration is crucial in controlling primary production in aquatic environments.
Nutrients, predominantly nitrogen and phosphorus, are often limiting factors for production in marine environments.
Eutrophication occurs when nutrients increase, potentially leading to harmful algal blooms and "dead zones" due to oxygen depletion.

Nutrient Limitations in Ecosystems

Regions such as the Sargasso Sea exhibit low phytoplankton densities despite nitrogen availability, indicating iron as a limiting micronutrient.
Upwelling areas, where deep nutrient-rich waters surface, support high primary production and biodiversity.

Primary Production in Terrestrial Ecosystems

In terrestrial ecosystems, primary production is primarily influenced by temperature and moisture, with wetter ecosystems exhibiting higher NPP.
Tropical rainforests, with warm and moist conditions, are the most productive terrestrial systems, while deserts and tundra have low productivity.

Climate Change Impacts

Climate change influences NPP, as observed by increases in NPP from 1982 to 1999 followed by declines due to drought and changing precipitation patterns.
Hotter droughts have led to increased wildfires and pest outbreaks, particularly in Southwest U.S. forests, decreasing tree mortality and reducing NPP.
Ecosystem carbon dynamics are affected by climate change, shifting systems from carbon sinks to sources depending on metabolic activities linked to temperature changes.

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Description

This quiz explores the concept of ecosystems, highlighting examples such as 'fox island' and different types of ecosystems like lakes, forests, and microcosms. Understand the interactions between living organisms and their abiotic environment, along with the boundaries of these systems.