Chapter 19 Nutrient Cycling and Retention Flashcards
The use, transformation, movement, and reuse of nutrients in ecosystems is called ______.
nutrient cycling
In a nutrient cycle, chemicals are stored in nutrient _____ or compartments.
pools
When a specific nutrient is absorbed faster than it is released into the environment, this type of nutrient pool is called a nutrient ______. If the nutrient is released faster than it is absorbed, the pool is a(n) ______ for that nutrient.
sink
source
Which of the following molecules in living organisms do not contain phosphorus?
glucose
What are the two main sources of phosphorus?
marine sediments
mineral deposits such as rocks
A friend tells a woman that some of the carbon in her body could have once been found in a dinosaur. The woman should ______.
agree because elements cycle through the environment
Plants are assisted in their uptake of phosphorus from the soil due to their interaction with mutualistic _____ fungi.
Mycorrhizae
In a nutrient cycle, the movement of nutrients move between pools is called nutrient ______
flux
Concerning the movement of phosphorus through the environment ______.
phosphorus can move from rivers into oceans
An example of a nutrient source would be ______.
burning of fossil fuels that add carbon dioxide to the atmosphere
Which of the following molecules found in living organisms does not contain nitrogen?
cellulose (fiber)
Phosphorus is essential to living organisms. For example, phosphorus is the main component of cell membranes when it is combined with lipids to form _____ molecules.
phospholipid
Nitrogen in the atmosphere is ______.
converted to other forms by cyanobacteria
the main pool of nitrogen in the environment
converted to other forms by algae
Sedimentary rocks especially rich in ______ are mined for fertilizer.
phosphorus
Nitrogen can enter the nutrient cycle through fixation by living organisms or through the energy and pressure generated by ______
lightning
Animals gain phosphorus, in the form of phosphate, by ______.
ingesting plants that contain phosphate
ingesting other animals that contain phosphorus compounds
One way humans overcome nitrogen limitation to plant growth is to _____ crops capable of nitrogen fixation with crops that have high nitrogen needs rather than just growing the same crop all the time. These crops add ammonium to the soil.
rotate
Phosphorus (or phosphate) can enter aquatic environments ______.
as runoff from land following rain storms
as runoff from land following the melting of snow
as runoff from fertilized farm fields
Amino acids, the building blocks of proteins, are composed of carbon, hydrogen, oxygen, and ______. This element is also crucial to primary production and is relatively scarce.
nitrogen
Fungi and bacteria release nitrogen as ammonium through the process called ______.
ammonification
The main pool of nitrogen is ______.
the atmosphere
The process of denitrification releases energy and is carried out by bacteria and converts ______.
nitrate to molecular nitrogen
Nitrogen fixation ______.
is carried out by mycorrhizal fungi
Because plant growth is dependent on nitrogen, and fixed nitrogen is relatively low in abundance, humans add _____ to the soil to increase crop production.
fertilizer
Atmospheric forms of carbon include carbon dioxide and \_\_\_\_\_ gas (CH4).
methane
Animals may gain nitrates from the ingestion of plants. When these animals die, the animals decompose. This decomposition leads to the production of ammonium. Eventually, bacteria convert ammonium to nitrate in the process called ______.
nitrification
In the nitrogen cycle, nitrogen is returned to the atmosphere through the process of ______.
denitrification
Most organisms add carbon dioxide to the atmosphere via respiration and some organisms removed it from the atmosphere in the process of _____.
photosynthesis
The burning of _____ fuels is a major source of atmospheric carbon dioxide. This carbon would otherwise remain out of the atmosphere for long periods of time.
fossil
Which of the following molecules found in living things always contain carbon?
organic molecules
Burning of fossils fuels has ______ the concentration of CO2 in the atmosphere since the industrial revolution, despite oceans acting as carbon ______.
increased; sinks
Which of the following is correct concerning the movement of carbon between organisms and the environment?
Respiration returns carbon to the atmosphere in the form of carbon dioxide.
Areas that may have higher levels of CO2 uptake (vs. output) that we know about are reducing the predicted effects of increased burning of fossil fuels are referred to as being the missing carbon
______
sink
Examples of carbon sinks, locations where carbon is relatively unavailable for long periods of time unless humans intervene, include ______.
carbonate rock
fossil fuels
soil
True or false: Decomposition rate is not affected by nutrient levels in soil.
false
Decomposition rates are affected by nutrient levels, temperature, and moisture.
When nitrogen is converted from an organic form to an inorganic form, the process is called ______. This process takes place during ______, which is the breakdown of organic matter.
mineralization; decomposition
The concentration of atmospheric carbon has ______ since the onset of the industrial revolution.
increased
True or false: Gallardo and Merino were the scientists who studied how chemical differences in leaves, such as lignin concentration, affect decomposition in woodland ecosystems.
true
The best current scientific estimates are that the missing carbon sinks that are moderating the increased CO2 input to the atmosphere (due to burning of fossil fuels) are ______.
northern and tropical forests
In a study performed by Gallardo and Merino to investigate the effects of litter chemistry on decomposition, the mesh bags have a side of 1 mm. This allowed aerobic ______ activity and small soil invertebrates to aid in decomposition.
microbial
Decomposition rate is mainly affected by moisture levels, the chemical composition of litter and the environment, and
______
temperature
As shown in the Gallardo and Merino study, elevated moisture levels (right-side graph) have a ______ effect on leaf decomposition allowing it to occur at a faster rate.
positive
The conversion of nutrients such as phosphorus from an organic form to an inorganic form is called _____
mineralization
Using the graph, results from research on decomposition rates forests show ______.
the toughness of plant leaves is inversely related to decomposition rates
The effects of leaf litter chemistry on decomposition in Mediterranean woodland ecosystems were studied by Gallardo and
merino
Based on research done in temperate forests by Melillo and colleagues, plants with ______ lignin:nitrogen ratios decomposed at a ______ rate.
lower; higher
Results of a study done on yellow poplar leaf decomposition in a stream habitat by Suberkropp and Chauvet indicated that ______.
higher nitrate concentration resulted in higher decomposition rates
In a study performed by Gallardo and Merino to investigate the effects of litter chemistry on decomposition ______.
mesh bags with leaf litter were collected and weighed every 2 months for 2 years
Using the graphs, the results of the Gallardo and Merino experiments showed ______.
higher levels of precipitation (right-side graph) are associated with higher levels of leaf decomposition
Because higher evapotranspiration rates ______ the rate of decomposition, decomposition in temperate ecosystems is usually ______ than in tropical ecosystems.
increase; lower
Using the graph, results from research on decomposition rates show ______.
plants with higher toughness:nitrogen ratios lost less mass
Research results (Melillo and colleagues) from two temperate forests suggest that higher decomposition rates of leaf litter in a North Carolina forest compared to a forest in New Hampshire may be due to greater availability of the nutrient ______ in the soil. An additional factor may have been the higher temperatures in North Carolina.
nitrogen
Research done by Takyu, Aiba, and Kitayama indicates that higher concentrations of ______ in the soil are associated with ______ rates of aboveground primary production.
phosphorus; higher
Suberkropp and Chauvet showed that as nitrate levels in a stream increased, decomposition of yellow poplar leaves ______.
increased
How does lignin content affect decomposition rates in freshwater ecosystems?
The higher the lignin content, the slower the decomposition rate.
At the highest phosphorus levels, leaf decomposition rates ______.
level off
True or false: Decomposition rates in tropical environments are lower than in temperate ecosystems.
false
they are higher because of the higher levels of evapotranspiration
When an atom of phosphorus enters the water column, it may pass through an algal cell to an invertebrate, to a fish, moving the nutrient downstream. This type of nutrient dynamic can be called ______.
nutrient spiraling
The term nutrient spiraling was coined by the scientist named Jack
webster
Research done by Takyu, Aiba, and Kitayama indicates that higher concentrations of phosphate in the soil are associated with ______.
higher rates of decomposition
increased rates of leaf litter fall
If the average time it takes for a nutrient to complete a cycle is held constant, what happens to the spiraling length as the downstream velocity of the nutrient increases?
It increases.
Gessner and Chauvet determined that higher lignin content in plant materials inhibits colonization by ______ that are mainly responsible for decomposition of leaves in stream habitats.
fungi
In a stream ecosystem, nutrient retentiveness is
______ related to spiraling length, meaning that as one value increases, the other value decreases.
inversely
Work done by Rosemond and colleagues suggests that leaf decomposition rate in streams increases in the presence of increased ______ concentration.
phosphorus
Grimm’s study showed that macroinvertebrates appear to affect the spiraling of nitrogen in aquatic habitats by ______.
reingestion of nutrients by the macroinvertebrates resulting in increased primary production
Because water currents move nutrients downstream, Webster coined the term nutrient _____ to describe stream nutrient dynamics.
spiraling
Nutrient cycling can be affected by animals transporting nutrients from one ecosystem to another. An example of this are the Pacific
______ that spend most of their lives at sea. However, after spawning in streams and lakes, the salmon die and their carcasses are utilized by other organisms.
salmon
The scientist who described how nutrients in streams are subject to downstream transport, causing cycling to not occur in one place is _____.
jack webster
Pocket gophers may increase plant diversity by increasing the ______ of nitrogen availability in the soil.
heterogeneity
In a river or stream where nutrient spiraling is occurring, nutrients may be used many times (cycled) before leaving a stream system, when the values for ______. (Recall the formula for nutrient spiraling is S = VT.)
V and T are low
Bison tend to feed on grasses that are ______ prairie dog mounds because the grasses are ______ in nitrogen content.
near; higher
In stream ecosystems, spiraling lengths that are ______ are associated with ______ nutrient retentiveness.
short; high
In the Serengeti ecosystem it was shown by McNaughton, Ruess, and Seagle that ______.
grazing by large herbivores resulted in biomass turnover in less than one year
Many macroinvertebrate detritivores reingest nutrients such as nitrogen by eating their
feces
Plants that grow in nutrient-rich environments tend to allocate more resources to shoots and leaves than to _____, compared to plants grown in nutrient-poor conditions.
roots
Vanni, Flecker, Hood, and Headworth studied ______.
how the N:P ratio in fish affect nutrient cycling
In the Hawaiian ecosystem, a scientific study showed that the introduced Myrica tree altered the _____ content in the soil
nitrogen
Pocket gophers where shown to affect the ______ cycle by bringing nutrient-______ soil to the surface, in the Cedar Creek Natural History Area.
nitrogen; poor
In the experiment performed by Likens and Bormann on the effects of deforestation on nutrient cycling, ______.
two stream valleys were studied for several years prior to tree removal from one valley
Work done by Whicker and Detling found that ______.
prairie dog grazing results in more nitrogen-rich young grass
One form of deforestation, which involves removing all trees from an area, is clear-cutting. When this occurs, nitrate losses from the environment _____
increase
Work done by McNaughton, Ruess, and Seagle indicates that large grazing animals, such as bison, ______ nutrient cycling in an ecosystem.
speed up
In the study done by Meyer and Likens on the movement of phosphorus in the Bear Brook ecosystem, inputs to the ecosystem included ______.
precipitation
seeps
Which of the following are true?
Plants growing in high-nutrient ecosystems grow at a faster rate than those in low-nutrient ecosystems.
Plants growing in low-nutrient ecosystems allocate more resources to root growth compared to shoot growth.
Using the graph as an aid, during years of high streamflow, Bear Brook ______.
exports of phosphorus were greater than inputs
In the Hawaiian ecosystem, the Myrica tree was introduced. Compared to the native trees in the Hawaii Volcanoes National Park, it ______.
has leaves that decompose at a higher rate
In the study done by Meyer and Likens, they recognized that in the Bear Brook ecosystem, there were annual pulses of phosphorus import and export. During which season occurred the greatest phosphorus import?
autumn
In the experiment performed by Likens and Bormann on the effects of deforestation on nutrient cycling, inputs to the stream ecosystems included fixation of atmospheric nitrogen, weathering of _____ bedrock, and precipitation.
granite
True or false: Nitrogen particulates can enter the atmosphere due to human actions, causing air pollution.
true
Nitrogen can enter the atmosphere from emissions from the burning of fossil fuels or as particulates.
Deforestation ______.
increases the levels of nitrate loss from deciduous forest ecosystems
In the study done by Meyer and Likens on the movement of phosphorus in the Bear Brook ecosystem, phosphorus was categorized as either dissolved, fine particulate, or ____ particulate.
coarse
Using the graph as an aid, during years of low streamflow, Bear Brook _____.
stores phosphorus
Eutrophication ______.
can lower water oxygen content
In the study done by Meyer and Likens, they recognized that in the Bear Brook ecosystem, there were annual pulses of phosphorus import and export. However, most phosphorus export was irregular because it was associated with ______.
flooding caused by storms
Increased human population densities are associated with ______.
increased nitrogen enrichment of river ecosystems
Examples of human (anthropogenic) sources of nitrogen enrichment of ecosystems include ______.
runoff from agricultural land into waterways
burning of fossil fuels
animal wastes seeping into the soil or waterways
A study concerning nitrate export in streams that drained watersheds in Baltimore County, Maryland, showed that land use affects the average nitrogen concentration. The highest levels of average nitrogen concentration were found in streams associated with ______ areas.
agricultural
Phosphorus inputs to Bear Brook were evenly divided about the three size fractions of phosphorus. However, the majority of phosphorus exports were ______.
fine particulates
Nutrient enrichment of an aquatic ecosystem can lead to increased primary production, this in turn can lead to anoxic conditions and other water quality problems. This process is called _____
Eutrophication
In major river ecosystems, such as the Mississippi, Thames, and the Amazon, the single variable that appeared to explain most of the variation in nitrate concentration and export was
______ population density.
human
A study concerning nitrate export in streams that drained watersheds in Baltimore County, Maryland, showed that land use affects the average nitrogen concentration. While all areas received similar amounts of atmospheric input, which of the following is true concerning the differences between the areas?
Urban sanitation systems can leak nitrogen, but the leaks are typically controllable.
True or false: In Groffman’s study of suburban watersheds, both nitrogen inputs and outputs were high.
false
The nitrogen output was only 1/4 of the input due to actively growing lawns, woodlots, and riparian areas.
A study concerning nitrate export in streams that drained watersheds in Baltimore County, Maryland, showed that land use affects the average nitrogen concentration. Rank the average nitrogen concentrations in the streams (in these areas) from lowest to highest (lowest at the top).
forested
urban
suburban
agricultural
In suburban areas, one contributor to increased nitrate input to stream ecosystems is the presence of
______ systems that can discharge nitrate when they leak.
septic
Which of the following could explain the high level of nitrogen retention in suburban watershed areas?
actively growing lawns
riparian areas
