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Ecology 2227 > Chapter 19 Nutrient Cycling and Retention > Flashcards

Chapter 19 Nutrient Cycling and Retention Flashcards

1
Q

The use, transformation, movement, and reuse of nutrients in ecosystems is called ______.

A

nutrient cycling

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2
Q

In a nutrient cycle, chemicals are stored in nutrient _____ or compartments.

A

pools

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3
Q

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.

A

sink

source

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4
Q

Which of the following molecules in living organisms do not contain phosphorus?

A

glucose

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5
Q

What are the two main sources of phosphorus?

A

marine sediments

mineral deposits such as rocks

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6
Q

A friend tells a woman that some of the carbon in her body could have once been found in a dinosaur. The woman should ______.

A

agree because elements cycle through the environment

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7
Q

Plants are assisted in their uptake of phosphorus from the soil due to their interaction with mutualistic _____ fungi.

A

Mycorrhizae

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8
Q

In a nutrient cycle, the movement of nutrients move between pools is called nutrient ______

A

flux

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9
Q

Concerning the movement of phosphorus through the environment ______.

A

phosphorus can move from rivers into oceans

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10
Q

An example of a nutrient source would be ______.

A

burning of fossil fuels that add carbon dioxide to the atmosphere

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11
Q

Which of the following molecules found in living organisms does not contain nitrogen?

A

cellulose (fiber)

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12
Q

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.

A

phospholipid

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13
Q

Nitrogen in the atmosphere is ______.

A

converted to other forms by cyanobacteria

the main pool of nitrogen in the environment

converted to other forms by algae

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14
Q

Sedimentary rocks especially rich in ______ are mined for fertilizer.

A

phosphorus

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15
Q

Nitrogen can enter the nutrient cycle through fixation by living organisms or through the energy and pressure generated by ______

A

lightning

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16
Q

Animals gain phosphorus, in the form of phosphate, by ______.

A

ingesting plants that contain phosphate

ingesting other animals that contain phosphorus compounds

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17
Q

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.

A

rotate

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18
Q

Phosphorus (or phosphate) can enter aquatic environments ______.

A

as runoff from land following rain storms

as runoff from land following the melting of snow

as runoff from fertilized farm fields

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19
Q

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.

A

nitrogen

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20
Q

Fungi and bacteria release nitrogen as ammonium through the process called ______.

A

ammonification

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21
Q

The main pool of nitrogen is ______.

A

the atmosphere

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22
Q

The process of denitrification releases energy and is carried out by bacteria and converts ______.

A

nitrate to molecular nitrogen

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23
Q

Nitrogen fixation ______.

A

is carried out by mycorrhizal fungi

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24
Q

Because plant growth is dependent on nitrogen, and fixed nitrogen is relatively low in abundance, humans add _____ to the soil to increase crop production.

A

fertilizer

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25
Q 
Atmospheric forms of carbon include carbon dioxide and 
\_\_\_\_\_ gas (CH4).
A

methane

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26
Q

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 ______.

A

nitrification

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27
Q

In the nitrogen cycle, nitrogen is returned to the atmosphere through the process of ______.

A

denitrification

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28
Q

Most organisms add carbon dioxide to the atmosphere via respiration and some organisms removed it from the atmosphere in the process of _____.

A

photosynthesis

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29
Q

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.

A

fossil

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30
Q

Which of the following molecules found in living things always contain carbon?

A

organic molecules

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31
Q

Burning of fossils fuels has ______ the concentration of CO2 in the atmosphere since the industrial revolution, despite oceans acting as carbon ______.

A

increased; sinks

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32
Q

Which of the following is correct concerning the movement of carbon between organisms and the environment?

A

Respiration returns carbon to the atmosphere in the form of carbon dioxide.

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33
Q

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
______

A

sink

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34
Q

Examples of carbon sinks, locations where carbon is relatively unavailable for long periods of time unless humans intervene, include ______.

A

carbonate rock

fossil fuels

soil

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35
Q

True or false: Decomposition rate is not affected by nutrient levels in soil.

A

false

Decomposition rates are affected by nutrient levels, temperature, and moisture.

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36
Q

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.

A

mineralization; decomposition

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37
Q

The concentration of atmospheric carbon has ______ since the onset of the industrial revolution.

A

increased

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38
Q

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.

A

true

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39
Q

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 ______.

A

northern and tropical forests

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40
Q

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.

A

microbial

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41
Q

Decomposition rate is mainly affected by moisture levels, the chemical composition of litter and the environment, and
______

A

temperature

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42
Q

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.

A

positive

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43
Q

The conversion of nutrients such as phosphorus from an organic form to an inorganic form is called _____

A

mineralization

44
Q

Using the graph, results from research on decomposition rates forests show ______.

A

the toughness of plant leaves is inversely related to decomposition rates

45
Q

The effects of leaf litter chemistry on decomposition in Mediterranean woodland ecosystems were studied by Gallardo and

A

merino

46
Q

Based on research done in temperate forests by Melillo and colleagues, plants with ______ lignin:nitrogen ratios decomposed at a ______ rate.

A

lower; higher

47
Q

Results of a study done on yellow poplar leaf decomposition in a stream habitat by Suberkropp and Chauvet indicated that ______.

A

higher nitrate concentration resulted in higher decomposition rates

48
Q

In a study performed by Gallardo and Merino to investigate the effects of litter chemistry on decomposition ______.

A

mesh bags with leaf litter were collected and weighed every 2 months for 2 years

49
Q

Using the graphs, the results of the Gallardo and Merino experiments showed ______.

A

higher levels of precipitation (right-side graph) are associated with higher levels of leaf decomposition

50
Q

Because higher evapotranspiration rates ______ the rate of decomposition, decomposition in temperate ecosystems is usually ______ than in tropical ecosystems.

A

increase; lower

51
Q

Using the graph, results from research on decomposition rates show ______.

A

plants with higher toughness:nitrogen ratios lost less mass

52
Q

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.

A

nitrogen

53
Q

Research done by Takyu, Aiba, and Kitayama indicates that higher concentrations of ______ in the soil are associated with ______ rates of aboveground primary production.

A

phosphorus; higher

54
Q

Suberkropp and Chauvet showed that as nitrate levels in a stream increased, decomposition of yellow poplar leaves ______.

A

increased

55
Q

How does lignin content affect decomposition rates in freshwater ecosystems?

A

The higher the lignin content, the slower the decomposition rate.

56
Q

At the highest phosphorus levels, leaf decomposition rates ______.

A

level off

57
Q

True or false: Decomposition rates in tropical environments are lower than in temperate ecosystems.

A

false

they are higher because of the higher levels of evapotranspiration

58
Q

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 ______.

A

nutrient spiraling

59
Q

The term nutrient spiraling was coined by the scientist named Jack

A

webster

60
Q

Research done by Takyu, Aiba, and Kitayama indicates that higher concentrations of phosphate in the soil are associated with ______.

A

higher rates of decomposition

increased rates of leaf litter fall

61
Q

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?

A

It increases.

62
Q

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.

A

fungi

63
Q

In a stream ecosystem, nutrient retentiveness is

______ related to spiraling length, meaning that as one value increases, the other value decreases.

A

inversely

64
Q

Work done by Rosemond and colleagues suggests that leaf decomposition rate in streams increases in the presence of increased ______ concentration.

A

phosphorus

65
Q

Grimm’s study showed that macroinvertebrates appear to affect the spiraling of nitrogen in aquatic habitats by ______.

A

reingestion of nutrients by the macroinvertebrates resulting in increased primary production

66
Q

Because water currents move nutrients downstream, Webster coined the term nutrient _____ to describe stream nutrient dynamics.

A

spiraling

67
Q

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.

A

salmon

68
Q

The scientist who described how nutrients in streams are subject to downstream transport, causing cycling to not occur in one place is _____.

A

jack webster

69
Q

Pocket gophers may increase plant diversity by increasing the ______ of nitrogen availability in the soil.

A

heterogeneity

70
Q

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.)

A

V and T are low

71
Q

Bison tend to feed on grasses that are ______ prairie dog mounds because the grasses are ______ in nitrogen content.

A

near; higher

72
Q

In stream ecosystems, spiraling lengths that are ______ are associated with ______ nutrient retentiveness.

A

short; high

73
Q

In the Serengeti ecosystem it was shown by McNaughton, Ruess, and Seagle that ______.

A

grazing by large herbivores resulted in biomass turnover in less than one year

74
Q

Many macroinvertebrate detritivores reingest nutrients such as nitrogen by eating their

A

feces

75
Q

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.

A

roots

76
Q

Vanni, Flecker, Hood, and Headworth studied ______.

A

how the N:P ratio in fish affect nutrient cycling

77
Q

In the Hawaiian ecosystem, a scientific study showed that the introduced Myrica tree altered the _____ content in the soil

A

nitrogen

78
Q

Pocket gophers where shown to affect the ______ cycle by bringing nutrient-______ soil to the surface, in the Cedar Creek Natural History Area.

A

nitrogen; poor

79
Q

In the experiment performed by Likens and Bormann on the effects of deforestation on nutrient cycling, ______.

A

two stream valleys were studied for several years prior to tree removal from one valley

80
Q

Work done by Whicker and Detling found that ______.

A

prairie dog grazing results in more nitrogen-rich young grass

81
Q

One form of deforestation, which involves removing all trees from an area, is clear-cutting. When this occurs, nitrate losses from the environment _____

A

increase

82
Q

Work done by McNaughton, Ruess, and Seagle indicates that large grazing animals, such as bison, ______ nutrient cycling in an ecosystem.

A

speed up

83
Q

In the study done by Meyer and Likens on the movement of phosphorus in the Bear Brook ecosystem, inputs to the ecosystem included ______.

A

precipitation

seeps

84
Q

Which of the following are true?

A

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.

85
Q

Using the graph as an aid, during years of high streamflow, Bear Brook ______.

A

exports of phosphorus were greater than inputs

86
Q

In the Hawaiian ecosystem, the Myrica tree was introduced. Compared to the native trees in the Hawaii Volcanoes National Park, it ______.

A

has leaves that decompose at a higher rate

87
Q

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?

A

autumn

88
Q

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.

A

granite

89
Q

True or false: Nitrogen particulates can enter the atmosphere due to human actions, causing air pollution.

A

true

Nitrogen can enter the atmosphere from emissions from the burning of fossil fuels or as particulates.

90
Q

Deforestation ______.

A

increases the levels of nitrate loss from deciduous forest ecosystems

91
Q

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.

A

coarse

92
Q

Using the graph as an aid, during years of low streamflow, Bear Brook _____.

A

stores phosphorus

93
Q

Eutrophication ______.

A

can lower water oxygen content

94
Q

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 ______.

A

flooding caused by storms

95
Q

Increased human population densities are associated with ______.

A

increased nitrogen enrichment of river ecosystems

96
Q

Examples of human (anthropogenic) sources of nitrogen enrichment of ecosystems include ______.

A

runoff from agricultural land into waterways

burning of fossil fuels

animal wastes seeping into the soil or waterways

97
Q

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.

A

agricultural

98
Q

Phosphorus inputs to Bear Brook were evenly divided about the three size fractions of phosphorus. However, the majority of phosphorus exports were ______.

A

fine particulates

99
Q

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 _____

A

Eutrophication

100
Q

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.

A

human

101
Q

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?

A

Urban sanitation systems can leak nitrogen, but the leaks are typically controllable.

102
Q

True or false: In Groffman’s study of suburban watersheds, both nitrogen inputs and outputs were high.

A

false

The nitrogen output was only 1/4 of the input due to actively growing lawns, woodlots, and riparian areas.

103
Q

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).

A

forested
urban
suburban
agricultural

104
Q

In suburban areas, one contributor to increased nitrate input to stream ecosystems is the presence of
______ systems that can discharge nitrate when they leak.

A

septic

105
Q

Which of the following could explain the high level of nitrogen retention in suburban watershed areas?

A

actively growing lawns

riparian areas

Ecology 2227 (22 decks)

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