In general, litter with a C/N ratio greater than 30 leads to immobilization, litter with a
C/N ratio less than 20 leads to mineralization, and litter with a C/N ratio of 20-30 leads to a
balance of immobilization and mineralization resulting in no net N production. If garlic mustard
leaf litter collected on the forest floor had 43.2 percent C and 1.16 percent N, this tissue would
lead to __________.
a balance of immobilization and mineralization
What happens to most of the nitrogen in a leaf every autumn?
It is resorbed by the tree.
It is released as N2 gas.
It is broken down in soil.
It is consumed by decomposers.
Net primary productivity in an ecosystem increases as mean annual temperature ____________.
and mean annual rainfall decreases
decreases and mean annual rainfall increases
increases and mean annual rainfall decreases
and mean annual rainfall increases
Which region contains the largest amount of the global nitrogen pool?
Aboveground terrestrial systems
An ecologist studying productivity in a sample of grasses measures gross primary productivity as
1000 kcal/m2/yr and autotrophic respiration as 100 kcal/m2/yr. Based on these calculations, the
net primary productivity would be
Match the answer to the question. Put the correct letter in blank below
________ is the process by which plants absorb a portion of their nutrients from senescing tissues to be
stored and used for the production of new tissues.
The breakdown of chemical bonds that were formed during the construction of plant and animal tissues
is called ________.
The release of organically bound nutrients into an inorganic form is called ________.
The introduction of high levels of nutrients into a body of water is called ________.
Precipitation brings appreciable quantities of nutrients into ecosystems that are collectively called
Large quantities of nutrients are bound tightly in ________ structure; they are not readily available until
released by the activities of decomposers.
Some nutrients are ________ from the soil and carried out of ecosystems by underground water flow to
The element ________ is a basic constituent of all organic compounds and is involved in the fixation of
energy by photosynthesis.
The difference between the rate of carbon uptake in photosynthesis and the rate of carbon loss due to
autotrophic and heterotrophic respiration is the net ________ productivity.
Nitrogen is generally available to plants in only two forms: ammonium and ________.
Biological nitrogen fixation is accomplished by symbiotic ________ living in mutualistic association with
Nitrogen can be returned to the atmosphere when certain bacteria convert it from nitrate into nitrogen
gas, which is a process called ________.
Microbial decomposition of organic matter results in NH4+ production through a process called
Nearly all of the phosphorus in terrestrial ecosystems comes from the ________ of calcium phosphate
___________ develop as a result of incomplete decomposition of organic matter in swamps and
The process of ____________ produces a form of nitrogen that is easily lost from soil through leaching.
____________ is when too much nitrogen enters an ecosystem and causes forest decline.
_________ primary productivity is the total rate of photosynthesis or energy assimilated by plants.
Plants assimilate energy through the process of _______________.
___________is the process that releases carbon
dioxide in the atmosphere.
B. nitrogen saturation
1. First describe three ways that nutrients can be lost from an ecosystem; then describe how
nutrients are replaced in those systems.
Your response should be at least 75 words in length.
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