2.7: Cycling of Matter in Ecosystems
pg. 48
Biogeochemical Cycles: movement of matter through the
biotic and abiotic parts of the environment.
Water Cycle: the series of processes that moves water
through the environment.
Carbon Cycle: the series of processes that moves carbon
compounds throughout the lithosphere, atmosphere,
hydrosphere, and biosphere.
Matter is anything that takes up space and has mass. For
organisms to live they require matter in the form of water
and nutrients. They get their nutrients from eating food and
drinking water. The matter taken in is also released back
into the environment as waste produces and is recycled to
be used again.
Cycles That Maintain Balance
The ecosystem undergoes a continuous cycle, where matter
is maintained and recycled continuously to maintain a
balance. The water and nutrients required for life already
exist in the environment and are formed during
biogeochemical cycles, where particles of matter are
consumed, rearranged, stored, and releases.
There are four main biogeochemical cycles; carbon, water,
nitrogen, and phosphorus.
The Water Cycle
The water cycle is the movement of water as a liquid, solid,
and gas around the Earth. Liquid water evaporates
becoming water vapour as it enters the atmosphere. The
water vapour forms the clouds, and as it cools it condenses
into rain, sleet, snow, or hail and falls from the sky to land,
rivers, oceans, lakes, ponds, etc. Some of the water will
sink into the soil forming ground water where plants can
absorb and use for survival. Plants will lose water, through
a process called transpiration and enters the atmosphere to
be cycled again.
Figure 2: The water cycle is one of the major biogeochemical cycles. Most water is
present in abiotic features such as lakes and oceans.
The Carbon Cycle
Carbon can be found in both biotic and abiotic features of
Earth. Carbon is found in the carbon dioxide, and in
glucose (sugar) formed during photosynthesis and used in
cellular respiration. The carbon is cycled between the biotic
and abiotic features.
A large amount of the carbon is not cycled and is stored in
deposits such as coal, limestone, ocean sediments, in the
form shells of marine animals, which eventually becomes
oil and natural gas, as it is compressed over millions of
years.
Figure 3: Most carbon moves through the cycle during photosynthesis and cellular
respiration.
How Human Activities Change the Carbon Cycle
Auto Emissions:
The fuel which is burnt in our automobiles and other
vehicles, such as, oil and natural gas, lead to environmental
pollution. During combustion carbon is released into the
atmosphere in the form of carbon dioxide, and carbon
monoxide, as well as nitrogenous oxides, and sulfuric
dioxide.
Deforestation:
The removal of trees from forests can also affect the carbon
cycle. Carbon is usually trapped in the cells of trees is
released back into the atmosphere as the trees are burnt or
decomposed.
The carbon stored in the trees released back into the
atmosphere. The carbon dioxide and carbon monoxide can
affect the environment, by trapping energy that would
otherwise be radiated into space. The trapped energy leads
to global warming, and climate change. The increase in
temperature changes rainfall, resources in habitats and
endangers living things.
Check Your Learning:
Questions 1 – 6, pg. 51
Wrap Up:
- Matter moves and cycles through ecosystems in
biogeochemical cycles (water, carbon, nitrogen,
phosphorus).
- Water moves through the water cycle as a liquid, gas, or
solid.
- Most carbon cycling happens during photosynthesis and
cellular respiration.
- Human activities can disturb the balance of any of the
biogeochemical cycles.
Focus On: Math – Graphing Two Sets of Data pg. 52
Using graphs allows scientists to visually interpret data
collected. Sometimes graphed data needs to be compared.
Putting both sets of data onto one graph allows for a greater
comparison.
Population Graphs in Action
Comparing the predator – prey relationship between the
Canadian Lynx and the snowshoe hare.
Present the Data on Two Graphs
Plot data table for each animal population.
Step 1: Label the x-axis “Year of Study”. The x-axis will be
the same for both graphs. Label the x-axis with dates from
TABLE 1.
Step 2: Determine the range of numbers to be plotted. The
snowshoe have population ranges in size from 5000 to 95
000. Label the y-axis “Hare population (in thousands).”
Number the y-axis from 0 to 100, in intervals of 10.
Step 3: Plot the data from TABLE 1. Join the points with a
line.
Step 4: Give your graph a title. A completed graph for the
hare population is shown in Figure 1:
Figure 1:
Step 5: Repeat steps 1 to 4 for the lynx population. Use a different scale for
the lynx population. A completed graph for the lynx population is shown in
Figure 2.
Figure 2:
Combine the Two Graphs
Step 1: Crete the x-axis. This will be the same as in both
Figure 1 and Figure 2.
Step 2: Draw and label a y-axis on the left side of the x-axis
that is the same as in Figure 1. Plot the hare population data
in table 1 as a line graph.
Step 3: Draw and label a y-axis on the right side of the xaxis that is the same as in Figure 2. Plot the lynx population
data in Table 1 as a line graph, using a different colour.
Step 4: Give your combined graph a Title.
Figure 3:
a) Examine the combined population graph shown in
Figure 3. What population patterns do you notice?
b) How do graphing two sets of data on one graph help
you see patterns in the populations?
c) Why do you think the changes in the lynx
population so closely follow the changes in the hare
populations?