Transcript Cycles in the Ecosystem

Cycles in the Ecosystem
Mineral Cycle
Carbon-Oxygen Cycle
The Mineral Cycle
Minerals are important for growth in
plants and animals.
Calcium helps bones and teeth grow
strong and helps send electrical signals
in your body.
Iron helps transport oxygen in your
blood.
Plants also need minerals,
which they get from soil.
 Three key minerals are needed for
plant growth:
 N = nitrogen
 P = phosphorus
 K = potassium
Nitrogen helps leaves and stems
grow. It also gives them a deep
green color.
Phosphorus promotes good root
growth and flower and seed
formation. It helps plants resist
disease.
Potassium forms strong stems and
helps fruit develop and ripen.
Plants get minerals from soil.
Soil formation
Soil is formed from rock that breaks
down.
The process of breaking down rocks or
removing minerals from rocks is called
weathering.
There are two types of weathering,
physical and chemical.
Physical weathering
Temperature changes cause rocks to expand
and contract, producing smaller particles.
Freezing water expands and cracks rock
apart.
Roots split rocks as they grow.
Wind blows sand into rock and sandblasts off
particles of the rock.
Glaciers and moving water carry particles that
scrape rock as they move over them.
Chemical Weathering
Plant roots produce chemicals that
dissolve minerals out of rock.
Acid rain falling on rock and soil
dissolves minerals from the rocks.
Weathering breaks rocks into smaller
and smaller pieces.
Pioneer plants like lichens and mosses
can grow on bare rock.
A lichen is a mix of a fungus and an
algae. The green algae provides food
through photosynthesis. The fungus
provides a home for the algae.
As the lichens grow and die, they add
rotting organic matter to the rock. This
organic matter is called humus.
Now, you have soil!
Minerals are put into the soil through
weathering. Once there, they are removed
and used by plants. Animals eat the plants
and the minerals move through them.
When the plants and animals die and
decompose, the minerals are released into
the soil to be cycled through again.
Minerals are removed from
ecosystems permanently
Leaching - minerals are dissolved by water
and carried away.
Erosion - wind and water carry minerals to
the ocean or elsewhere
Mining - minerals are removed faster than
they can be replaced and used by humans
In all cases, minerals are no longer available
to be used in an ecosystem.
The Phosphate Cycle
Can there be too
much fertilizer??
Yes! Too much fertilizer can be harmful
to plants and the environment.
Plants can “Burn” if they have too
much nitrogen. If an animal urinates on
grass, you will see a brown spot
surrounded by a ring of good green
growth. As the fertilizer dilutes to a
good concentration, plants will grow.
Lake Eutrophication
Farms are a big source of excess fertilizer.
Livestock and plant fertilizers both add
nitrogen and phosphorous to the land.
When farmers fertilize fields, excess fertilizer
is leached into soil and eroded away. The
runoff goes into streams and lakes.
What does the fertilizer do in lakes?
Lake Eutrophication
Fertlizer causes an algae bloom (when
algae grows out of control).
Eventually, the algae dies.
When it dies, bacteria start to
decompose the dead algae.
Decomposition uses oxygen.
Lake Eutrophication
As the oxygen is used, oxygen levels in
the lake fall.
The fish that depend on the oxygen
begin to die.
Soon, if the process continues,
everything in the lake will die.
The lake will no longer support life.
Carbon-Oxygen Cycle
 Carbon and oxygen are cycled through the
ecosystem in the form of carbon dioxide (CO2)
and oxygen (O2).
 CO2 in the air is used by plants to produce O2.
 The process is called photosynthesis.
6CO2 + 6H2O
sunlight
->
C
H
O
+
6
O2
6
12
6
l
chlorophyll
Photosynthesis
 Plants take in CO2 from the air and
water through the roots. Using energy
from the sun and chlorophyll, they
convert that energy into sugar and
oxygen.
 Sugar is used for energy and to build
organic compounds. Organic
compounds contain carbon.
 Oxygen is a waste product.
Photosynthesis
 Most of the oxygen on Earth is
produced by algae in the oceans. Trees
are also an important source.
 Animals eat plants and use the organic
compounds for energy and to build
other compounds.
Cellular Respiration
 Plants and animals use oxygen given off by
plants to burn sugar.
The process is called respiration.
C6H12O6 + 6O2 -----------> 6CO2 + 6H2O
 Bacteria and fungi also produce CO2 through
decomposition. When O2 is not present during
decomposition, the organic compounds don’t
break down all the way and the products stink.
Short-term cycle
Photosynthesis and respiration are
short-term storage methods for carbon.
Animal return only about 12% of carbon
to the atmosphere.
Plants and decomposers return about
43% each.
Carbon sinks
A sink is a reservoir. Some carbon is
stored for long periods of time.
Bones and shells that don’t decompose
often form limestone over time.
Limestone is a long-term carbon sink.
Fossil fuels - dead dinosuars - were
also a long-term carbon sink……..
Until we started burning them!
Human impact on C-O cycle
 In nature, the exchange of CO2 and O2 through
plants and animals is balanced.
Carbon is stored in living matter and sinks in an
ecosystem.
 Humans have upset that balance by burning
fossil fuels (wood, oil, coal).
Combustion
Combustion is combining carbon with
oxygen in the air. CO2 is released.
Plants can not use the extra CO2 fast
enough and it builds up in the
atmosphere
Consequences include global warming
and acid rain.