Transcript Ch46_The_Global_Ecosystem

46
The Global Ecosystem
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
One aspect of ecosystem function:
Net primary productivity (NPP)—rate at which an
ecosystem produces primary-producer biomass.
NPP can be estimated by instruments on satellites that
measure wavelengths of light reflected from the
Earth’s surface.
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
NPP varies among ecosystem types, mostly due to
variation in climate and nutrient availability.
Tropical forests, swamps, and marshlands are the most
productive.
Cultivated land is less productive than many natural
ecosystems.
Figure 46.1 NPP Varies among Ecosystem Types
Figure 46.2 Terrestrial NPP Corresponds to Climate
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
Discuss why NPP (net primary productivity), usually
measured as grams of primary-producer biomass
produced per unit of area per year, is a measure of
ecosystem function.
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
NPP (net primary productivity), usually measured as grams
of primary-producer biomass produced per unit of area
per year, is a measure of ecosystem function because
a. NPP measures the rate of exchange of materials
(especially carbon) between biotic and abiotic
components of ecosystems.
b. NPP measures the net rate with which solar energy is
captured by an ecosystem’s primary producers.
c. Both a and b
d. None of the above
e. I don’t understand the question.
Figure 46.3 Terrestrial NPP Varies with Temperature and Precipitation
Figure 46.3 Terrestrial NPP Varies with Temperature and Precipitation (Part 1)
Figure 46.3 Terrestrial NPP Varies with Temperature and Precipitation (Part 2)
Figure 46.4 Marine NPP Is Highest around Coastlines
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
Compare the following
maps of terrestrial and
marine NPP.
With a partner or group,
discuss:
• What does the
terrestrial pattern
suggest determines
terrestrial NPP?
• What does the
marine pattern
suggest determines
marine NPP?
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
Compare the following
maps of terrestrial and
marine NPP.
The patterns for
terrestrial NPP suggest
it is linked to
a. temperature.
b. precipitation.
c. latitude.
d. All of the above
e. None of the above
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
Compare the following
maps of terrestrial and
marine NPP.
The patterns for marine
NPP suggest it is
limited by
a. latitude.
b. distance from shore.
c. upwelling.
d. runoff.
e. b, c, and d
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
As winds push water across the ocean surface, water rises up from
underneath the displaced water to replace it. This is called
“upwelling.” Upwelling occurs in the open ocean and especially
along coastlines. The water that rises up from deeper levels of the
ocean is colder and rich in nutrients. These nutrients fertilize the
surface waters and result in higher biological productivity. Algal
blooms provide more food for fish, resulting in growth in fish
populations when and where upwelling is strong.
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
Fisheries are directly impacted by the strength of upwelling. Without
nutrients from the upwelling, there are few phytoplankton, and with
few phytoplankton, little food for fish.
Off California, upwelling of cold water has become less common since
1975. What do you predict will result if less upwelling is indeed a
long-term trend?
Concept 46.1 Climate and Nutrients Affect Ecosystem Function
Fisheries are directly impacted by the strength of upwelling. Without
nutrients from the upwelling, there are few phytoplankton, and with
few phytoplankton, little food for fish.
Off California, upwelling of cold water has become less common since
1975. Which of the following scenarios might you predict if less
upwelling is indeed a long-term trend?
a. Fisheries will benefit.
b. Fish populations will decline as the strength of upwelling
decreases.
c. More nutrients will likely rise to the surface.
d. Phytoplankton growth will decrease as upwelling weakens.
e. Both b and d
Figure 46.5 Chemical Elements Cycle among Compartments of the Biosphere
Figure 54.20 Review: Generalized scheme for biogeochemical cycles
Figure 46.6 The Global Water Cycle
Figure 46.7 The Global Nitrogen Cycle
Figure 46.8 Where Does the Extra Nitrogen Come From?
Figure 46.8 Where Does the Extra Nitrogen Come From? (Part 1)
Figure 46.8 Where Does the Extra Nitrogen Come From? (Part 2)
Figure 46.9 High Nutrient Input Creates Dead Zones
Figure 46.9 High Nutrient Input Creates Dead Zones
Figure 46.10 The Global Carbon Cycle
Figure 46.11 Earth’s Radiation Balance
Figure 46.12 Atmospheric Greenhouse Gas Concentrations Are Increasing
Figure 46.12 Atmospheric Greenhouse Gas Concentrations Are Increasing (Part 1)
Figure 46.12 Atmospheric Greenhouse Gas Concentrations Are Increasing (Part 2)
Figure 46.13 Global Temperatures Are Increasing
Figure 46.14 Global Precipitation Patterns Have Changed
Apply the Concept, Ch. 46, p. 905
Figure 46.15 Climate Change Affects Life Histories
Concept 46.2 Biological, Geological, and Chemical Processes Move Materials through Ecosystems
Discuss which of the following processes results in a net
flux that removes carbon from the atmospheric pool of
carbon:
• Plant respiration
• Plant photosynthesis (gross primary productivity)
• Burning of fossil fuels
Concept 46.2 Biological, Geological, and Chemical Processes Move Materials through Ecosystems
Which of the following processes results in a net flux that
removes carbon from the atmospheric pool of carbon?
a. Plant respiration
b. Plant photosynthesis (gross primary productivity)
c. Burning of fossil fuels
d. All of the above
e. None of the above
Concept 46.3 Certain Biogeochemical Cycles Are Especially Critical for Ecosystems
The Northern Hemisphere of Earth has a greater land surface than that
of the Southern Hemisphere, and more of Earth’s plants (especially
forests) occur in the Northern Hemisphere.
Discuss the pattern of seasonal variation in CO2 levels seen in this
Mauna Loa, Hawaii graph, and discuss how plant photosynthesis
and respiration can explain this predictable seasonal pattern.
Concept 46.3 Certain Biogeochemical Cycles Are Especially Critical for Ecosystems
Which of the following statements could explain the
seasonal variation in CO2 levels in the atmosphere?
a. Atmospheric CO2 levels increase during the Northern
Hemisphere summer because plants respire more at
this warmer time.
b. Atmospheric CO2 levels decrease during the
Northern Hemisphere winter because plants
photosynthesize more at this colder time.
c. The greater total terrestrial biomass in the Northern
Hemisphere compared with the Southern
Hemisphere drives these seasonal CO2 patterns.
d. All of the above
e. None of the above
Concept 46.3 Certain Biogeochemical Cycles Are Especially Critical for Ecosystems
Do the seasonal shifts in CO2 levels that result from seasonal
differences in photosynthetic rates predominating in the Northern
Hemisphere explain the trend for annual CO2 levels (increasing over
time, in this graph from 2006 to 2011)?
a. Yes
b. No
c. I don’t understand the question.
Concept 46.4 Biogeochemical Cycles Affect Global Climate
Discuss the validity of the following statements regarding
the greenhouse effect:
• Prior to the industrial revolution (starting around
1880), Earth had no carbon dioxide in its atmosphere.
• The composition and thickness of a planet’s
atmosphere affect its surface temperatures.
• Air temperature is the only factor influenced by the
changing composition of Earth’s atmosphere.
Concept 46.4 Biogeochemical Cycles Affect Global Climate
Which of the following statements are true regarding the
greenhouse effect?
a. Prior to the industrial revolution (starting around
1880), Earth had no carbon dioxide in its
atmosphere.
b. The composition and thickness of a planet’s
atmosphere affect its surface temperatures.
c. Air temperature is the only factor influenced by the
changing composition of Earth’s atmosphere.
d. All of the above
e. None of the above
Concept 46.5 Rapid Climate Change Affects Species and Communities
Corals, which secrete calcareous skeletons that over time
form the large physical structure of reef communities, rely
on a mutualism with a photosynthetic alga, and without
this mutualism they cannot grow. Reefs have the highest
biodiversity within marine ecosystems, and are important
for supporting fisheries. Reef organisms have evolved
over hundreds of millions of years to cope with recurring
disturbance, damage, and destruction, followed by
recovery or regrowth. However, recent climate change
appears to be occurring at rates faster than reefs can
tolerate.
Reefs are temperature-sensitive and a rise in temperature
as small as 1 degree Celsius can result in “bleaching,”
as algae react to the warmer water by producing oxygen
compounds that are toxic to the coral, resulting in the
coral ejecting their algal support system, leaving the
reefs starved of nutrients and deathly white.
Concept 46.5 Rapid Climate Change Affects Species and Communities
If climate change is predicted to raise ocean temperatures
by 1–3°C by the year 2050, what impact do you expect
this might have on coral reef ecosystems?
Discuss.
Concept 46.5 Rapid Climate Change Affects Species and Communities
If climate change is predicted to raise ocean temperatures
by 1–3°C by the year 2050, which of the following
outcomes might you expect?
a. More bleaching events will occur.
b. Corals will be less able to grow.
c. Coral reefs may almost entirely disappear by 2050.
d. Fisheries will decline.
e. All of the above
Concept 46.6 Ecological Challenges Can Be Addressed through Science and International
Cooperation
Do you think that indefinite economic growth is possible
given the ecological limits of our planet?
a. Yes
b. No
c. I don’t understand this question.