Ecology Chp 20

1. The tropical rainforest in Costa Rica would most likely have a leaf area index of
a. 0.01–0.04.
b. 0.1–0.4.
c. 1–2.
d. 10–12.

The figure shows the CO2 uptake by various leaf layers in a tropical forest. Leaf layer 1, at the top of the canopy, has the highest net rates of photosynthesis and layer 15 has the lowest net rates. What principles of production explain this pattern?
a. Leaves at the top of the canopy are larger than leaves at the bottom of the forest.
b. Gross carbon uptake is highest in top leaves relative to metabolic losses because upper leaves are in full sunlight.
c. Respiratory costs are increased in upper leaves relative to lower leaves because of the cost of transporting water and nutrients from roots to the top of the canopy.
d. The most productive plants in the forest reach the canopy first and maintain their productive advantage.

The figure shows CO2 uptake by various leaf layers in a tropical forest. If a native forest with 15 leaf layers is replaced with a palm oil plantation that has 3 leaf layers, there will be a(n) _______ of _______ maximum net CO2 uptake because of ________.
a. decrease; 0.7 g/m2/hr; a reduction in net photosynthesis due to fewer leaves
b. decrease; 0.5 g/m2/hr; a reduction in net photosynthesis due to fewer leaves
c. increase; 0.7 g/m2/hr; reduced respiration loss due to fewer inefficient leaves
d. increase; 1.2 g/m2/hr; a greater proportion of high efficiency with top canopy leaves

Chemical energy derived from the fixation of carbon by photosynthesis and chemosynthesis is known as _______ production.
a. primary
b. gross
c. secondary
d. net

The total amount of photosynthesis is referred to as
a. net primary production (NPP).
b. gross primary production (GPP).
c. net photosynthetic production (NPP).
d. gross photosynthetic production (GPP).

Which of the following would likely have the greatest proportion of productivity going into its own respiration?
a. A short evergreen tree in New England
b. A bunch of ferns in Canada
c. A large tree in the Brazilian tropical rainforest
d. A flower in the Brazilian tropical rainforest

Suppose that the net primary productivity of a particular ecosystem is 80 units per year. The respiration rate of primary producers is 30 units per year, and the respiration rate of herbivores is 10 units per year. The gross primary productivity is _______ units per year.
a. 40
b. 50
c. 70
d. 110

If the GPP of an aquatic ecosystem is 180 units per year, and the NPP is 100 units, what is the respiration rate of the primary producers?
a. 80 units per year
b. 100 units per year
c. 180 units per year
d. 260 units per year

If the NPP of an ecosystem is 240 units per year, and the respiration by autotrophs is 110 units, what is the amount of energy available for increases in plant biomass?
a. 110 units per year
b. 130 units per year
c. 240 units per year
d. 350 units per year

A large plant that grows in a warm, swampy environment and faces substantial herbivory most likely
a. a low leaf area index.
b. allocates a relatively large proportion of its NPP to roots.
c. allocates a relatively large proportion of its NPP to secondary compounds.
d. is iron limited.

In most ecosystems, as NPP changes during ecosystem development, it is highest during _______ succession.
a. primary
b. early
c. the intermediate stages of
d. late

Which figure best represents the changes in NPP during succession in the typical forest ecosystem?
a. Figure A
b. Figure B
c. Figure C
d. Figure A if a tropical forest; Figure B if a temperate forest

. Suppose that the aboveground biomass of a section of a grassland ecosystem is 400 kilograms at the start of the growing system. A month later, it is 1,600 kilograms. During that month, the _______ is _______ kilograms.
a. NPP; 400
b. NPP; 1,200
c. GPP; 400
d. GPP; 1,200

The use of harvest techniques to estimate NPP would be most problematic in _______ because _______.
a. temperate grasslands; the growth rate is very rapid
b. temperate grasslands; tissues that die decompose rapidly
c. tropical rainforests; tissues that die decompose rapidly
d. temperate forests; the growth rate is very rapid

For which purpose would a minirhizotron be a useful tool?
a. Harvesting root biomass
b. Measuring oxygen, carbon dioxide, and other gases at roots
c. Viewing roots
d. Estimating light absorption

Which statement about roots and root NPP is false?
a. Root NPP is more difficult to estimate than aboveground NPP because roots turn over more slowly.
b. The smallest roots are the most likely to turn over.
c. Roots do not transfer carbon to symbionts.
d. In order to accurately measure root NPP with harvest methods, roots must be harvested more frequently than aboveground biomass.

Which of the following is not an advantage of remote sensing technologies over harvesting estimates of NPP?
a. They can provide more frequent estimates.
b. They can provide more accurate estimates.
c. They can be used over a greater area.
d. They do not cause destruction of the area.

Harvesting cannot be used to estimate NPP for phytoplankton because
a. the individual phytoplankton are too small to be harvested.
b. the amount of biomass available at any given time is too low.
c. phytoplankton turn over very slowly.
d. rates of photosynthesis are too high to measure properly.

Which method(s) of estimating NPP is typically used in aquatic ecosystems?
a. Harvesting only
b. Harvesting and remote sensing
c. Remote sensing only
d. Remote sensing and estimating rates of photosynthesis and respiration in water bottle samples

The normalized difference vegetation index (NDVI) explores the difference in absorption by plants and soil as a proxy to infer plant biomass. If NDVI uses a 600 nm and 1,000 nm wavelength in its estimation, what other wavelengths of light would be useful in distinguishing plants from soil?
a. 400
b. 700
c. 1,300
d. 1,900

Suppose that the NEE of a boreal forest ecosystem is 120 units per month. The respiration by autotrophs is 60 units per month, and the respiration by heterotrophs is 30 units per month. What is the GPP of the forest?
a. 60 units per month
b. 90 units per month
c. 150 units per month
d. 210 units per month

Suppose that the NEE of a boreal forest ecosystem is 120 units per month. The respiration by autotrophs is 60 units per month, and the respiration by heterotrophs is 30 units per month. What is the NPP of the forest?
a. 60 units per month
b. 90 units per month
c. 150 units per month
d. 210 units per month

Which value can be estimated most directly from the eddy covariance?
a. NEE
b. NPP
c. GPP
d. Heterotrophic respiration

How does one estimate the NPP if one knows the NEE (net ecosystem exchange)?
a. NPP = NEE – heterotrophic respiration
b. NPP = NEE + autotrophic and heterotrophic respiration
c. NPP = NEE + heterotrophic respiration
d. NPP = NEE – atmospheric CO2

In some ecosystems, NPP actually decreases at very high levels of precipitation. Which of the following is not a likely reason for such declines in NPP?
a. Respiration of heterotrophs increases at high precipitation levels.
b. High precipitation levels can lead to the leaching of nutrients from the soil.
c. High precipitation levels can lead to low oxygen levels in the soil.
d. In areas where precipitation is extremely high, it is often cloudy, decreasing the amount of available sunlight.

In experiments measuring the NPP of grassland ecosystems over time and at different sites, Lauenroth and Sala discovered that
a. all grasslands respond to increased precipitation in the same way.
b. the greatest response to increased precipitation occurred at one site over a period of time.
c. some grasslands have different inherent abilities to increase growth in response to increased precipitation.
d. NPP decreased as precipitation increased.

Plant species from resource-poor communities often have low growth responses to fertilization because these plants typically have a
a. high tolerance for excess nutrients.
b. low tolerance for excess nutrients.
c. high intrinsic growth rate.
d. low intrinsic growth rate.

Which statement accurately describes a way plants allocate carbon that is not used in respiration?
a. Plants allocate carbon as a defense against herbivory.
b. Plants allocate almost all carbon to increasing photosynthetic tissue.
c. Plants growing in areas with high plant density allocate a higher proportion of NPP to roots relative to leaves and stems.
d. Plants growing in deserts allocate a lower proportion of NPP to roots relative to leaves and stems.

In which biome would you most likely see the greatest percentage of NPP devoted to roots?
a. Pine savannas in Belize
b. Tundra in Alaska
c. Boreal forests in Russia
d. Tropical forest in Panama

In his experiments in lakes in Ontario, Canada, Schindler found evidence for phosphorus limitation of NPP. A massive increase in _______ was responsible for the increase of NPP in response to phosphorus addition.
a. cyanobacteria
b. red algae
c. green algae
d. brown algae

Which of the following is responsible for the most NPP produced within river and stream ecosystems?
a. Phytoplankton suspended in the upper layers of the water
b. Macrophytes in shallow areas
c. Terrestrial plants
d. The actions of detritivores

What did John Martin mean when he said “Give me half a tankerload of iron, and I’ll give you an Ice Age”?
a. Iron added to ocean water decreases NPP, and that decrease would lead to more carbon dioxide being taken up by phytoplankton. That would lead to the removal of carbon dioxide from the atmosphere, thus reducing the greenhouse effect.
b. Iron added to ocean water increases NPP, and that increase would lead to less carbon dioxide being taken up by phytoplankton. With phytoplankton taking up less carbon dioxide, more carbon dioxide would be removed from the atmosphere, thus reducing the greenhouse effect.
c. Iron added to ocean water increases NPP, and that increase would lead to more carbon dioxide being taken up by phytoplankton. That would lead to the removal of carbon dioxide from the atmosphere, thus reducing the greenhouse effect.
d. Iron added to ocean water changes the specific heat of water, such that water can hold less heat. This leads to subsequent cooling of the atmosphere.

How does hypoxia in ocean ecosystems result from the addition of limited nutrients?
a. The over-consumption of phytoplankton from consumers increases the CO2 levels, driving out oxygen.
b. The increased growth of phytoplankton utilizes the available oxygen, limiting photosynthesis for other plants.
c. Saprophytic organisms exhibit increased growth which results in an over-consumption of oxygen producing autotrophs.
d. Limiting nutrients bind oxygen, making it unavailable for autotrophs to use.

How does the addition of nutrients in agricultural runoff decrease NPP in ocean ecosystems?
a. The increased growth of kelp forests and sea grasses are not as efficient at photosynthesis as phytoplankton.
b. The increased growth of phytoplankton shade out lower growing plants, limiting the ability for photosynthesis.
c. The increased growth of kelp forests and sea grasses reduces the amount of light reaching phytoplankton, which limits their ability for photosynthesis.
d. The increased growth of phytoplankton uses the available oxygen which limits photosynthesis of other plants.