Chapter 18 Homework

If Brazil is clearing 15,515 hectares of forested areas (primarily rainforest) per year, how many hectares of that 15,515 are likely cleared for commercial agriculture, given what you know about the causes of Latin American deforestation? Round your answer to a whole number. (Chapter 18 Infographic)

(15,515) * (0.67) = 10,395.05 = 10,395

Brazil has cleared 42 million hectares of rainforest since 1990, an area the size of California. If 67 percent of this cleared land was for commercial agriculture, how many hectares is that? Round your answer to one decimal place. (Chapter 18 Infographic)

(42,000,000) * (0.67) = 28,140,000 = 28,140,000.0

Label the correct parts of the graphic illustrating how greenhouse gases warm the Earth's surface. (Figure 18.7)

(From left to right) ⚪ (B) Some incoming solar radiation absorbed by Earth's surface ⚪ (C) Energy reemitted to atmosphere as IR radiation ⚪ (A) Incoming solar radiation reflected back to space ⚪ (E) Some IR radiation lost to space ⚪ (D) Some IR radiation absorbed by greenhouse gases

Label the stages of the hydrologic cycle in the figure below. (Figure 18.12)

(From left to right) ⚪ (E) Uptake by plants ⚪ (B) Precipitation ⚪ (F) Water percolation ⚪ (D) Runoff ⚪ (G) Groundwater flow ⚪ (H) Condensation ⚪ (A) Transpiration ⚪ (C) Evaporation

Label the following points in the Northern Hemisphere on the convection cell illustration. (Figure 18.13)

(From top to bottom) ⚪ (A) Cool dry air sinks ⚪ (B) Moist warm air clashes with polar cold fronts. ⚪ (D) Some cool dry air sinks; rest is deflected. ⚪ (C) Moist warm air rises

Based on the image, what percentage of Latin American deforestation results from all kinds of agriculture combined? (Chapter 18 Infographic)

94% of deforestation

Which of the following accurately describes the biosphere?

All living organisms, Earth's atmosphere and the surface of the Earth

Almost all producers use carbon dioxide to produce sugars, which are then used as the backbone of all other organic molecules. At 1:50, the animation points out the difference between how aquatic producers acquire carbon dioxide and how terrestrial producers (primarily plants) acquire carbon dioxide. How do they differ?

Aquatic producers absorb dissolved carbon dioxide from the water, while terrestrial producers absorb carbon dioxide from the atmosphere.

Jennifer Balch first burned her experimental plot in 2004 and was surprised to see the plants show resistance to the fire. What happened to the plant community after the experimentally burned site experienced drought in 2005 and was burned again?

Because of the stress already experienced from burning, the majority of the trees died and where they died grasses invaded.

Biofuels are primarily made from plants. Ethanol, a biofuel, is made by distilling grain crops like corn or soybeans and is said to be "carbon neutral." What does this mean in terms of the carbon cycle?

Biofuels release CO2 when they are burned, but the carbon was fixed by plants taking in CO2 from the current atmosphere. Therefore, the same carbon keeps circulating.

California recently ordered a mandatory 25% reduction in water use throughout the state as the result of a historic drought that has entered its fourth year. The Sierra Nevada mountain range in California had virtually no snow pack at the end of the 2014-15 winter. California produces one-third of the U.S. supply of vegetables and two-thirds of our fruits and nuts. Review how climate change is changing rainfall patterns in the Amazon and its effects, and apply this to what is happening in California. What is the chain of events that has occurred with the start of the drought?

First event 1. The average global temperature rises. 2. Weather patterns are disrupted, causing precipitation to move north and south around California. 3. Precipitation decreases across the state of California 4. Snow pack in California's Sierra Nevada is reduced to a fraction of normal. 5. Stream and river levels are greatly reduced due to lack of melt water; reservoir levels start to drop. 6. Insufficient water is available for agricultural irrigation, production falls, and produce prices rise nationally. Last event

If the rainforest is replaced by grassland, how are the following parts of the hydrologic cycle affected? Sort as to whether the variable will increase or decrease.

Increase ➡ Runoff Decrease ➡ Transpiration, Condensation, & Precipitation

A family in St. Louis has owned three car dealerships for about 40 years. The car dealership recently suffered a financial loss when a thunderstorm that produced golf-ball-sized hail damaged 700 cars. The granddaughter of the original owner (who plans to take over operations when her father retires) was discussing the loss when her grandmother commented that it seemed like bad hailstorms were happening more often than when they started the family business. This sparked the granddaughter's curiosity, and she met with the accountant to summarize what hail storms have cost her family's group of dealerships over the last 46 years. Here is what they discovered. Does it appear that the climate has changed, producing more extreme weather events in the St. Louis region?

Maybe, the number of storms has increased, but we have to see the change for 30 years for it to be considered a new pattern in climate.

Put the following steps of the hydrologic cycle in the correct sequence, starting with what happens after precipitation falls and moves into soil.

Precipitation 1. Water is taken in by plant roots. 2. Water vapor is released from plant leaves. 3. Water vapor condenses to form clouds. 4. Clouds release precipitation 5. Water runoff travels from rivers to oceans Evaporation

Which would result in the greatest reduction of the human ecological footprint? (How Big Is Your Ecological Footprint?)

United States population reduces their ecological footprint by 15%.

You are a lucky student who gets to spend a year working with Jennifer Balch in the Amazon rainforest. Your assignment is to measure air humidity at specific intervals on a straight line that goes from an area that recently suffered a natural fire to an area deep in the rainforest. What would you hypothesize about the pattern of air humidity levels from the burned area to the deep forest?

The humidity levels will increase as you move from the burn area to deeper in the rainforest.

The Amazon rainforest is not the only place on Earth to experience deforestation. According to "U.S. Forest Facts and Historical Trends" published by the USDA, there were approximately 423 million hectares of forests in 1630 in the territory that would become the United States. By 1997, that amount had dropped to 302 million hectares, a loss of 121 million hectares, or 29 percent of forested areas. Fortunately, the amount of forests in the United States has remained fairly stable since 1997. What effect did the loss of these forests have on carbon cycling in the United States?

The loss of forests reduced the amount of carbon dioxide being fixed in photosynthesis, turning these areas into carbon sources rather than carbon sinks.

Wildfires are a common occurrence in California because of a long-term climate pattern that results in a Mediterranean-like climate typified by mild, wet winters and hot, dry summers with low humidity—ideal conditions for wildfires. California averages about 202,751 acres burned each year. However, wildfires were rampant in 2017, burning more than 500,000 acres. One of the signatures of climate change that scientists predicted decades ago is an increase in the intensity of climate-related events such as wildfires and hurricanes. After several years of severe drought in California, a very welcome El Niño delivered record rainfall and snow to the state in 2016, which helped to refill empty reservoirs, lakes, and streams. Plentiful precipitation encouraged plant growth statewide, greening large areas of the state that had seen relatively little vegetation growth after years of drought. Which statement best describes the probable relationship between the record-setting wet year in 2016 and the record-setting wildfires of 2017?

The wet year in 2016 caused a significant amount of vegetation growth, which provided fuel for wildfires in 2017 after the vegetation died out as usual during the hot, dry summer.

Which process moves carbon into underground storage?

decomposition

Decreasing greenhouse gases in the atmosphere:

increases infrared radiation lost to outer space.

The movement of Earth's convection cells at 30° latitude typically results in a desert biome, while movement of its convection cells at the equator results in areas of tropical rainforests. Which statements best explain the movement of water in these convection cells that results in two very different biomes, rainforest and desert?

✔ At the equator, direct sunlight warms the air; the warm, moist air rises, cools, and releases precipitation before moving north or south. ✔ At 30° latitude, cool, dry air descends, warms at Earth's surface while moving north or south, gains moisture, and then rises, releasing precipitation as it approaches 60° latitude.

The environment includes both biotic (living) and abiotic (nonliving) components. Which parts of the environment are biotic?

✔ Soil bacteria ✔ Butterflies ✔ Fish

Why would this researcher burn the Amazon rainforest in order to study it instead of simply studying areas that have already burned?

✔ to return to the same site for repeated measurements in subsequent years ✔ to collect data about the forest before the burn ✔ to control the conditions of the burn