I worked on these with Mariko!
1. Why did ecologists want to reintroduce wolves to Yellowstone Park? What goals did they have, and have their goals been achieved?
Yellowstone Park once had a large wolf population that was wiped out by farmers and ranchers. This led the population of elk and deer to explode, where they started to overgraze plant life in the area. Ecologists wanted to reintroduce wolves to restore this lost biodiversity; whether or not the wolves directly caused this is still up to debate, but biodiversity has been restored in Yellowstone Park in the years following.
2. Describe nine major types of terrestrial biomes.
Scientists define many different types of biomes. One classification lists thirteen distinct major world biomes: tropical rainforest and subtropical moist forest, tropical and subtropical seasonal forests, tropical grasslands and savannas, desert and dry shrublands, temperate rainforest, temperate conifer forests, temperate broadleaf and mixed forests, Mediterranean woodlands and scrub, temperate grasslands and savannas, boreal forests, tundra, rock and ice, and montane grasslands and shrublands.
3. Explain how climate graphs (as in fig. 5.6) should be read.
The horizontal axis shows months of the year and the vertical axes show temperature and precipitation. Dry months are when precipitation drops below temperature, and are indicated in yellow. Wet months are when precipitation stay above temperature, and are areas in blue.
4. Describe conditions under which coral reefs, mangroves, estuaries, and tidal pools occur.
Coral reefs occur where shallow, clear warm water supports photosynthesis in algae species that hellp nourish the coral. Mangroves occur in shallow tidal mudflats along warm, calm marine coasts. Estuaries are formed wherever rivers empty into the ocean, mixing fresh water with salt water. Tidal pools occur along rocky shorelines in depressions that cause the water to flood only at high tide but still retain some water at low tide. There is significant wave action here that allows life for only specialized animals and plants.
5. Throughout the central portion of North America is a large biome once dominated by grasses. Describe how physical conditions and other factors control this biome.
Because there is not enough rain to support forests, grass is abundant. Deep roots help them to survive drought, and also the annual winter accumulation of dead leaves keeps the soil rich. Unfortunately, the rich soil has been converted to farmland with lots and lots of corn, wheat, and other crops. Now soil erosion is common, and weeds can spread.
6. Explain the difference between swamps, marshes, and bogs.
Swamps are wetlands with trees. Marshes are wetlands without trees. Bogs are areas of water-saturated ground that consists of layers of accumulated dead vegetation, also called peat.
7. How do elevation (on mountains) and depth (in water) affect environmental conditions and life-forms?
Elevation and depth affect environmental conditions and therefore different life-forms exist due to different temperatures as well as different pressures (less pressure at high altitude, huge amounts of pressure underwater). At higher elevation, plants are usually less abundant and smaller as there is less nutrition for them as well as more extreme ranges of temperature that they have to tolerate. Less plant life is less biological material that can be used to feed animals, hence the relative lack of creatures living higher up. In the benthic zone, the relative lack of light filtering down prevents the growth of photosynthetic organisms, explaining the lack of plant life deep underwater. However, a different community lives and thrives there from the dead biological material that sinks underneath, leading to a different sort of unique ecosystem to form.
8. Figure 5.15 shows chlorophyll (plant growth) in oceans and on land. Explain why green, photosynthesizing organisms occur in long bands at the equator and along the edges of continents. Explain the very dark green areas and yellow/orange areas on the continents.
Photosynthesis requires sunlight, and there is much more sunlight throughout the year around the equator. Along the edges of continents, the water is more shallow and therefore warmer than the middle of the ocean. This also promotes plant growth. Very dark green areas on the continents have high biological productivity, whereas yellow/orange areas are biologically rich.
9. Define biodiversity and give three types of biodiversity essential in preserving ecological systems and functions.
Biodiversity is the variety of living things with unique and productive characteristics and the complex ecological relationships that exist between them. The three types of biodiversity are genetic diversity, species diversity, and ecological diverstiy.
10. What is a biodiversity "hot spot"? List several of them (see fig. 5.22).
Biodiversity hotspots are where there are large concentrations of unique species and biodiversity. These include Brazillian Carrado, Central Chile, Indo-Burma, and many others.
11. How do humans benefit from biodiversity?
They benefit from the exercise that nature walks and other wildlife recreation give them, and they also benefit from the aesthetics. They also benefit emotionally by feeling like they are trying to protect a species. So many natural medicinal products are also harvested from nature; their discovery would not have happened without biodiversity.
12. What does the acronym HIPPO refer to?
Habitat destruction, invasive species, pollution, population (human), and overharvesting. To me it just makes me think of greedy corpulent American hypocrites.
13. Have extinctions occurred in the past? Is there anything unusual about current extinctions?
Extinctions have occured in the past, but human involvement has increased the extinction rate by crazy amounts!
14. Why are exotic or invasive species a threat to biodiversity? Give several examples of exotic invasive species (see fig. 5.27).
Because invasive species generally do not have predators and have unlimited resources in their new habitat, they hurt stable ecosystems. Some examples include the Eurasian milfoil which grows in water and displaces native vegetation. The water hyacinth grows in water and blocks boat traffic and prevents swimming and fishing.
15. What is the Endangered Species Act? Describe some of the main arguments of its proponents and opponents.
In 1973, the Endangered Species Act was passed to protect animals that are at risk for extinction even if they are not directly useful to humans. Its proponents say that all species are important for ecosystems. Opponents say that the laws violate their property rights.
16. What is a flagship or umbrella species? Why are they often important, even though they are costly to maintain?
An umbrella species is a species that requires a large area of undisturbed habitat to maintain their population. Examples include the spotted owl, the tiger, or the gray wolf. Flagship species are pretty or cool organisms that many people react to emotionally, like the giant panda or bald eagle. They are advocates for the public to preserve biodiversity.