Lecture 07: Vegetational Biomes Exam Questions

Question 1: What role do Hadley cells have in determining weather patterns? What effect do Hadley cells have on the climate at their outer reaches (i.e., 30° N and S).

Tropical air circulates at the range of the cell, first rising as warm, less dense air near the equator (where the sun warms it most), then moving north or south, gradually cooling and getting more dense, then sinking down to the surface towards the northern end (above the equator) and the southern end (below the equator), collecting all the vapor there and creating dry conditions, and returning towards the equator, precipitating the vapor it collected along the way over the equatorial rain forest.

Question 2: Sitting at 47° N, why are Seattle winters so warm and Ann Arbor (42° N) winters so cold? Give specific examples and discuss the major factors in determining regional climate.

Seattle's proximity to the ocean likely influences the weather conditions, perhaps from the warm currents, while Ann Arbor is more towards the middle of the continent, and thus not subject to such influences. The different climate zones can give rise to certain biomes based on soil, climate, weather patterns, and vegetation (Seattle in a temperate rainforest, and Ann Arbor in a temperate deciduous forest region)

Question 3: Identify the order or “great group” of the soil cross-section pictured below. Describe the soil horizons and explain the weathering processes for this cross section.


Citation: http://img.sparknotes.com/figures/A/a4d938a405b10475f48eea440b31bab3/Soil_Horizons.jpg

See page 79-80 in Ricklefs!

Question 4: The Tundra biome circles the Arctic, covering much of Northern Canada, Russia, and Alaska. Under the hearty tundra vegetation lay a thick ice sheet. With current climate change projections and warming trends, what are possible impacts on tundra flora and fauna and on the freshwater supply more generally?

[Here is a link to NOAA’s Arctic Change website: http://www.arctic.noaa.gov/detect/land-tundra.shtml. This link discusses the impacts climate change is having and will have on the arctic regions).

Answer: When the permafrost melts it would allow increased volume for organic activity to occur in the tundra soils. Depending on the drainage patters and landscape the water from the melted ice would either flow into rivers or accumulate in wetlands. If the soils remain aerobic then there is potential for large amounts of soil organic matter to become decomposed releasing CO2 into the atmosphere. If the soils become waterlogged due to the melted ice, you could have anaerobic respiration releasing CH4, methane, as well as denitrification, releasing nitrogen gasses into the atmosphere. In summation the fauna biomass would increase due to more available soil, water, and warmth. However, it is likely that the affects of respiration and potential denitrification could outweigh any carbon sequestration provided by the increased fauna in the tundra.

Question 5: Climate is the major determinant of plant growth form and distribution. Climate defines the boundaries of terrestrial biomes (biological communities and ecosystems grouped into categories based on climate and dominant plant forms). What does nutrient cycling have to do with these statements?

Climate can affect the patterns of nutrient cycling—for instance, colder, drier conditions cause nutrients to decompose and be assimilated slower than warmer, wetter conditions

Question 6: Why do the tropics experience such high rates of primary productivity when they have such nutrient-poor soils?

Plant litter decomposes quickly in rainforests due to high temperatures and moisture, and thus provides quickly absorbed nutrients to the growing plants. This rapid cycling, along with supporting the productivity, is very vulnerable to any disturbances, including clearcutting or slash-and burn farming.

Question 7: What are the factors that affect soil formation?

Cl, O, R, P, T (ClORPT)
Climate: precipitation, freeze thaw cycles, vulcanism
Organisms: decomposers, worms, bacteria, fungi
Relief (topography): steep slopes=land slides and exposure of new parent material, hydrology, geomorphology
Parent Material: alkaline, acidic, volcanic etc.
Time: how long has it been weathering and what have been the frequency and magnitude of disturbances.

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