ECOL 3500 Exam 3 Guide - exam 3 review PDF

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ECOL 3500 Exam 3 Guide

Textbook Notes Chapter 19 - Community Succession 1. Succession: the process of succession in a community is the change in species composition over time. a. Seral stage: cach stage of community change during the process of succession b. Pioneer species: The earliest species to arrive at a site. These species typically have the ability to disperse long distances and arrive quickly at a disturbed site. c. Climax community: the final seral stage in this process of succession. A climax community is generally composed of the group of organisms that dominate in a given biome. 2. Observing successions directly 3. Observing successions indirectly a. Chronosequencing: is used to create a model of the sequence of communities that exist over time at a given location. The model, called a chronosequence, helps ecologists understand how succession has progressed over time in an area. b. Carbon dating: identifies the age of the pollen in each layer. Dating the pollen helps determine changes in the species of plants around the lake over hundreds or even thousands of years 4. Primary succession: development of communities in habitats that are initially devoid of plants and organic soil, such as sand dunes, lava flows, and bare rock. a. These inhospitable environments are colonized by species, such as lichens and mosses, that require no soil, and that can live on the surfaces of rocks, and drought-tolerant grasses that are able to colonize dry sand dunes. i. The species that first colonize these places produce bits of organic matter that combine with the processes of rock weathering and microbial activity to create soils that make the site more hospitable for other species. 5. Secondary succession: the development of communities in habitats that contain no plants but do have organic soil. a. For example, secondary succession occurs in fields that have been plowed or forests that have been uprooted by a hurricane. Such habitats typically contain well-developed soils. These soils may also include plant roots and seeds, both of which contribute to rapid growth of new plants after the disturbance. 6. Early vs. Late Succession Plant Species

ECOL 3500 Exam 3 Guide

a. 7. Facilitation: a mechanism of succession in which the presence of one species increases the probability that a second species can become established. a. Early-succession species do this by altering the environmental conditions of the site in a manner that makes it more suitable for other species to establish and less suitable for themselves. 8. Inhibition: is a mechanism of succession in which one species decreases the probability that a second species will become established. a. Common causes of inhibition include competition, predation, and parasitism. That is, individuals of one species can inhibit those of other species by outcompeting them for resources, eating them, or attacking them with noxious chemicals or antagonistic behavior. b. Early in succession, inhibition can prevent movement toward a climax community, while late in succession, inhibition can prevent the pioneer species from colonizing and surviving. c. Priority effect: The arrival of one species at a site that affects the subsequent colonization of other species 9. Tolerance: a mechanism of succession in which the probability that a species can become established depends on its dispersal ability and its ability to persist under the physical conditions of the environment. a. For example, species that can tolerate the stressful environmental conditions of early succession—such as low moisture or more extreme temperature fluctuations—can become established quickly and dominate early stages of succession. These species do not alter the environment in ways that either help or inhibit other species, but once a stress-tolerant species becomes established, it can be affected by interactions with other species b. For example, superior competitors that arrive later will eventually replace the stresstolerant species. 10. Transient climax community: a climax community that is not persistent a. A transient climax occurs when a site is frequently disturbed so that the climax community cannot continue to perpetuate itself.

ECOL 3500 Exam 3 Guide 11. Fire-maintained climax community: when a successional stage persists as the final seral stage due to periodic fires 12. Grazer-maintained climax community: when a successional stage persists as the final seral stage due to intense grazing Chapter 23 - Conservation of Global Biodiversity 1. (23.1) Instrumental value of biodiversity: focuses on economic values that species can provide, such as lumber for building or crops for eating a. Provisioning services: are benefits of biodiversity that provide products humans use, including lumber, fur, meat, crops, water, and fiber. In many cases, plants and animals from the wild have been cultivated or domesticated and then selectively bred to enhance their valuable qualities. b. Regulating services: benefits of biodiversity that include climate regulation, flood control, and water purification. i. For example, wetlands absorb large amounts of water and so prevent flooding from water runoff during rainy periods. c. Cultural services: benefits of biodiversity that provide aesthetic, spiritual, or recreational value. i. For example, cultural services include the benefits that people obtain when they go hiking, camping, boating, or birdwatching. d. Supporting services: benefits of biodiversity that allow ecosystems to exist, such as primary production, soil formation, and nutrient cycling. 2. Intrinsic value of biodiversity: recognizes that species have inherent value that is not tied to any economic benefit. Of course, species and ecosystems can have both instrumental and intrinsic values. 3. (23.2) Mass extinction rates: are defined as events in which at least 75 percent of the existing species go extinct within a 2-million-year period. a. Earth has undergone 5 over the last 500 millions years b. First mass extinction: about 443 Mya, most species lived in the oceans. An ice age caused sea levels to drop and the ocean chemistry to change, which resulted in 86 percent of species going extinct. c. Second mass extinction: happened 359 Mya when much of the ocean lacked oxygen— for reasons that are unclear—and 75 percent of all species went extinct. d. Third mass extinction: 248 Mya—an astounding 96 percent of all species then present on Earth went extinct. e. The fourth mass extinction: occurred 200 Mya, caused 80 percent of the world’s species to go extinct. Hypotheses for the causes of this fourth extinction include increased volcanic activity, asteroid collisions with Earth, and climate change. f. The fifth mass extinction: happened 65 Mya and is best known as the one that led to the extinction of dinosaurs. This event is attributed to several factors. First, volcanic eruptions and changes in climate caused long periods of cold weather. This was followed by a massive asteroid that struck the Yucatan Peninsula in Mexico 4. Sixth mass extinction -

ECOL 3500 Exam 3 Guide a. Conifers: include pines, spruces, firs, cedars, and redwoods, and the survival prospects of 95 percent of these species have been assessed. i. Of the 606 species of conifers, none has gone extinct. Of those species that have sufficient data for assessment, 50 percent are categorized as of least concern, 16 percent are near-threatened, and 34 percent are threatened. b. Birds: since the year 1500, 156 of these (1.4 percent) have gone extinct. Of the remaining species for which there are reliable data, 77 percent have sufficiently abundant populations to be categorized as least concern, 9 percent are nearthreatened, and 13 percent are threatened with extinction. c. Reptiles: Twenty-eight species (0.4 percent) have gone extinct during the last 500 years. Of those remaining with sufficient data for assessment, 68 percent are of least concern, 8 percent are near-threatened, and 24 percent are threatened. d. Mammals: During the past 500 years, 83 mammal species (1.5 percent) have gone extinct. Of those remaining for which there are reliable data, researchers found that 67 percent of the species are categorized as of least concern, 8 percent are nearthreatened, and 25 percent are threatened. e. Amphibians: During the past 500 years, 33 species (0.5 percent) have gone extinct. Of the remaining species with sufficient data, 50 percent are of least concern, 8 percent are near-threatened, and a staggering 42 percent of amphibian species are threatened. f. Fish: Since the year 1500, 64 fish species are now extinct. Of those remaining with reliable data, 77 percent of the species are categorized as of least concern, 4 percent are near-threatened, and 18 percent are threatened. 5. (23.3) Humans are the primary cause for loss of biodiversity a. Habitat loss b. Overharvesting i. Collapsed fishery: When a commercially important fish species no longer has a population that can be fished c. Introduced species i. Biotic homogenization: As the movement of people, cargo, and species becomes more common among the regions of the world, the unique species compositions originally found in different regions are slowly become more similar d. Pollution i. Biomagnification: The process of increasing the concentration of a contaminant as it moves up the food chain e. Global climate change i. Half-life: A helpful way to assess this persistence is to measure the time required for the chemical to break down to half of its original concentration 6. (23.4) Reversing the loss of biodiversity a. Habitat protection i. Minimal viable population: is the smallest population size of a species that can persist in the face of environmental variation. b. Reduced harvesting c. Introducing species

ECOL 3500 Exam 3 Guide

Chapter 5 - Climates and Soils 1. (5.1) Greenhouse effect: This process of solar radiation striking Earth, being converted to infrared radiation, and then being absorbed and reradiated by atmospheric gases back to Earth. a. About one-third of the solar radiation emitted toward Earth is reflected by the atmosphere—the 600-km thick layer of air that surrounds the planet—and heads back into space. b. The remaining solar radiation penetrates the atmosphere. Much of the high-energy radiation—including ultraviolet radiation—is absorbed in the atmosphere. c. The rest passes with most of the visible light through the atmosphere. d. When this radiation subsequently strikes clouds and the surface of Earth, a portion is reflected back into space and the rest is absorbed. e. As clouds and Earth’s surface absorb this radiation, they begin to warm and emit lower-energy infrared radiation. f. Infrared radiation is readily absorbed by gases in the atmosphere. The gases are warmed by the infrared radiation and then re-emit infrared radiation in all directions. Some of this energy goes out into space and some goes back toward the planet’s surface.

g. 2. Greenhouse gases a. Excluding water vapor, 99% of atmosphere is N2 and O2, but these are NOT greenhouse gases b. Most prevalent are H20 and CO2, but there is also CH4, N20, and O3 c. H20 comes from large bodies of water and the transpiration of plants d. CO2 comes from decomposition, respiration of organisms, and volcanic eruptions e. CH4 comes from anaerobic decomposition f. N2O comes from wet soils and low-oxygen regions of water bodies

ECOL 3500 Exam 3 Guide g. O3 comes from ultraviolet radiation breaking apart O2 Molecules in the atmosphere and causing each molecule to combine with another O2 molecule 3. (5.2) Unequal heating of the Earth from the Sun a. Path and angle of the sun i. Sun must pass through the Earth’s atmosphere → less distance for sun to travel through atmosphere for the equator than the poles ii. Angle of the sun’s rays → near the equator, there is a perpendicular angle causing a more intense beam of light over a smaller area, while near the poles the angle is less intense over a larger area iii. Albedo effect → surfaces reflect more sunlight than others

iv. b. Seasonal heating of the earth → caused by the tilt of the earth’s axis

i. 4. (5.3) Atmospheric convection currents: are the circulations of air between the surface of Earth and the atmosphere. The patterns of air circulation play a major role in the location of tropical rainforests, deserts, and grasslands throughout the world. 5. Properties of air

ECOL 3500 Exam 3 Guide a. Air density: In regard to density, when air warms, it expands and becomes less dense. As a result, when air becomes warmer next to the surface of Earth, it becomes less dense than the air above it. This causes the warm air to rise b. Water Vapor saturation point: as air temperature increases, its capacity to contain water vapor—the gaseous form of water—increases. i. Although the capacity to contain water increases at higher temperatures, there is always a limit, known as the saturation point. ii. When the water vapor content of air exceeds the saturation point at any given temperature, the excess water vapor condenses and changes into either liquid water or ice. When the water vapor content is below the saturation point, liquid water or ice can be converted to water vapor. iii. As a result, the excess vapor changes phases to liquid water and produces clouds and precipitation. The relationship between temperature and water vapor saturation affects patterns of evaporation and precipitation around the world. c. Latent-heat release: water vapor converted back to liquid water releases energy in the form of heat. i. Latent heat release is significant because whenever water vapor exceeds its saturation point, condensation will cause a release of heat that warms the surrounding air. d. Adiabatic heating and cooling: Air pressure is related to the frequency of collisions among air molecules, which also influences temperature. Lower rates of collision cause lower temperatures. i. Adiabatic cooling: As a result, when air moves higher up into the atmosphere and experiences lower pressure, the air expands and the temperature decreases ii. Adiabatic heating: Conversely, when air moves down to Earth’s surface and experiences higher pressure, the air compresses and the temperature increases in a process. 6. Formation of atmospheric convection currents

ECOL 3500 Exam 3 Guide

a. b. Hadley cells: The two circulation cells of air between the equator and 30° N and 30° S latitudes c. Intertropical convergence zone: The area where the two Hadley cells converge and cause large amounts of precipitation d. Polar cells: The atmospheric convection currents that move air between 60° and 90° latitudes 7. Earth’s Rotation and the Coriolis Effect

a. b. Coriolis effect: The deflection of an object’s path due to the rotation of Earth

ECOL 3500 Exam 3 Guide

c. 8. Ocean currents on climate a. Gyres: large-scale water circulation patterns between continents

i. b. Upwelling: Any upward movement of ocean water i. As surface water moves away from land, cold water from beneath is drawn upward. Strong upwelling zones occur on the western coasts of continents where gyres move surface currents toward the equator and then veer from the continents. As surface water moves away from the continents, it is replaced by

ECOL 3500 Exam 3 Guide water rising from greater depths. Because deep water tends to be rich in nutrients, upwelling zones are often regions of high biological productivity c. El Niño-Southern Oscillation d. Thermohaline circulation: a global pattern of surface- and deep-water currents that flow as a result of variations in temperature and salinity that change the density of water.

i. 9. Geographic features that can affect local and regional climates a. Continental land area b. Proximity to coasts c. Rain shadows: When winds blowing inland from the ocean encounter coastal mountains, the mountains force the air upward, which causes adiabatic cooling, condensation, and precipitation. The air, which is now dry and warmed by latent heat release, descends the other side of the mountain, warms adiabatically, and travels across the lowlands beyond, where it creates relatively warm, arid environments 10. Regional climates a. Tropical climates: characterized by warm temperatures and high precipitation, occur in regions near the equator b. Dry climates: at approximately 30° N and 30° S latitudes. Are not only affected by latitude, however. Many dry climates are caused by rain shadows. c. Moist subtropical mid-latitude climates: characterized by warm, dry summers and cold, wet winters d. Moist continental mid-latitude climates: exist at the interior of continents and typically have warm summers, cold winters, and moderate amounts of precipitation e. Polar climates: very cold temperatures and relatively little precipitation. 11. (5.6) Soil: the layer of chemically and biologically altered material that overlies bedrock or other unaltered material at Earth’s surface

ECOL 3500 Exam 3 Guide 12. Parent material: Because the layer of bedrock that underlies soils plays a major role in determining the type of soil that will form above it, soil scientists call bedrock the parent material. 13. Soil horizons: layers of the soil that are determined by their composition and processes 14. Leaching: Groundwater removes some substances by dissolving them and moving them down through the soil to lower layers 15. Weathering: the physical and chemical alteration of rock material near Earth’s surface. It occurs whenever surface water penetrates the parent material 16. CEC: The ability of a soil to retain these cations, called its cation exchange capacity , provides an index to the fertility of that soil. 17. Podsolization: under mild temperatures and moderate precipitation, sand grains and clay particles resist weathering and become stable components of the soil. This allows soils to retain relatively high fertility. However, in acidic soils typical of cool, moist regions, clay particles break down in the E horizon, and their soluble ions are transported down to the lower B horizon. 18. Laterization: breakdown of clay particles, which causes silicon to leach from the soil and leaves oxides of iron and aluminum to dominate throughout the soil profile Chapter 3.2 - Primary Productivity and Energy Cycling 1. Electromagnetic radiation: the energy from the sun. Is packaged in small particle-like units called photons. a. The energy of photons is related positively to their frequency and inversely to their wavelength; the highest energy photons have the highest frequency and the shortest wavelengths. 2. Visible light: Between the two extremes of infrared and ultraviolet radiation are wavelengths collectively known as visible light which are visible to the human eye

a. 3. Photosynthetically active region: consists of wavelengths of light that are suitable for photosynthesis. This range of wavelengths falls between about 400 nm (violet) and 700 nm (red). Plants, algae, and some bacteria absorb these wavelengths and assimilate their energy by photosynthesis

ECOL 3500 Exam 3 Guide 4. Chloroplasts: Eukaryotic photosynthetic organisms contain specialized cell organelles a. Chloroplasts contain stacks of membranes known as thylakoids and a fluid-filled space surrounding the thylakoids called the stroma. Embedded within the thylakoid membranes are several kinds of pigments that absorb solar radiation, including chlorophylls and carotenoids. 5. Photosynthesis: involves photosynthetic pigments absorbing energy from photons of light. This energy is then converted into chemical energy stored in the high-energy bonds of organic compounds. In its simplest form, photosynthesis is the process of combining CO 2, H2O, and solar energy to produce glucose (C6H12O6) and oxygen a. This simple equation summarizes a long chain of complex chemical reactions that takes place in two parts: light reactions and the Calvin cycle 6. Calvin cycle: The cell uses the energy in these compounds to convert CO2 into glucose in a process known as the Calvin cycle, which takes place in the stroma of the chloroplast. a. 3 biochemical pathways of the Calvin Cycle → C3, C4, and CAM p...