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Environmental Sys. & Soc. Study Guide Pages 46-68 (by Kyleigh Estes) Energy Stores and Flows Interpreting diagrams: Boxes=stores Arrows=flows o Sometimes the width of the arrow can represent the amount of energy (J) in that flow. Energy Loss: Mammals lose more energy to the environment because of the high levels of respiration needed to maintain body temperature and higher activity Herbivores (plant eaters) take in large amounts of indigestible substances like cellulose and lose the energy from these substances in feces. Transfer and Transformation of Materials within an Ecosystem Unlike energy, nutrients are recycled in ecosystems This recycling is necessary to the Earth in order to maintain the availability of nutrients. Carbon Cycle: Stores of Carbon: o Biological molecules (e.g. carbohydrates, fats, proteins) o Biomass o Fossil Fuels (e.g. coal, gas, peat, oil) o Limestone Figure 1: Carbon Cycle Diagram Processes that return Carbon to the atmosphere o Weathering of limestone o Acid rain o Combustion of fossil fuels Nitrogen Cycle: Nitrogen is an essential building block of amino acids and nucleic acids and is the most abundant gas in the atmosphere. The Nitrogen Cycle is driven by four types of bacteria: o Nitrogen-fixing bacteria o Decomposers o Nitrifying bacteria o Denitrifying bacteria Figure 2: Nitrogen Cycle Diagram Lightning fixes atmospheric nitrogen into ammonia. Ammonia is also found in excretory products from decomposers, along with ammonium compounds. The ammonia is oxidized by the nitrifying bacteria and is turned into nitrates. The denitrifying bacteria then return it to the atmosphere. Water (Hydrologic) Cycle: Refers to the entire path of water through the atmosphere, lithosphere, and biosphere. Figure 3: Hydrologic Cycle Diagram Productivity Primary vs. Secondary: Primary productivity—The gain by producers (autotrophs) in energy or biomass per unit area per unit time Conversion of solar energy Depends on amount of sunlight, availability of growth factors, and ability of producers to use energy in order to synthesize organic compounds. At its highest where growth conditions are optimal Secondary productivity—The biomass gained by heterotrophic organisms, through feeding and absorption, measured in units if mass or energy per unit area per unit time. Depends on amount of food present and the efficiency of consumers turning it into new biomass. Gross vs. Net: Gross productivity (GP)—The total gain in energy or biomass per unit area per unit time Net productivity (NP)—The gain in energy or biomass per unit area per unit time remaining after allowing for respiratory losses Population Changes Limiting Factors and Carrying Capacity: Carrying capacity—The maximum number of organisms that an area or ecosystem can sustainably support over a long period of time Limiting factors: Temperature Water and nutrient availability S and J Curves: S-Curve: o Graphical approach to depicting population change that occurs in 3 stages. o 3 Stages Exponential growth—Population grows at an increasingly rapid rate Transitional—Population growth slows considerably, but continues to grow due to limiting factors. Plateau—Population growth stabilizes at a lower level J-Curve: o Graph that shows only the exponential growth of a population Survivorship Curves: Show changes in the survivorship over the lifespan of species “r” and “K” Strategists “r” Strategists “K” Strategists Initial colonizers Dominant species Large number of a few species Diverse range of species Highly adaptable Generalists Rapid growth and development Slow development Early reproduction Delayed reproduction Short life Longer living Small size Larger size Very productive Less productive Factors that influence survivorship rates: o Competition for resources o Adverse environmental conditions o Predator-prey relationships Density Dependency: Density-dependent factors—A limiting factor related to population density that acts as a negative feedback mechanism and can include: o The size of the breeding population o The size of the territory Density-independent factor—A limiting factor related to population density that are generally abiotic and affect the population and can include: o Weather (drought, fire, hurricane) o Long-term climate change Internal vs. External Factors: Internal factors—Density-dependent fertility or size of breeding territory External factors—Predation or disease Human Involvement: Population Growth Caused by Human Population Decline/Extinction Caused by Involvement Human Involvement Increase available resources (e.g. farming) Change the physical environment and cause habitat disruption (e.g. draining of bodies of water) Reduce competition (e.g. pesticides) Change the biological environment by introducing a new species Reduce predators (e.g. over-hunting large Overkill (e.g. big-game hunting) carnivores) Introduce animals to new areas (e.g. game Cause secondary extinctions (e.g. loss of releases) food species) Succession: Different types of succession o On bare rock= lithosere o In a freshwater habitat= hydrosere o In a dry habitat=xerosere Primary succession—succession occurring on a previously uncolonized substrate Secondary succession—succession occurring in a place where a previous community has been destroyed (faster than primary succession because of the presence of soil)