Comprehensive Study Notes: Environmental Science and Global Change

1.1: Introduction to Ecosystems

Ecosystem: A community of living (biotic) organisms interacting with the non-living (abiotic) components of their environment as a system through various nutrients and energy cycles.
Organism: A living thing that can function on its own.
Species: Organisms that resemble each other; are similar in genetic makeup, chemistry, and behavior; and are able to interbreed and produce fertile offspring. * Interspecific: Means between different species.
Population: Organisms of the same species that interact with each other and occupy a specific area.
Community: Population of different species.
Ecological Niche: A particular area within a habitat occupied by an organism, as well as its function within its community. * Physical environment: Influences how organisms affect and are affected by resources and competitors. * Niche: Reflects specific adaptations acquired through evolution. * Niche Characteristics: Habitat, interactions with living/nonliving factors, role in the food web, and types/amounts of resources available.
Symbiosis: Close and long-term biological interaction between two different organisms of the same or different species. * Amensalism: One species suffers while the other is unaffected (e.g., black walnut tree releasing chemicals that kill neighboring plants). * Commensalism: One organism benefits while the other is unaffected. Forms include transportation, housing, or using something created by another. * Competition: Driving force of evolution for food, mating, or territory. * Intraspecific: Between members of the same species. * Interspecific: Between members of different species. * Mutualism: Both species benefit. * Parasitism: One species benefits while the other is harmed. * Predation: Predators hunt and kill prey. * Opportunistic: Kill and eat almost anything. * Specialist: Prey only upon certain organisms. * Saprotrophism: Saprotrophs obtain nutrients from dead/decaying matter through absorption of soluble organic compounds.
Law of Tolerance: States that the existence, abundance, and distribution of species depend on the tolerance level of each species to physical and chemical factors.
Limiting Factor: Any abiotic factor limiting population growth. * Terrestrial factors: Soil nutrients, water, light, and temperature. * Aquatic factors: $pH$ , dissolved oxygen, light, and degree of salinity.
Predator-Prey Cycles: Based on feeding relationships; as prey population multiplies, predators increase until prey populations dwindle.
Resource Partitioning: * Morphological partitioning: Species evolve different structures to use the same resource. * Spatial partitioning: Competing species use the same resource in different areas. * Temporal partitioning: Species use the same resource at different times.

1.2: Terrestrial Biomes

Biomes: Regional/global biotic communities characterized by dominant plant life and prevailing climate. Temperature and precipitation are the primary determinants.
Deserts: Defined by rainfall, not temperature. * Rainfall: Less than $20\,\text{inches}$ ( $50\,cm$ ) per year. * Location: Between $15^{\circ}$ and $35^{\circ}$ north and south latitudes. * Succulents: Store water in fleshy stems/leaves; have deep or shallow roots, open stomata at night, and waxy leaves to minimize transpiration. * Cactus: Sharp spines for shade/defense; secrete toxins to prevent interspecific competition. * Wildflowers: Dependent on water for germination; short life spans; store biomass in seeds. * Animals: Small, nocturnal, and often spend time in underground burrows. * Aestivation: A summer hibernation.
Forests: Cover $33\%$ of Earth's land (primarily North America, Russian Federation, South America); account for $75\%$ of gross primary productivity. * Closed canopy: Tree crowns cover > 20\% of ground surface ( $80\%$ of biome). * Open canopy: Tree crowns cover < 20\% of ground surface.
Tropical Rainforests: Near the equator; rainfall exceeds $80\,\text{inches}$ ( $200\,cm$ ) annually. Soil is nutrient-poor due to rapid assimilation. Trees have buttressed trunks and large dark green leaves.
Temperate Deciduous Forests: Found in eastern North America, NE Asia, Europe. Temperature range: $-20^{\circ}F$ to $85^{\circ}F$ ( $-30^{\circ}C$ to $30^{\circ}C$ ). Precip: $30-60\,\text{inches}$ ( $75-150\,cm$ ). Fertile soil from decaying leaf litter.
Temperate Coniferous Forest: Mild winters, heavy rainfall. Conical trees shed snow; dark green needles absorb light and have thick waxy coatings to reduce transpiration.
Taiga (Boreal Forest): Largest terrestrial biome. Southern Taiga is evergreen conifer; Northern Taiga is more barren near the tundra. Soil is thin, acidic, and nutrient-poor.
Grasslands: * Savannas (Tropical): Scattered trees; rainfall $20-50\,\text{inches}$ ( $50-130\,cm$ ) over $6-8$ months, followed by drought. * Temperate Grasslands: Hot summers, cold winters, moderate rainfall. Examples: veldts (S. Africa), pampas (Argentina), steppes (Russia), plains/prairies (N. America). Fertile soil from deep multi-branched roots.
Tundra: * Arctic Tundra: Cold, desert-like around the North Pole. Features permafrost (permanently frozen subsoil). Growing season averages $50\,\text{days}$ . Precipitation $6-10\,\text{inches}$ ( $15-25\,cm$ ). * Alpine Tundra: High altitudes on mountains where trees cannot grow. Growing season is roughly $180\,\text{days}$ ; night temps fall below freezing.

1.3: Aquatic Biomes

Water Properties: High thermal capacity; buoyancy reduces need for legs/trunks; screens UV radiation; effective dispersal of gametes.
Antarctic: Coldest climate; interior averages $-70^{\circ}F$ ( $-57^{\circ}C$ ). Sea is productive due to summer phytoplankton supporting large krill populations.
Marine: Oceans cover $75\%$ of Earth; salt concentration is roughly $3\%$ .
Ocean Circulation: * Convection: Warm liquid rises, cool sinks. * Thermohaline currents: Conveyor belt driven by temperature and salinity. Cold salty water sinks in the North Atlantic (Norwegian Sea), flows south, and rises in Pacific/Indian Oceans.
Ocean Zones: * Littoral: Intertidal zone near shore. * Neritic: Extends to continental shelf edge. * Photic: Upper layer reaching $1\%$ sunlight depth.
Corals: Marine invertebrates living in colonies of polyps (exoskeleton made of calcium carbonate ( $CaCO_3$ )). Energy comes from zooxanthellae dinoflagellates. * Fringing reefs: Grow near coastlines, narrow lagoons. * Barrier reefs: Parallel to coast, separated by deep/wide lagoons. * Atolls: Rings of coral in the middle of the sea around sunken volcanoes.
Lakes: Standing freshwater. * Zones: Benthic (bottom), Limnetic (well-lit open surface), Littoral (shallow near shore), Profundal (deep, dark, low oxygen). * Oligotrophic: Young, deep, nutrient-poor, clear water. * Mesotrophic: Middle-aged, moderate nutrients. * Eutrophic: Old, shallow, nutrient-rich, murky, low oxygen.
Lake Stratification: * Epilimnion: Sun-warmed surface layer. * Hypolimnion: Cold, dense bottom layer. * Thermocline: Thin middle layer with rapid temperature change.
Seasonal Turnover: Happens twice a year in fall and spring as water reaches its maximum density at $4^{\circ}C$ ( $39^{\circ}F$ ), causing mixing of surface and bottom waters.
Wetlands: Areas covered by water part of the year. * Ecological Services: Absorbing excess flood water, acting as carbon sinks, recharging groundwater, nurseries for fish. * Degradation: Draining for agriculture (salinization/compaction), damming (blocking sediment), grazing (streambank destabilization), and invasive species (competing with natives).
Rivers and Streams: * Source Zone: Cold, clear headwaters, high oxygen. * Transition Zone: Slower, warmer, more sediment. * Floodplain Zone: Murky, warm water; tributaries join to form rivers emptying into estuaries. * Riparian Areas: Lands adjacent to water with hydrophilic vegetation.

1.4 - 1.7: Biogeochemical Cycles

Carbon Cycle: Building block of life (CO_2 < 1\% of atmosphere). * Sinks: Forests ( $90\%$ of above-ground carbon), Oceans (phytoplankton/kelp), Sedimentary deposits (Limestone ( $CaCO_3$ ) is the largest reservoir). * Human Impact: Combustion of fossil fuels/deforestation has increased oceanic acidity, slowing natural precipitation of calcium carbonate.
Nitrogen Cycle: Nitrogen makes up $78\%$ of the atmosphere. * Nitrogen Fixation: $N_2$ converted to ammonia ( $NH_3$ ) or nitrate ( $NO_3^-$ ) by bacteria like Rhizobium or lightning. * Nitrification: Ammonia ( $NH_3$ ) converted to nitrite ( $NO_2^-$ ) and nitrate ( $NO_3^-$ ). * Assimilation: Plants absorb $NH_3$ , $NH_4^+$ , and $NO_3^-$ via roots. * Ammonification: Decomposers convert waste to ammonia ( $NH_3$ ) and ammonium ions ( $NH_4^+$ ). * Denitrification: Anaerobic bacteria convert ammonia back into $N_2$ and $N_2O$ .
Phosphorus Cycle: No atmospheric component. Primary sink is sedimentary rock. Released via weathering. Excess runoff from fertilizers leads to cyanobacteria/algae blooms and hypoxia.
Hydrologic Cycle: * Oceans hold $97\%$ of water; source of $78\%$ of precipitation and $86\%$ of evaporation. * Terms: Condensation, Evaporation, Evapotranspiration, Infiltration, Precipitation, Runoff. * Aquifers: Confined (artesian) vs. Unsaturated zones. Water table is the level where ground is saturated.

1.8 - 1.10: Energy Flow and Productivity

Photosynthesis: Carbon dioxide and light energy used to produce carbohydrates. Plants absorb more $CO_2$ than they emit, acting as net sinks.
Trophic Levels: Position in the food chain.
Second Law of Thermodynamics: Energy transfer results in waste (entropy).
10% Rule: Only roughly $10\%$ of energy is transferred to the next trophic level; the rest is lost as heat.
Solar Energy Distribution: * $35\%$ heats water/land and evaporates water. * $15\%$ reflected to space; $80\%$ absorbed by Earth. * $1\%$ of available solar energy used for photosynthesis.
Productivity: * Gross Primary Production (GPP): Rate at which plants fix chemical energy as biomass. * Net Primary Production (NPP): $NPP = GPP - R$ (where $R$ is respiration).

2.1 - 2.7: Biodiversity and Ecosystem Change

Biodiversity Levels: Genetic, Species, and Ecosystem diversity.
Anthropogenic Loss: Burning fossil fuels ( $pH$ change from acid rain), Deforestation, Overfishing, Pesticides, and GMOs (decreased genetic variation).
Population Bottleneck: Large reduction in population size due to catastrophe, leading to loss of genetic diversity.
Species Types: * Generalist: Varied diet, lives in many environments (e.g., raccoons). * Specialist: Specific habitat/diet (e.g., giant panda).
Island Biogeography: Determined by immigration and extinction. Closer and larger islands have higher biodiversity.
Natural Disruptions: * Volcanoes: Form soil, create early atmosphere, but sulfur gas can cool the troposphere by $2-3\,\text{degrees}$ . * Wildfires: Clear dead vegetation, add nutrients via ash; some plants require fire for life cycles.
Sea Level Change: $30\%$ from glacier melt, $30\%$ from thermal expansion, $40\%$ from coastal land subsidence.
Ecological Succession: * Primary: On barren land (e.g., lava) with no soil; takes > 1000\,\text{years}. * Secondary: Recolonization after disturbance where soil exists; takes $50-200\,\text{years}$ . * Pioneer Species: Mature rapidly, short-lived, generalists ( $r$ -strategists).
Species Roles: * Keystone species: Essential for diversity (e.g., sea stars, grizzly bears). * Indicator species: Reflect environmental health (e.g., lichens for air pollution, mosses for acidic soil).

3.1 - 3.9: Population Dynamics

r-Strategists: Many offspring, low parental care, mature rapidly, small, short-lived, Type III survivorship (e.g., insects).
K-Strategists: Few offspring, high parental care, stabilize near carrying capacity ( $K$ ), larger, long-lived, Type I or II survivorship (e.g., elephants, humans).
Survivorship Curves: * Type I (Late Loss): Most deaths at the end of life span. * Type II (Constant Loss): Uniform death rates. * Type III (Early Loss): Prevalent death for young members.
Growth Curves: * J-Curve: Exponential/logarithmic growth in new environments until crash. * S-Curve: Slows and stabilizes at carrying capacity ( $K$ ) due to environmental resistance.
Rule of 70: Doubling time $dt = \frac{70}{r}$ , where $r$ is growth rate percentage.
Age-Structure Diagrams: * Pyramid: High birth rates, growing population. * Bell: Stable population. * Urn: Declining population (post-reproductive group largest).
Demographic Transition: * Stage 1 (Pre-Industrial): High birth/death rates, low growth. * Stage 2 (Transitional): Death rates drop, population rises rapidly. * Stage 3 (Industrial): Birth rate falls, growth slows. * Stage 4 (Post-Industrial): Zero population growth.

4.1 - 4.9: Earth Systems and Resources

Plate Tectonics: Alfred Wegener's Pangaea theory ( $200\,\text{million}$ years ago). * Convergent: Plates move together, forming subduction zones or orogenic belts (e.g., Cascade Mountains). * Divergent: Plates move apart (e.g., Mid-Atlantic Ridge). * Transform: Plates slide past (e.g., San Andreas fault).
Soil Layers: Surface Litter (O), Topsoil (A), Zone of Leaching (E), Subsoil (B), Weathered Parent Material (C).
Soil Texture: Gravel, Sand (coarse), Loam (mix of clay/sand/silt/humus), Silt (fine), Clay (very fine, low permeability).
Atmosphere Composition: Nitrogen ( $78\%$ ), Oxygen ( $21\%$ ), Water Vapor ( $0-4\%$ ), Carbon Dioxide (< 1\%).
Atmosphere Structure: * Troposphere: $0-6\,\text{miles}$ ( $0-10\,km$ ); where weather occurs; temperature decreases with height. * Stratosphere: $6-30\,\text{miles}$ ( $10-50\,km$ ); contains ozone ( $O_3$ ); temperature increases with altitude.
Wind Patterns: * Coriolis Effect: Causes winds to spiral clockwise (North) or counterclockwise (South). * Hadley Cells: Near equator; high humidity and heavy rain. * Polar Vortex: Low-pressure zone of cold air atop poles.
ENSO (El Niño/Southern Oscillation): * El Niño: Trade winds weaken; warm water piles up off S. America; upwelling decreases/fish die. * La Niña: Stronger trade winds; increased upwelling; cooler sea temperatures.

5.1 - 5.12: Land and Water Use

Tragedy of the Commons: Resource depletion in shared areas (Hardin, 1968).
Agriculture: * Green Revolutions: 1st (fertilizers/pesticides); 2nd (GMOs like BT corn). * Irrigation: Ditch, Drip (most efficient), Flood (cheap), Furrow, Spray. * IPM (Integrated Pest Management): Combines biology/chemistry/physics to control pests; reduces bioaccumulation.
Meat Production: CAFOs (Concentrated Animal Feeding Operations) house large numbers; cause nitrogen/phosphorus pollution.
Urbanization: Movement to cities. Smart growth promotes mixed-use planning and greenbelts.
IPAT Formula: $I = P \times A \times T$ (Impact = Population $\times$ Affluence $\times$ Technology).

6.1 - 6.12: Energy Resources

Units: $1\,HP = 746\,\text{watts}$ . kWh is billing unit.
Fossil Fuels: * Coal Types: Lignite (brown coal), Bituminous (electric power), Anthracite (residential heating). * Fracking: Injecting water/chemicals to fracture bedrock for gas.
Nuclear Power: U-235 fission. Control rods absorb neutrons; Moderator slows neutrons.
Renewables: * Biomass: Anaerobic digestion produces methane. * Solar: Passive (structural features) vs. Active (collectors/pumps). * Hydroelectric: Dams provide $6.5\%$ of US electricity. * Wind: Most efficient electricity production. One megawatt offsets $2,600\,\text{tons}$ of $CO_2$ .

7.1 - 7.8: Atmospheric Pollution

Smog: * Industrial (Gray): Sulfur-based from coal; forms sulfuric acid ( $H_2SO_4$ ). * Photochemical (Brown): Nitrogen-based; catalyzed by UV radiation; forms ozone ( $O_3$ ) and PANs.
Pollutants: CO, Lead, Nitrogen Oxides, Sulfur Dioxide, Particulate Matter ( $PM_x$ ), VOCs.
Acid Rain: Wet/dry deposition of sulfur/nitrogen oxides. Causes acid shock in lakes.
Urban Heat Island: Metropolitan areas warmer than surroundings due to lack of vegetation and heat absorption by asphalt.

8.1 - 8.7: Aquatic and Terrestrial Pollution

Eutrophication: Human-induced nutrient increase. Leads to algal blooms and hypoxia ( $DO$ depletion).
Oil Spills: Microorganisms, dispersants, or skimming used for cleanup.
Water Testing: Alkalinity, BOD (approximate level of biodegradable waste), Coliforms (bacteria from intestines), Turbidity (light scattering).
Waste Disposal: MSW (trash), Hazardous, Radioactive. * Sanitary Landfills: Waste isolated from environment. * Incineration: Conversion to ash/heat.

9.1 - 9.6: Global Change

Ozone Depletion: Caused by CFCs/Halons in stratosphere. Montreal Protocol (1987) phased these out.
Greenhouse Gases: $CO_2$ (fossil fuels), Methane ( $CH_4$ - agriculture/landfills), Nitrous oxide ( $N_2O$ - fertilizers).
Global Warming Effects: Sea level rise from thermal expansion/melting ice. Arctic release of methane from permafrost creates a positive feedback loop.
Ocean Acidification: $CO_2$ reacts with seawater to form carbonic acid; reduces ocean $pH$ .
Invasive Species: High dispersal, generalist diet, rapid reproduction (e.g., Zebra mussels, Water hyacinth).
Endangered Species: High risk of extinction. Factors include specialized diet (Pandas), slow movement (Tortoises), or commercial value (Elephants, Rhinos).