Comprehensive AP Environmental Science Notes (Unit 1)

Unit 1: The Living World – Ecosystems

  • Core idea: ecosystems are dynamic networks of living (biotic) and nonliving (abiotic) components that cycle energy and matter.
  • Key distinctions:
    • Energy flows through ecosystems (inputs/outputs) but is not recycled; matter cycles within biogeochemical cycles.
    • Organisms occupy roles (producers, consumers, decomposers) within trophic structures.
  • System concepts (as taught in this course):
    • Inputs, Processes, Outputs form a system representation of ecosystems (Inputs → Processes → Outputs).
    • Resources (water, nutrients, light, space) influence interactions such as predation, mutualism, commensalism, parasitism, competition.
  • Major units covered (Unit 1 topics):
    • 1.1 Introduction to Ecosystems
    • 1.2 Terrestrial Biomes
    • 1.3 Aquatic Biomes
    • 1.4 The Carbon Cycle
    • 1.5 The Nitrogen Cycle
    • 1.6 The Phosphorus Cycle
    • 1.7 The Hydrologic (Water) Cycle
    • 1.8 Primary Productivity
    • 1.9 Trophic Levels
    • 1.10 Energy Flow and the 10% Rule
    • 1.11 Food Chains and Food Webs
  • Essential knowledge prompts:
    • What is my place in this environmental conundrum?
    • How do biotic and abiotic factors influence biomes across time and space?
    • How do energy flows and biogeochemical cycles inform about change in ecosystems?
  • Key concepts and definitions:
    • Ecosystem: a system formed by the interaction of living organisms with their physical environment.
    • Autotrophs/Producers: organisms that synthesize organic matter from inorganic energy sources (usually sunlight) via photosynthesis or chemosynthesis.
    • Heterotrophs/Consumers: organisms that obtain energy by consuming others.
    • Detritivores and Decomposers: organisms that break down dead organic matter, recycling nutrients.
    • Primary Productivity: rate at which energy from the sun is captured and converted to chemical energy by photosynthetic organisms.
    • Net Primary Productivity (NPP): the energy stored in producers that remains after accounting for respiration. Relationship: ext{NPP} = ext{GPP} - R
    • Gross Primary Productivity (GPP): total rate of photosynthetic production of organic molecules.
    • Trophic levels: producers → primary consumers → secondary consumers → tertiary consumers → detritivores/decomposers (in food web context).
    • Energy Flow in ecosystems: energy decreases as it moves up trophic levels; typically only ~10% of energy is transferred to the next level (the 10% rule).
    • Food Chains vs Food Webs: chains are linear feeding relationships; webs are interconnected networks of who eats whom.
  • Equations and quantitative ideas (LaTeX):
    • Energy transfer across trophic levels (10% rule): E{i+1} = 0.1 imes Ei
    • Primary production and energy budget: ext{NPP} = ext{GPP} - R where R represents respiratory losses by producers.
    • Photosynthesis (simplified overall equation): 6 \, CO2 + 6 \, H2O + ext{light energy} \rightarrow C6H{12}O6 + 6 \, O2
  • Biomes and abiotic/biotic drivers:
    • Terrestrial biomes defined by climate, soil, and dominant life forms (e.g., taiga, temperate forests, tropical forests, desert, tundra, grasslands, etc.).
    • Abiotic factors shaping biomes include temperature, precipitation, light, soil type, and disturbance regimes.
  • Primary productivity and limiting factors:
    • In terrestrial systems, temperature and moisture are primary constraints; in aquatic systems, light and nutrient availability (N, P) are limiting factors.
    • Net primary production varies with climate, nutrient availability, and community structure.
  • Niche, competition, and community structure:
    • Niche: the role of a species in its ecosystem (what it eats, where it lives, how it reproduces).
    • Competitive exclusion principle: two species competing for the same niche cannot stably coexist; niche partitioning reduces overlap.
    • Resource partitioning and realized vs fundamental niches explain coexistence and community diversity.
  • Ecosystem services (link to Unit 9 later): biodiversity and ecosystem processes support provisioning, regulating, supporting, and cultural services that benefit humanity.
  • Labs and activities mentioned (context):
    • Tragedy of the Commons, Berlese Funnel; Ecology Lab activities; Ecological Sampling Lab; X2 Test of Association practice; FRQ 101; Timeline of ESS historical events; Footprints Labs for Units 1 and 2.
  • Connection to real-world relevance:
    • Understanding how energy and matter flow through ecosystems informs resource management, conservation biology, and sustainability planning.
    • The SDGs (page 6) tie into ecosystem stewardship and human well-being across global contexts.

Unit 2: Biodiversity

  • Core concepts:
    • Biodiversity includes species diversity, genetic diversity, and ecosystem diversity (habitat diversity).
    • Abundance (number of individuals per species), Species Richness (number of species in an area), and Biodiversity as variation at genetic, species, and ecosystem levels.
    • Higher biodiversity generally correlates with greater ecosystem stability and resilience.
  • Key metrics and indices:
    • Species Richness (α diversity) = number of species in a given area.
    • Species Evenness (β diversity) = how evenly individuals are distributed among species.
    • Shannon Diversity Index (H') to quantify diversity: H' = - \sum{i=1}^S pi \ln pi, \quad pi = \frac{n_i}{N} where
    • S = number of species,
    • n_i = number of individuals of species i,
    • N = total individuals across all species.
    • Simpson’s Diversity Index (D): D = \sum{i=1}^S pi^2, \quad pi = \frac{ni}{N}; sometimes reported as 1 - D to reflect increasing diversity with higher value.
    • Sequential Comparison Index (SCI): counts order of species observed to estimate diversity (method-specific, illustrated in class materials).
  • Biodiversity in practice:
    • Gorongosa example cited for describing richness, evenness, and the importance of distribution across species.
    • Focus on how habitat diversity, resource heterogeneity, and disturbance regimes influence α, β, and γ diversity.
  • Applications and implications:
    • Biodiversity is a key indicator of ecosystem health and resilience to stressors such as pollution, invasive species, and climate change.
  • Foundational quotes and ideas:
    • Edward O. Wilson quote about biodiversity contributing to ecosystem stability and the world’s balance.

Unit 3: Populations

  • Core ideas (as implied by unit structure and slides):
    • Population size dynamics, carrying capacity, and the factors that regulate population growth.
    • r-selected vs K-selected life history strategies:
    • r-selected: high fecundity, little parental care, high juvenile mortality, rapid population growth (early successional species).
    • K-selected: few offspring, higher parental investment, greater likelihood of reaching adulthood (late successional species).
    • Population growth and resource availability interplay to shape carrying capacity and stability.
  • Invasive species tendency:
    • Invasive species often display r-selected traits and can disrupt native communities by outcompeting incumbents.

Unit 4: Earth Systems and Resources

  • Biogeochemical cycles overview:
    • Carbon Cycle, Nitrogen Cycle, Phosphorus Cycle, Hydrologic (Water) Cycle.
    • Sinks, reservoirs, and processes that transfer elements among air, water, soil, vegetation, and rocks.
  • Law of Conservation of Matter:
    • Matter is recycled in biogeochemical cycles; it is not created or destroyed (energy is dissipated as heat).
    • Cycles are mediated by biological assimilation (uptake by autotrophs), decomposition, weathering, atmosphere–ocean exchange, etc.
  • Specific cycles (highlights):
    • Carbon Cycle: photosynthesis, respiration, decomposition, fossil fuels, combustion; biggest sinks include oceans and fossil fuels as a stored reservoir.
    • Nitrogen Cycle: fixation, nitrification, assimilation, ammonification, denitrification; nitrogen fixation by bacteria (including legume root nodules) converts N2 to ammonia (NH3). An example chemical representation: ext{N}2 + 8 ext{H}^+ + 8 e^- ightarrow 2 ext{NH}3 + ext{H}_2
    • Phosphorus Cycle: geologic sources; no atmospheric phase; major sink in rocks; erosion releases phosphate (PO4^{3-}) into soils and waterways; phosphorus is often a growth-limiting nutrient in aquatic systems; eutrophication can result from excess P.
    • Hydrologic Cycle: evaporation, transpiration, condensation, precipitation, infiltration, runoff, groundwater movement; oceans are the largest reservoir; powered by solar energy; 71% of Earth is covered by water.
  • Limiting factors and productivity:
    • Terrestrial primary productivity limited by temperature and moisture; aquatic productivity limited by light and nutrient availability (N and P).
  • Productivity terminology:
    • GPP: gross primary production; total photosynthetic energy captured.
    • NPP: net primary production; energy stored in biomass after respiration; units: ext{g m}^{-2} ext{yr}^{-1} as a common metric.
  • Daisyworld and Daisyworld-like models are used to illustrate feedbacks between climate and biosphere in simplified systems (conceptual example of Gaia-like feedback).

Unit 5: Land and Water Use

  • Key topics (inferred from slide titles and units):
    • Habitat loss and fragmentation; land-use change and its impact on biodiversity.
    • Sustainable agriculture, irrigation methods, soil formation and erosion, and the Green Revolution.
    • Urbanization and its ecological footprint; methods to reduce environmental harm while supporting human needs.
  • Human impacts and policy notions:
    • HIPPCO (Habitat Loss, Invasive species, Pollution, Population growth, Overexploitation) as a framework for major biodiversity threats.
    • Reserve design considerations for conservation: size, continuity, edge effects, isolation, protection level, uniformity, human pressures.
  • Ecosystem services (Unit 9 context):
    • Biodiversity supports provisioning (food, materials), regulating (climate, flood control), supporting ( nutrient cycling ), and cultural (aesthetic, recreational) services.

Unit 6: Energy Resources and Consumption

  • Energy sources and transitions:
    • Fossil fuels (coal, oil, natural gas) and their environmental impacts.
    • Renewable energy options: wind, solar, hydroelectric, biomass, geothermal, nuclear (as a low-emission option in some analyses).
  • Energy units and efficiency:
    • Energy flow and trophic transfer efficiency; Pyramid concepts (production, biomass, and numbers pyramids).
    • Production efficiency concept: PE = energy stored in growth / energy used in growth and respiration.
  • The Green Revolution and agricultural energy use:
    • Intensification of farming, fertilizer use, and associated energy inputs; implications for sustainability and ecosystem health.
  • Atmospheric and terrestrial pollution connections to energy use:
    • Combustion of fossil fuels releases pollutants; links to acid rain, ozone formation, and climate change.

Unit 7: Atmospheric Pollution

  • Major pollutants and processes:
    • Sulfur oxides (SOx) and nitrogen oxides (NOx) from burning fossil fuels; production of acid rain and deposition; impacts on lichens and ecosystems.
    • Greenhouse gases (CO2, CH4, N2O, fluorinated gases) drive climate change and alter seasonal cycle patterns.
    • Ozone depletion (stratospheric O3) and human-made chlorofluorocarbons historically contributed to ozone layer thinning.
  • Indoor and outdoor pollutants:
    • Indoor air pollutants; photochemical smog formation; thermal inversions.
  • Planetary boundaries context:
    • Nine key planetary boundaries related to climate change, biosphere integrity, land-system change, freshwater use, biogeochemical flows (N, P), ocean acidification, aerosol loading, stratospheric ozone depletion, and novel chemicals. These boundaries indicate tipping points for Earth system stability.

Unit 8: Aquatic and Terrestrial Pollution

  • Water pollution and eutrophication:
    • Excess nutrients (nitrogen, phosphorus) lead to algal blooms, dead zones, and oxygen depletion via microbial decomposition.
    • Distinguish between point-source and non-point-source pollution; sewage and industrial discharges contribute to Biological Oxygen Demand (BOD).
  • Marine vs freshwater pollution:
    • BIOACCUMULATION and BIOMAGNIFICATION concerns with persistent pollutants (POPs, heavy metals) in aquatic food webs.
  • Waste and plastics:
    • Plastic pollution and microplastics as widespread contaminants affecting aquatic and terrestrial ecosystems.

Unit 9: Global Change

  • Mass extinctions and historical context:
    • There have been five major mass extinctions; we are currently in a potential sixth extinction driven by human activities (habitat loss, climate change, invasive species, etc.).
  • Planetary boundaries applied to Global Change:
    • Climate change, biosphere integrity, land-system change, freshwater use, biogeochemical flows, ocean acidification, atmospheric aerosol loading, stratospheric ozone depletion, and novel chemicals.
  • Invasive species and HIPPCO ties to global change:
    • Invasive species spread through global movement and trade; management requires prevention, early detection, rapid response, and adaptation strategies.

Science Practices and Assessment Tools

  • Practices emphasized in AP Environmental Science:
    • Science Practices Concept Explanation
    • Visual Representation (Quizlet)
    • Text Analysis
    • Scientific Experiments
    • Data Analysis
    • Mathematical Routines
    • Environmental Solutions
  • Lab and field expectations:
    • Heavily lab-based course with approximately 25% of time in labs.
    • One formal lab report per semester as a formative assessment; labs will be tested with exam-style questions.
    • Reading load is significant: plan for about 1 hour to 1.5 hours of reading per hour of class.

Exam Format and Scoring (APES)

  • Exam sections:
    • Section I: Multiple Choice – 80 questions, 1 hour 30 minutes, 60% of exam score.
    • Section II: Free Response – 3 questions, 70 minutes, 40% of exam score.
    • Calculator use is allowed for all sections (per the notes).
  • Free Response Question types:
    • Q1: Design an investigation with a scenario and data/model; Q2: Analyze a problem and propose a solution with data/model; Q3: Analyze and perform calculations to propose a solution with an authentic scenario.
  • AP Score interpretation (overview): score of 5 indicates Extremely Well Qualified; 4 Well Qualified; 3 Qualified; 2 Possibly Qualified; 1 No Recommendation.

Labs, Models, and Conceptual Tools

  • Tragedy of the Commons (public-resource management framework)
  • Berlese Funnel (invertebrate sampling technique)
  • Daisyworld (conceptual model of planet-sized feedbacks with a simple biota)
  • Ecological Sampling Lab and X2 Test practice (statistical association tests)
  • Ecosystem service valuation and trade-offs; climate-related modeling and scenario analysis
  • Island Biogeography and keystone species concepts as models for understanding diversity and ecosystem function

Key Formulas and Quick References (for quick study)

  • Net Primary Productivity: ext{NPP} = ext{GPP} - R
  • 10% Energy Transfer Rule: E{i+1} = 0.1 imes Ei
  • Photosynthesis (overall): 6 \, CO2 + 6 \, H2O + ext{light energy} \rightarrow C6H{12}O6 + 6 \, O2
  • Carbon Cycle: major reservoirs include atmosphere, biosphere, oceans, sediments, and fossil fuels; major processes include photosynthesis, respiration, decomposition, combustion, weathering.
  • Nitrogen Cycle: key steps include nitrogen fixation, ammonification, nitrification, assimilation, and denitrification; representative reactions include:
    • Nitrogen fixation (biology): ext{N}2 + 8 \text{H}^+ + 8 e^- \rightarrow 2 \text{NH}3 + \text{H}_2
    • Nitrification/assimilation: NH3 → NO2^- → NO3^-
    • Denitrification: NO3^- → N2
  • Shannon Diversity Index: H' = - \sum{i=1}^S pi \, \ln pi, \quad pi = \frac{n_i}{N}
  • Simpson's Index (common form): D = \sum{i=1}^S pi^2, \quad pi = \frac{ni}{N} and often reported as 1 - D for intuitive diversity interpretation.
  • Biogeochemical cycles note: matter is conserved; energy is dissipated as heat; cycles link the atmosphere, hydrosphere, lithosphere, and biosphere.
  • Primary production productivity units: \text{g m}^{-2} \text{yr}^{-1} for GPP/NPP; energy budgets often expressed in terms of J or g per unit area per year.

Reminders for Exam Preparation

  • Be comfortable tracing energy flow from producers to various consumer levels and identifying where efficiency losses occur (respiration, heat loss).
  • Be able to interpret climatographs and climatograms, including how precipitation and temperature influence biomes.
  • Practice drawing and interpreting pyramids (energy, biomass, and numbers) and calculating trophic efficiency.
  • Be ready to discuss environmental policy contexts (HIPPCO, ecosystem services, biodiversity value) and to apply these concepts to case studies like habitat loss, invasive species, and pollution problems.
  • Review the questions and formats for FRQ sections, including designing investigations, analyzing problems, and performing calculation-based solutions.
  • Understand the role of keystone and indicator species in ecosystem health and how their presence or absence signals ecosystem change.

Quick References to Real-World Relevance

  • The SDGs and sustainable development goals featured (page 6) connect biological concepts to global policy and practical action.
  • Ecosystem services valuation (~provisioning, regulating, supporting, cultural) links biology to economics and ethics in environmental decision-making.
  • Planetary boundaries framework helps contextualize human impacts within a system-wide limits model.
  • Case studies like Mt. St. Helens illustrate succession dynamics and resilience after disturbance, while Surtsey gives insight into primary succession on new land.

About Dr. Bair (Contextual}

  • The slides include information about the instructor, teaching philosophy, and office hours, emphasizing accessibility, student questions, and mock-exam preparation as part of AP ES success.