AP Environmental Science
Unit 1: Ecosystems
1.1 Intro to Ecosystems
In a predator-prey relationship, predators are organisms that eat another organism (prey
Symbiosis is a close and long-term interaction between two different species in an ecosystem
Competition can occur within or between species in an ecosystem where there are limited resources
Resource partitioning, using resources in different ways, places, or times, reduces competition
1.2 Terrestrial Biomes
Biomes contain characteristic communities of plants and animals that result from and adapted to its climate
Terrestrial biomes include taiga, temperate rainforests, temperature seasonal forests, tropical rainforests, shrubland, temperate grassland, savanna, desert, and tundra
Global distribution of nonmineral terrestrial natural resources like water and trees vary because of combination of climate, geography, latitude and altitude, nutrient availability, and soil
Worlwide distribution of biomes constantly changes (and has changed in the past) due to global climate changes
1.3 Aquatic Biomes
Freshwater biomes include streams, rivers, ponds, lakes, all vital resources for drinking water
Marine biomes include oceans, coral reefs, marshland, and estuaries
Algae in marine biomes supply a large portion of Earth’s oxygen and take in carbon dioxide from the atmosphere
Global distribution of marine natural resources like fish vary because of combination of salinity, depth, turbidity, nutrient availability, temperature
1.4 The Carbon Cycle
The carbon cycle is the movement of carbon between sources and sinks
Some of the reservoirs where carbon occurs hold carbon for long periods of time, while some hold them for short periods
Carbon cycles between photosynthesis and cellular respiration in living things
Plant and animal decomposition → storage of carbon over millions of years
Burning of fossil fuels quickly moves stored carbon into carbon dioxide (atmospheric carbon)
1.5 The Nitrogen Cycle
The nitrogen cycle is the movement of nitrogen between sources and sinks
Microorganisms in the soil play major role
Nitrogen fixation → assimilation → ammonification → nitrification → denitrification
In nitrogen fixation atmospheric nitrogen is converted by soil bacteria into ammonia → ammonia in the soil converts to ammonium, which can be taken by organisms
Availability of nitrogen compounds in the soil is limited by rate of nitrogen fixation, limits primary production by plants and other producers
The largest reservoir of nitrogen is the atmosphere, most reservoirs where nitrogen occur hold nitrogen for short periods of time
1.6 The Phosphorus Cycle
The phosphorus cycle is the movement of phosphorus between sources and sinks
Major reservoirs of phosphorus are rock and ocean sediments that have phosphorus-bearing minerals
Phosphorus cycle lacks a significant atmospheric omponent
Phosphorus is scarce in ecosystems because rocks weather slowly → phosphorus limiting nutrient for plants and producers, particularly in freshwater/some terrestrial ecosystems
1.7 The Hydrologic (Water) Cycle
The hydrologic cycle is the movement of water in its solid, liquid, and gas forms between sources and sinks
The oceans are the primary reservoir of water at the Earth’s surface, ice caps and groundwater are smaller reservoirs
1.8 Primary Productivity
Primary productivity is the rate at which sunlight is converted itno organic compounds via photosynthesis over a unit of time
Gross primary productivity is the total rate of photosynthesis in a given area
Net primary productivity is the rate of energy storage by photosynthesizeres in a given area, after subtracting energy lost due to respiration
Productivity is measured in units of energy per unit are per unit time (ex: kcal/m²/yr)
Most red light is absorbed in the upper 1m of water, blue light only penetrates deeper than 100m → affects photosynthesis in aquatic ecosystems where photosynthesizers adapted to address lack of visible light
1.9 Trophic Levels
All ecosystems depend on a continuous flow of energy in order to maintain structure and transfer of matter between environment and organisms via biogeochemical cycles
Biogeochemical cycles are essential for life, each cycle demonstrates conservation of matter
In terrestrial and near-surface marine ecosystems energy flows from the sun to producers in the lowest trophic levels and then upward to higher trophic levels
1.10 Energy Flow and the 10% Rule
Only about 10% of energy is transferred from one trophic level to the next
Loss of energy that occurs when energy moves to higher levels can be explained through the laws of thermodynamics
1.11 Food Chains and Food Webs
Food chains depict the flow of energy and matter from producers to consumers
Food webs are models of interlocking patterns of food chains that depict the flow of energy and matter in two or more food chains
Detritivores and decomposers play an essential role in food chains/webs by returning nutrients to soil
Positive and negative feedback loops can play a role in food webs, when one species is removed from or added to a web, the rest of the web can be affected
Unit 2: Biodiversity
2.1 Introduction to Biodiversity
Biodiversity in an ecosystem involved genetic diversity, species diversity, and habitat diversity
The more genetically diverse a population is, the better it can respond to environmental stressors
Population bottlenecks can lead to loss of genetic diversity
Ecosystems that have large numbers of species are more likely to recover to disruptions
Species richess is the number of different species in an ecosystem
Loss of habitat → loss of specialist species → loss of generalist spoecies → reduced numbers of species that have large territorial requirements
2.2 Ecosystem Services
There are 4 types of ecosystem services: provisioning, regulating, cultural, supporting
Human activities can disrupt ecosystem services → economic, ecological consequences
2.3 Island Biogeography
Island biogeography is the study of ecological relationships and the distribution of organisms on islands, and these organisms’ community structures
Islands have been colonized in the past by new species coming from elsewhere
Many island species have became specialists/generalists because of limited resources on most islands
Long term survival of specialists may be troubled by invasive species (typically generalists), which outcompete specialists
2.4 Ecological Tolerance
Ecological tolerance is the range of conditions that an organism can endure before injury or death
Can apply to individuals and species
2.5 Natural Disruptions to Ecosystems
Natural distruptions to ecosystems have consequences that can be greater than human disruptions
Earth system processes can be periodic, episodic, or random
Earth’s climate has changed over geological time for many reasons
Sea level has changed due to changes in glacial ice amount on Earth
Major environmental change → major habitat change
Wildlife engages in migration for a variety of reasons, including natural disruptions
2.6 Adaptations
Natural selection causes populations to adapt to their environment over genertions
Environmental changes may threaten a species’ survival, requiring individuals to alter adapt, move, or die
2.7 Ecological Succession
There are two types of ecological succession: primary and secondary succession
A keystone species is a species whose activities have a significant role in determining the ecosystem’s community
An indicator species is a species that by its presence, abundance, scarcity, or chemical composition, demonstrates an aspect of the quality of an ecosystem
Pioneer members of an early successional species commonly move into unoccupied habitat and over time adapt to its particular conditions, resulting in the origin of new species
Succession in a disturbed ecosystem will affect biomass, species richness, and net productivity over time
Unit 3: Population
3.1 Generalist and Specialist Species
Specialist species are advantaged in habitats that have constant conditions
Generalist species are advantaged in habitats that have changing conditions
3.2 K-Selected r-Selected Species
K-selected species tend to be large, few offspring per reproduction event, live in stable environments, expend lots of energy for each offspring, mature after many years of youth, have long life spans, reproduce more tan once in their life, have parental care, competiton in K-selected habitats are high
More affected by invasive species
R-selected species tend to be small, many offspring, expend little energy for each offspring, mature early, have short life spans, may produce only once in their lifetime, competition for resoruces in r-selected habitats are low
Less affected by invasive species, typically are the invasive species
Biotic potential is the maximum reproductive rate of a population in ideal conditions
Many species are not uniquely r or K selected, or changes strategies in different conditions
3.3 Survivorship Curves
Survivorship curves are lines that displays the relative survival rates of individuals of the same age in a population, from birth to max age
There are Type I, Type II, Type III curves, with K-selected species typically having a type I or II curve and r-selected having type III curve
3.4 Carrying Capacity
When a population exceeds carrying capacity (K), overshoot occurs
Population overshoot → resource depletion due to famine, disease, competiton → dieback of population
3.5 Population Growth and Resource Availability
Population growth is limited by limiting factors, like resources and space
Resource availability and total resources are limited
Abundance of resources → population growth accelerates
Shrinking of resources → unequal distribution of resources, increased deaths, decreased fertility, population growth decline
3.6 Age Structure Diagrams
Population growth rates can be shown from age structure diagram shapes
A rapidly growing population will have a higher proportion of younger people compared to stable or declining populations
3.7 Total Fertility Rate
Total fertility rate (TFR) is affected by age where females have first child, education for females, family planning, government acts and policies
If fertility rate is at replacement levels, population is considered stable
Factors associated with infant mortality rates include if motehrs ahvea ccess to good healthcare and nutrition
Changes → changes in infant mortality rates
3.8 Human Population Dynamics
Human population growth determined by birth/death/immigration/emigration rates
Birth/death rates affected by education, family planing, healthcare, nutrition
Malthusian theory identifies Earth’s global population will be limited and will reach carrying capacity
Population growth affected by density-dependent and density-independent factors
Rate of natural increase (RNI) measures population growth or decline, calculated by subtracting crude death rate from birth rate
Doubling time is found by dividing 70 by the annual population growth rate expressed as percentage
3.9 Demographic Transition
Demographic transition is the transition from high to lower birth and death rates in a place as development occurs
Demonstrated through DTM 4-stage model
Developing countries have higher infant mortality rates, more children in workforce than developed countries
Unit 4: Earth Systems and Resources
4.1 Plate Tectonics
Convergent boundaries result in the creation of mountains, island arcs, earthquakes, volcanoes
Divergent boundaries result in seafloor spreading, rift valleys, volcanoes, and earthquakes,
Transform boundaries can result in earthquakes
Maps that show plate boundaries can determine location of volcanoes, island arcs, earthquakes, hot spots, and faults
Earthquakes occur when stress overcomes a locked fault, releasing stored energy
4.2 Soil Formation and Erosion
Soils are formed when parent material is weathered, transported, and deposited
Soils are catergorized by horizons based on their composition and organic material
Soil can be eroded by wind or water
Protecting soil can protect water quality as soil filter and clean water that moves through them
4.3 Soil Composition and Properties
Water holding capacity varies with different soil types
Water retention contributed to land productivity and fertility of soil
Particle size and composition of soil horizon affects porosity, permeability, and fertility of soil
There are methods to test chemical, physical, biological properties of soil
Soil texture triangles allow identification and comparison of soil types based on percentages of clay, silt, and sand
Loam consists of clay, silt, and sand that can support a variety of crops
4.4 Earth’s Atmosphere
The atmosphere is made of up major gases, each with its own relative abundance
The layers of the atmosphere are based on temperature gradients, include the troposphere, stratosphere, mesosphere, thermosphere, and exosphere
4.5 Global Wind Patterns
Global wind patterns result from the most intense solar radiation arriving at the equator, resutling in density differences and the Coriolis effect
4.6 Watersheds
Characteristics of a watershed include area, length, slope, soil, vegetation types, and divides with adjacent watersheds