Midterm #1 Review Terms to Know

Tundra

• Absence of trees; grasses, mosses, lichen

• Extreme cold; little precipitation

• Soil poor in nutrients; permafrost

• N. of Arctic Circle; high-latitude; polar regions

• N. America, Asia, & Europe

Taiga (aka coniferous forest or boreal forest)

• Evergreen forests; conifers -> pine, fir, spruce

• Largest biome on Earth

• Cold; moderate precipitation; acidic soils

• High northern latitudes

• N. America, Asia, & Europe

Temperate Forest

• Deciduous (leaf-bearing) broadleaved trees

• Experience all 4 seasons

• Moderate precipitation; nutrient-dense soils

• N. & S. of Equator; mid-latitudes

• N. America, Asia, Europe

Tropical Rain Forest

• Broadleaved trees; very biodiverse

• Warm temps; copious rainfall

• Nutrients in biomass -> soils nutrient-poor

• Found near Equator

• S. America, Africa, Asia

Tropical Savanna

• Grasslands; scattered trees & shrubs

• Warm temps; distinct wet & dry seasons

• Porous, acidic soil

• N. & S. of Equator; low-latitudes near tropics

• S. America, Africa, Asia, Australia

Temperate Grassland

• Absence of trees; herbaceous plants -> grasses

• Moderate temp; seasonal & dry

• Soils deep & rich in organic matter

• N. & S. of Equator; mid-latitudes

• N. America, Asia, Europe

Desert

• Support very little plant life

• High, variable temps; very little precipitation

• Bare rock or sand dunes

• N. & S. of Equator; low-latitudes; subtropics

• Africa, Asia, Australia

Maquis (aka chaparral)

• Scrubby evergreen underbrush

• Hot, dry summers; cool, moist winters

• Soil low in nutrients

• N. & S. of Equator; mid-latitudes; along Mediterranean shores

• Africa, Asia, Europe

Biome

• Large community of plants & animals

• Defined by unique climate, weather, & soil type

Environment

• Made up of living (biotic) & non-living (abiotic) factors & conditions

• 4 interrelated spheres: lithosphere, atmosphere, hydrosphere, & biosphere

Lithosphere

• Rigid, outermost solid shell of Earth

• Composed of continental & oceanic crust + upper brittle mantle

• Divided into major & minor tectonic plates that float & move around

• Rock cycle provides soil, rock, & minerals

Atmosphere

• Envelope of gases surrounding Earth held close by gravity; temp changes w/ altitude

• Composed primarily of nitrogen (78%) & oxygen (21%) w/ other trace gases

• Divided into troposphere, stratosphere, mesosphere, & thermosphere

• Blocks harmful solar radiation, traps heat, provides oxygen to breathe, + other services

Hydrosphere

• Combined total mass of water found on, under, & above surface

• Composed of liquid water (oceans, lakes, rivers), solid frozen ice (glaciers, ice caps), & gaseous atmospheric water vapor

• Oceans contain ~97% of Earth’s water (saltwater)

  • Freshwater accounts for remaining 3%, most is frozen & unavailable for use

• Drives global hydrological cycle, regulates climate, provides crucial habitats for aquatic ecosystems

Biosphere

• Made up of all living organisms (biotic components, flora & fauna) & their interactions w/ physical environments

• Encompasses portions of lower atmosphere, hydrosphere, & upper lithosphere where life exists

• Driven by primary production (autotrophs converting solar or chemical energy into organic biomass to fuel the ecosystem)

• Connected via food webs; transferring energy & nutrients from primary producers through consumers to decomposers

Climate Archive

• Time series of measurements w/ sufficient length, consistency, & continuity to determine climate variability & change

• Sedimentary rocks are #1 archive scientists use to reconstruct past climates

• Other natural archives (proxies) incl. coral reefs (limestone), tree rings, sediment cores, & ice cores

Theory of Plate Tectonics

• Earth’s rigid outer shell (lithosphere) is broken into several large & small plates moving relative to one another

• Movement of rock slabs across globe can release extensive amounts of CO₂

• Drives geological processes at plate boundaries (convergent, divergent, transform)

Convergent Plate Boundary

• Plates move toward each other; Earth’s crust is destroyed

• Aka subduction zone; commonly found on margins of continental land masses

• Map symbol teeth point in direction that subducting plat (dense oceanic crust) is moving

Divergent Plate Boundary

• Plates move away from each other; new crust is created

• Aka spreading center or mid-ocean ridge (ex: Mid-Atlantic Ridge)

• Most in deep ocean; form long volcanic mountain chains (longest mountain ranges on Earth)

Transform Fault

• Plates slide horizontally past one another; crust neither created nor destroyed

• Almost all transform boundaries are in deep ocean & connect offset divergent boundaries

Lapse Rate

• Rate at which air temp decreases w/ height/altitude

• Sunlight warms surface, warming air above it; as distance from surface increases, temp decreases

• Present in troposphere & mesosphere

Temperature Inversion

• Phenomenon where air temp increases w/ height/altitude

• Occurs when warm air sits above denser, colder air

• Present in stratosphere (warmed by ozone absorbing UV) & thermosphere (warmed by absorbing X-rays/gamma rays)

Troposphere

• Lowest atmospheric layer (0-15 km); held to planet by gravity; mainly composed of N₂ & O₂

• Name from Greek topos = mixing (convection); vertical currents over-turning air

• Characterized by standard lapse rate

• Where all weather & climate occurs; majority of clouds & water vapor occur here

Stratosphere

• 15-50 km; held to planet by gravity; mainly composed of N₂ & O₂

• Air flow is horizontal (back & forth)

• Characterized by temp inversion

• Contains ozone layer (O₃) which filters/absorbs harmful UV radiation; warming

Mesosphere

• 50-90 km; held to planet by gravity; mainly composed of N₂ & O₂

• Characterized by lapse rate

• Protects from extraterrestrial impacts; vaporizing ~40 tons of meteors daily

Thermosphere

• 90-500 km; held to planet by gravity; mainly composed of N₂ & O₂

• Characterized by temp inversion

• Absorbs most energetic photons (X-rays & gamma rays)

• Where auroras take place

Evaporation

• Phase change of water from liquid to gas

• Cools surrounding environment

• Largest hydrologic flows occur directly between oceans & atmosphere

Condensation

• Phase change of water from gas to liquid

• Warms surrounding environment

• Water vapor attached to dust particles (condensation nuclei) to form clouds

Precipitation

• Water particles falling from sky in liquid or solid form (ex: rain, snow, hail)

• Occurs when cloud particles grow too large to remain suspended

• Requires condensation nuclei in troposphere to form

Transpiration

• Process where plants take in water through roots & release moisture + oxygen into atmosphere

• Occurs through stomata on underside of leaves

• Water transported up plant via xylem & down via phloem

Sublimation

• Direct phase change of water from solid to gas

• Ex: glacial ice converting directly to vapor

Deposition

• Direct phase change of water from gas to solid

• Ex: frost forming on windshield

Stomata

• Tiny openings/pores on back/underside of plant leaves (singular: stoma)

• Allow plants to release water vapor (transpiration) & oxygen during gas exchange

Interspecific Competition

• Competition for shared limited resources between members of different species w/in a community

Intraspecific Competition

• Competition for shared, limited resources between members of the same species w/in a community

Food Web

• Interlinked network of food chains showing feeding interactions among species in ecological community

• Transfers energy & nutrients from primary producers through consumers to decomposers

• Greater species diversity/complexity increases food web stability by providing alternative energy pathways

Primary Producer

• Autotrophic organisms converting solar or chemical energy + CO2 into organic biomass (carbohydrates)

• Forms base of every food web via photosynthesis (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂)

Primary Consumer

• Herbivores/grazers that feed directly on primary producers

Secondary Consumer

• Carnivores that feed on primary consumers/herbivores

Tertiary Consumer

• Top carnivores that feed on secondary consumers

• Exist at high trophic levels w/ small population sizes, making them more vulnerable to habitat loss & extinction

Predator

• Species that hunt, kill, & consume prey

• Regulates prey populations & can exert top-down control across lower trophic levels

Grazer

• Herbivorous organism that feeds on primary producers (plants, algae)

Consumer

• Heterotrophic organisms that feed on other organisms for energy & nutrients

• Subdivided into primary, secondary, & tertiary

Decomposer

• Scavenger organisms (ex: bacteria, fungi, water mold) that feed on nonliving organic matter/dead organisms

• Breaks down organic waste to recycle nutrients back into ecosystem

Detritus

• Nonliving particulate organic matter (ex: feathers, fecal matter, decaying plant/animal tissue)

Trophic Level

• Position or feeding stage an organism occupies w/in a food chain/web

• Trophic level efficiency is ~10% (90% lost as heat, respiration, & waste)

• Biomass & available energy decrease w/ each higher level; top levels have fewer indvs

Trophic Cascade

• Indirect influence of top predators across multiple lower trophic levels

• Eradicating top carnivores causes herbivore populations to explode, leading to overconsumption of primary producers

Canis lupus

• Scientific name for grey wolf; acts as keystone species in N. American ecosystems

• Preys on elk to regulate herbivore numbers

• Reintroduction to Yellowstone (1995) relieved grazing pressure, allowing aspen trees & habitat to rebound via trophic cascade

Cervus canadensis

• Scientific name for elk; primary consumer/herbivore in N. American forest ecosystems

• Preyed upon by grey wolf

• Skyrocketed in population when wolves were eradicated, causing severe overgrazing of aspen trees

Biodiversity

• Variability among living organisms on Earth, incl. w/in, & between species & ecosystems

• Key to ecosystem stability; complex food webs w/ high biodiversity withstand species loss better