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Biomes Video Notes — Terrestrial & Aquatic Biomes (Vocabulary Flashcards)

Core concepts and framework

  • Biosphere and biomes: life on Earth is organized into areas with similar features and life communities; terrestrial biomes are characterized by plant communities, which are driven by temperature and precipitation. Biomes are patches across the planet, not isolated single zones.
  • Terrestrial biomes vs aquatic biomes: land-based systems vs freshwater and saltwater systems (oceans, rivers, lakes, wetlands). Both host a variety of organisms and illustrate how climate and environment shape life.
  • Convergent evolution (informal note): similar environmental pressures in different places can lead to similar plant/animal traits in taxa that are not closely related. The instructor notes this concept but says you don’t need to memorize the term for the class; it helps explain why biomes in distant regions may look similar.
  • Visualization tool: plot temperature vs precipitation to visualize how different biomes relate to climate. Some biomes have wide temperature ranges; others have variable precipitation. Temperature (annual average) and precipitation (annual) are key axes shaping plant communities.
  • Climate change context (forward look): biomes are not static in the real world. Climate events (ice ages, glacial cycles) and human activities (CO₂ and greenhouse gas increases) shift biome distributions. Climate models predict gains/losses of forests, desertification, and shifts in agricultural suitability. Impacts on human well-being include agriculture, cities, and resource distribution.
  • Regional patterns in climate change: global averages mask regional differences (e.g., U.S. West Coast vs Southeast). Eastern United States may show different shifts than western regions; climate change effects vary spatially.
  • A second regional visualization: Eastern U.S. study shows shifts from cold-region maples/beech/birch toward more southern-style species (opine, hickory) in some colder regions.

Terrestrial biomes by latitude zones

  • Tropics near the equator: warm and generally wet, with little seasonality in temperature.
  • Temperate zones: distinct seasons, broadly between the tropics and polar regions; more pronounced temperature variation.
  • Polar zones: cold conditions, very short growing seasons, and extreme environments.
  • The equator is termed the tropic zone; moving away yields temperate and then polar zones as latitude increases.

Tropical biomes

  • Tropical rainforest
    • Key traits: very high plant biomass, dense vegetation, high biodiversity, constant solar energy and warmth; soil tends to be poor, but nutrient turnover is rapid because of continuous leaf litter and decay; layers (canopy, understory) create many niches and drive speciation.
    • Climate: very high annual precipitation and high average temperatures; soils not typically nutrient-rich but turnover supports dense biota.
    • Human impact: deforestation leads to nutrient depletion and system degradation; soil is quickly exhausted once cleared.
    • Example visualization notes mentioned: precipitation blue bars and temperature red line in town charts; rainforest shows high precipitation and warmth year-round.
  • Tropical seasonal forest (also called tropical deciduous forest)
    • Key traits: high overall rainfall but with distinct wet and dry seasons; biomass is substantial but varies with seasonality.
    • Plant life is less dense than rainforest due to seasonal moisture swings; evergreen vs deciduous dynamics shift with the seasons.
    • Temperature remains warm year-round, enabling year-round photosynthesis but with seasonal growth patterns.
  • Tropical savanna
    • Key traits: highly seasonal moisture; open grasslands with scattered trees; long dry season with a warm climate.
    • Ecology: open habitat favors large herbivore herds and migratory predators; grass-dominated with large grazing communities; predators also migrate with resources.
    • Classic example used: Botswana; dry summer period with warmth persists.

Temperate zone biomes (dominant in many mid-latitude regions; ~60% of Earth's landmass)

  • Temperate deciduous forest (e.g., much of Eastern United States)
    • Key traits: hardwood-dominated forests; distinct seasons; growing season ranges from 4 to 10 months; moisture varies; historically heavily modified by humans (land clearing, agriculture).
    • Human history impact: by the 1920s much of the Eastern U.S. forest had been cleared; forests regrew but in altered states with invasive species, disease, and insects (e.g., chestnut blight eliminated a large portion of American chestnut).
    • Massachusetts example: relatively consistent precipitation with notable temperature variations and seasonal patterns; climate change could alter moisture and temperature regimes.
  • Temperate evergreen (conifers; often called temperate coniferous forests)
    • Dominant trees: cone-bearing evergreens; dry-season influence drives conifer dominance in some regions; some areas have temperate rainforest characteristics (e.g., parts of Oregon/Washington).
    • Fire regimes: fire historically part of the system; fire suppression has altered species like sequoias; contemporary management emphasizes prescribed fire to maintain ecosystem health.
    • Notable geography: coastal western U.S. and parts of Canada; includes dry summer climates with less rainfall than deciduous zones.
  • Chaparral (Mediterranean-type scrub)
    • Key traits: low-water, drought-tolerant vegetation with fire-adapted species; thick cuticles, succulents, and adaptations to conserve water; regular cyclic fire is typical.
    • Example imagery: scrubby, dense, fire-prone landscapes; Santa Barbara region as a reference.
  • Temperate grasslands (e.g., North American prairies; steppe regions)
    • Key traits: too dry for dense forests but not dry enough for deserts; cold winters, moderate to low precipitation that supports grasses; much of the original grassland has been converted to agriculture.
    • Ecological notes: prairie dogs aerate soil, fix nitrogen via associated plants, and serve as food for predators; keystone species relationships include the black-footed ferret and prairie chicken.
    • Regional example: Central United States (Kansas pictured) with a distinct seasonal climate and grassland productivity.
  • Additional temperate examples (regional notes)
    • Southern Chile fescue-dominated, drought-adapted grasslands; high herbivore support; diverse plant communities in open grasslands.

Polar biomes

  • Boreal forest (taiga)
    • Location: northern North America (Canada) and similar latitudes; conifer-dominated forests.
    • Climate: very cold, wet enough to support trees; growing season < 4 ext{ months}; permafrost is present at depth.
    • Permafrost: permanently frozen soil layer; limits root depth and plant life; a key constraint shaping ecosystem structure.
  • Tundra
    • Climate: extremely cold and dry; very short growing season; no large trees due to permafrost and cold soils.
    • Characteristics: barren-looking, with small plants and specialized adaptations to cold/global conditions; permafrost underlies the soil and trees are largely absent.
  • Polar ice zone
    • Features: extreme cold; life adapted to icy conditions; organisms such as penguins (in some polar regions) exhibit unique reproductive and migratory strategies; many life forms adapted to insulation and aquatic lifestyles.

Desert biomes

  • Desert (hot and cold varieties; present in tropics, temperate zones, and polar regions)
    • Key trait: extreme dryness defines desert ecosystems; may experience long dry spells (e.g., up to 3 ext{ years}) without rainfall.
    • Plant adaptations: water storage (cacti, succulents); drought tolerance; slow growth and rare flowering after rain events.
    • Animal adaptations: high efficiency water use; nocturnal or burrowing lifestyles; many organisms can survive long periods without water.
    • Examples: Sonoran Desert with cacti; kangaroo rats; grasshopper mice as notable desert fauna.

Mountains and coastlines as habitat modifiers

  • Mountains (not biomes themselves, but ecologically influential)
    • Elevation gradients create temperature drops with altitude, enabling multiple biomes along a single mountain (e.g., Chaparral at lower elevations, Temperate Evergreen higher up, Boreal Forest near the peaks).
    • Rain shadow effect: moisture from oceans rises, cools, and precipitates on windward sides; leeward sides become drier, often hosting deserts; this drives distinct habitat patterns on opposite slopes.
    • Tectonics: mountain ranges form via plate tectonics; different ranges have different ages (e.g., Rockies are relatively young and sharp; Appalachians are ancient and eroded).
  • Coastlines
    • Salt tolerance and wind adaptation: coastal plants evolve salt tolerance and wind-resilience (e.g., live oaks in coastal Georgia; palm trees with reduced branching for wind resistance).
    • Dune stabilization: species like sea oats stabilize dunes; mangroves stabilize coastlines in tropical regions and help reduce erosion.
    • Interactions with land: coasts create unique habitats where terrestrial and aquatic systems interact, influencing biodiversity and ecosystem services.

Freshwater biomes

  • Overview: two-thirds of Earth’s surface is water; freshwater is only a small fraction but highly valued for ecosystems and humans.
  • Freshwater distribution and salinity
    • Global water distribution: ext{Earth's surface water} imes ext{(majority saline)}
      ightarrow ext{Oceans dominate; freshwater is limited}
    • Ocean share: rac{2}{3} of Earth’s water is in oceans; the oceans account for the majority of Earth’s water resource.
    • Salinity contrast: marine salinity ≈ 3.5 ext{ ext{%}}, freshwater salinity ≈ 0.005 ext{ ext{–}}0.0 ext{ ext{5%}}; freshwater contains far less salt but is vital for life and agriculture.
  • Streams and rivers
    • Perennial streams: flow year-round (e.g., Chattahoochee River).
    • Intermittent streams: flow only during precipitation events; dry for most of the year.
    • Channel and riparian zone: water channel plus banks with sediment and a riparian plant community that stabilizes banks, shades the water, and provides detritus for food webs.
    • Ecological importance: riparian vegetation stabilizes soils, shades streams, supplies organic debris for aquatic food webs, and helps filter nutrients.
    • Floodplains: periodically flood; sediment settles during overflow, creating nutrient-rich soils ideal for agriculture but riskier for human development; important for flood control and sediment/nutrient cycling.
    • Human impacts: deforestation and erosion increase flood damage and sediment loads; damming alters sediment flow and downstream ecology.
  • Lakes and ponds
    • Definitions: lakes are bodies of water (> 5 ext{ ha}); ponds are smaller; open vs closed basins depend on inflow/outflow.
    • Volume and lifespan: lakes are numerous (hundreds of millions of inland bodies of water); open basins can store large volumes; many lakes have lifespans on the order of up to 10^6 years (natural contexts); artificial reservoirs fill with sediment more quickly.
    • Littoral zone: zone where water meets land; shallow waters with abundant light support rich plant and invertebrate communities; high productivity and strong interface with terrestrial ecosystems.
  • Wetlands
    • Definition: areas where soil is saturated for long periods; waterlogged soils create low-oxygen conditions; hydrophyte plants dominate;
    • Ecosystem services: store water, recharge groundwater, slow water flow, flood control, improve water quality by filtering nutrients and contaminants, and provide wildlife habitat.
    • Major types:
    • Marshes: periodically or continuously flooded; dominated by herbaceous plants (grasses); coastal marshes (salt marshes) along coasts; inland marshes exist as well.
    • Swamps: dominated by woody plants; flood-tlooded or waterlogged; high groundwater recharge, diverse reptiles, and rich biodiversity; include coastal mangrove swamps and temperate swamp systems.
    • Bogs: highly acidic soils; defined by sphagnum moss and peat; low nutrient availability; support carnivorous plants adapted to low-nutrient environments.
    • Fens: less acidic than bogs; receive nutrients from groundwater and rock leaching; higher nutrients than bogs; important habitat for many species; example: Everglades (large fen-like wetland in Florida).
  • Carnivorous plants in wetlands
    • Carnivory in plants: photosynthetic but nutrient-poor soils drive insects/other organisms to supplement nutrients (N, P, K, Mg, Mn, etc.).
    • Common types: Venus flytrap, sundews, pitcher plants, bladderworts; each has different trapping mechanisms (trigger hairs, sticky trapping surfaces, downward hairs, slippery edges, nectar lures).
    • Notable examples: Venus flytrap native to North Carolina; pitcher plants in Georgia and the Southeastern U.S.; sundews and bladderworts widespread in bogs and wetlands.
    • Reproductive strategies: some carnivorous plants flower before pitchers develop to avoid capturing pollinators; other species separate flowering and pitcher development in time or space to minimize pollinator capture.
    • Conservation concerns: carnivorous plants are often threatened by habitat loss and poaching; bogs and pitcher-plant habitats are fragmenting due to development and agriculture.

Estuaries

  • Definition: zones where freshwater from rivers meets saltwater from oceans; brackish water supports unique communities.
  • Key features: shallow, high light penetration supports productive photosynthesis; juvenile stages of many marine species use estuaries as nurseries due to shelter and food availability.
  • Importance to humans: fisheries and shellfish industries; estuaries provide flood/storm surge protection, sediment and nutrient absorption, and filtration similar to wetlands.
  • Ecological connectivity: estuaries connect rivers to oceans and link terrestrial, freshwater, and marine ecosystems.

Oceanic biomes and processes

  • Intertidal zone
    • Location: coastline where ocean meets land; alternates between submerged and exposed with tides.
    • Biodiversity: highly diverse and specialized communities; organisms cope with changing salinity, moisture, and temperature.
  • Coral reefs
    • Distribution: largely in tropical regions near the equator, typically within roughly ext{±}20^ ext{o} of the equator; warm water is essential for coral growth.
    • Functions and services: complex habitats supporting vast biodiversity; protect coastlines from erosion; support fisheries; carbon cycling and nutrient dynamics; tourism and cultural value.
    • Current concerns: reefs are declining in many areas due to warming oceans, acidification, pollution, and overfishing; the Great Barrier Reef is a widely publicized example of decline.
  • Sharks as apex predators and keystone species
    • Role: apex predators with cascading effects on marine ecosystems; keystone species that help maintain balance in biodiversity and predator–prey dynamics.
    • Threats: overfishing and removal of sharks can cause outbreaks of other species (e.g., cow-nose rays) and reduce overall biodiversity; efforts to protect sharks are important for ecosystem stability.
  • Rays and mating strategies in the ocean
    • Mobula (mobular) rays: example of reproductive strategy where populations group to mate; exploring how males attract females and how females respond.
    • Concept: grouping for reproduction can create signals that help individuals stand out; study of these dynamics illustrates mate selection in wide, open marine environments.
  • Global scale facts about oceans
    • Oceans cover 71 ext{ ext%} of Earth's surface and contain rac{2}{3} of Earth's water in total; they have powerful control over climate and weather patterns through heat and moisture transport.
    • Salinity contrast: oceans are saltier (3.5 ext{ ext%}) than freshwater (0.005 ext{ ext%} to very low), influencing organism distributions and chemical processes.
    • Ocean–climate interactions: oceans absorb carbon dioxide, influence temperature, and are warming and expanding in some areas, driving sea-level rise; ongoing studies on how ocean chemistry and circulation affect global climate.
  • Intertidal zone as contact with land
    • These zones exhibit extreme environmental changes with tides, affecting salinity, moisture, and temperature; organisms display unique adaptations to cope with rapid changes.

Coral reefs and broader oceanic context (recap of key points)

  • Coral reefs are concentrated in tropical zones; they provide critical ecosystem services and are indicators of ocean health.
  • Sharks and rays illustrate how apex predators and mating strategies operate in marine systems, and how human impacts can ripple through food webs.
  • The vast ocean serves as a global climate engine, shaping temperature and precipitation patterns across continents and oceans.

Climate change and biome shifts: synthesis

  • Biome stability is challenged by climate change: warming, altered precipitation, and shifting growing seasons modify plant communities and ecosystem function.
  • Arctic changes may lead to forest expansion into areas historically tundra or boreal zones; some regions may experience forest gains, others desertification or biome reorganization.
  • Regional variability matters: some areas within a biome may experience different rates of change due to local factors (e.g., soil, moisture, fire regimes).
  • Human systems and biomes are tightly linked: agriculture, urban development, and resource extraction depend on stable biome distributions; shifts can affect food security, water resources, and biodiversity.

Quick reference: numerical and definitional anchors (LaTeX-formatted)

  • Global land and water distribution:
    • Ocean cover: 0.71 \ ( ext{or } 71 ext{\%}) of Earth's surface.
    • Freshwater share (overall): 0.01 \ ( ext{approximately } 0.01 ext{\% of all freshwater}) of Earth’s water in lakes and rivers is accessible freshwater? (Note: overall freshwater is a tiny fraction of total water)
    • Seawater salinity: 3.5\%
    • Freshwater salinity (typical): 0.005\%\ ( ext{or } 0.00005)
  • Lake and pond metrics:
    • Lake size threshold: > 5 \text{ ha} means a body of water is labeled a lake; smaller bodies are ponds.
    • Largest lakes statistic: a note on open basins and landforms; lakes often have lifespans up to \sim 10^6 \text{ years} under natural conditions.
  • Growing seasons:
    • Temperate deciduous zones: growing season ranges from 4 \text{ to } 10 \text{ months}.
    • Boreal/tundra zones: growing seasons often < 4 \text{ months} (tundra) or even shorter in extreme regions.
  • Vegetation and biomes:
    • Deserts: dryness is the defining feature; can be hot or cold; plant adaptations include water storage and drought tolerance.
    • Chaparral: Mediterranean scrub with fire-adapted species and drought-tolerant traits (thick cuticles, succulents).
    • Rain shadows: moisture-laden air loses its moisture on the windward side of mountains, producing wetter habitats there and drier habitats leeward.
  • Ecosystem services (wetlands, estuaries, oceans):
    • Water storage, flood control, groundwater recharge, sediment and nutrient cycling, water purification, fisheries support, habitat for biodiversity.

Study tips and connections

  • Link climate to plant communities: always consider how temperature and precipitation drive dominant plants, which then define animal communities and ecosystem processes.
  • Visualize climate space: use the precipitation vs temperature concept to place each biome and understand gradients near biome borders.
  • Think about humans in the system: deforestation, urbanization, dams, and climate change all alter biome boundaries, productivity, and ecosystem services.
  • Carnivorous plants as a case study: adaptions to nutrient-poor soils show how organisms balance photosynthesis with nutrient scavenging in wetlands.
  • marine ecology takeaways: apex predators such as sharks maintain ecological balance; coral reefs provide habitat and protect coastlines but are vulnerable to warming and acidification.

Quick glossary (selected terms)

  • Riparian zone: the interface between land and a river or stream where vegetation stabilizes banks and provides habitat.
  • Littoral zone: shallow area along the shore where light reaches the bottom, supporting abundant plant and animal life.
  • Estuary: transition zone where freshwater mixes with seawater; nutrient turnover and juvenile habitats are common.
  • Permafrost: permanently frozen soil layer found in boreal and polar regions.
  • Convergent evolution: independent evolution of similar features in species of different lineages due to similar environmental pressures (not required to memorize, but useful for understanding biome similarities).
  • Keystone species: a species with a disproportionate effect on its environment relative to its abundance (e.g., sharks in marine ecosystems).
  • Floodplain: flat area around a river channel that is regularly flooded, contributing to nutrient-rich soils and fertile agricultural land.

Notes on how these ideas connect to your coursework

  • The modules build from global-scale climate drivers to regional patterns and then to specific biomes and organisms, tying ecological theory to real-world examples (e.g., chestnut blight, prairie dogs, mangroves, coral reefs).
  • Climate change discussion provides a forward-looking context: understanding biomes helps anticipate water, food, and habitat security challenges.
  • The material emphasizes both the diversity of life and the processes that shape that diversity (disturbance regimes, nutrient cycling, fire, water flow, sediment transport).