geography unit 2

Define habitat (macrohabitat)

The natural environment in which an organism lives, used at a large scale to mean a broad environmental category defined by certain plants and climate conditions.

Define microhabitat and microclimate

A smaller-scale environment within a macrohabitat (e.g., the cooler part of a tree canopy near the trunk) where local environmental conditions differ from the surrounding area.

Define lithology

The physical characteristics of rocks and geological formations in an area (e.g., sedimentary rock, unconsolidated sediments, evaporites, metamorphic rock, volcanics).

Define bioclimate

Climate conditions defined specifically by temperature and precipitation patterns (annual averages and seasonal extremes).

three main regional classification systems for habitats

Ecoregions: Created by the US EPA; nested into 4 hierarchical levels based on plants, landforms, soils, and climate

Ecological Land Units (ELUs): Created by the USGS and ESRI on a 250m grid based on bioclimate, landforms, lithology, and land cover.

Biomes: Very large-scale classifications defined primarily by bioclimate axes on land and light/depth/distance to land in oceans.

What are examples of landforms used to define ecological regions?

Flat plains, escarpments, hills, low mountains, high mountains/deep canyons, and surface water (lakes/reservoirs).

What are examples of land cover types?

Bare ground, urban areas, shrubland, grassland, cropland, open forest, closed forest, snow/ice, and water.

bioclimate axes

mean annual temperature (y-axis, tracking latitude) and mean annual precipitation (x-axis)

deciduous forests vs. rain forests

Deciduous forests: Receive moderate annual precipitation; trees drop their leaves seasonally (autumn/winter) as an adaptation to cold or dry conditions.

Rain forests: Receive the highest precipitation of any biome; remain green and active year-round with extremely high productivity.

temperate forests vs. tropical forests

Temperate forests: Grow in mid-latitudes with moderate average temperatures and distinct seasonal temperature changes (cold winters, warm summers, or rainy seasons).

Tropical forests: Grow near the equator with hot average temperatures that remain relatively constant

Describe the Tundra biome

Cold, dry areas located between the treeline and ice caps. Features low-growing plants (lichens, mosses), low species diversity, low productivity, and high vulnerability to climate change (permafrost thaw).

Describe the Desert biome

Defined by receiving less than 50 cm of precipitation per year. Features high amounts of bare ground, low productivity, and organisms uniquely adapted to extreme water scarcity. Most occur between 20 to 30 degrees North or South latitude.

Describe the Savanna biome

Hot, dry areas featuring a mixed woodland and grassland structure (open canopy with scattered trees like African acacias or Australian eucalyptus). Prone to frequent fires (every 1 to 5 years).

Describe the Boreal Forest (Taiga)

Coniferous forest found exclusively in the Northern Hemisphere (due to lack of landmass at equivalent southern latitudes). Accounts for roughly one-third of all global forests.

What percentage of Earth's surface and primary production comes from the oceans?

Oceans cover 70% of Earth's surface, hold 97% of its water, and account for 50% of global primary production.

What proportion of marine species depend on coral reefs?

25% of all marine species live in coral reefs at some point in their life cycle.

Name the 5 oceans

Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean.

Define the Neritic zone

The shallow coastal water zone where light reaches the ocean floor, encompassing highly productive ecosystems like estuaries, lagoons, and coral reefs.

Pelagic vs. Benthic zones

Pelagic: The open water column above the seafloor.

Benthic: The ecological region at the very bottom (sea floor), including sediment and organisms living on or burrowing in it.

Define the Abyssal zone

The deep-sea region of the open ocean (2,000 to 6,000 meters deep or more) characterized by complete darkness, near-freezing temperatures, and high pressure.

Define coral reefs

Durable physical structures built over thousands of years by colonies of tiny coral polyps interacting in a symbiotic relationship with photosynthetic algae (zooxanthellae).

Define hydrothermal vents

Deep-sea vents where chemoautotrophic bacteria use inorganic chemicals (like hydrogen sulfide) as an energy source instead of sunlight, supporting a unique food web independent of the sun.

Symbiotic relationship

A close, physical partnership between two species where both typically benefit.

Superorganism

A colony of individual organisms (like coral polyps) functioning collectively as a single unified entity.

Bioluminescence

The production and emission of light by living organisms, common in deep-sea species for mating or attracting prey.

Metapopulation

A group of spatially separated populations of the same species that interact through individual movement.

Dispersal

The movement of individuals between habitat patches.

Connectivity

The degree to which landscape patches are connected by dispersal.

Source

A habitat patch where reproduction exceeds mortality, producing excess individuals that emigrate to other patches.

Sink

A habitat patch where local reproduction is insufficient to maintain the population; it persists only through continuous immigration from sources.

Equilibrium species richness (S)

The predictable number of species on an island where the rate of new species immigration equals the rate of local extinction.

Rescue effect

The process where immigration from a nearby source population boosts a declining island population, preventing local extinction.

Species-Area Effect

larger geographic areas/islands host a greater number of species because they encompass more diverse ecoregions and resources, which lowers extinction rates.

How do island size and distance to the mainland affect immigration and extinction curves?

Distance (Isolation): Near islands have higher immigration rates than far islands because travel is easier. (lower extinction rates)

Area (Size): Large islands have lower extinction rates than small islands because they offer more resources and less competitive exclusion. (higher immigration rates)

What are examples of oceanic dispersal mechanisms?

Swimming, flying, hitching a ride on mobile animals (birds/turtles), floating, rafting on floating logs/vegetation, or drifting on human-made debris (e.g., tsunami debris).

Habitat fragmentation

The division of once-continuous, widespread habitats into smaller, isolated patches due to human land-use changes (roads, cities, agriculture).

Inbreeding depression

A loss of biological fitness in small, isolated populations due to the mating of closely related individuals, which accumulates harmful recessive genes and reduces genetic diversity.

What are the primary structural components of an effective wildlife crossing system?

Overpasses: Wide vegetated bridges preferred by large mammals (like elk and deer).

Underpasses: Ground-level bridge clearances preferred by species like cougars.

Tunnels: Enclosed, dark, moist underground routes designed for amphibians, reptiles, and small mammals.

Fencing/Exclusion systems: Tall fencing along highways that channels wandering animals directly to crossings.

What are examples of negative impacts of wind power on biodiversity?

Habitat fragmentation from access roads, introduction of invasive plant species along disturbed corridors, and high mortality rates from bird and bat collisions with wind turbines placed along ridgeline wildlife corridors.

What is the significance of the Wallis Annenberg / Liberty Canyon Wildlife Crossing?

It is a massive wildlife overpass built across the 101 freeway in Southern California to reconnect the fragmented habitats of the Santa Monica Mountains and Simi Hills. Its primary ambassador species is the mountain lion (exemplified by the late P-22), and it was made possible through extensive public-private partnerships involving state agencies, federal groups, non-profits, and private philanthropy.