BIOGEOGRAPHY & EARTH SYSTEMS — EXAM STUDY GUIDE

Biogeography

It looks at where plants and animals live on Earth and why they live there.

Biodiversity

All the different kinds of life in an area — plants, animals, fungi, and even tiny microbes — and how many of each there are.

3 Types of Biodiversity

Species Diversity, Ecosystem Diversity, Genetic Diversity

Species Diversity

how many different species are present in an ecosystem and how large in species each one is (shows how stable an ecosystem is)

Species Abundance

the number of individuals of each species

Ecosystem Diversity

the range of different ecosystems there is such as forests, deserts, wetlands, etc within a region. this just reflects how the biotic (living factors) and abiotic (nonliving factors) adapt to their surroundings.

Genetic Diversity

the genetic variation in a species that explains their ability to adapt and modify to changing conditions around them

High Diversity means ...

ecological stability

Declining Biodiversity means ...

Environmental stress

Tropical rainforests has (High or low Diversity)?

high diversity

Deserts and Tundra have (High or low Diversity)?

Low diversity due to heat

Abiotic (Non-Living) Factors Affecting Plant and Animal Distributions

light, moisture, temperature, wind, soil, topography, and disturbances

Abiotic factor - Light

essential for photosynthesis, affects plant behavior through the amount and timing of light, which influences growth forms, animal migration, and flowering cycles (photoperiodism). Plants growing in low-light environments adapt by growing larger leaves, while plants in extreme light environments adapt by becoming drought-tolerant.

Abiotic factor - Moisture

controls vegetation more strongly than temperature. Desert adaptations: water‑storage tissues, reduced leaf area. Rainforest reliance: continuous high moisture inputs.

Abiotic factor - Temperature

Sets physiological limits; cold climates host fewer species.

Abiotic factor - Wind

Wind increases evaporation and heat loss, shapes how plants grow, and can keep them short or even knock them over. It also spreads seeds and pollen. For animals, wind affects how they fly, find food, and migrate.

Abiotic factor - Soil

Soil affects how deep plants can root, how many nutrients they get, and how much water the ground holds. Different soils support different types of plants. Since animals rely on these plants, soil conditions also influence where animals can live.

Abiotic factor - Topography

Land features like slope and elevation create small climate differences. Sunny slopes are warmer and drier, while shaded ones stay cooler and moister. Big mountain ranges block winds and storms, causing very different climates and plant life on the windward vs. leeward sides.

Abiotic factor - Disturbances

Fires, storms, volcanoes, and human activities change ecosystems by clearing plants, changing the soil, and starting new growth. Some ecosystems get these disturbances often, and many species there are adapted to survive them.

Biological Factors Shaping Distribution

Evolution & Endemism, Migration & Dispersal, Reproductive Success, Population Die‑off & Extinction

Evolution & Endemism

isolation leads to species found only in one region.

Migration & Dispersal

movement across landscapes expands ranges.

Reproductive Success

influences population persistence.

Population Die‑off & Extinction

reduces local diversity and can reshape communities.

Biogeochemical Cycles

The way chemical elements are moved from different organisms and Earth's physical systems

Biogeochemical Cycle - (Hydrologic)

Water movement through the atmosphere, land, organisms, and oceans.

Biogeochemical Cycle - (Carbon)

Photosynthesis ↔ respiration ↔ decomposition ↔ combustion.

Biogeochemical Cycle - (Nitrogen)

Atmospheric N₂ → usable forms (fixation, nitrification, denitrification) → N₂.

Biogeochemical Cycle - (Oxygen)

Release by photosynthesis; removal by respiration & weathering.

Habitat

Physical environment where a species lives.

Niche

The role of a species in its environment — what it eats, where it lives, and how it interacts with other species and its surroundings.

Fundamental Niche

All the conditions and resources a species could use if there were no competition or other limits.

Realized Niche

The conditions and resources a species actually uses in the wild, after competition and other limits are considered.

Endemic Species

Species that are found only in one specific place due to isolation and nowhere else in the world."

Succession

The natural process is where ecosystems change over time, with one group of plants and animals gradually replacing another.

Primary Succession

The process where life starts in a place that had no soil or living organisms, like bare rock, and gradually builds an ecosystem.

Secondary Succession

The process where an ecosystem recovers after it's been disturbed, like after a fire or farming, but the soil is still there.

Net Primary Productivity (NPP)

The amount of energy plants make through photosynthesis is what's left over after they use some for their own growth and maintenance.

Igneous Rock

Rock formed from cooled magma or lava.

Intrusive (plutonic)

Rocks that form when magma cools slowly inside the Earth, creating large, visible crystals.

Extrusive (volcanic)

Rocks that form when lava cools quickly on the Earth's surface, resulting in small or no visible crystals.

Sedimentary Rocks

Rocks are made from layers of sediment pressed together. They're common on land and help us understand past environments and how landscapes changed

Clastic Sedimentary Rocks

Made from broken pieces of other rocks that get squeezed together. (Sandstone)

Chemical Sedimentary Rocks

Formed when minerals dissolve in water and then crystallize again. (Rock Salt)

Organic Sedimentary Rocks

Made from the remains of living things like plants or shells. (Fossils)

Metamorphic Rocks

Rocks changed by heat and pressure into new forms.

Foliated metamorphic rocks

Metamorphic rocks with layered or banded textures caused by pressure aligning the minerals

Non-Foliated Metamorphic Rocks

rocks that do not have a layered or banded appearance

The Rock Cycle: A Dynamic System

The ongoing process where rocks change from one type to another—igneous, sedimentary, and metamorphic—through heat, pressure, melting, and erosion.

1) Weathering produces

sediments

2) erosion....

transports the sediment

3) deposition and lithification create

new sedimentary rock

4) Burial, pressure, and heat lead to

metamorphism

5) melting produces

magma which resets the rock cycle

Classic four-part landform analysis model

A method for studying landforms by looking at: Structure, process, slope, and drainage

Classic four-part landform analysis model: (Structure)

Structure is the type and arrangement of rocks in an area. It includes things like rock layers, faults, and fractures. Structure controls how a landscape forms because some rocks resist erosion better than others. For example, hard igneous rocks can form ridges, while layered sedimentary rocks can create plateaus or slopes. It's the foundation for understanding any landform.

Classic four-part landform analysis model: (Process)

Processes are the forces that shape landforms—like uplift and faulting inside Earth, or weathering and erosion on the surface. These processes work together with rock structure to create different landscape features

Classic four-part landform analysis model: (Slope)

Slope shape and steepness show how structure and processes interact. Strong rocks make steep slopes; weaker ones make gentle slopes. Weathering, mass wasting, and drainage shape slopes, which also respond to climate and vegetation.

Classic four-part landform analysis model: (Drainage)

Drainage refers to the pattern and behavior of streams and rivers across a landscape.

Geologic Time

A very long timescale over which landscapes slowly change.

Lithosphere

The rigid outer layer of Earth, made of the crust and upper mantle forming tectonic plates

Asthenosphere

Weak, partially molten layer enabling plate motion.

Seismic Waves

Vibrations from earthquakes that travel through Earth. Two types, P-Waves and S-Waves

P-Waves

The fastest seismic waves that compress and expand the ground as they move. They travel through solids, liquids, and gases.

S-Waves

Slower seismic waves that move the ground side-to-side. They can only travel through solids, not liquids.

Shadow Zone

Zone where seismic waves do not arrive, proving a liquid core.

Heat originates from...

radioactive decay and leftover energy from planetary formation.

Mantle Convection

The slow, circular movement of hot rock rising and cooler rock sinking in Earth's mantle. This motion determines where crust is created, where it is destroyed, and where compression and extension occur

Divergent Plate Boundaries

where tectonic plates move apart and create a new crust

Divergent Plate Boundaries mainly happen in two main settings ...

Mid-ocean ridges, such as the Mid-Atlantic Ridge, where new oceanic crust forms and continental rifts, such as the East African Rift, where continents thin and may eventually split.

Continental Drift

The idea that Earth's continents slowly move over time.

Seafloor Spreading

Formation of new oceanic crust at ridges.

Convergent Boundary

A place where two tectonic plates move toward each other.

Subduction zones generate...

deep ocean trenches, powerful earthquakes, and explosive volcanic eruptions.

Transform Plate Boundaries

Places where tectonic plates slide past each other sideways

hotspots

Places where very hot material rises from deep inside Earth and melts through the crust, creating volcanoes.

Mantle Plumes

Columns of very hot rock rising from deep in the mantle, which can create hotspots and volcanoes at the surface.

Volcanism

When molten rock, gas, or ash from inside Earth escapes to the surface, forming volcanoes and lava flows.

Magma Chemistry

Mafic, Intermediate, Felsic

Mafic (basaltic)

Dark, low-silica, fast-flowing, and produce less explosive eruptions.

Intermediate (andesitic)

Medium silica, thicker lava, and moderately explosive eruptions.

Felsic (rhyolitic)

High silica, very thick lava, and extremely explosive eruptions.

Viscosity

How thick or sticky a liquid is. In volcanology, it describes how easily magma flows—thicker magma flows slowly and can cause explosive eruptions.

Types of Volcanoes - Shield Volcanoes

Wide, gently sloping volcanoes made from low-viscosity, fast-flowing lava.

Types of Volcanoes - Composite Volcanoes

Tall, steep volcanoes built from alternating layers of lava and ash. Eruptions can be very explosive.

Types of Volcanoes - Cinder Cones

Small, short-lived, steep-sided volcanoes are made from ash, cinders, and rocks that fall around a vent. Eruptions are short but explosive.

Types of Volcanoes - Lava Domes

Rounded, steep mounds formed by thick, slow-moving lava that piles up near a volcanic vent explode violently

lava types - Pahoehoe

smooth, rope-like texture

Lava Types - Aa

rough, blocky texture

Lava Types - Pillow lava

forms underwater

Lava Types - Columnar basalt

forms as thick lava cools and contracts, creating polygonal columns

The Role of Internal Processes

Internal processes like magma movement, earthquakes, and uplift shape Earth's surface by creating mountains, volcanoes, and faults.

Calderas

Large depressions formed by volcanic collapse.

Lahar

Mudflow triggered by volcanic activity.

Weathering

breakdown of rocks at the Earth's surface into smaller pieces - influenced by climate, time, vegetation, and rock type

Driving Agents for Weathering - (Mechanical forces)

temperature fluctuations, ice expansion, and crystal growth

Driving Agents for Weathering - (Chemical Reactions)

involving water, oxygen, carbon dioxide, and dissolved ions.

Driving Agents for Weathering - (Biological Activity)

including root growth, burrowing animals, and microbial processes

Driving Agents for Weathering - (Gravity)

which contributes indirectly by promoting mass movement once the weathering weakens the rock.

How does temperature and pressure cause mechanical weathering?

Minerals expand and contract at different rates due to temperature changes, loosening bonds. Pressure release (unloading) exposes rocks, causing sheets to peel off (exfoliation)