Graduate Ecology Course
Biomes of Earth
Nine modules on Earth’s major ecological zones — climate drivers, vegetation structure, animal communities, biogeochemistry, and conservation status. From equatorial rainforest to polar tundra to the abyssal ocean.
About This Course
A biome is a continental-scale ecological unit defined by climate rather than by geography or taxonomy. Humboldt’s 1799–1804 American expeditions first noticed that similar vegetation forms recur at similar latitudes and altitudes on different continents — the foundational observation for biome classification. Whittaker’s 1975 temperature–precipitation diagram and Holdridge’s life-zone system formalised the quantitative framework.
This course covers the seven classical terrestrial biomes, the principal aquatic systems, and a global synthesis comparing net primary productivity, carbon storage, biodiversity, and climate-change exposure. Each module includes a Python simulation, MathJax derivations of key relationships, and an academic-reference bibliography.
Key Concepts
Kleiber-like NPP Scaling
\( \text{NPP} \propto T \cdot f(\text{P}, \text{PET}) \)
Walter Aridity Index
\( AI = P / \text{PET} \)
Biome Climate Envelope
\( B = f(\text{MAT}, \text{MAP}) \)
C4 Water-Use Efficiency
\( \text{WUE}_{C_4} \gg \text{WUE}_{C_3}\ \text{at high}\ T \)
Permafrost Carbon Stock
\( \sim 1500\ \text{Gt C above}\ T < 0\ {}^\circ\text{C} \)
Arctic Amplification
\( \Delta T_{Arctic} / \Delta T_{global} \approx 2\text{-}4 \)
Nine Modules
M0
Overview & Classification
Humboldt 1799 convergent vegetation, Whittaker T-P diagram, Holdridge life zones, ecological hierarchy, NPP as master variable.
M1
Tropical Rainforests
ITCZ convection 2000 mm/yr, 4-layer vertical stratification, Neotropical-Afrotropical-Indomalayan blocks, latitudinal diversity gradient, Amazon tipping point.
M2
Temperate Forests
Abscisic-acid-driven deciduousness, Alfisols with clay B horizon, East-Asian Pleistocene refugia diversity anomaly, spring ephemerals, bird migration.
M3
Grasslands & Savannas
Fire-grazing-drought disturbance triad, C3/C4 photosynthesis, 8 Mya C4 grass expansion, Serengeti wildebeest migration, below-ground biomass 50-80%.
M4
Deserts
Four formation mechanisms (subtropical high, rain shadow, cold current, continental interior), CAM photosynthesis, kangaroo-rat metabolic water, Sahel desertification.
M5
Boreal Forest (Taiga)
Circumpolar 17 M km², needle-leaf/dark-crown geometry, 550 Gt C in peatlands, 1500 Gt C in permafrost, 10-year lynx-hare Lotka-Volterra cycle.
M6
Tundra
Arctic amplification 2-4× global warming rate, Yedoma permafrost 400 Gt C, cushion-plant microclimate, shrubification, caribou migration disruption.
M7
Aquatic Biomes
Ocean photic/mesopelagic/bathypelagic/abyssal zones, 50% of O2 from phytoplankton, coral Symbiodinium 1°C bleaching, Living Planet Index -84% freshwater.
M8
Global Comparison
NPP bar chart (coral reef 2500 > tropical forest 2200 > desert 45), area-weighted table, RCP8.5 biome-shift projections, further-reading bibliography.
Cross-References
Biomes sit at the crossroads of physical climate, life, evolution, and conservation. Each of these courses on CoursesHub digs deeper into one face of that picture, and several of them are referenced inside the biome modules as you read.
Climate & Earth System
- Climate Science & Physics — radiative transfer, atmospheric dynamics, ocean circulation, GCMs.
- Climate & Biodiversity — how warming reshapes biome boundaries, phenology, the sixth mass extinction.
- Climatology & Meteorology — Köppen classification, monsoons, ITCZ.
- Atmospheric Science — precipitation, lapse rates, boundary-layer dynamics.
- Oceanography — for the marine-biome module.
- Earth Sciences — soils, weathering, biogeochemical cycles.
Biology & Ecology
- Biogeography — Wallace, MacArthur-Wilson island biogeography, regional realms.
- Ecological Biochemistry — allelopathy, mycorrhizae, coral reef chemistry.
- Ocean Biodiversity — pelagic and benthic life across depth.
- Savanna Megafauna — the megafaunal grazers that shape the savanna biome.
- Predators — trophic cascades, Yellowstone wolves, biome-shaping predation.
- Origin of Life — how biomes (and life) bootstrapped on early Earth.
Plants & Trees
- Tree Biophysics — xylem hydraulics, why some forests can grow tall and others can’t.
- Plant Biochemistry — C3/C4/CAM photosynthesis, drought response, secondary metabolites.
- Flower Biology — pollinator co-evolution biome-by-biome.
- Wheat Biophysics — agro-ecology of the temperate-grassland biome.
Animals by biome
- Polar Bears, Polar Penguins, Polar Seals, Emperor Penguin — tundra & polar marine biomes.
- Elephant, Rhinoceros, Giraffe, Hippopotamus — tropical savanna fauna.
- Camel, Reptiles — desert biome adaptations.
- Cetacean, Seal Biophysics — marine biomes from temperate to polar.
- Bird & Monarch Migration — seasonal biome transitions.
- Bees, Ants, Insects, Spiders — arthropod diversity across biomes.