African Physical Geography, Climate, and Biomes

Vocabulary practice flashcards covering African geological history, climatology, precipitation regimes, and Frank White's phytochoria / vegetation centres of endemism.

Craton

An ancient crystalline basement rock formation dating from the Precambrian ($4.6\,\text{Ba} - 541\,\text{Ma}$) and Palaeozoic ($541 - 252\,\text{Ma}$), which may be covered by younger sedimentary rock.

Mesozoic Geological Formations

Geological formations dating from $225 - 65\,\text{Ma}$ that typically comprise marine sediments such as limestones, some of which are located in terrestrial domains and support caves.

Rift Valley

An axis along which continental crust thins out during rifting, leading to breakage that produces faulting, basins (lakes), and shoulders during the Cenozoic ($65\,\text{Ma} - \text{today}$).

Intertropical Convergence Zone (ITCZ)

A band of humidity and low pressure created by intense solar heating that moves north and south across the equator every six months, governing seasonality throughout Africa.

Arid Climate

A climatic category characterized by receiving between $1\,\text{mm}$ and $400\,\text{mm}$ of annual rainfall.

Semi-arid, Subtropical, and Temperate Climates

Climatic classifications characterized by receiving between $400\,\text{mm}$ and $800\,\text{mm}$ of annual rainfall.

Seasonally Dry Climate

A climatic category defined by receiving an annual rainfall between $800\,\text{mm}$ and $1400\,\text{mm}$.

Wet Tropical Climate (Non-seasonal)

A non-seasonal climate classification defined by receiving more than $1400\,\text{mm}$ ($>1400\,\text{mm}$) of annual rainfall.

Phytochoria

Geographic floristic units established on Frank White's 1983 vegetation map of Africa, consisting of regional centres of endemism, regional transition zones, and regional mosaics.

Guineo-Congolian Centre of Endemism

The African rainforest zone located roughly $5^\circ\,\text{N}$ and $5^\circ\,\text{S}$ of the Equator, characterized by a canopy $\ge 30\,\text{m}$ tall, $80\%$ endemic plant species, and $1600 - 2000\,\text{mm}$ of annual rainfall.

Zambezian Centre of Endemism

The richest and most diversified woodland vegetation zone in Africa, located in the tropical summer rainfall zone with tree height $\le 25\,\text{m}$, canopy cover not exceeding $40\%$, and $8500$ plant species ($54\%$ endemic).

Sudanian Centre of Endemism

A narrow woodland belt extending from coastal Senegal to the Ethiopian Highlands, featuring rainfall patterns similar to the Zambezian zone and containing $\le 2750$ plant species, of which one-third ($1/3$) are endemic.

Somalia-Masai Centre of Endemism

A regional centre occupying large sections of East Africa and southern Arabia, characterized by deciduous bushland, thicket, wooded grasslands, trees rarely exceeding $8\,\text{m}$ in height, and annual rainfall often $\le 500\,\text{mm}$.

Serengeti Grassland

A sporadic, infrequently distributed vegetation type that develops wherever woody plants cover less than $10\%$ ($<10\%$) of the landscape and annual rainfall is between $100\,\text{mm}$ and $250\,\text{mm}$.

Wooded Grassland

A vegetation type within the Serengeti and Somalia-Masai ecosystems that develops specifically in areas receiving between $250\,\text{mm}$ and $500\,\text{mm}$ of annual rainfall.

Afromontane Centre of Endemism

An archipelago-like floristic centre confined to high mountains, hosting $4000$ plant species (with abundant ferns and mosses) and experiencing regular nightly and seasonal frosts.

Afro-alpine Bamboo Forest

Dense thickets of giant grasses measuring $2 - 20\,\text{m}$ in height that grow vigorously on deep volcanic soils in alpine regions where annual precipitation exceeds $1250\,\text{mm}$.

Fynbos

An endemic, hard-leaved shrubland plant measuring $1 - 3\,\text{m}$ in height, representing the prevalent vegetation of the Cape and Karoo-Namib Centres of Endemism.

Cape and Karoo-Namib Centres of Endemism

High-elevation floristic centres ($1000 - 1500\,\text{m}$, with peaks $\ge 2000\,\text{m}$) receiving $300 - 2500\,\text{mm}$ (up to $5000\,\text{mm}$) of rainfall, largely devoid of true forest except for small scrub forest patches, and dominated by fynbos.

Desert Biome (Sahara, Namib, Somalia)

Arid regions where precipitation is less than $200\,\text{mm}$ per year, dropping to as low as $10\,\text{mm}$ in extreme areas.