🌱 SOILS AND NATURAL VEGETATION OF THE WORLD World Geography · Ch 22

SSC / Railway / UPSC / BPSC — World Geography Mind Map Series

🧪 Soil Science — Pedology

Pedalfer Soil

  • Rich in Aluminium (Al) and Iron (Fe)
  • Legacy humid/leached-soil concept; colour and fertility vary.
  • Common in temperate, eastern parts of USA

Pedocal Soil

  • Rich in Calcium (Ca)
  • Forms in drier, temperate areas — grasslands and bushes are the usual vegetation
📌 Leaching process Promoted by humid, high-rainfall conditions and percolating water; not restricted to low latitudes.
🪨 Soil Strata (Horizons)
O HorizonOrganic layer (humus, decomposed matter)
A HorizonTopsoil (mineral + organic mix)
B HorizonSubsoil (mineral accumulation / illuviation)
C HorizonRelatively little-altered parent material; regolith is a broader term.
⚠ Exam Trap
The A Horizon is the true Topsoil (not "subsoil"); the B Horizon is the actual Subsoil where leached minerals accumulate — these two are frequently swapped.
📉 Soil Erosion / Degradation / Deterioration

Transfer of Fertile Elements

Loss of topsoil by wind, water, or human activity leading to reduced agricultural productivity

Decrease in Soil Quality

Salinity of soil due to excessive irrigation • Loss of nutrients

🛡️ Soil Conservation Methods
MethodDetails
MulchingLaying organic layers like straw on the ground between crops
Crop RotationAlternating different crops in the same field each season to maintain soil fertility
Contour PloughingPloughing along the contour lines of the slope to reduce water runoff
Shelter BeltRows of trees planted to protect soil from wind erosion
Rock DamProtecting drains with heaps of rocks • Preventing soil erosion
📌 Azolla Increases soil fertility in paddy cultivation
⚡ Quick Recall
Shelter Belts guard against wind erosion; Contour Ploughing guards against water runoff erosion — different methods target different erosion agents.
🌳 Major Types of Forests
Forest TypeKey Features
Tropical Evergreen RainforestEvergreen broad-leaved tropical rainforest; Amazon’s ‘Lungs of the Earth’ is a popular metaphor, not a literal oxygen-balance claim. Green anacondas occur in tropical South American wetlands/river systems.
Tropical Deciduous Forest (Monsoon Forest)Trees shed leaves in a specific season • Major trees: Sal, Teak, Neem, Shisham
Temperate Deciduous ForestSeasonally leaf-shedding broadleaf forests, e.g. maple, elm and ash; monal is associated especially with Himalayan montane habitats.
Temperate Evergreen ForestBroad category in mild temperate climates; composition varies and can include broad-leaved or coniferous evergreens.
Coniferous Forest / Taiga ForestHigh-latitude boreal/coniferous forest; typical genera: spruce, fir, pine and larch. Polar bears primarily inhabit Arctic sea-ice/coastal environments.
Tundra (Largely Treeless Biome)Low shrubs, sedges, grasses, mosses and lichens; large trees generally absent.
📌 Mountain forests Mountain vegetation varies with altitude/region; broad-leaved and coniferous forests occur in different belts.
📌 Herbicide A weedkiller, used to destroy unwanted plants
⚠ Exam Trap
Amazon: tropical evergreen broadleaf rainforest (‘Lungs’ is a metaphor); taiga: boreal coniferous forest with spruce, fir, pine and larch.
🌿 Natural Vegetation
  • Natural Vegetation depends on temperature and humidity
📂 Major Vegetation Types of the World
Vegetation TypeRegion / Details
TropophyteAdapted to alternating wet and dry seasons
HygrophyteMoisture-loving plants of very humid/wet terrestrial habitats
XerophyteDesert region vegetation
HydrophyteWaterlogged region vegetation
HalophyteVegetation of saline regions
LithophyteVegetation growing on hard rocks
MesophytePlants adapted to moderate moisture
CryophyteVegetation of tundra and cold region
⚡ Quick Recall
Xerophyte (desert, dry) and Hydrophyte (waterlogged, wet) are opposite extremes on the moisture spectrum of vegetation types.
🌾 Grasslands

Tropical Grasslands

  • Savanna (Africa)
  • Campos (Brazil)
  • Bushveld / savanna (South Africa); parkland describes scattered-tree structure.
  • Llanos (Venezuela and Colombia)

Temperate Grasslands

  • Prairies (USA and Canada)
  • Pampas (Argentina)
  • Veld (South Africa)
  • Downs (Australia)
  • Eurasian Steppe: eastern Europe through Russia/Kazakhstan toward Mongolia and northern China
  • Puszta (Hungary)
⚠ Exam Trap
"Selvas" refers to the dense Amazon rainforest region, not a grassland — don't confuse it with Llanos or Campos, which are the true South American grasslands.
📝 Quick Reference — Key Facts
FactDetails
Soil SciencePedology
Pedalfer SoilRich in Aluminium (Al) and Iron (Fe)
Pedocal SoilRich in Calcium (Ca)
Popular Amazon Nickname (Metaphor)Amazon Rainforest
Wetland / Rainforest River-System SnakeGreen anaconda — tropical South American wetlands/river systems
Taiga = Coniferous ForestBoreal conifers: spruce, fir, pine, larch; polar bear is not defining taiga fauna.
Tundra vegetationMosses, lichens, sedges, grasses and dwarf shrubs; largely treeless
SavannaTropical grassland – Africa
PrairiesTemperate grassland – USA and Canada
PampasTemperate grassland – Argentina
SteppeBroad Eurasian temperate grassland belt
PusztaTemperate grassland – Hungary
VeldTemperate grassland – South Africa
DownsTemperate grassland – Australia
⚡ Quick Recall
Each continent has its own name for temperate grassland: Prairies (N. America), Pampas (S. America), Steppe (Asia), Veld (Africa), Downs (Australia), Pustaz (Europe/Hungary).
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