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

BPSC / BSSC — World Geography Mind Map Series

🧪 Soil Science — Pedology

Pedalfer Soil

  • Rich in Aluminium (Al) and Iron (Fe)
  • Very fertile, dark brown or black soil
  • 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 Occurs in low-latitude regions (high rainfall areas)
🪨 Soil Strata (Horizons)
O HorizonOrganic layer (humus, decomposed matter)
A HorizonTopsoil (mineral + organic mix)
B HorizonSubsoil (mineral accumulation / illuviation)
C HorizonWeathered parent rock (regolith)
⚠ 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 RainforestGreen throughout the year, broad leaves • Rainfall more than 200 cm • Equatorial/tropical regions – Indonesia, Brazil, etc. • Amazon Rainforest ("Lungs of the Earth") • Home to the Anaconda, world's largest snake
Tropical Deciduous Forest (Monsoon Forest)Trees shed leaves in a specific season • Major trees: Sal, Teak, Neem, Shisham
Temperate Deciduous ForestMajor trees: Maple, Elm, Ash • Home to Pheasant and Monal birds
Temperate Evergreen ForestCoastal regions of middle latitudes • Bamboo, Pine and Eucalyptus trees • Commonly used in social forestry
Coniferous Forest / Taiga ForestEvergreen trees with soft wood • Pine, Deodar trees • Home to animals like the Polar bear
Tundra ForestCovered with snow • Vegetation limited to mosses, lichens and algae (no large trees)
📌 Mountain forests Broad-leaved coniferous trees found here
📌 Herbicide A weedkiller, used to destroy unwanted plants
⚠ Exam Trap
Amazon Rainforest = "Lungs of the Earth" (Tropical Evergreen); Taiga = Coniferous, softwood forest with Pine/Deodar — two very different forest biomes, don't mix their signature facts.
🌿 Natural Vegetation
  • Natural Vegetation depends on temperature and humidity
📂 Major Vegetation Types of the World
Vegetation TypeRegion / Details
TropophyteTropical climatic region vegetation
HygrophyteEquatorial tropical humid (marshy) region vegetation
XerophyteDesert region vegetation
HydrophyteWaterlogged region vegetation
HalophyteVegetation of saline regions
LithophyteVegetation growing on hard rocks
MesophyteVegetation of temperate region
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)
  • Parkland (South Africa)
  • Llanos (Venezuela and Colombia)

Temperate Grasslands

  • Prairies (USA and Canada)
  • Pampas (Argentina)
  • Veld (South Africa)
  • Downs (Australia)
  • Steppe (Asia — Manchuria region of China and Russia)
  • Pustaz (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)
Lungs of the EarthAmazon Rainforest
World's largest snakeAnaconda (Tropical Rainforest)
Taiga = Coniferous ForestEvergreen, soft wood, Pine, Deodar, Polar bear
Tundra vegetationMosses, lichens and algae (no large trees)
SavannaTropical grassland – Africa
PrairiesTemperate grassland – USA and Canada
PampasTemperate grassland – Argentina
SteppeTemperate grassland – Asia, Manchuria (China and Russia)
PustazTemperate 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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