Deserts of Planet Earth

Introduction

• Deserts: Stark landscapes with minimal vegetation, revealing Earth's "bones."
• Found worldwide from the Sahara to Sonora, Gibson to Gobi.
• Defined by lack of water and sparse vegetation.

Biome Characteristics

• Definition: Deserts have bare earth, either between plants or completely bare.
• Classification: Using LONS08; distinguished from scrublands that have full grass coverage.
• Largest Biome: Largest land area of any biome, present on every continent.

Types of Deserts

• Subdivisions:
  • Hot and Cold
  • Arid and Semi-arid
• Hot Deserts: Subtropical, mild winters, hot summers.
• Cold Deserts: Temperate zones, hot summers, extremely cold winters.
• Koppen Climate Zones: Hot deserts in BWh and BSh; Cold deserts in BWk and BSk.

Climate and Geography

• Aridity Index: Highest in hot deserts; ratio of evapotranspiration to available water.
• Geological Features:
  • Exposed rocks reveal colors: white (sodium/calcium), red (iron), black (basalt), beige (sandstone).
  • Temperature variation leads to rock weathering and sand dune formation.
  • Ergs: Large desert sand areas like Taklamakan in Central Asia.

Salt and Plant Adaptations

• Salt in Deserts: Rivers deposit salt; ancient seas formed salt lakes.
• Adaptations:
  • Halophytes: Salt-tolerant plants.
  • Xerophytes: Drought-resistant, retain moisture, close stomata.
  • Succulents: Store water, thick stems (e.g., cacti).

Notable Deserts

• North America: Great Basin (cool), Mojave, Sonoran, Chihuahuan (hot).
• South America: Atacama (driest), Patagonia (cool).
• Africa: Sahara (largest), Namib, Kalahari.
• Asia: Arabian, Syrian, Iranian, Thar, Gobi (cold).
• Australia: Semi-arid, "red centre."

Flora in Deserts

• Widespread Families:
  • Daisy, Frankenia, Artemisia (sagebrush), Chenopodium, Atriplex (saltbushes).
• Regional Variants:
  • South America: Sparse in Atacama, shrubs in Patagonia.
  • Africa/Middle East/Asia: Wormwood, Tamarisk, date palms.
  • Australia: Spinifex, Bush tomato, Desert Oak.
  • North America: Saguaro Cactus, Blue Agave, Joshua Tree, Creosote Bush.

Desert Wildlife

• Limited due to lack of vegetation.
• Mostly reptiles and insects (snakes, scorpions).

Cultural Impact

• Deserts inspire art and literature (e.g., Arabian Nights, Western genre).
• Unique beauty and cultural significance.

Conclusion

• Deserts are a significant biome with unique characteristics and adaptations.
• Stay tuned for the next episode on grasslands.