Xerophytic Features: Plants have adapted to survive long droughts through features like deep taproots to reach low water tables, thick corky bark to reduce transpiration, and the ability to shed leaves (deciduousness) during the dry season.
Pyrophytic Nature: Many savanna grasses and trees are fire-resistant; grasses often grow in thick tufts with dormant buds protected underground, allowing rapid regrowth after a fire has cleared the surface.
Storage Organs: Trees like the Baobab have evolved swollen trunks to store thousands of liters of water, acting as a reservoir during the months of drought.
Herbivore Diversity: The savanna supports the world's greatest diversity of hoofed mammals (ungulates), such as zebras, wildebeests, and giraffes, which utilize different 'grazing niches' to avoid direct competition.
Migration Patterns: Large herds undertake massive seasonal migrations, following the rains to find fresh grass and water sources as local supplies vanish during the dry season.
Predator-Prey Balance: High herbivore density supports a large population of carnivores (lions, cheetahs, hyenas), creating a complex food web that is highly sensitive to changes in water availability.
| Feature | Savanna (Tropical Grassland) | Steppe (Temperate Grassland) |
|---|---|---|
| Temperature | Hot year-round () | Extreme seasonal range ( to ) |
| Trees | Scattered, drought-resistant trees | Virtually treeless due to low moisture/cold |
| Seasons | Wet and Dry seasons | Four distinct seasons (Spring, Summer, Autumn, Winter) |
| Soil | Acidic, thin organic layer, nutrient-poor | Highly fertile, deep organic humus (Chernozem) |
Identify Limiting Factors: When asked why savannas don't become forests, always cite the combination of seasonal water deficit, fire frequency, and herbivore pressure (grazing/browsing).
Analyze the Ecocline: Remember that vegetation height and density decrease as you move away from the equator; 'Wooded Savanna' is closest to the rainforest, while 'Grass Savanna' is closest to the desert.
Adaptation Links: Be prepared to link specific plant features (e.g., umbrella canopy) to environmental stressors (e.g., high insolation and water loss).
