savanas

Savannas are tropical grassland ecosystems characterized by a continuous cover of grasses with widely spaced trees or shrubs. They occur in regions with pronounced wet and dry seasons and are found across Africa, South America, Australia, and parts of Asia. Annual rainfall typically ranges from about 400 to 1,500 millimeters, with a long dry season that limits tree growth and favors grasses. Fire and herbivory are central factors in maintaining the landscape, as periodic fires reduce woody encroachment and promote nutrient cycling.

The vegetation is adapted to fire and drought. Grasses are persistent and often have deep root systems, while many trees resprout after fire. Soils in savannas are frequently nutrient-poor and can experience leaching during the wet season, which influences species composition and productivity. The balance between grasses and scattered trees creates a mosaic of open habitats and woody patches that supports unique ecological dynamics.

Savannas support a diverse array of wildlife. In Africa, large herbivores such as zebras, wildebeest, gazelles, elephants, and giraffes feed on grasses and shrubs, with predators including lions and cheetahs present in the ecosystem. In the Americas and Australia, savanna-like landscapes host different assemblages of mammals, birds, and reptiles, with migrations and seasonal movements closely tied to rainfall and forage availability. Fire regimes, grazing pressure, and climate variability drive ongoing changes in structure and composition.

Human use and conservation are important aspects of savannas. They are widely used for pastoralism, grazing, and agriculture, and are vulnerable to land conversion, overgrazing, and fire management changes. Conservation efforts focus on protected areas, sustainable grazing practices, fire management, and restoration of degraded savannas to preserve biodiversity, ecosystem services, and cultural values.