Britannica Sources used in this answer

Why is much of a savanna’s plant biomass found below the ground?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Flat savanna plain with scattered acacia trees under a partly cloudy sky in Serengeti National Park, Tanzania. — Savanna A savanna marked with acacia trees in Serengeti National Park, Tanzania. Africa's Serengeti Plain is commonly used as an example of the savanna biome—a hot, seasonally dry ecological region characterized by an open tree canopy (i.e., scattered trees) above an understory of continuous grasses.

In savanna ecosystems, a significant portion of plant biomass is located below the ground primarily as an adaptation to the marked seasonal variations in moisture and the prevalence of wildfire.12

While aboveground plant parts, such as grasses, often die back or dry out during the long dry season, the subterranean organs—including roots and tubers—remain protected from these harsh surface conditions. This belowground storage provides a more stable environment where the contrast in food availability is less extreme than on the surface.2

Additionally, many savanna plants have evolved to regenerate quickly from buds located underground or beneath thick bark following fire events. Because these subterranean structures are shielded from the heat of fires that frequently sweep across the landscape, they allow plants to survive and recover effectively once the wet season returns. Consequently, in some regions, the belowground biomass can be up to four times greater than the aboveground component, particularly during the dry season.12