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How do dead grass and wood return nutrients to savanna ecosystems?
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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, dead grass and wood return nutrients to the soil primarily through two processes: decomposition and fire.1
- Decomposition: A significant portion of dead organic matter, including grass and wood, is broken down by termites. These insects are responsible for decomposing approximately 30 percent of such matter. Additionally, soil microorganisms like bacteria and fungi play a vital role in recycling chemical elements by breaking down organic matter, which releases nutrients back into the soil for future plant uptake.23
- Fire: Savannas are characterized by frequent wildfires, which are often fueled by dried grass. These fires rapidly consume dead plant material, releasing mineral nutrients that are then available for reuse in subsequent plant growth.21
This rapid nutrient turnover is essential for maintaining the savanna's biological productivity, as it allows the ecosystem to efficiently recycle resources despite the generally low fertility of the soil.21