What stops the grassland from becoming forestry?

Grasslands are typically maintained by factors such as periodic fires, grazing by herbivores, and climatic conditions that inhibit tree growth. Fire removes young saplings and prevents tree establishment, while grazing pressure keeps vegetation short and reduces competition for resources. Additionally, grasslands often have soil and moisture conditions that favor grasses over trees, making it challenging for forests to take hold. Together, these elements create a stable ecosystem that supports grassland rather than forest growth.