The primary role of herbivores in food webs is to act as primary consumers that transfer energy from producers (plants) to higher trophic levels. By grazing on vegetation, herbivores regulate plant populations, which promotes plant diversity and health. Their feeding behavior can influence soil nutrient cycling and habitat structure, further impacting other species within the ecosystem. This role is vital for maintaining the balance of food webs, supporting predator populations, and contributing to ecosystem resilience.