What type of ecosystem is primarily dominated by grasses rather than large trees?

The ecosystem that is primarily dominated by grasses rather than large trees is best classified as grasslands. Grasslands are characterized by vast open spaces where grasses thrive in the absence of significant tree cover. They typically feature a range of grasses, herbs, and occasional flowering plants, with conditions that support these types of vegetation, including periodic droughts, fires, and varying soil types that favor grass growth.

In contrast, temperate forests host a diverse array of trees and plants, providing a more densely wooded environment. Savannas, while characterized by grasses, also contain scattered trees and are often found in warmer climates, which distinguishes them from true grasslands. Tropical rainforests are lush, dense ecosystems with a high diversity of trees and plant species, which again contrasts sharply with the open, grassy nature of grasslands. Thus, the focus on grasses as the dominant vegetation clearly identifies grasslands as the correct choice.