Final answer:
In a temperate forest ecosystem, wolves preying on beavers are consumers, specifically carnivores, that can also act as keystone species significantly impacting the ecosystem's structure and biodiversity.
Step-by-step explanation:
In a temperate forest ecosystem, where wolves prey heavily on beavers, the wolves act as consumers within the food chain. Specifically, they are considered carnivores, which are animals that feed on other animals. The beavers, in contrast, are herbivores that feed on trees and aquatic plants, making them primary consumers. Wolves impact the abundance and distribution of their prey and can therefore play a significant role as keystone species, influencing the overall structure and biodiversity of their ecosystem. Their predation can release pressure on vegetation from herbivory, leading to changes in the composition and abundance of plant and animal species present.