What are ecosystem engineers?

Ecosystem engineers are fundamentally species that create, modify, or maintain habitats in a way that significantly influences ecosystem structure and functionality. These organisms play a crucial role in shaping their environment through their physical activities, such as dam-building beavers that create ponds and wetlands, or trees that alter soil structure and provide habitats for various other species.

By changing the physical characteristics of their environment, ecosystem engineers can increase habitat complexity, create new niches, and improve resource availability, benefiting a diverse range of other species. This can lead to enhanced biodiversity in the ecosystem, as various organisms may rely on the habitat or resources created by the engineer species.

In contrast, the other options do not accurately describe ecosystem engineers. Competing species share resources without changing the habitat, while predators primarily focus on food sources rather than habitat modification. Decomposing fungi, although vital for nutrient cycling, do not create or maintain habitats in a broad ecological sense akin to what ecosystem engineers do. Thus, the definition of ecosystem engineers aligns closely with species that actively shape their habitats, making the correct option about species that create and maintain habitats clear and relevant.