What does it mean for an ecosystem to be described as "highly productive"?

An ecosystem described as "highly productive" indicates that it exhibits a large total biomass over time. This productivity is typically the result of a combination of high rates of photosynthesis, efficient nutrient cycling, and favorable environmental conditions that support a wide array of plant and animal life.

In highly productive ecosystems, such as tropical rainforests or coral reefs, the abundance of primary producers (like plants and algae) leads to a significant accumulation of organic material, which can support a diverse array of consumers, including herbivores and predators. This high biomass not only signifies the health and sustainability of the ecosystem but also its ability to produce food, oxygen, and habitat for other organisms.

The other options reflect characteristics that do not necessarily align with high productivity. For instance, low biodiversity and the presence of only a few species can indicate a stressed or unstable ecosystem, while minimal nutrient cycling often leads to lower productivity. Therefore, the hallmark of a highly productive ecosystem is its ability to sustain a large total biomass over time through effective processes that support growth and diversity.