What defines the maximum number of organisms that can be sustained in an environment over a long period?

The correct answer relates directly to the concept of carrying capacity, which refers to the maximum number of individuals of a particular species that an environment can support sustainably over time. This concept is essential in ecology because it helps to determine the balance between the available resources (such as food, water, and habitat space) and the needs of the population. When a population exceeds its carrying capacity, it can lead to resource depletion, habitat destruction, and ultimately a decline in the population as individuals may compete for dwindling resources.

Understanding carrying capacity is crucial in managing wildlife populations and ecosystems. For example, if a deer population in a forest exceeds the carrying capacity, it could lead to overgrazing, which would affect plant life and potentially create a negative feedback loop that impacts the overall health of the ecosystem. Environmental factors such as food availability, predation, disease, and climatic conditions can influence the carrying capacity as well, reflecting the dynamic nature of ecosystems.