What does carrying capacity refer to?

Carrying capacity specifically refers to the maximum population size that an environment can sustainably support without degrading its resources. This concept encompasses the availability of food, water, shelter, and space, which are vital for a given species within an ecosystem. When a population exceeds its carrying capacity, it can lead to resource depletion, environmental degradation, and ultimately a decline in population numbers as conditions become unsustainable.

The other options do not fully capture the essence of carrying capacity. The number of species in an ecosystem relates more to biodiversity than to the specific population limits of a single species. The extent of arable land is concerned with agricultural potential rather than the overall population limits of different organisms. Lastly, the total resources available in a region can contribute to carrying capacity, but it does not define it directly, as carrying capacity is ultimately tied to a specific population and its interaction with those resources.