Final answer:
The carrying capacity of an ecosystem is the maximum population size of a species that can be sustained by the available resources without harming the environment. It's a balance between resource availability and population size, ensuring ecological sustainability.
Step-by-step explanation:
An ecosystem's carrying capacity is the maximum population size that it can sustain, given the resources available in the ecosystem. The concept of carrying capacity, often denoted as K, reflects the largest population size that can be supported in an area without harming the environment. It represents the number of individuals of a species that can be supported by the limited resources of a habitat. When the ecosystem's resources are depleted due to overpopulation, the population growth rate will slow, eventually reaching a stable state, which is the carrying capacity. In real-world scenarios, populations typically exhibit exponential growth only until resources become limited.
Ecologically sustainable populations do not exceed their ecosystems' carrying capacities, ensuring that their environmental impact does not degrade the capacity of the ecosystem to meet the health and survival needs of the population. Conversely, ecologically unsustainable populations expand beyond what the available resources can support, leading to degradation of the ecosystem or shortages in resources such as food and water.