Carrying Capacity

The carrying capacity is the maximum population that can be supported by an ecosystem. The carrying capacity entirely depends on the amount of available resources. In nature, resources are finite (limited), so there will always be a maximum capacity. The more resources there are, the higher the carrying capacity. The less resources there are, the lower the carrying capacity.
Carrying capacity can change from season to season, or even change suddenly, depending on the resources available. Factors that prevent populations from growing further are called limiting factors. For plants, the limiting factor is often space. While trees release tons of seeds every year, very few new trees grow because there just isn't enough space to support them. Aquatic ecosystems are often limited by the amount of oxygen present in the water, while species on land are often limited by the amount of water or food. Temperature can also be a limiting factor.
Populations that surpass the carrying capacity cannot be supported- there are not enough resources for everyone. For this reason, stable populations tend to remain near the carrying capacity in a state of equilibrium.

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