What does nutrient cycling refer to?

Nutrient cycling refers to the exchange of organic and inorganic matter back into living systems. This process involves the movement of nutrients like carbon, nitrogen, phosphorus, and potassium through various biotic (living) and abiotic (non-living) components of the ecosystem. These nutrients are taken up by organisms from the soil, water, and atmosphere, utilized for growth and metabolism, and eventually returned to the environment through decomposition, excretion, and other processes. This cycling is crucial as it helps maintain ecosystem productivity and stability by ensuring that essential nutrients are available for various forms of life.

The other choices reflect different ecological concepts that do not directly define nutrient cycling. The movement of organisms through different habitats describes species migration and distribution rather than nutrient movement. The transfer of energy between trophic levels pertains to food chains and webs, focusing on energy flow rather than the cycling of nutrients. The distribution of nutrients in a specific geographic area highlights spatial aspects of nutrient availability but does not capture the dynamic process of nutrient cycling that is essential for ecosystem function.