How does internal nutrient cycling occur in ecosystems?

Internal nutrient cycling in ecosystems is primarily facilitated by the assimilation of ammonium and nitrates by plants. This process is essential because it allows plants to uptake these forms of nitrogen, which are critical for their growth and development. When plants absorb ammonium (NH4+) and nitrates (NO3-), they use these nutrients to synthesize amino acids, proteins, nucleic acids, and other vital compounds necessary for their metabolic processes.

Once these compounds are built into plant tissues, they can enter the food web when plants are consumed by herbivores or decomposed by detritivores. This movement of nutrients from soil to plants and then to other organisms exemplifies the internal cycling of nutrients, where elements like nitrogen are continually recycled within the ecosystem, providing sustainability and supporting diverse life forms.

In contrast, while the assimilation of sulphates and phosphates by plants does contribute to nutrient cycling, it is not as central to the nitrogen cycle as ammonium and nitrates. The conversion of carbon dioxide into organic matter is a crucial part of photosynthesis and contributes to overall ecosystem productivity, yet it does not specifically address the cycling of nutrients that occur once they are utilized by plants. Furthermore, returning carbon to the atmosphere primarily relates to processes like respiration and