Final answer:
Tropical rainforests receive nutrients from decomposing organic matter on the forest floor and through nutrient cycling by its diverse flora and fauna, including epiphytes that absorb water and minerals from the air.
Step-by-step explanation:
Tropical rainforests get their nutrients primarily from the decomposition of organic matter on the forest floor rather than from the soil, which is typically low in nutrients due to heavy rainfall leaching them away. The nutrients are in the surface layer of the ground built up from fallen leaves, branches, and other debris that decompose, providing nourishment for plants. Additionally, the high biodiversity within these forests plays a role in nutrient cycling, including the epiphytes that live on branches high in the canopy, which capture and absorb water and minerals, contributing to the nutrient availability.