Final answer:
The primary ecological function of fungi is that of decomposer, breaking down dead organic matter and recycling nutrients. They make nutrients accessible to plants and other organisms and hold significance for human uses in food, medicine, and fermentation.
Step-by-step explanation:
The primary ecological function of fungi is that of decomposer. Fungi are fundamentally important in the nutrient cycle of ecosystems as they break down and recycle nutrients from dead organic matter. They thrive in various environments as saprotrophs, using their exoenzymes to decompose complex organic substances like cellulose and lignin in dead wood, thus converting them into absorbable nutrients like glucose. These nutrients are then made available for uptake by plants and other organisms within the ecosystem.
Moreover, fungi offer critical advantages to plants through symbiotic relationships such as mycorrhizae, where fungi increase the surface area for water and nutrient absorption for the host plant, thus enhancing plant growth. Besides their ecological role, fungi are also important to humans for food, medicine, and as agents of fermentation in various food preparations.