Chapter 29: Fungi: The Recycling Networks

Fungi are the purest biological realization of the closure sector: sessile heterotrophs whose Life loops wind dominantly along the η-fiber, with w_π = 0 and w_γ = 0. This chapter develops the biology behind that formal characterization. Mycelial networks are distributed recycling architectures whose graph topology maximizes absorptive surface area. Saprotrophic decomposition—the closure sector’s defining act—reverses the complexity gradient of photosynthesis, with fungi holding a monopoly on lignin degradation that shaped the Carboniferous geological record. Mycorrhizal symbiosis couples the closure and source sectors through phosphorus-for-carbon exchange, connecting 90% of land plants into the Wood Wide Web. The four fungal strategies—saprotrophic, mycorrhizal, parasitic, and lichenized—represent distinct modes of η-fiber operation.