Real decomposition is ecological succession: waves of different decomposer guilds replace each other because each wave changes the chemistry it depends on. This model integrates coupled logistic-growth equations for four guilds every frame, each competing for a shared nutrient pool R and reshaping O₂ and pH as they grow:
- Aerobic bacteria bloom first — fast growth while O₂ and R are both high — then consume the O₂ they need, undercutting themselves.
- Anaerobic bacteria replace them as O₂ falls, fermenting the remaining nutrient and acidifying the substrate (dropping pH).
- Fungi tolerate the acidic, low-O₂ conditions bacteria struggle in and rise as bacterial biomass (their food) accumulates.
- Nematodes are grazers: their growth term is proportional to total microbial biomass (a predator–prey coupling), so they lag every microbial peak.
Temperature scales every rate with a Q10≈2 factor (biological reactions roughly double per 10°C, within limits). Moisture follows a peaked response — too dry halts microbial activity, too wet starves the substrate of oxygen and speeds the anaerobic takeover. Click the decaying block to drop in a fresh pulse of organic matter (re-oxygenating and re-feeding the system) and watch succession restart locally.