A MODEL OF LITTER DECOMPOSITION AND ACCUMULATION IN GRASSLAND ECOSYSTEMS

Litter dynamics of grassland ecosystems was studied by modelling. Dyna mics of litter production, decomposition and accumulation is described by a general mathematical model: dX(t)/dt=g(t)-k(t). X(t), where t is rime, X(t) is litter biomass, g(t) is production rate and k(t) is dec omposition rate. The litter long-term dynamics characters in grassland ecosystems were analysed. (1) If yearly decomposition rate and yearly input are steady, then the litter goes to steady state. The litter wi ll gradually rise to steady state if yearly input is more than yearly decomposition. It will gradually decrease to steady state if yearly in put is less than the yearly decomposition. (2) If the decomposition ra te and production rate all change periodically, then the litter will r each a periodically changing state.