Abstract: In this paper,a simulation model is presented for describing the radiation characteristicsin a forest canopy with specially designated leaf angie distributions.After giving leaf areaindex and reflection and trasmission coefficients of leaves,the model can give a series ofvalues,such as downward and upward radiant fluxes,net radiation and relative net radiationfor each layer of the canopy,and the reflection,transmission and extinction coefficients of thewhole canopy.

Key words: Brown-red soil of south Hubei Province, Agroecosystem, Boron balance