Abstract: Silicon is an important mineral element on the earth, because of its crucial role in many biogeochemical processes. Traditionally, silicon cycling is thought to be mainly controlled by rock weathering, subsequent mineral dissolution, and final aggradation in waters. Actually, plants react on the biogeochemical cycling of silicon. A great pool of silicon is contained as the accumulations of amorphous silica (SiO₂·nH₂O) in living plant tissues, known as biogenic silica (BSi), phytolith or opal. The annual fixation of BSi by terrestrial plants ranges from 1.68×10⁹ to 5.60×10⁹ t. After decomposition, about 92.5% of the BSi from litterfall is absorbed by plants again, and the rest 7.5% remains in soil. Because the silicon absorbed by plants from soil BSi pool is far more than that released by weathering, plant-soil internal cycling can greatly affect the dissolved silicate fluxes from terrestrial ecosystem to rivers and oceans. The annual fixation of BSi by diatom in ocean is from 5.60×10⁹ to 7.84×10⁹ t, about 97% of which is absorbed by diatom again before reaching seabed, and only 1.43×10⁸—2.55×10⁸ t (about 3%) is buried in sediment yearly. In this way, diatom plays an important role in the aquatic cycling of silicon. In conclusion, plants are very important in both terrestrial and aquatic biogeochemical cycling of silicon, and thus, the effects of plants must be considered in the study of global biogeochemical cycling of silicon.

Key words: Landscape diversity, Dynamic simulation, Management measures, Korean pine broad-leaved forest