Abstract: The shading of revetment trees and lake herbaceous plants has formed a unique environment of light limi-ting in some water areas of southern lakes. We conducted laboraoty decomposition experiments to analyze the resi-dual amount of decomposition substrates, lignin and cellulose content during the decomposition of fallen leaves of woody plants (Osmanthus fragrans and Ficus microcarpa) and herbaceous plants (Canna glauca and Myriophyllum verticillatum). The aim was to explore the decomposition of fallen leaves and the degradation of lignin and cellulose of woody and herbaceous plants. The results showed that after 140 days of decomposition, the mass loss rates of O. fragrans, F. microcarpa, C. glauca, and M. verticillatum were 46.0%, 42.3%, 74.4%, and 68.6%, respectively. The decomposition rate of woody plants was significantly lower than herbaceous plants. In the early stage of decomposition (0-7 days), the mass loss rate and decomposition rate (k) were the highest throughout the entire experiment for all the four species. The cellulose of the four plants showed a state of high degradation, and the lignin degradation rates of O. fragrans (42.9%) and F. microcarpa (38.9%) were significantly higher than herbaceous plants. The lignin degradation rate of O. fragrans was significantly positively correlated with k value, while the lignin and cellulose degradation rates of F. microcarpa and herbaceous plants were not significantly correlated with k value, indicating that lignin degradation might be a key factor affecting the decomposition of woody plants in shaded water environments and regulating carbon cycling in shaded lakes.

Key words: light avoidance, woody plant, herbaceous plant, decomposition rate