Litter decomposition of epiphytic lichens, bryophytes, and vascular plants on the forest floor and canopy in a cool-temperate old-growth forest

Abstract

The litter of non-vascular plants, such as epiphytic lichens and bryophytes, contributes to soil formation in the forest floor and tree canopy of old-growth forests. In this study, we investigated litter decomposition to elucidate the ecological functions of non-vascular plants in forest ecosystems. Focusing on a cool-temperate old-growth forest in Japan, we conducted litter bag experiments to examine rates of change in the mass of litter from epiphytic lichens, epiphytic bryophytes, and vascular plants (host tree leaves) after three months and one year. Litter bags were installed at three microsites: on the ground, in thick canopy soil, and in thin canopy soil. The results showed that lichen and bryophyte litter decomposed more slowly than vascular plant litter in ground and thick canopy soil. No significant differences in mass loss rates were observed between the ground and thick and thin canopy soils. However, the contributions of lichens and bryophytes to decomposition at the ground and canopy levels were slightly influenced by environmental variables, such as soil temperature, soil volumetric water content, and canopy openness. A litter bag experiment with a mixture of the three litter species showed no general synergistic effect of mixed litter on vascular plants. This study provides insights into the ecological functions of non-vascular plants in forest ecosystems, emphasizing their role in the dynamics of litter decomposition.