Using mosses to restore ecosystem function to the Loess Plateau, China

Background/Question/Methods As an important component of biological soil crusts, mosses are commonly found in plant interspaces in the revegetated grass lands in the Loess Plateau region of China. These mosses exert a profound influence on this system by influencing the water-runoff infiltration balance, reducing soil wind and water erosion and increasing soil fertility. Although there have been studies documenting the ecological functions of moss crusts, few have examined their role in rehabilitation or the recovery of the moss crusts themselves, despite opportunities to grow mosses artificially to enhance rehabilitation efforts. We used field plots and indoor controlled experiments to examine the influence of moss crusts on soil erosion and soil fertility as well as the germination of four typical plants seeds. We also investigated ways to grow mosses under lab and field conditions.   

Results/Conclusions Results: 1) while dark cyanobacteria crusts of 80% coverage reduced soil loss by 92% compared with bare soil, a 60% moss crusts completely eliminated soil erosion. 2) Soil fertility, especially organic material (OM) and total nitrogen (TN), were improved significantly by moss crusts. Contents of OM and TN in the well-developed moss crusts were 19.46±1.85 g·kg^-1 and 0.96±0.06 g·kg^-1, respectively, which was 4.2 and 2.4 times higher than that in the control soil. The average contribution of 1 m² biocrusts to nutrients accumulation in the surface 0-4cm soils per year during the first 20 years were approximately 50.15 g OM, 1.95 g TN, 0.44 g total phosphors, 0.16 g available nitrogen, 0.01 g available phosphors and 0.13 g available potassium. 3) Seed germination rates showed an inconsistent response to the presence of moss crusts. Germination rates of seeds with hair were reduced by moss crusts compared with bare soil. However, seeds with smooth surface had higher germination rates on moss crusts than those on the bare soil. 4) We inoculated the soil surface with 500 g·m^-2 grinded moss crusts. After 80 days at 20°C, we obtained 76% moss cover. 17°C and 100% water holding capacity were the optimal temperature and moisture to moss crusts formation. The formation of moss crusts could be accelerated by adding glucose and magnesium sulfate to the substrate. We inoculated the soil with 1250 g·m^-2 grinded moss crusts in the field plots, 30%-60% moss covers were formed six months later, which reduced soil loss by 60%. It is effective to use mosses to restore the ecological function in the Loess Plateau region.