Soil fauna effect on Dryas octopetala litter decomposition in an Alpine tundra of the Changbai Mountains, China

Soil fauna are critical for litter decomposition via physical fragmentation, chemical digestion, and changing activity of microorganisms, yet a few studies have been performed regarding the effects of soil fauna on alpine tundra litter decomposition. To better understand the effects of soil fauna on alpine tundra litter decomposition, we set up a litterbag experiment to determine the characteristics of the Dryas octopetala decomposition, and the diversity of the soil fauna in the litterbags, as well as the influence of the soil fauna on the decomposition in the tundra of the Changbai Mountains over a 36-month period. We found that the decomposition rate of the coarse mesh (2 mm) litterbags was faster than that of the fine mesh (0.01 mm) litterbags. The percentage of the mass lass of litter in the coarse mesh litterbags (2 mm) was 47.60%, while that in the fine mesh (0.01 mm) litterbags was 34.11% at the end of the experimental period (36th month of decomposition), and the contribution of soil fauna to the litter decomposition was confirmed to be 30.50%. The characteristics of litter decomposition exhibited some seasonal and annual differences. In addition, the diversity of the soil fauna in the litterbags was different during each of the years of the experiment. However, there were no significant differences observed during the same year. The effect of soil fauna on the litter decomposition was not obvious at the beginning of the experiment, and soil fauna contribution had a significant negative relationship with mass loss of litter. Our results provide experimental evidence that soil fauna can promote the decomposition of Dryas octopetala litter, but soil fauna contribution decreased with litter decomposition in the alpine tundra ecosystem.