Effects of fungal addition on dune plant litter decomposition in Horqin Sandy Land, northern China

Background/Question/Methods Horqin Sandy Land lies in the semiarid area of southeastern Inner Mongolia, northern China. Due to overgrazing and arable cultivation, this region is one of the most severely desertified areas in northern China. Previous studies showed that litter decomposition rates were significantly different between litter species and habitat in this area. However, how litter will decompose after adding cellulose decomposing fungi is still unknown. Six fungal strains, selected for their ability to decompose coarse cellulose in sandy soils of Horqin Sandy land, northern China, were added to litters from the trees Pinus sylvestris, Populus simonii, shrubs Caragana microphylla, Artemisia halodendron, and the grasses Setaria viridis and Pennisetum centrasiaticum. The litters were incubated one year in the field in litter-bags, and sampled three times. Each litter received fungal cellulose decomposing strain inoculations: No strain, each of six single strains, respectively, and all strains. Litter was placed both at the surface and buried at 10 cm depth.

Results/Conclusions The result showed that no strain litter decomposed at about 30% of the rate of all strains, while single strains were intermediate, not significantly different between single strains. Surface showed about half the rate of buried, and there were major rate differences between litters; grass-derived litters showed the highest rates. The results were analyzed in relating to climate using ICBM (Introductory Carbon Balance Model) soil carbon model. Two rate-controlling factors (k_Y, initial decomposition constant and h, humification quotient) were fitted to the decomposition data. Factors k_Y an h were adjusted to the different litter species. Treatment effects were described by a common rate multiplier resulting in surface decomposition rates 0.45 of those in buried; no strain was 0.3 and single strains all were 0.8 of those with all strains. Fungal addition could accelerate litter decomposition in degraded sand dune ecosystem. Manipulation of the magnitude and diversity of the decomposer community in sand dune soils can change thus change soil process rates, and rate differences may be described by simple, multiplicative factors.

Key words: Litter decomposition; cellulose decomposing fungi; ICBM model; Inner Mongolia