Abstract:

To explore the relationships between soil bacterial-feeding nematodes and soil microbial biomass under biocrusts in desert areas. Sand dune soil under biocrusts in the artificial vegetation areas at the southeast edge of Tengger desert was studied. Soil samples of 0-10 cm under cyanobacteria-lichen and moss crusts were collected. Moreover， soil bacterial-feeding nematodes with 15， 30， 45， 60， 90， 120 and 150 individuals in per gram of soil were inoculated in soil， and the soils of uninoculated bacterial-feeding nematodes were the contrasts. Soil microbial biomass carbon and nitrogen in inoculated and uninoculated bacterial-feeding nematodes were tested after a period cultured time. The result showed that soil microbial biomass carbon and nitrogen were significantly increased by soil bacterial-feeding nematodes （P<0.05） with less than 90 individuals in per gram of soil. However， soil microbial biomass carbon and nitrogen showed a change from a positive correlation to a negative correlation with the reproduction or too much inoculated density of bacterial-feeding nematodes under both cyanobacteria-lichen and moss crusts. In addition， crust types also significantly affected soil microbial biomass carbon and nitrogen （P<0.05）， which late-successional moss crusts had higher soil microbial biomass carbon and nitrogen than early-successional cyanobacteria-lichen crusts. Therefore， the certain density of soil bacterial-feeding nematodes can obviously improve soil microbial biomass in the artificial vegetation areas at the southeast edge of Tengger desert， indicating that the suitable density of soil bacterial-feeding nematodes can promote the restoration and improvement of soil in desert areas.

Key words: desert areas, soil bacterial-feeding nematodes, soil microbial biomass, biocrusts, inoculated density, crust types