干旱区生态环境知识资源中心

The vertical distribution of soil nematodes down to a depth of 50 cm was studied in an age sequence of 0-, 5-, 10-, and 22-year-old Caragana microphylla plantations (treatments) in the Horqin Sandy Land, Northeast China. The abundances and generic compositions of nematode fauna in five soil layers (0-10, 10-20, 20-30, 30-40, and 40-50 cm) were analyzed. 42 genera were observed in the nematode suspensions, and Acrobeles was the dominant genus in all treatments. The results showed that the total number of nematodes and the generic diversity in an age sequence of C. microphylla plantations decreased with increasing soil depth. Significant differences in the numbers of total nematodes, bacterivores (BF), plant parasites (PP), and omnivores-predators (OP) were observed between treatments and depths. BF was the most abundant trophic group in our study, followed by OP. The numbers of OP showed an obviously increasing trend with increasing age of C. microphylla plantation. The vertical distribution of the soil nematode communities was related to gradual changes in soil chemical properties, and it indicated that C. microphylla plantations have played positive roles in improving soil environmental conditions and restoring desertified ecosystems in the Horqin Sandy Land. The ecological indices selected were influenced by plantation chronosequence but not by soil depth.