Abstract:

The relationship of mycorrhizae and diversity of microbial community in rhizosphere soils of Robinia pseudoacacia plantation and secondary plantation at different ages on the Loess Plateau was measured with by BIOLOG method. It was found that in 8, 15, 23 and 30 a plantation forestland, with the age increased, the mycorrhizal infection rate increased at the early stage and then declined. The average well color development (AWCD) increased. The richness index(S) and the Shannon index (H) increased at the early stage and reached to peak value at 23 a and then gradually declined, The mycorrhizal infection rate were significantly correlated with the number of nodules were significant correlation (y = 414.82x-188.73, r=0.927, p<0.05) in different forestlands. The principal component analysis showed that with the ages increased, the microbial community structure and function in rhizosphere soils of R.pseudoacacia plantation existed continuity of the time. The secondary forest perfomed better than the same age plantation, and its capacity of carbon utilization was similar to that of the older plantation. The correlation analysis of the mycorrhizal infection rate and the number of nodules, the number of bacteria colonies, the richness index(S), the Shannon index (H) indicated that, the arbuscular mycorrhizae promoted the stabilization and function diversity of microbial community in rhizosphere soils of R.seudoacacia. The mycorrhizae influenced more significantly the microbial community of younger R.pseudoacacia plantation in terms of afforestation time and it had more remarkable effects on diversity of microbial community of secondary forest than R.pseudoacacia plantation with regard of afforestation measures.

Key words: Robinia pseudoacacia, mycorrhizal infection rate, BIOLOG, microbial community, function diversity