Abstract:

Soil microbe quantities，microbial carbon and nitrogen contents，and their fractal characteristics were studied in seven typical vegetation restoration patterns in Nverzhai watershed in northwest Hunan，including Pinus massoniana natural forest (Ⅰ)，Cunninghamia lanceolata plantation (Ⅱ)，Eucommia ulmoides plantation (Ⅲ)，Vernicia fordii plantation (Ⅳ)，Machilus pingii secondary forest (Ⅴ)，Phyllostachys edulis-C. lanceolata mixed forest (Ⅵ)，wasteland-shrub (Ⅶ). It was found that the bacterial number was 2.153×10⁵～5.60×10⁶ cfu·g^-1 which was the highest proportion of 72.83%～92.77% in total soil microbe，followed by actinomycial and fungous ones whose number and proportion were 7.57×10⁴～3.89×10⁵ cfu·g^-1，6.44%～25.61% and 4.60×10³～4.77×10⁴ cfu·g^-1，0.79%～1.99% respectively. Soil microbial biomass C(MBC) was higher in all the other six forest patterns than in Ⅶ，and ranked as the following: Ⅴ(38.99%～39.67%)＞Ⅲ(30.90%～35.31%)＞Ⅵ(23.86%～26.60%)＞Ⅳ(10.17%～10.24%)＞Ⅱ(5.89%～6.11%)＞Ⅰ(0.27%～1.09%)＞Ⅶ in the soil layer of 0～40 cm. Except for pattern Ⅰ，soil microbial biomass N(MBN) was higher in the other five forest patterns than that in Ⅶ，with a rank of Ⅴ(43.46%～44.27%)＞Ⅵ(29.10%～29.60%)＞Ⅲ(22.91%～24.11%)＞Ⅱ(5.20%～5.93%)＞Ⅳ(2.20%～4.45%)＞Ⅶ. These results showed that MBC and MBN of pattern Ⅶ were lower than that of forest patterns on the whole. There was an obvious fractal characteristics between MBC and bacterial number (D=5.446 5，R=0.672 0，P=0.008 5)，followed by MBC and actinomycial number (D=5.358 4，R=0.639 1，P=0.013 9)，MBN and bacterial number (D=3.687 4，R=0.593 2，P=0.025 3). However，the fractal model of MBN and actinomycial number was not significant (R=0.332 1，P=0.246 0)，and there also did not exist fractal relations for MBC，MBN and fungous number.

Key words: vegetation restoration patterns, soil microbe quantities, soil microbial biomass C, soil microbial biomass N, fractal characteristics