[Experiment on pruning of Cistanche deserticola inoculated in artificial Haloxylon ammodendron forest].

At present, the objective of cutting and pruning Cistanche deserticola is to harvest in successive years and enhance the harvesting yield and quality of C. deserticola in the process of the artificial cultivating C. deserticola. An experiment was conducted focusing on cutting and pruning C. deserticola in artificial forests of Haloxylon ammodendron drip-irrigated with saline water at the hinter-land of the Taklimakan desert, according to different growth stages and lengths. The results were following: (1) The effect of cutting on C. deserticola was similar to that of pruning, which resulted in three kinds of morphological types, not related to the bloom and size of C. deserticola. (2) The growth forms were diversified after pruning. Among them, there had sprouting new body, died or maintaining life with no sprouting, mildewed on its surface layer, etc. However, some of new bodies were sprouting from the lower part of the old body. The death rate of bloomed C. deserticola was higher than that of the underground, and the death rate of the 40 cm in stubble height for C. deserticola was higher than those with the stubble height of 20 cm and 5 cm. (3) Most of the diameter of living C. deserticola after pruning was increasing, but some of them changed little. (4) The mildew and rot of C. deserticola and the broken of the roots of the H. ammodendron and the fallen of the point of the inoculated when it was dug, which would cause the death of the C. deserticola. On the other, the yield-increasing effect and the economic benefit of the techniques of the pruning of Cistanche would need further research and evaluate. Therefore, the application of this technique needs to be cautious.

[Variation characteristics of soil microbial activities in the Tarim Desert Highway shelter forests, Xinjiang of Northwast China].

By the methods of Biolog, fumigation extraction, and colorimetric titration, this paper determined the soil carbon sources metabolic intensities, microbial biomass, and enzyme activities in the Tarim Desert Highway shelter-forests with different plantation times, and analyzed the variation characteristics of soil microbial activities in these shelter forests. With the increasing planting years of the shelter forests, the soil microbial metabolic activities (AWCD) and microbial diversity indices enhanced obviously, but the AWCD values in different soil layers had no significant differences. The soil catalase activity among the forests had no significant difference, but the soil cellulase and sucrase activities varied significantly. The soil microbial biomass carbon and nitrogen increased with the increasing planting years of the shelter forests, having a significant difference among the forests, but the microbial biomass phosphorus had no significant difference. The AWCD values had significant correlations with soil available nutrient contents, but less correlations with soil bulk density and moisture content. It was suggested that under the present management patterns and climate conditions, the soil metabolic activities in the Tarim Desert Highway shelter forests would be improved continuously with the increasing planting years of the forests.

[Relationships of soil microbial biomass with soil environmental factors in Tarim Desert highway shelter-forest].

By using correlation analysis, this paper studied the relationships of soil microbial quantity and biomass with soil physical and chemical factors and enzyme activities in highway shelter-forests of Tarim Desert, aimed to approach the interactions between microbes and environmental factors in aeolian sandy soil of extremely arid area. The results showed that soil microbial quantity and biomass in the shelter-forests had an increasing trend with the decrease of soil bulk density and particle size (R < -0.84) and the increase of soil moisture content and porosity (R > 0.85), with the correlation between soil microbial biomass and soil bulk density as the key. Soil microbial quantity and biomass were positively correlated with soil nutrient contents, mainly caused by the correlations of soil actinomycetes and microbial biomass C and P with soil available nutrients. Greater differences (R = 0.51-0.91) were observed in the correlations of soil enzyme activities with soil microbial quantity and biomass, which was mainly determined by the correlations of soil invertase and phosphatase activities with soil actinomycetes and microbial biomass C. The increase of soil salt content was not favorable to the accumulation of soil microbial biomass (R < -0.71), and there was a higher positive correlation (R > 0.63) between soil microbial amount and biomass. In practice, good soil condition should be established in the forestlands of arid area for the development of soil microbes and the promotion of soil matter cycling.