[Carbon source metabolic diversity of soil microbial community under different climate types in the area affected by Wenchuan earthquake].

The MS8.0 Wenchuan earthquake in 2008 led to huge damage to land covers in northwest Sichuan, one of the critical fragile eco-regions in China which can be divided into Semi-arid dry hot climate zone (SDHC) and Subtropical humid monsoon climate zone (SHMC). Using the method of Bilog-ECO-microplate technique, this paper aimed to determine the functional diversity of soil microbial community in the earthquake-affected areas which can be divided into undamaged area (U), recover area (R) and damaged area without recovery (D) under different climate types, in order to provide scientific basis for ecological recovery. The results indicated that the average-well-color-development (AWCD) in undamaged area and recovery area showed SDHC > SHMC, which was contrary to the AWCD in the damaged area without recovery. The AWCD of damaged area without recovery was the lowest in both climate zones. The number of carbon source utilization types of soil microbial in SHMC zone was significantly higher than that in SDHC zone. The carbon source utilization types in both climate zones presented a trend of recover area > undamaged area > damaged area without recovery. The carbon source metabolic diversity characteristic of soil microbial community was significantly different in different climate zones. The diversity index and evenness index both showed a ranking of undamaged area > recover area > damaged area without recovery. In addition, the recovery area had the highest richness index. The soil microbial carbon sources metabolism characteristic was affected by soil nutrient, aboveground vegetation biomass and vegetation coverage to some extent. In conclusion, earthquake and its secondary disasters influenced the carbon source metabolic diversity characteristic of soil microbial community mainly through the change of aboveground vegetation and soil environmental factors.

[Growth-promoting effect and triptolide production regulation of endophytic bacteria from Tripterygium wilfordii].

A total of twenty-three endophytic bacteria were isolated from Tripterygium wilfordii, among which three strains were selected for further studying based on their capabilities of growth-promotion and wheat germination. All three isolated strains could produce phytohormone and siderophore, and LG3 and LJ10 strains were capable of dissolving phosphorus. Additionally, LG3 and LY4 strains were both proved to have nitrogen-fixing function and 1-aminocyclopropane-1carboxy-late deaminase activity. Bacterial 16S rDNA sequence identification and homology analysis suggested that LG3 and LY4 strains belonged to the Enterobacter and LJ10 belonged to the Pantoea. The results of reinoculation experiment demonstrated that three endophytic bacteria could not only promote the growth of Tripterygium wilfordii, but also improve the triptolide contents of different organs significantly.

[Nitrogen leaching and associated environmental health effect in sloping cropland of purple soil].

In this paper, we monitored different forms of nitrogen (N) transported by the subsurface flow under three different natural rainfall events and different fertilizations and conducted an associated risk evaluation on environmental health, which provides scientific basis for controlling N non-point pollution and establishing a reasonable fertilization system in purple soil area. The results showed that there were different forms of N transport by subsurface flow under different rainfall events, where in dissolved nitrogen (DN) accounted for about 53.74% - 99.21%, and nitrate (NO3(-) -N) accounted for about 35.70% - 93.65% of DN, and especially under the moderate rainfall, NO3(-) -N could reach 84.09% - 93.65% of DN. The different N fluxes were the highest under moderate rainfall among different rainfall events, in which the flux of total nitrogen (TN), DN, particle nitrogen (PN), ammonia (NH4(+) -N) and nitrite (NO2(-) -N) reached 737.17, 711.12, 26.06, 12.70 and 0.46 mg x m(-2), respectively, and the NO3(-)-N flux was as high as 686.12 mg x m(-2), showing a huge potential threat on groundwater health. Through the risk assessment on N pollution for groundwater quality, we concluded that the straw returning could be used to effectively alleviate the N leaching and groundwater N pollution; especially, the combined application of organic and chemical fertilizer could effectively mitigate the groundwater pollution, improve soil fertility and increase crop yield.

[Population life process and spectral analysis of rare and endangered plant Alsophila spinulosa].

According to population life table and survival analysis theory, the time-specific life table and the survival function curve of Alsophila spinulosa population were established and drawn based on height class, and the life process of the population was analyzed. The results revealed that the population structure of A. spinulosa was of the type ascending at early stage and stable at late stage. The peak of expected life appeared at the 4th age class, indicating the relative good survival quality at this phase, and the survival curve belonged to the typical form of Deevey-III. There existed three death peak phases in the population life process, i.e., the growth stages from 2nd to 3rd age class, from 10th to 11th age class, and from 12th to 13th age class. With the increase of age class, the population survivability dropped down monotonously, and ow nosy, a the accumulative mortality rose up correspondently. The variation extent was high in early phase and low in anaphase. The death density function curve displayed the characteristics of descent in early phase and stabilization in anaphase, and the concave point occurred at 4th age class. Spectral analysis showed that the quantitative fluctuation of A. spinulosa population was multi-harmonic superposition with large cycles containing small cycles. The influences of these cycles dropped with the diminishment of cycle length, and the effect of fundamental wave was most prominent.