Effects of bacteria on early-stage litter decomposition in Wudalianchi volcanic forest.

To understand the role of microorganisms in litter decomposition and nutrient cycling in volcanic forest ecosystem, we conducted in-situ litterbag decomposition experiment and used Illumina MiSeq high-throughput sequencing to analyze the response of bacterial community structure and diversity during the decomposition of litters from Larix gmelinii, Betula platyphylla and Populus davidiana, the dominant tree species in volcanic lava plateau of Wudalianchi. The results showed that mass remaining percentage of litters of three species after 18-month decomposition was 63.9%-68.1%. Litter of B. platyphylla decomposed the fastest, with significant difference in N, C:N, and N:P before and after decomposition. The richness of bacterial species and diversity index differed significantly among the three litters. Proteobacteria, Actinomycetes, and Bacteroidetes were the dominant bacterial groups at the phylum level, while Rhizobium, Sphingomonas, and Pseudomonas were the dominant groups at the genus level, with significant difference among the three litters. After 18 months, the dominant bacterial groups in litter tended to be consistent with those in volcanic lava platform soil. In the volcanic forest ecosystem, bacterial diversity and community structure were mainly affected by P, C:N, and N:P in the litter.

[Effects of water levels in heterogeneous habitats on sexual reproductive allocation of Deyeuxia angustifolia.] / å¼‚è´¨ç”Ÿå¢ƒæ°´ä½å·®å¼‚å¯¹å°å¶ç« æœ‰æ€§ç¹æ®–åˆ†é çš„å½±å“.

Taking Deyeuxia angustifolia as the research object, a representative plant of wetland in Sanjiang Plain, we analyzed the variations of individual size and biomass among the habitats of swamp wetlands, swampy meadows, typical meadows and miscellaneous grass meadows, and the relationship between reproductive components and plant biomass. We explored the effects of water level on individual biomass and reproductive allocation of D. angustifolia in different types of wetlands. The results showed that plant biomass, height and the characteristics of sexual reproduction significantly decreased with the increases of water level. The reproductive thresholds of D. angustifolia in miscellaneous grass meadow, typical meadow, swampy meadow, and swamp wetland were 0.245, 0.149, 0.148 and 0.157 g, respectively. There was a significantly negative correlation between plant size and reproductive allocation in three habitats except swampy meadow. Compared with individual size, soil water content had a stronger effect on reproductive allocation of D. angustifolia. The different investment between individual size and reproductive allocation in different habitats was the basic condition that contributes to the good ecological adaptability of D. angustifolia.

[Short-term response of carbon emission to snow cover change in Calamagrostis angustifolia wetlands of Sanjiang Plain, Northeast China]. / ä¸‰æ±Ÿå¹³åŽŸå°å¶ç« æ¹¿åœ°ç¢³æŽ’æ”¾å¯¹é›ªè¢«å˜åŒ–çš„çŸ­æœŸå“åº”.

To understand the response of Calamagrostis angustifolia wetland of the Sanjiang Plain to changes in snow cover, we examined the greenhouse gases emission flux of the removed snow treatment (0 cm, RS), the added snow treatment (50 cm, AS) and the control (20 cm, CK) of a C. angustifolia wetland, and their relations with environmental factors with the method of the static chamber-gas chromatography. The results showed that soil temperature, soil water content, and carbon emissions were lowest during the snow-covering period under all treatments, and gradually increased with time. With the increases of time and snow thickness, soil temperature was rised and the difference of three treatments gradually was decreased. Soil water content of RS was always lower than that of CK and AS. AS and CK could promote soil CO2 emission compared with RS during and after snowmelt. The soil cumulative CH4 emissions differed little among the treatments. There was significant correlation between soil temperature and cumulative CO2 and CH4 emissions. With the increases of soil temperature, soil cumulative CO2 emission continued to increase and soil cumulative CH4 emission decreased firstly and then increased rapidly. Soil water content was significantly correlated with cumulative CO2 and CH4 emissions. As the soil moisture increased, the cumulative soil CO2 emission gradually increased, reaching a certain threshold and then flattening, while soil cumulative CH4 emission continuously increased.

[Fungal diversity in the brown coniferous forest soils of Daxing'anling Mountains, Northeast China]. / å¤§å ´å®‰å²­æ£•è‰²é’ˆå¶æž—åœŸå£¤çš„çœŸèŒå¤šæ ·æ€§.

To explore the distribution of fungal community in soil of brown coniferous forest in Daxing'anling and its relationship with soil characteristics, soil fungal community structure and diversity in three forest types, light brown coniferous forest, grass brown coniferous forest, and typical brown coniferous forest, were analyzed by high-throughput sequencing technology. The relationship between soil fungal community and soil characteristics was analyzed by R and SPSS 17.0 software. The results showed that soil physical and chemical characteristics differed significantly across the three brown coniferous forests. A total of 111 species belonged to six phyla, 23 class, 46 orders, 74 families and 88 genera were recorded in this study. Ascomycetes and basidiomycetes were dominant phyla. There were significant differences in relative abundance of phyla among three forest types. There was no significant difference in the Ace and Chao1 diversity indices among three brown coniferous forests, whereas there were significant differences in the Shannon and Simpson indices. Results from canonical correlation analysis and correlation analysis showed that both α and ß diversity were significantly correlated with soil moisture, soil pH, soil organic matter, soil total nitrogen, and soil total potassium. The results indicated that soil characteristics were important factors affecting soil fungal diversity of brown coniferous forest in Xing'an larch forest in Daxing'anling.

Responses of greenhouse gas emission to simulated nitrogen deposition in Calamagrostis angustifolia wetlands of Sanjiang Plain, China.

A long-term simulated nitrogen deposition experiment was carried out in Ecological Locating Research Station of the Institute of Nature and Ecology of Heilongjiang Academy of Sciences, with three different treatments including low nitrogen treatment (40 kg N·hm-2·a-1), high nitrogen treatment (80 kg N·hm-2·a-1) and the control (0 kg N·hm-2·a-1). The greenhouse gas emission fluxes were measured using a static box-gas chromatography method, with environmental factors being simultaneously investigated to understand the responses of greenhouse gas emission to the nitrogen deposition in the Calamagrostis angustifolia wetland. The results showed that low and high nitrogen treatments significantly increased the greenhouse gas emission fluxes. The CO2 emission flux increased by 47.5% and 47.9%, the CH4 emission fluxes increased by 76.8% and 110.1%, and the N2O emission fluxes increased by 42.4% and 10.6% in low nitrogen treatment and high nitrogen treatment, respectively. Low nitrogen input changed the seasonal dynamics of N2O emission fluxes but had no significant effect on that of CO2 and CH4 emissions. High nitrogen treatment did not affect the seasonal dynamics of greenhouse gas emissions. Soil temperature significantly positively correlated with CO2 and CH4 emission fluxes. There was no correlation between soil temperature and N2O emission flux because the factors affecting N2O emission were complex.

[Fungal Community Structure of Different Degeneration Deyeuxia angustifolia Wetlands in Sanjiang Plain].

To understand the wetland soil fungal community structure and diversity in different degeneration Deyeuxia angustifolia wetlands, the topsoil (0-20) of three different degeneration D. angustifolia wetlands were collected in the Sanjiang Plain field experiment station of the Institute of Nature and Ecology, Heilongjiang Academy of Sciences. The distribution and variation of soil fungal diversity were assessed by high-throughput sequencing method. The results showed that Shannon-Wiener index increased from marsh Deyeuxia angustifolia wetland marsh meadow Deyeuxia angustifolia wetland meadow Deyeuxia angustifolia wetland. Sequence blast showed that the fungal taxonomy belonged to Ascomycota, Basidiomycota, Chytridiomycota, Fungi_unclassified, Zygomycota, which dominant fungi were Fungi_unclassified (75.12%),Ascomycetes (56. 56%), Basidiomycetes (72.65%) in the three degeneration wetlands, respectively. The fungal structure compositions and diversities of marsh meadow Deyeuxia angustifolia wetland and meadow Deyeuxia angustifolia wetland were similar according to Heatmap analysis. The fungal community structure was influenced by soil nutrients (explained 88.62%) and plant composition (explained 9.85%) through the Variation partition analysis (VPA). In conclusion, the fungal community structure was significantly different, which was influenced by soil water content, in different degeneration Deyeuxia angustifolia wetlands in Sanjiang plain. The results may supply scientific basis for studying fungal diversity and spatial heterogeneity in degeneration wetlands.

Fabrication and properties of TiO2 nanofilms on different substrates by a novel and universal method of Ti-ion implantation and subsequent annealing.

We report a new, novel and universal method to fabricate high-quality titanium dioxide (TiO2) nanofilms on different substrates by a solid phase growth process of ion implantation and subsequent annealing in oxygen atmosphere. Ti ions were implanted into fused silica, soda lime glass, Z-cut quartz, or (0001) α-sapphire by a metal vapor vacuum arc (MEVVA) ion source implanter to fluences of 0.75, 1.5 and 3 × 10(17) ions cm(-2) with a nominal accelerating voltage of 20 kV. To understand the influence of the annealing temperature, time, and substrate on the formation and phase transformation of the TiO2 nanofilms, the Ti-ion-implanted substrates were annealed in oxygen atmosphere from 500 to 1000 °C for 1-6 h. The formation of TiO2 nanofilms resulted from the slow out-diffusion of implanted Ti ions from the substrates which were then oxidized at the surfaces. The thickness and phase of the nanofilms can be tailored by controlling the implantation and annealing parameters. Since the TiO2 nanofilms are formed under high temperature and low growth rate, they show good crystallinity and antibacterial properties, with good film adhesion and stability, suggesting that the TiO2 nanofilms formed by this method have great potential in applications such as antibacterial and self-cleaning transparent glass.

[Beta diversity of successional series in mash communities of Sanjiang Plain, China].

Four typical successional series in the marsh communities of Sanjiang Plain were selected to investigate the changes of their beta diversity. The results indicated that from the 'starting community' to the 'end community', which had the most and the least moisture level in the series, respectively, the similarity coefficient between each community and 'starting' community decreased with decreasing moisture gradient and increasing horizontal distance. The species turnover speed among the communities in each series had an increasing trend from lowland to upland. In the process of succession, the general trend was that the total number of plant species increased while the common species decreased, with the beta diversity between communities increased gradually. The analysis of succession mechanism supported the 'initial floristics composition hypothesis', and the plant Calamagrostis angustifolia would intensify its dominance in the mash of Sanjiang Plain.

[Spatio-temporal dynamics of nitrogen in agricultural ditch systems in Sanjiang Plain].

Agricultural drainage water sampling was conducted along ditch systems from 1st order to 5th order in Nongjiang River and Bielahonghe River during June to September, 2005. The spatio-temporal dynamics of nitrogen concentrations in agricultural ditch systems were analyzed. Results showed that there were higher concentrations of nitrogen in Bielahonghe ditch system. Peak values of TN, NH4(+) -N and NO3(-) -N moved from 1" order to 3rd and 5th order in Nongjiang and Bielahonghe ditch systems respectively. The retention of nitrogen in Bielahonghe ditch system was more than Nongjiang ditch system. The temporal dynamics of TN and NH4(+) -N were parallel in the two ditch systems, which decreased from June to September. But the temporal dynamics of NO3(-) -N had no obvious trend. The relationships between TN and NH4(+) -N and NO3(-) -N were positively correlated in both Nongjiang and Bielahonghe ditch systems, fitting for Power model and Cubic model respectively. The relationships between TN and NH4(+) -N and NO3(-) -N can be described by multi-variance linear regression, which explained 78% of TN concentration in Bielahonghe ditch system.