Land use alters arbuscular mycorrhizal fungal communities and their potential role in carbon sequestration on the Tibetan Plateau.

Loss of belowground biodiversity by land-use change can have a great impact on ecosystem functions, yet appropriate investigations remain rare in high-elevation Tibetan ecosystems. We compared arbuscular mycorrhizal (AM) fungal communities in arable soils with those in native forest and grassland in southeast Tibet and investigated their potential contribution to carbon sequestration. The AM fungi were abundant and diverse.

Temperature-mediated local adaptation alters the symbiotic function in arbuscular mycorrhiza.

Variation in the symbiotic function of arbuscular mycorrhizal fungi (AM fungi) has been demonstrated among distinct biotic and abiotic interactions. However, there is little knowledge on how local temperature conditions influence the functional divergence of AM symbionts in alpine ecosystems. Here, we conduct a reciprocal inoculation experiment to explore the three-way interactions among plants, AM fungal inoculum and temperature at sites of contrasting elevation.

Responses of arbuscular mycorrhizal symbionts to contrasting environments: field evidence along a Tibetan elevation gradient.

Plant adaptation to alpine ecosystems is not fully explained by plant physiological and morphological traits. Arbuscular mycorrhizal (AM) associations may be involved in mediating plant performance in response to environmental differences. Little is known, however, as to whether or not a close relationship exists between plant performance and arbuscular mycorrhizal fungus status across environmental gradients.

[Change of arbuscular mycorrhizal fungi community in response to elevational gradients on the Tibetan Plateau, China].

The community structure of arbuscular mycorrhizal fungi (AMF) and mycorrhizal infection in the main herbaceous plants were studied along the elevational gradients on the Tibetan Plateau, and AMF community was characterized based on spore morphology. Community of AMF at lower elevations (2200-3400 m) in southeast Tibetan Plateau included 11 genera, covering 31 species, whereas AMF at intermediate elevations (3400-3900 m) in central Tibet included 11 genera, covering 20 species, and that at higher elevations (4300-5300 m) in northern Tibet included 6 genera, covering 14 species. With the increase of elevation, both spore density (r = 0.

The key factor limiting plant growth in cold and humid alpine areas also plays a dominant role in plant carbon isotope discrimination.

Many environmental factors affect carbon isotope discrimination in plants, yet the predominant factor influencing this process is generally assumed to be the key growth-limiting factor. However, to our knowledge this hypothesis has not been confirmed. We therefore determined the carbon isotope composition (δ(13)C) of plants growing in two cold and humid mountain regions where temperature is considered to be the key growth-limiting factor.

Altitudinal distribution patterns of AM fungal assemblages in a Tibetan alpine grassland.

A better understanding of biogeography of Glomeromycota is essential for the conservation of arbuscular mycorrhizal (AM) fungal species and the ecosystem services that they provide worldwide. We examined the spatial dynamics of AM fungi along two slopes (4149 m a.s.

Contribution of arbuscular mycorrhizal fungi of sedges to soil aggregation along an altitudinal alpine grassland gradient on the Tibetan Plateau.

The diversity of arbuscular mycorrhizal fungi (AMF) in sedges on the Tibetan Plateau remains largely unexplored, and their contribution to soil aggregation can be important in understanding the ecological function of AMF in alpine ecosystems. Roots of Kobresia pygmaea C.B.

Molecular diversity of arbuscular mycorrhizal fungi associated with two co-occurring perennial plant species on a Tibetan altitudinal gradient.

Plant communities on Mount Segrila on the Tibetan Plateau show distinct changes at different altitudes, but little information is available on belowground communities of arbuscular mycorrhizal fungi (AMF). Root samples of two co-occurring species, Pennisetum centrasiaticum and Kobresia sp., growing in open grasslands at eight altitudes (3,446-4,556 m) were analyzed for diversity of AMF by PCR, cloning, and sequencing.

[Ecological distribution of arbuscular mycorrhizal fungi in alpine grasslands of Tibet Plateau].

Seventy soil samples with the roots of 37 dominant or common plant species on the grasslands in south and north Tibet Plateau were collected to study the ecological distribution of arbuscular mycorrhizal (AM) fungi in the investigation area. A total of 35 AM fungi species belonging to 5 genera were isolated, among which, 18 species belonged to Glomus, 9 species belonged to Acaulospora, 6 species belonged to Scutellospora, 1 species belonged to Entrophospora, and 1 species belonged to Paraglomus. There were 23 AM fungi species belonging to 4 genera isolated from south Tibet, and 22 species belonging to 4 genera from north Tibet.

[Influence of soil factors on species diversity of arbuscular mycorrhizal (AM) fungi in Stipa steppe of Tibet Plateau].

This study was based on the isolation and identification of arbuscular mycorrhizal (AM) fungi collected from the alpine Stipa steppe of north Tibet, and focused on the influence of soil texture, pH, organic matter, and available P on the spore density, isolation frequency, relative abundance, importance value, species diversity, and species evenness of the AM fungi. In the rhizosphere soil of the steppe, a total of 15 species AM fungi were isolated and identified, including 9 species of Glomus, 6 species of Acaulospora, and 1 species of Scutellospora. Among them, Glomus and Acaulospora were the dominant genera, and Glomus claroideum and Acaulospora laevis were the dominant species.

[Spatial-temporal variation of soil organic carbon and its relations to soil physical properties in degraded alpine grasslands].

By using grid sampling method, the spatial-temporal variation of soil organic carbon (SOC) and its relations to soil physical properties in degraded alpine grasslands in North Tibet were studied. The SOC content and its density both in surface (0-10 cm) and in subsurface (10-20 cm) layers decreased in order of slightly degraded grassland > normal grassland > moderately degraded grasslands > seriously degraded grasslands, and the differences of SOC content and its density between the two layers showed the same variation trend. An opposite trend was observed in the annual variation rates of SOC content and its density in different grasslands, and the variation was larger in surface than in subsurface layer.

Alcohol consumption and metabolic syndrome among Shanghai adults: a randomized multistage stratified cluster sampling investigation.

Aim: To examine the relations of alcohol consumption to the prevalence of metabolic syndrome in Shanghai adults.

Methods: We performed a cross-sectional analysis of data from the randomized multistage stratified cluster sampling of Shanghai adults, who were evaluated for alcohol consumption and each component of metabolic syndrome, using the adapted U.S.

[Characterization of soil biological properties on degraded alpine grasslands].

The study of degraded alpine grasslands in northern Tibet showed that compared with normal alpine grassland, slightly degraded alpine grassland had higher amounts of soil bacteria, fungi and actinomyces, higher activities of cellulase, urease and alkali phosphatase, and higher contents of microbial biomass C and N and organic matter in its 2-10 cm soil layer, while these parameters were much lower on moderately or severely degraded alpine grassland. There was a positive correlation between soil microbial biomass C/N (B(C)/B(N)) and soil total C/N (T(C)/T(N)), with coefficient value (r) being 0.9088 (P < or = 0.

[Field inoculation effect of AM fungi on Tibet plateau Stipa bungeana grassland].

A field experiment was conducted on the Tibet plateau Stipa bungeana grassland to investigate the effects of arbuscular mycorrhizal fungi (AMF) inoculation on S. bungeana growth and its phosphorus uptake, and on soil microbial communities under unsterilized condition. The results showed that AMF inoculation increased the AMF spore density, infection rate and infection intensity in rhizosphere soil significantly, but had less effect on arbuscule richness.

[Effects of environmental factors on AM fungi around steppe plant roots in Tibet Plateau].

The study on the representative steppe plant species in Tibet Plateau showed that the density of AM fungi spores in host plant rhizosphere did not correlate with the infection rate of AM fungi. The big changes in air temperature and rainfall at different altitudes played an important role in determining the growth and infection of AM fungi specific to steppe plants, and steppe type and soil texture also had obvious effects on AM fungi's growth and infection. Within a certain range, the spore density increased significantly with increasing soil pH (r = 0.

[Microbial characteristics of straw-amended degraded soils in central Tibet and its effect on soil fertility].

This paper studied the dynamics of microbial communities in degraded soils of central Tibet under straw amendment and its effect on soil fertility. The results showed that straw amendment, and soil covering with spring highland barley (Hordeum vulgare var. nudum) straw in particular, could supply a beneficial soil environment for the relatively balanced growth of soil microbes, e.

[Effects of forms and application rate of nitrogen fertilizer on yield and qualities of tobacco in southeast Tibet].

Field experiments in southeast Tibet were conducted to study the effect of nitrogenous fertilizer supply and its forms on tobacco. The result indicated that the yield, production value, and the contents of nicotine, potassium oxide and total nitrogen of the cured leaves were positively correlated to the amount of N application, and significantly and negatively correlated to the percentage of superior-medium class leaves of tobacco and contents of deoxidize sugar. The highest yield and best quality of tobacco were obtained by applying 75 kg N per hectare.