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using a closed chamber technique. Strong methane emission at the rate of 26.2G1.2 and 7.8G1.1 mg CH 4 m L2 h L1 was observed for a grass community in a Kobresia humilis meadow and a Potentilla fruticosa meadow, respectively. A shrub community in the Potentilla meadow consumed atmospheric methane at the rate of 5.8G1.3 mg CH 4 m L2 h L1 on a regional basis; plants from alpine meadows contribute at least 0.13 Tg CH 4 yr L1 in the Tibetan Plateau. This finding has important implications with regard to the regional methane budget and species-level difference should be considered when assessing methane emissions by plants.

Grassland fire, as an important ecological factor, is quite influential in determining the structural and functional stability of ecosystem. In this work, the fire‐induced changes on the vegetation and soil microbial community were studied in alpine meadow. Microbial community composition was assessed by phospholipid fatty acid (PLFA) analysis, and functional diversity was determined by Biolog EcoPlate method. Our results showed that burning caused a significant increase in plant functional group coverage, biomass of grasses, soil bulk density and the ratio of roots to soils. Fire also caused an increase in soil pH and a decrease in total soil nutrient contents and soil moisture. The average well colour development of soil microorganism, the microbial functional diversity and the number of carbon source utilisation were also significantly affected by fire. Total bacteria PLFA, Gram‐positive bacteria (G+) PLFA, Gram‐negative bacteria (G−) PLFA and total PLFA of the burnt sites all increased significantly in burnt soil. The BACT/FUNG, SAT/MONO and G+/G− ratio also appeared to be higher in burnt sites. The total PLFA, G+ PLFA and G− PLFA are closely related to the plant community quantitative characteristics and soil nutrients. The total PLFA, bacteria and G+ PLFA are significantly correlated with the soil total nutrients and available nutrients. These results suggest that the ability of soil microorganisms to use a single‐carbon substrate was increased after a fire event. Grassland fire not only has direct impacts on plant community structure and function but also indirectly alters the soil microbial properties because of fire‐induced changes in plant community. Copyright © 2015 John Wiley & Sons, Ltd.

We conducted a field experiment in two alpine meadows to investigate the short-term effects of nitrogen enrichment and plant litter biomass on plant species richness, the percent cover of functional groups, soil microbial biomass, and enzyme activity in two alpine meadow communities. The addition of nitrogen fertilizer to experimental plots over two growing seasons increased plant production, as indicated by increases in both the living plant biomass and litter biomass in the Kobresia humilis meadow community. In contrast, fertilization had no significant effect on the amounts of living biomass and litter biomass in the K. tibetica meadow. The litter treatment results indicate that litter removal significantly increased the living biomass and decreased the litter biomass in the K. humilis meadow; however, litter-removal and litter-intact treatments had no impact on the amounts of living biomass and litter biomass in the K. tibetica meadow. Litter production depended on the degree of grass cover and was also influenced by nitrogen enrichment. The increase in plant biomass reflects a strong positive effect of nitrogen enrichment and litter removal on grasses in the K. humilis meadow. Neither fertilization nor litter removal had any impact on the grass biomass in the K. tibetica meadow. Sedge biomass was not significantly affected by either nutrient enrichment or litter removal in either alpine meadow community. The plant species richness decreased in the K. humilis meadow following nitrogen addition. In the K. humilis meadow, microbial biomass C increased significantly in response to the nitrogen enrichment and litter removal treatments. Enzyme activities differed depending on the enzyme and the different alpine meadow communities; in general, enzyme activities were higher in the upper soil layers (0-10 cm and 10-20 cm) than in the lower soil layers (20-40 cm). The amounts of living plant biomass and plant litter biomass in response to the different treatments of the two alpine meadow communities affected the soil microbial biomass C, soil organic C, and soil fertility. These results suggest that the original soil conditions, plant community composition, and community productivity are very important in regulating plant community productivity and microbial biomass and activity.