Timing and duration of phenological sequences of alpine plants along an elevation gradient on the Tibetan plateau

Abstract Soil CO2-fixing microbes play a significant role in CO2-fixation in the terrestrial ecosystems, particularly in the Tibetan Plateau. To understand carbon sequestration by soil CO2-fixing microbes and the carbon cycling in alpine meadow soils, microbial diversity and their driving environmental factors were explored along an elevation gradient from 3900m to 5100m, on both east and west slopes of Mila Mountain region on the Tibetan Plateau. The CO2-fixing microbial communities were characterized by high-throughput sequencing targeting the cbbL gene，encoding the large subunit for the CO2-fixing protein ribulose 1, 5-bisphosphate carboxylase/oxygenase. The overall OTU abundance is concentrated at an altitude between 4300m~4900m. The species richness and distribution uniformity on the east slope is better than those on the west slope. In terms of microbial community composition, Proteobacteria is dominant, and the most abundant genera are Cupriavidus, Rhodobacter, Sulfurifustis and Thiobacillus. The CO2-fixing microbial community structure dramatically shifted along the elevation. It was jointly driven by vegetation coverage, soil moisture content, and soil organic carbon and soil particle size, and most environmental factors are positively correlated. Our results are helpful to understand the variation in soil microbial community and its role in soil carbon cycling along elevation gradients.

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Response of Soil Respiration to Grazing in an Alpine Meadow at Three Elevations in Tibet

The Scientific World JOURNAL ◽

10.1155/2014/265142 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 13

Author(s):

Gang Fu ◽

Xianzhou Zhang ◽

Chengqun Yu ◽

Peili Shi ◽

Yuting Zhou ◽

...

Keyword(s):

Tibetan Plateau ◽

Soil Respiration ◽

Alpine Meadow ◽

Elevation Gradient ◽

Major Type ◽

The Tibetan Plateau ◽

Total N ◽

Organic C ◽

Nitrate N ◽

Ammonium N

Alpine meadows are one major type of pastureland on the Tibetan Plateau. However, few studies have evaluated the response of soil respiration (Rs) to grazing along an elevation gradient in an alpine meadow on the Tibetan Plateau. Here three fenced enclosures were established in an alpine meadow at three elevations (i.e., 4313 m, 4513 m, and 4693 m) in July 2008. We measuredRsinside and outside the three fenced enclosures in July–September, 2010-2011. Topsoil (0–20 cm) samples were gathered in July, August, and September, 2011. There were no significant differences forRs, dissolved organic C (DOC), and belowground root biomass (BGB) between the grazed and ungrazed soils. Soil respiration was positively correlated with soil organic C (SOC), microbial biomass (MBC), DOC, and BGB. In addition, bothRsand BGB increased with total N (TN), the ratio of SOC to TN, ammonium N (NH4+-N), and the ratio ofNH4+-N to nitrate N. Our findings suggested that the negligible response ofRsto grazing could be directly attributed to that of respiration substrate and that soil N may indirectly affectRsby its effect on BGB.

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