Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/bg-2017-66
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 Mar 2017
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Biogeosciences (BG).
Seasonal and interannual dynamics of soil microbial biomass and available nitrogen in an alpine meadow in the eastern part of Qinghai-Tibet Plateau, China
Bo Xu1,2, Jinniu Wang1,3, Ning Wu1,3, Yan Wu1,3, and Fusun Shi1,3 1Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
2Aba Teachers University, Aba, Sichuan 623002, China
3Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chinese Academy of Sciences, Chengdu 610041, China
Abstract. Soil microbial activity occurs seasonally in frozen alpine soils during cold seasons and plays a crucial role in available N pool accumulation in soil. The intra- and interannual patterns of microbial and nutrient dynamics reflect the influences of changing weather factors, and thus provide important insights into the biogeochemical cycles and ecological functions of ecosystems. We documented seasonal and interannual dynamics of soil microbial and available N in an alpine meadow in the eastern part of Qinghai-Tibet Plateau, China between April 2011 and October 2013. Soil samples were collected in the middle of each month and were analyzed for water content, microbial biomass C (MBC) and N, dissolved organic C and N, and inorganic N; soil microbial community compositions were measured by the dilution-plate method. Fungi and actinomycetes dominated the microbial community during the non-growing seasons, and the number of bacteria increased considerably during the early growing seasons. Consistently increasing trends of MBC and available N pools were observed during the non-growing seasons. MBC sharply declined during soil thaw and was accompanied by a peak of available N pool. Induced by soil temperatures, significant shifts in the structure and functions of microbial communities were found during the winter-spring transition and largely contributed to microbial reduction. Divergent seasonal dynamics of different N forms showed a complementary nutrient supply pattern during the growing season. Similar interannual dynamics were observed between microbial biomass and available N pools, and soil temperature and water condition were the primary environmental factors driving these year-to-year fluctuations. Under the background of changing climate, the seasonal soil microbial activity and nutrient supply patterns will be further changed, having important implications to the productivity and biodiversity of alpine ecosystems.

Citation: Xu, B., Wang, J., Wu, N., Wu, Y., and Shi, F.: Seasonal and interannual dynamics of soil microbial biomass and available nitrogen in an alpine meadow in the eastern part of Qinghai-Tibet Plateau, China, Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-66, in review, 2017.
Bo Xu et al.
Bo Xu et al.
Bo Xu et al.

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Short summary
The Qinghai-Tibet Plateau is sensitive to the climate change. We documented seasonal and interannual dynamics of soil microbial and available N in an alpine meadow in this region. Consistently increasing trends of microbial biomass and available N pools were observed during the non-growing season. Significant shifts in microbial communities largely contributed to microbial reduction during soil thaw. Divergent seasonal dynamics of different N forms showed a complementary nutrient supply pattern.
The Qinghai-Tibet Plateau is sensitive to the climate change. We documented seasonal and...
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