Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 2
Biogeosciences, 15, 567–579, 2018
https://doi.org/10.5194/bg-15-567-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 15, 567–579, 2018
https://doi.org/10.5194/bg-15-567-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 29 Jan 2018

Research article | 29 Jan 2018

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 Bo Xu et al.
  • 1Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
  • 2College of Resources and Environment, Aba 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 varies 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 the 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 was collected in the middle of each month and analyzed for water content, microbial biomass C (MBC) and N (MBN), dissolved organic C and N, and inorganic N. Soil microbial community composition was measured by the dilution-plate method. Fungi and actinomycetes dominated the microbial community during the nongrowing seasons, and the proportion of bacteria increased considerably during the early growing seasons. Trends of consistently increasing MBC and available N pools were observed during the nongrowing seasons. MBC sharply declined during soil thaw and was accompanied by a peak in available N pool. Induced by changes in soil temperatures, significant shifts in the structures and functions of microbial communities were observed during the winter–spring transition and largely contributed to microbial reduction. The divergent seasonal dynamics of different N forms showed a complementary nutrient supply pattern during the growing season. Similarities between the interannual dynamics of microbial biomass and available N pools were observed, and soil temperature and water conditions were the primary environmental factors driving interannual fluctuations. Owing to the changes in climate, seasonal soil microbial activities and nutrient supply patterns are expected to change further, and these changes may have crucial implications for the productivity and biodiversity of alpine ecosystems.

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The Qinghai–Tibet Plateau is sensitive to 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 nongrowing 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 climate change. We documented seasonal and...
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