Seasonal and interannual dynamics of soil microbial biomass and available nitrogen in an alpine meadow in the eastern part of Qinghai-Tibet Plateau, China

2017 ◽  
Author(s):  
Anonymous
2018 ◽  
Vol 15 (2) ◽  
pp. 567-579 ◽  
Author(s):  
Bo Xu ◽  
Jinniu Wang ◽  
Ning Wu ◽  
Yan Wu ◽  
Fusun Shi

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.


2017 ◽  
Author(s):  
Bo Xu ◽  
Jinniu Wang ◽  
Ning Wu ◽  
Yan Wu ◽  
Fusun Shi

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.


2021 ◽  
Vol 12 ◽  
Author(s):  
Jihui Fan ◽  
Tianyuan Liu ◽  
Ying Liao ◽  
Yiying Li ◽  
Yan Yan ◽  
...  

The biogeographic characteristics of soil microbial biomass stoichiometry homeostasis and also its mechanisms are commonly thought to be key factors for the survival strategies and resource utilization of soil microbes under extreme habitat. In this work, we conducted a 5,000-km transect filed survey in alpine grassland across Qinghai–Tibet Plateau in 2015 to measure soil microbial biomass carbon (MBC) and nitrogen (MBN) across alpine steppe and meadow. Based on the differences of climate and soil conditions between alpine steppe and meadow, the variation coefficient was calculated to investigate the homeostatic degree of MBC to MBN. Furthermore, the “trade-off” model was utilized to deeply distinguish the homeostasis degree of MBC/MBN between alpine steppe and meadow, and the regression analysis was used to explore the variability of trade-off in response to environmental factors in the alpine grassland. The results showed that the coefficient of variation (CV) of MBC/MBN in alpine meadow (CV = 0.4) was lower than alpine steppe (CV = 0.7). According to the trade-off model, microbial turnover activity of soil N relative to soil C increased rapidly and then decreased slightly with soil organic carbon (SOC), soil total nitrogen (STN), and soil water content across alpine meadow. Nevertheless, in alpine steppe, SOC/STN had a positive effect on microbial turnover of soil N. These results suggested that water, heat, and soil nutrients availability were the key factors affecting the C:N stoichiometry homeostasis of soil microbial biomass in Qinghai–Tibet Plateau (QTP)’s alpine grassland. Since the difference of survival strategy of the trade-off demands between soil C and N resulting in different patterns and mechanism, the stoichiometry homeostasis of soil microbial biomass was more stable in alpine meadow than in alpine steppe.


2017 ◽  
Vol 28 (5) ◽  
pp. 1538-1548 ◽  
Author(s):  
Changting Wang ◽  
Genxu Wang ◽  
Pengfei Wu ◽  
Rashid Rafique ◽  
Hongbiao Zi ◽  
...  

2016 ◽  
Vol 36 (18) ◽  
Author(s):  
何芳兰 HE Fanglan ◽  
金红喜 JIN Hongxi ◽  
王锁民 WANG Suoming ◽  
韩生慧 HAN Shenghui ◽  
曾荣 ZENG Rong ◽  
...  

2018 ◽  
Author(s):  
wenjuan zhang ◽  
xian xue ◽  
fei peng ◽  
quangang you ◽  
jing pan ◽  
...  

Soil microbial community structure is an effective indicator to reflect changes in soil quality. Little is known about the effect of alpine meadow degradation on the soil bacterial and fungal community. In this study, we used the Illumina MiSeq sequencing method to analyze the microbial community structure of alpine meadow soil in five different degradation levels (i.e., non-degraded (ND), slightly degraded (LD), moderately degraded (MD), severely degraded (SD), and very severely degraded (VD)) in the Qinghai-Tibet Plateau. Proteobacteria, Actinobacteria, and Acidobacteria were the mainly bacterial phyla in meadow soil across all five degradation levels investigated. Basidiomycota was the mainly fungal phylum in ND; however, we found a shift from Basidiomycota to Ascomycota with an increase (severity) in degradation level. The overall proportion of Cortinariaceae exhibited high fungal variability, and reads were highest in ND (62.80%). Heatmaps of bacterial genera and fungal families showed a two-cluster sample division on a genus/family level: (1) an ND and LD group and (2) an SD, VD, and MD group. Redundancy analysis (RDA) showed that 79.7%and 71.3% of the variance in bacterial and fungal composition, respectively, could be explained by soil nutrient conditions (soil organic carbon, total nitrogen, and moisture) and plant properties (below-ground biomass). Our results indicate that meadow degradation affects both plant and soil properties and consequently drives changes in soil microbial community structure.


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