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Microbial carbon dynamics in nitrogen amended Arctic tundra soil: measurement and model testing


Stapleton, LM and Crout, NMJ and Sawstrom, C and Marshall, WA and Poulton, PR and Tye, AM and Laybourn-Parry, J, Microbial carbon dynamics in nitrogen amended Arctic tundra soil: measurement and model testing, Soil Biology and Biochemistry, 37, (11) pp. 2088-2098. ISSN 0038-0717 (2005) [Refereed Article]

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DOI: doi:10.1016/j.soilbio.2005.03.016


We examined the responses of grazers (protozoa and nematodes) and their main food sources to low levels of nitrogen (N) fertilisation and applied carbon (C) flux models to our data. Replicate plots of tundra soil adjacent to the Kongsfjorden (Svalbard 788N) were amended with ammonium and nitrate at concentrations of 1 and 5 kg N haK1 to assess the impact of anthropogenic N deposition over three summers. Bacterial abundance as determined using the fluorochrome SYBR Green and epifluorescence microscopy ranged between 9.73!108 and 102.49!108 cells/g dry wt of soil, with a significant response to N addition occurring only during the second sampling in 2001. Despite little change in bacterial biomass, bacterial production (measured by the incorporation of 3H thymidine into DNA) during the second sampling in 2002, increased in NH4 enriched plots compared to control and NO3 amended plots, indicating that NH4 was the preferred source of inorganic N. The main bacterial predators were heterotrophic flagellates (HNAN) and naked amoebae, which showed no significant response to the N addition. HNAN showed a correlation with bacterial abundance suggesting a dependence on bacteria as a food source. The inability of a microbial C flux model to fit our data (RWSS/dataZ18.6, r2Z0.088) was at least partly due to insufficient bacterial production to meet the C demands of predator taxa, and high variability in the data over time. This is reflected in the performance statistics for model variants where select microbial taxa and data were removed. The optimal model in terms of predictive utility was a model with data from 2002 only, minus naked amoebae (RWSS/dataZ2.45, r2Z0.806).

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial ecology
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Biodiversity in Antarctic and Southern Ocean environments
UTAS Author:Laybourn-Parry, J (Professor Johanna Laybourn-Parry)
ID Code:49096
Year Published:2005
Web of Science® Times Cited:28
Deposited By:Research Division
Deposited On:2007-11-13
Last Modified:2009-06-09

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