Effects of elevated nitrogen and temperature on carbon and nitrogen dynamics in Alaskan arctic and boreal soils
[1] Plant productivity in upland tundra and boreal forest is demonstrably limited by nitrogen (N) and indirect evidence from field studies suggests that decomposition by soil microbes may be similarly limited. As climate warms at high latitudes, understanding the response of soil organic matter (SOM...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.3390 http://www.lter.uaf.edu/pdf/1686_Lavoie_Mack_2011.pdf |
| Summary: | [1] Plant productivity in upland tundra and boreal forest is demonstrably limited by nitrogen (N) and indirect evidence from field studies suggests that decomposition by soil microbes may be similarly limited. As climate warms at high latitudes, understanding the response of soil organic matter (SOM) decomposition to increased soil temperature may be crucial for determining the net effect of warming on ecosystem carbon (C) balance because temperature directly affects decomposition but also because it has an indirect effect on C balance via nutrient mineralization. We incubated northern Alaskan soils at two temperatures (5°C and 15°C) and two levels of N addition (with and without) to directly test for N limitation of SOM decomposition and to explore the interaction between temperature and N limitation. Over the entire 924 day incubation of organic and mineral soils from two ecosystem types, we measured microbial respiration; over the initial 90 days of the incubation, we measured microbial biomass N, net N mineralization, and the isotopic signatures (d 13 C and D 14 C) of microbial respiration. Across soil layers and ecosystem types, temperature always had a strong positive effect on SOM decomposition rates, whereas N addition had positive, negative, and neutral effects. |
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