期刊
ECOSYSTEMS
卷 14, 期 5, 页码 804-817出版社
SPRINGER
DOI: 10.1007/s10021-011-9447-5
关键词
Arctic; climate change; deciduous shrubs; net nitrogen mineralization; snow manipulation; soil organic matter
类别
资金
- NSF [DEB-0516041, DEB-0516509, DEB-0423385]
- Directorate For Geosciences
- Office of Polar Programs (OPP) [806271] Funding Source: National Science Foundation
Climate warming in The Arctic may lead to a shift from graminoid to shrub dominance, which may, in turn, alter the structure and function of the ecosystem through shrub influences on the abiotic and/or biotic controls over biogeochemical cycles of carbon (C) and nitrogen (N). In Arctic tundra, near Toolik Lake, Alaska, we quantified net N-mineralization rates under ambient and manipulated snow treatments at three different plant communities that varied in abundance of deciduous shrubs. Our objective was twofold: (1) to test whether the amount of snow that can accumulate around Arctic deciduous shrubs maintains winter soil temperatures high enough to stimulate microbial activity and increase soil N levels (effect of soil microclimate) and (2) to compare the relative effects of snow versus shrubs on N availability via effects on the main drivers of N-mineralization: SOM quality versus microclimate. Winter snow addition had a positive effect on summer, but not winter, N-mineralization rates. Soil organic matter quality had a nine times larger effect on N-mineralization than did soil microclimate in the summer season and only SOM quality had a detectable effect on N-mineralization in the winter. Here we conclude that on a short time scale, shrub interactions with snow may play a role in increasing plant available N, primarily through effects on the summer soil microenvironment. In addition, differences in SOM quality can drive larger differences in net N-mineralization than changes in soil microclimate of the magnitude of what we saw across our three sites.
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