Net nitrogen mineralization from shrub gradient and snow manipulations, near Toolik field station, collect in the summer of 2006 and winter of 2006-2007

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 and height of deciduous shrubs. Our objective was twofold: 1) to test whether the amount of snow that accumulates 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 shrubs on N availability via effects on the controls over N mineralization (effect of soil organic matter (SOM) quality). Net nitrogen mineralization was measured using in situ soil cores capped with mixed bed ion exchange resin bags. Seperate cores were incubated in the organic and mineral soils at 10 cm depth in the ambient and snow addition treatments located in moist acidic tundra and two seperate shrub tundra plant communities. Organic soil cores were incubated in the summer and winter while mineral soils were only incubated in the winter.