The Effects of Snow, Soil Microenvironment, and Soil Organic Matter Quality on N Availability in Three Alaskan Arctic Plant Communities

TitleThe Effects of Snow, Soil Microenvironment, and Soil Organic Matter Quality on N Availability in Three Alaskan Arctic Plant Communities
Publication TypeJournal Article
Year of Publication2011
AuthorsDeMarco J., Mack M.C, Bret-Harte MS
JournalEcosystemsEcosystemsEcosystems
Volume14
Pagination804-817
Date PublishedAug
ISBN Number1432-9840
Accession NumberISI:000292813800010
Keywordsarctic, climate change, climate-change, deciduous shrubs, ecosystems, microbial activity, net nitrogen mineralization, nitrogen mineralization, nutrient, permafrost, responses, shrub tundra, snow manipulation, soil organic matter, tundra soils, vegetation
Abstract

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.

Short TitleEcosystemsEcosystems
Alternate JournalEcosystems