Effects of drainage and temperature on carbon balance of tussock tundra microcosms

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TitleEffects of drainage and temperature on carbon balance of tussock tundra microcosms
Publication TypeJournal Article
Year of Publication1996
AuthorsJohnson, LC, Shaver, GR, Giblin, AE, Nadelhoffer, KJ, Rastetter, EB, Laundre, JA, Murray, GL
JournalOecologia
Volume108
Issue4
Pagination737-748
Accession NumberARC298
KeywordsEriophorum vaginatum D 04140 Taiga/tundra
Abstract

We examined the importance of temperature (7 degree C or 15 degree C) and soil moisture regime (saturated or field capacity) on the carbon (C) balance of arctic tussock tundra microcosms (intact blocks of soil and vegetation) in growth chambers over an 81-day simulated growing season. We measured gaseous CO sub(2) exchanges, methane (CH sub(4)) emissions, and dissolved C losses on intact blocks of tussock (Eriophorum vaginatum) and intertussock (moss-dominated). We hypothesized that under increased temperature and/or enhanced drainage, C losses from ecosystem respiration (CO sub(2) respired by plants and heterotrophs) would exceed gains from gross photosynthesis causing tussock tundra to become a net source of C to the atmosphere. The field capacity moisture regime caused a decrease in net CO sub(2) storage (NEP) in tussock tundra microcosms This resulted from a stimulation of ecosystem respiration (probably mostly microbial) with enhanced drainage, rather than a decrease in gross photosynthesis. Elevated temperature alone had no effect on NEP because CO sub(2) losses from increased ecosystem respiration at elevated temperature were compensated by increased CO sub(2) uptake (gross photosynthesis). Although CO sub(2) losses from ecosystem respiration were primarily limited by drainage, CH sub(4) emissions, in contrast, were dependent on temperature. Furthermore, substantial dissolved C losses, especially organic C, and important microhabitat differences must be considered in estimating C balance for the tussock tundra system. As much as similar to 20% of total C fixed in photosynthesis was lost as dissolved organic C. Tussocks stored similar to 2x more C and emitted 5x more methane than intertussocks. In spite of the limitations of this microcosm experiment, this study has further elucidated the critical role of soil moisture regime and dissolved C losses in regulating net C balance of arctic tussock tundra.

DOI10.1007/BF00329050
Short TitleEffects of drainage and temperature on carbon balance of tussock tundra microcosms