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The article offers information on the estimation of carbon dynamics of boreal forest in Yukon River Basin (YRB) in Alaska. It states that carbon transfer rate of boreal forest ecosystems have substantial consequences for efforts to moderate the rise of atmospheric carbon dioxide. It further highlights that regional assessment indicates that forest vegetation carbon storage has increased but reports that the total soil carbon storage has remained unchanged.

Peatlands store 30% of the world’s terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen located just outside the Bonanza Creek Experimental Forest in interior Alaska. The drought (lowered water table position) treatment was a weak sink or small source of atmospheric CO2 compared to the moderate atmospheric CO2 sink at our control. This change in net ecosystem exchange was due to lower gross primary production and light-saturated photosynthesis rather than increased ecosystem respiration. The flooded (raised water table position) treatment was a greater CO2 sink in 2006 due largely to increased early season gross primary production and higher light-saturated photosynthesis. Although flooding did not have substantial effects on rates of ecosystem respiration, this water table treatment had lower maximum respiration rates and a higher temperature sensitivity of ecosystem respiration than the control plot. Surface soil warming increased both ecosystem respiration and gross primary production by approximately 16% compared to control (ambient temperature) plots, with no net effect on net ecosystem exchange. Results from this rich fen manipulation suggest that fast responses to drought will include reduced ecosystem C storage driven by plant stress, whereas inundation will increase ecosystem C storage by stimulating plant growth. [ABSTRACT FROM AUTHOR]

To determine the influence of fire and thermokarst in a boreal landscape, we investigated ↑600 years of vegetation succession from peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate that succession proceeded from a terrestrial forest to a sedge-dominated wetland over 100 years ago and to a Sphagnum-dominated bog in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing season temperature record from Fairbanks. The concurrent wetland succession and reduced growth of black spruce trees indicates a non-linear ecosystem-level response to a change in regional climate. In 2001, fire was observed coincident with permafrost collapse and resulted in lateral expansion of the bog. These observations and the peat profile suggest that future warming and/or increased fire disturbance could promote permafrost degradation and bog expansion, and increase carbon storage in the collapse; however, the development of drought conditions could reduce the success of black spruce and Sphagnum, decreasing long-term ecosystem carbon storage in the adjacent landscape. [ABSTRACT FROM AUTHOR]