Change in Arctic CO₂Flux Over Two Decades: Effects of Climate Change at Barrow, Alaska

Abstract

A significant difference in net ecosystem carbon balance of wet sedge ecosystems in the Barrow, Alaska region was observed between CO2 flux measurements obtained during the International Biological Program in 1971 and measurements made during the 1991‐1992 growing seasons. Currently, high‐center polygons are net sources of CO2 to the atmosphere of ≈14 gC·m‐2·yr‐1, while low‐center polygons are losing ≈3.6 gC·m‐2·yr‐1, and ice wedge habitats are accumulating 4.0 gC·m‐2·yr‐1. On average, moist meadow habitats characteristic of the IBP‐II site are currently sources of ≈1.3 gC·m‐2·yr‐1 to the atmosphere compared to the reported accumulation of ≈25 gC·m‐2·yr‐1 determined in 1971. This difference in ecosystem function over the last two decades may be due to the recently reported increase in surface temperatures resulting in decreases in the soil moisture status. These results point to the importance of long‐term research sites and databases for determining the potential effects of climate change on ecosystem function.

The Polar Vegetation Photosynthesis and Respiration Model: a parsimonious, satellite-data-driven model of high-latitude CO<sub>2</sub> exchange

“…Field observations at the main Barrow EC site have indicated full flooding following snowmelt, with vegetation that consists mainly of wet sedges, moss, lichens and grasses (Oechel et al, 1995;Harazono et al, 2003). The Atqasuk EC site is located ≈ 100 km south of Barrow, and is both warmer and drier than the Barrow site.…”

Seasonal patterns of carbon dioxide and water fluxes in three representative tundra ecosystems in northern Alaska

“…Historically, Arctic tundra has acted as a strong carbon sink because low temperatures and poor soil drainage limit decomposition more than primary production. However, some studies indicate that the Alaskan tundra is becoming a net source of CO 2 during the growing season, with larger positive values of net ecosystem exchange (NEE, where a positive value of NEE denotes a source of CO 2 , and a negative value denotes a sink; Oechel et al 1995, Kwon et al 2006). This switch is generally thought to be due to drying and warming of the tundra, and consequently higher rates of soil decomposition (Kwon et al 2006, Oberbauer et al 2007.…”

Effects of short-term ecosystem experimental warming on water-extractable organic matter in an ombrotrophic Sphagnum peatland (Le Forbonnet, France)

“…Peatlands are predominantly abundant in continental boreal and sub-boreal regions where a greater temperature increase is expected over the next century (Immirzi and Maltby, 1992;IPCC, 2007). If environmental constraints which favour C sequestration change (Davidson and Janssens, 2006), peatlands may switch from a C sink to a C source function (Oechel et al, 1995;Waddington and Roulet, 1996).…”