Controlling factors on the interannual CO₂ budget at a subarctic black spruce forest in interior Alaska

Abstract

A B S T R A C TThe eddy covariance method was applied to measure net ecosystem CO 2 exchange (NEE) at a subarctic black spruce forest in interior Alaska during 2003 and 2004. To clarify the budget of CO 2 , we divided photosynthesis and respiration by applying the Carbon Budget Analysis Tool, in which the potential photosynthetic rate, the light use efficiency, and the suppression factors on photosynthesis were evaluated.The potential photosynthetic rate and the light use efficiency were related with the understory leaf area index. The determined optimal temperature of photosynthesis was higher than 15 • C, which was higher than that of other boreal forests. Drought in midsummer of 2004 suppressed both photosynthesis and respiration, but the suppression was more effective in photosynthesis, resulting in a slightly decreased NEE. Cumulative respiration and photosynthesis were 2.

Sources and sinks of carbon in boreal ecosystems of interior Alaska: A review

“…The amount of carbon uptake and biomass production in different ecosystem types depends on the complex interplay between successional stage, water balance, nutrient availability, and topography. For example, in black spruce forests where CO 2 f luxes were measured, hot and dry summer conditions resulted in half the CO 2 uptake of the previous growing season (Ueyama et al, 2006). Similar conditions in a black spruce forest in interior Alaska resulted in a net f lux of CO 2 to the atmosphere (Euskirchen et al, 2014).…”

Novel Patterns of Seasonal Photosynthetic Acclimation, Including Interspecific Differences, in Conifers over an Altitudinal Gradient

“…In the Colorado climate, the highest levels of light harvesting (after rapid relaxation of sustained photoprotection) were seen in the mild spring season (Zarter et al, 2006b), where apparent water availability was higher than in the summer, while Korean fir exhibited evidence for higher light harvesting in the summer than in the spring. These differences suggest that precipitation patterns and water availability are key to when light harvesting and forest carbon gain are maximal, which is consistent with total forest carbon gain for Colorado (with moist springs and dry summers; Monson et al, 2002) versus conifers in regions with moist summers (Zha et al, 2004;Lagergren et al, 2005;Ueyama et al, 2006;Etzold et al, 2011). In Korean fir, the disengagement of photoprotection (return to a xanthophyll cycle conversion state of 30-35% accompanied by increases in F o , F m , and F v /F m ) during the transition from winter to spring was not accompanied with an immediate return to overall summer pigment composition.…”

Applications of NOAA/AVHRR and Observed Fluxes to Estimate 3 Regional Carbon Fluxes over Black Spruce Forests in Alaska

“…An underestimation of LAI measured by the plant canopy analyzer was reported and the correction was provided (e.g., Chen et al, 1997). However, the correction was only 9 higher, because the LAI of the black spruce trees contributed 14-23 to the whole stand on our site (Ueyama et al, 2006). Also, the LAI was applied to reflect the seasonal variation of vegetation activity in the empirical model, so the uncorrected LAI was used in this study to link the field data and satellite data.…”

“…We have observed carbon fluxes at a subarctic black spruce forest in interior Alaska since fall 2002, and some parameters affecting the carbon budget were examined (Ueyama et al, 2006). As the black spruce is dominant in Alaska's boreal forests, we tried to evaluate the carbon budget over the breadth of Alaska and its seasonal change by synthesizing both remote sensing data and field observation data.…”