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| Titel |
Carbon Dynamics of Forest Floor and Stem in Black Spruce Forest Soils, Interior Alaska |
| VerfasserIn |
Yongwon Kim, Seong-deog Kim, Woongji Kim |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250034057
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| Zusammenfassung |
| Our automated open/close chamber system (AOCC) consists of eight chambers, a pump, CO2
gas analyzer, and a datalogger for CO2 data on the lichen, tussock, feather moss, and
sphagnum moss of a black spruce forest, Interior Alaska, during the growing seasons of 2007
and 2008. During the observing periods of 2007 and 2008, the seasonal NEE was
0.127±0.049 and -0.039±0.025 mgCO2/m2/s in tussock regime, and 0.006±0.011 and
0.028±0.017 mgCO2/m2/s in sphagnum moss, respectively. Air temperature is a more
significant regulator than soil temperature in determining the GPP and Re of forest floor
vegetations. Air temperature explained 77–95% of the variability in GPP and Re of the floor
vegetations. The contributions (%) of simulated seasonal GPP to the black spruce forest
during non-growing periods (DOY 1–120 and 244–365) and during the growing period
(DOY 121–243) of 2007 are 63–72%, 20–25%, and 8–18%, respectively. This
indicates that the floor CO2 exchange, as well as the contribution of winter carbon
emission, is a component of the regional carbon budget that cannot be neglected. As
the result of simulated GPP and Re in tussock during 2007, tussocks are found to
have on atmospheric CO2 release, similar to results of observation for 63-day of
2007.
On the other hand of stem respiration rates of black spruce (Picea Mariana), the
continuous measurement of stem respiration was conducted in black spruce stands of
different ages (4.3 to 13.5 cm in DBH) in Interior Alaska during the growing seasons of 2007
and 2008, using a pump, CO2 analyzer, chambers, and data-logger. The averaged whole stem
respiration rate is 0.011±0.005 mgCO2/m2/s (range 0.005±0.002 to 0.015±0.008
mgCO2/m2/s, CV 45%) in black spruce stands, indicating remarkably diurnal and seasonal
variations of stem respiration among the stems during the growing season. It is found that
metabolism exhibits 1.5-fold higher in the younger black spruce stand than in the older.
Temperatures in the air and stem are significant regulators in determining stem
respiration. The annual stem respiration rates simulated by Q10 value based on air
temperature are 41.2 and 36.8 gC/m2during 2007 and 2008, respectively, which
corresponds to 5.2 and 5.0% of ecosystem respiration and GPP during 2007. This
suggests that stem respiration is a significant component in the scaling-up of the
regional carbon budget in a black spruce forest, Interior Alaska. Quantification
of the effects of regional change on the black spruce forest carbon balance and
atmosphere-forest interactions requires a better understanding of respiration response. |
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