5:15 PM - 6:30 PM
[ACG22-P05] Estimation of understory carbon budget and environmental factors influencing on the processes in a larch forest on the northern foot of Mount Fuji
Keywords:Understory carbon budget, CO2, Chamber, Soil respiration, Larch forest
To understand the impact of forest understory carbon budget and environmental factors influencing on processes of understory carbon cycle, we set multi-channel automated chamber measurement system in larch forest on northern foot of Mt. Fuji in 2006. The control unit of chamber system mainly consisted of a data logger (CR1000, Campbell Scientific), an infrared gas analyzer (LI820, LI-COR) and an air compressor. We set soil chambers (90 cm × 90 cm × 50 cm) for soil CO2 flux measurement. Surroundings of the half of those soil chambers were root cut with chainsaw until 25 cm depth for the measurement of heterotrophic respiration (Rh), and the remaining control chambers were used for soil respiration (Rs) measurement. We also set plant chambers (90 cm × 90 cm × 100 cm) which included understory vegetation to measure understory net CO2 exchange (NUE), understory respiration (Ru) and understory gross primary production (GPP_u).
We got continuous data for 8 years from 2006 to 2013 with chamber measurement method. Comparison with eddy-covariance data showed that annual Ru accounted for 68.6% of annual ecosystem respiration, and annual GPP_u accounted for 16.3% of annual gross primary production of the larch forest. Primary factor for GPP_u was light intensity of forest understory, and positive correlation between annually estimated GPP_u and annual average of understory PPFD (R2 = 0.64) was confirmed. Remarkable exponential correlations between soil temperature and Rs, Rh and Ru were observed, and total Q10 values for Rs, Rh and Ru were 2.49, 2.57 and 2.25, respectively. On the other hand, influence of soil moisture on those soil CO2 fluxes were minor except summer season when soil moisture was notably decreased due to few rainfall.