Respiratory carbon losses in a managed oak forest ecosystem

Respiratory carbon losses from a mixed oak forest ecosystem following experimental manipulations were examined for their magnitudes and biophysical regulations. To quantify these losses, respiration measurements from chamber-based ecosystem components of sapwood, snags, down-logs, and soil, using chamber-based methods, were collected from experimental stands 8 yr after the manipulations of: non-harvest (NHM), uneven-aged (UAM), and even-aged (EAM) managements. Temperature and respiration relationships (R = R0 × eβ×T) were used to estimate annual ecosystem respiration. The annual respiration rates were 1684 g C m−2 yr−1 in the NHM, 1787 g C m−2 yr−1 in the UAM, and 1231 g C m−2 yr−1 in the EAM stands. Harvesting reduced annual ecosystem respiration in the EAM stands by 28% compared to the NHM stands. Soil respiration was the largest component and contributed from 72% to 85% of the total respiration. The sapwood and leaf respiration were the second largest components of ecosystem respiration in both NHM and UAM stands, but down-logs were the second largest component in the EAM stands. Harvest significantly affected ecosystem respiration, with intensity driving changes in component respiration.

► Chamber-based ecosystem components respiratory C losses were estimated 8-yrs after treatments.
► Temperature and respiration relationships were used to estimate annual ecosystem respiration.
► Soil respiration was the largest component and contributed from 72% to 85% of the total respiration.
► Harvest intensity was the driving force in the component respiration among treatments.