Temporal trends and sources of variation in carbon flux from coarse woody debris in experimental forest canopy openings

• Published in: Oecologia Vol. 179; no. 3; pp. 889 - 900
• Main Authors: Forrester, J. A, Mladenoff, D. J, D’Amato, A. W, Fraver, S, Lindner, D. L, Brazee, N. J, Clayton, M. K, Gower, S. T
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2015; Springer; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Canopies; canopy gaps; carbon; Carbon - analysis; Carbon - metabolism; Carbon Cycle; Carbon dioxide; Carbon Dioxide - analysis; Carbon Dioxide - metabolism; coarse woody debris; Community composition; community structure; decayed wood; Deciduous forests; Ecology; ECOSYSTEM ECOLOGY; Ecosystem ecology - Original research; Fluctuations; forest canopy; Forests; fungal communities; Fungi; Growing season; hardwood forests; Hydrology/Water Resources; Life Sciences; Plant Sciences; second growth; stumps; temperature; Trees - microbiology; Wood; Wood - microbiology; Heterotrophic respiration; Wood-decay fungi; Carbon flux; Coarse woody debris; Canopy gap; Stumps
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-015-3393-4

Pulses of respiration from coarse woody debris (CWD) have been observed immediately following canopy disturbances, but it is unclear how long these pulses are sustained. Several factors are known to influence carbon flux rates from CWD, but few studies have evaluated more than temperature and moisture. We experimentally manipulated forest structure in a second-growth northern hardwood forest and measured CO₂ flux periodically for seven growing seasons following gap creation. We present an analysis of which factors, including the composition of the wood-decay fungal community influence CO₂ flux. CO₂ flux from CWD was strongly and positively related to wood temperature and varied significantly between substrate types (logs vs. stumps). For five growing seasons after treatment, the CO₂ flux of stumps reached rates up to seven times higher than that of logs. CO₂ flux of logs did not differ significantly between canopy-gap and closed-canopy conditions in the fourth through seventh post-treatment growing seasons. By the seventh season, the seasonal carbon flux of both logs and stumps had decreased significantly from prior years. Linear mixed models indicated the variation in the wood inhabiting fungal community composition explained a significant portion of variability in the CO₂ flux along with measures of substrate conditions. CO₂ flux rates were inversely related to fungal diversity, with logs hosting more species but emitting less CO₂ than stumps. Overall, our results suggest that the current treatment of CWD in dynamic forest carbon models may be oversimplified, thereby hampering our ability to predict realistic carbon fluxes associated with wood decomposition.