Carbon stocks across a chronosequence of thinned and unmanaged red pine (Pinus resinosa) stands

• Published in: Ecological applications 2012-06, Vol.22 (4), p.1297-1307
• Main Authors: Powers, Matthew D., Kolka, Randall K., Bradford, John B., Palik, Brian J., Fraver, Shawn, Jurgensen, Martin F.
• Format: Article
• Language: English
• Subjects: Carbon - chemistry; Carbon - metabolism; Carbon Cycle; carbon dynamics; carbon storage; Chippewa National Forest, Minnesota, USA; Chronosequences; Coniferous forests; Dead wood; Ecosystem; Forest ecology; Forest ecosystems; Forest litter; forest management; Forest soils; Forest stands; Forestry - methods; Mineral soils; Minnesota; Pinus - physiology; Pinus resinosa; red pine; Soil - chemistry; Stand age; thinning; Time Factors; Trees - physiology
• ISSN: 1051-0761; 1939-5582
• DOI: 10.1890/11-0411.1

Forests function as a major global C sink, and forest management strategies that maximize C stocks offer one possible means of mitigating the impacts of increasing anthropogenic CO 2 emissions. We studied the effects of thinning, a common management technique in many forest types, on age-related trends in C stocks using a chronosequence of thinned and unmanaged red pine ( Pinus resinosa ) stands ranging from 9 to 306 years old. Live tree C stocks increased with age to a maximum near the middle of the chronosequence in unmanaged stands, and increased across the entire chronosequence in thinned stands. C in live understory vegetation and C in the mineral soil each declined rapidly with age in young stands but changed relatively little in middle-aged to older stands regardless of management. Forest floor C stocks increased with age in unmanaged stands, but forest floor C decreased with age after the onset of thinning around age 40 in thinned stands. Deadwood C was highly variable, but decreased with age in thinned stands. Total ecosystem C increased with stand age until approaching an asymptote around age 150. The increase in total ecosystem C was paralleled by an age-related increase in total aboveground C, but relatively little change in total belowground C. Thinning had surprisingly little impact on total ecosystem C stocks, but it did modestly alter age-related trends in total ecosystem C allocation between aboveground and belowground pools. In addition to characterizing the subtle differences in C dynamics between thinned and unmanaged stands, these results suggest that C accrual in red pine stands continues well beyond the 60-100 year management rotations typical for this system. Management plans that incorporate longer rotations and thinning in some stands could play an important role in maximizing C stocks in red pine forests while meeting other objectives including timber extraction, biodiversity conservation, restoration, and fuel reduction goals.