QUANTIFICATION OF WOOD-CARBON TRANSFER TO SOIL ORGANIC MATTER POOLS – DISTRIBUTION AND FORMS

Author

Samuel Mensah Opoku, Michigan Technological UniversityFollow

Date of Award

2023

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Forest Science (PhD)

Administrative Home Department

College of Forest Resources and Environmental Science

Advisor 1

Andrew J. Burton

Committee Member 1

Trista Vick-Majors

Committee Member 2

Evan S. Kane

Committee Member 3

Martin F. Jurgensen

Committee Member 4

Carl C. Trettin

Abstract

Deadwood is a major forest carbon (C) pool, yet, little is known regarding the ultimate amounts of deadwood-derived C moved into labile versus stable soil pools, and as mediated by deadwood type, site conditions and decomposing organisms during decomposition. The lack of information on deadwood-derived C incorporation into soil may negatively impact global C reporting and monitoring. Furthermore, data is lacking on the capacity of tropical forest soils to sequester C despite their recognized role in climate change mitigation. This research provided information on the proportions of wood-derived C moving into labile (FLF), occluded (OCC) and protected (HF) C fractions of surface and subsoils from ¹³C-labeled trembling aspen, paper birch and loblolly pine logs decomposing in bioclimatically-diverse US forests, and in plots with or without termites, as well as soil C storage for intact and degraded forest cover types in tropical forests of Ghana. During 8 years of log decomposition, early stages of decay led to wood C movement to surface soil labile pools that were vulnerable to further decomposition. However, in the longer term, C moved into more stable HF in both surface and subsoils. During 9 years of decomposition in three bioclimatically diverse sites, log C moving into soil to a 50 cm depth varied by site and species, with greater movement of log C occurring in a warm, moist forest site, and with aspen contributing more C to soil than pine. Though log C primarily resided in surface soil, significant portions were in HF increasing its protection against further decompostion. Wood C movement into soil pools was not greatly affected by subterranean termites, as comparable proportions of log C moved into soil with and without termites at riparian and upland locations. Meanwhile, in the tropics, we found that disturbed or degraded forests of Ghana lose little soil C if forests maintain vegetative cover of some type following disturbance. Overall, this research confirmed deadwood-derived C movement into soil pools, including stable HF, and variation related to deadwood type and site. The outcomes will help refine terrestrial C modeling and inform management efforts seeking to increase soil C sequestration.

Recommended Citation

Mensah Opoku, Samuel, "QUANTIFICATION OF WOOD-CARBON TRANSFER TO SOIL ORGANIC MATTER POOLS – DISTRIBUTION AND FORMS", Campus Access Dissertation, Michigan Technological University, 2023.

https://doi.org/10.37099/mtu.dc.etdr/1628