This study investigated differences in forest structure, organic layer thickness, soil organic carbon, and permafrost depth between late-successional (LS) and postfire (PF; 90-120 years since burn) plots under black spruce (Picea mariana (Mill.) B.S.P.) growing on fine-textured, poorly drained lacustrine sediments in the Copper River Basin, Alaska. Although live stem and seedling density and organic layer thickness were not significantly different between PF and LS plots (28 ± 7 cm and 31 ± 10 cm, respectively), we did find a significant difference in soil organic carbon (SOC) stocks (30 ± 10 kg·m-2 and 46 ± 12 kg·m-2, respectively) permafrost depth (90 ± 28 cm and 56 ± 12 cm, respectively). OLT was linearly related to 1 m SOC stocks for LS plots but not for PF plots, and LS plots had a greater proportion of highly decomposed (humic) material in the organic layer. The soil properties of PF plots appear to be on a trajectory of recovery toward those of LS plots with respect to SOC stocks, permafrost depth, and organic layer composition. However, PF plots remain different despite nearly 100 years since fire disturbance and thus they are potentially more sensitive to changes in future fire frequency or climate.
Bibliographical noteFunding Information:
This work was supported in part by University of Minnesota - Minnesota Agricultural Experiment Station funding to N.A. Jelinski, USDA - Natural Resources Conservation Service (USDA- NRCS) Agreement No. 68-7482-15-531 to N.A. Jelinski, and a USDA- NRCS Conservation Innovation Grant to the Ahtna Intertribal Resource Commission (AITRC, Mile 187 Glenn Highway, Glennallen, Alaska, USA). Work performed by E. GreyBear and K. Finnesand was in part supported by AITRC. This work was completed by A. Williams outside of her official duty as an NRCS employee. The findings and conclusions in this publication are those of the author(s) and should not be construed to represent any official Minnesota Department of Natural Resources, USDA, or US government determination or policy. The authors thank M.H. Clark, C.-L. Ping, and N. Parry for motivating discussions about Copper River Basin soils; K. Linnell (Executive Director, AITRC) for providing cultural perspectives on lands and land management; S. Daszkiewicz, C. Cole, and D. Mulligan for assistance in the field; and S. Bauer and K. Ring for assistance in the laboratory.
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- Black spruce
- Soil carbon