Recovery of Aboveground Plant Biomass and Productivity after Fire in Mesic and Dry Black Spruce Forests of Interior Alaska

• Published in: Ecosystems (New York) 2008-03, Vol.11 (2), p.209-225
• Main Authors: Mack, Michelle C., Treseder, Kathleen K., Manies, Kristen L., Harden, Jennifer W., Schuur, Edward A. G., Vogel, Jason G., Randerson, James T., Chapin, F. Stuart
• Format: Article
• Language: English
• Subjects: Aboveground biomass; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomass; Biomass production; Biomedical and Life Sciences; Boreal forests; Chronosequences; Climate change; Deciduous trees; Ecology; Ecosystems; Environmental Management; Forest & brush fires; Forest and land fires; Forest ecosystems; Forest fires; Forest soils; Fundamental and applied biological sciences. Psychology; General aspects; Geoecology/Natural Processes; Hydrology/Water Resources; Life Sciences; Permafrost; Phytopathology. Animal pests. Plant and forest protection; Picea mariana; Plant biology; Plant biomass; Plant Sciences; Plants; Shrubs; Synecology; Understory; Weather damages. Fires; Wildfires; Zoology
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/S10021-007-9117-9

Plant biomass accumulation and productivity are important determinants of ecosystem carbon (C) balance during post-fire succession. In boreal black spruce (Picea mariana) forests near Delta Junction, Alaska, we quantified aboveground plant biomass and net primary productivity (ANPP) for 4 years after a 1999 wildfire in a welldrained (dry) site, and also across a dry and a moderately well-drained (mesic) chronosequence of sites that varied in time since fire (2 to ~116 years). Four years after fire, total biomass at the 1999 burn site had increased exponentially to 160 ± 21 g m⁻² (mean ± 1SE) and vascular ANPP had recovered to 138 ± 32 g m⁻² y⁻¹, which was not different than that of a nearby unburned stand (160 ± 48 g m⁻² y⁻¹) that had similar pre-fire stand structure and understory composition. Production in the young site was dominated by re-sprouting graminoids, whereas production in the unburned site was dominated by black spruce. On the dry and mesic chronosequences, total biomass pools, including overstory and understory vascular and non-vascular plants, and lichens, increased logarithmically (dry) or linearly (mesic) with increasing site age, reaching a maximum of 2469 ± 180 (dry) and 4008 ± 233 g m⁻² (mesic) in mature stands. Biomass differences were primarily due to higher tree density in the mesic sites because mass per tree was similar between sites. ANPP of vascular and non-vascular plants increased linearly over time in the mesic chronosequence to 335 ± 68 g m⁻² y⁻¹ in the mature site, but in the dry chronosequence it peaked at 410 ± 43 g m⁻² y⁻¹ in a 15-year-old stand dominated by deciduous trees and shrubs. Key factors regulating biomass accumulation and production in these ecosystems appear to be the abundance and composition of re-sprouting species early in succession, the abundance of deciduous trees and shrubs in intermediate aged stands, and the density of black spruce across all stand ages. A better understanding of the controls over these factors will help predict how changes in climate and fire regime will affect the carbon balance of Interior Alaska.