Succession-driven changes in soil respiration following fire in black spruce stands of interior Alaska

• Published in: Biogeochemistry 2006-08, Vol.80 (1), p.1-20
• Main Authors: O'Neill, Katherine P, Richter, Daniel D, Kasischke, Eric S
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Aquatic plants; Biological and medical sciences; Boreal forests; Bryopsida; burnt soils; Carbon dioxide; carbon sequestration; Chronosequences; colonizing ability; coniferous forests; Decomposition; degradation; depth; Earth sciences; Earth, ocean, space; Ecological succession; Exact sciences and technology; fires; Forest soils; Fundamental and applied biological sciences. Psychology; gas emissions; gas exchange; Marine and continental quaternary; Microclimate; Mineral soils; Mosses; mosses and liverworts; Organic soils; photosynthesis; Picea mariana; regression analysis; Respiration; Soil ecology; Soil moisture; soil organic matter; Soil respiration; Soil temperature; Soil water; Source-sink relationships; statistical models; Surficial geology; Synecology; Terrestrial ecosystems; thawing; Thermal decomposition; Wildfires
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-005-5964-7

Boreal forests are highly susceptible to wildfire, and post-fire changes in soil temperature and moisture have the potential to transform large areas of the landscape from a net sink to a net source of carbon (C). Understanding the ecological controls that regulate these disturbance effects is critical to developing models of ecosystem response to changes in fire frequency and severity. This paper combines laboratory and field measurements along a chronosequence of burned black spruce stands into regression analyses and models that assess relationships between moss succession, soil microclimate, decomposition, and C source-sink dynamics. Results indicate that post-fire changes in temperature and substrate quality increased decomposition in humic materials by a factor of 3.0 to 4.0 in the first 7 years after fire. Bryophyte species exhibited a distinct successional pattern in the first five decades after fire that corresponded to decreased soil temperature and increased C accumulation in organic soils. Potential rates of C exchange in mosses were greatest in early successional species and declined as the stand matured. Residual sources of CO₂ (those not attributed to moss respiration or humic decomposition) increased as a function of stand age, reflecting increased contributions from roots as the stand recovered from disturbance. Together, the field measurements, laboratory experiments, and models provide strong evidence that interactions between moss and plant succession, soil temperature, and soil moisture largely regulate C source-sink dynamics from black spruce systems in the first century following fire disturbance.