Dynamics of Postfire Aboveground Carbon in a Chronosequence of Chinese Boreal Larch Forests. Issue 12 (12th December 2018)

• Record Type: Journal Article
• Authors: Yang, Yuan Z.; Cai, Wen H.; Yang, Jian; White, Megan; Lhotka, John M.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 12(2018)
• Page Start: 3490
• Page End: 3506
• Publication Date: 2018-12-12
• Subjects: aboveground carbon -- postfire -- carbon dynamics -- stand density -- boreal larch forests -- ecosystem resilience; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1029/2018JG004702
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Boreal forests store a large proportion of the global terrestrial carbon (C), while wildfire plays a crucial role in determining their C storage and dynamics. The aboveground C (AC) pool is an important component of forest C stocks. To quantify the turning point (transforming from C source to C sink) and recovery time of postfire AC, and assess how stand density affects the AC, 175 plots from eight stand age classes were surveyed as a chronosequence in the Great Xing'an Mountains of Northeast China. Linear and nonlinear regression analyses were conducted to describe postfire AC recovery patterns. The results showed that (1) postfire AC exhibited a skewed U‐shaped pattern with the turning point at approximately year 30, when the change rate of AC shifted from negative to positive, (2) it took more than 120 years for this forest ecosystem to recover 80% of AC in unburned old‐growth (200 years) stands, and (3) there was an overall positive relationship between AC and stand density over the entire range of stand age classes; and such relationship was stronger during the early‐ and late‐successional stages, but weaker ( p > 0.05) during the midsuccessional stage. Although boreal larch forests have been C sinks under historical fire free intervals, predicted increases in fire frequency could potentially shift it to a C source. Understanding postfire AC dynamics in boreal larch forests is central to predicting C cycling response to wildfire and provides a framework for assessing ecosystem resilience to disturbance in this region. Plain Language Summary: Boreal forests store more than 32% of total global forest carbon (C), but this C pool is very susceptible to wildfires which are one of the most pervasive disturbances in the boreal biome. Identifying the dynamic trajectory and recovery pattern of postfire aboveground C (AC) storage is crucial for understanding the global ecological significance of wildfire disturbance. A total of 175 plots from eight stand age classes were surveyed in the Great Xing'an Mountains of Northeast China to quantify ecological resilience, and further examine the relationship between various components of AC and stand density throughout successional stages. Our data analysis showed that the AC pool could be a C source to the atmosphere for several decades following fire disturbances; and it would take more than a century for the AC to recover 80% of that in old‐growth boreal larch forests in Northeastern China. Increases in fire frequency due to climate change and human activities will increase C emission, which may significantly influence the regional C budget. Stand density was considered as a positive factor on AC accumulation following wildfire, but this effect may be counteracted by variation in tree size due to site productivity in other successional stages. Key Points: Postfire dynamics of aboveground carbon storage were depicted over a 200‐year chronosequence in boreal larch forests Aboveground carbon transformed from a source to a sink after 30 years, and it took over 120 years to recover 80% of old‐growth stands There was a positive relationship between aboveground carbon and stand density over the entire range of stand age classes