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.
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This work was funded by the National Key R & D Program of China (2016YFA0600804), National Natural Science Foundation of China (31500387, 41222004, & 41501200), Open Project Program of Key Laboratory of Environment Change and Resources Use in Beibu Gulf (Guangxi Teachers Education University), Ministry of Education (GTEU‐KLXTJJ‐201718, GTEU‐KLXTJJ‐201720).
All data used in this study are available in the supporting information (Data Set S1).
Yang, Yuan Z.; Cai, Wen H.; Yang, Jian; White, Megan; and Lhotka, John M., "Dynamics of Postfire Aboveground Carbon in a Chronosequence of Chinese Boreal Larch Forests" (2018). Forestry and Natural Resources Faculty Publications. 28.