Decay rate of Larix gmelinii coarse woody debris on burned patches in the Greater Khingan Mountains

Abstract

The decomposition of coarse woody debris (CWD) affects the energy flow and nutrient cycling in forest ecosystems. Previous studies on CWD have focused on the input, decomposition, reserve dynamics, and CWD functions, but coarse woody debris decomposition is complex and the results from different regions vary considerably. It is not clear which factors affect decay rate (k), especially at different decomposition stages. In this study, a single-exponential decay model was used to analyze the characteristics of CWD decomposition in Larix gmelinii forests over the 33 years following a fire in the Greater Khingan Mountains. The results show that the decay rate of coarse woody debris was positively correlated to decay class. The average decomposition rate was 0.019, and 41 years and 176 years are needed for a 50% and 95% mass loss, respectively. CWD nutrient content, density, and water content could explain the variance in the decay rate (~ 42%) of the decay factors such as amount of leaching, degree of fragmentation, respiration of the debris, and biotransformation, and varied significantly between different decay classes. Using the space–time substitution method, this study arranged the coarse woody debris of different mortality times to form a 33 year chronosequence which revealed the decomposition process. It was concluded that the decay rate was mainly explained by structural component of the debris and its nitrogen and water contents. This paper quantifies the indicators affecting CWD decay to explain the decomposition process.

Decomposition and Nutrient Release from Larix olgensis Stumps and Coarse Roots in Northeast China 33-Year Chronosequence Study

“…The average annual decomposition rate constant (k) of stumps and coarse roots was higher than that of CWD in a larch plantation (0.019 (0.009-0.037)) [36]. In addition, the k value of stumps and coarse roots (0.071) is also higher than the average annual decomposition rate constant of fallen larch wood (0.0136) [37].…”

Forest succession trajectories after fires in valleys and on slopes in the Greater Khingan Mountains, China

“…This method is primarily used to study slow/long-term ecological processes, and widely used in ecology and geomorphology using spatial data to replace different stages of the process (Ma et al 2017;Damgaard 2019;Huang et al 2020a).…”

“…1 Study area and selected burn locations surrounding the Landsat images (the same year or 1 year after the fire) of each burn scar; the Landsat image of burned area h is not shown because it was very close to g number of fires exceeds 35, and the average area burnt is 76,600 ha, usually by predominantly moderately intense fires, with few fires of low and high intensity. Topography, climate, and vegetation types tend to cause spatial heterogeneity of fire intensity (Liu 2011;Huang et al 2020a;Yuan 2020). Due to the relatively simple vegetation composition, the area is ideal for studying postfire vegetation recovery processes.…”