Effects of fire on soil respiration and its components in a Dahurian larch (Larix gmelinii) forest in northeast China: Implications for forest ecosystem carbon cycling-

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Structure Equation Model

Effects of fire on soil respiration and its components in a Dahurian larch (Larix gmelinii) forest in northeast China: Implications for forest ecosystem carbon cycling

https://doi.org/10.1016/j.geoderma.2021.115273 

Abstract

Fire plays a critical part in regulating soil carbon (C) budgets in forest ecosystems. However, few studies have focused on the effects of fire on soil respiration (Rs) and its heterotrophic (Rh) and autotrophic (Ra) components. In this study, we examined the response of Rs, Rh, and Ra to fire and the driving factors that affect Rs after a fire disturbance in a Dahurian larch (Larix gmelinii) forest in northeastern China. Fire disturbance significantly increased Rh by approximately 24% and significantly reduced Ra by approximately 66% in burned plots compared to unburned plots. The ratio of Rh to Rs significantly increased from 0.57 in the unburned plots to 0.79 in the burned plots. Fire disturbance also led to cumulative Rs C efflux increasing by approximately 10% and 28% during the growing season and the period of spring freeze–thaw cycles (FTC) in the burned plots. Furthermore, using structural equation modelling, we showed that T5 (soil temperature at 5 cm depth) was the main abiotic factor affecting Rs in both unburned and burned plots. Fine root biomass (FR) was the dominant biotic driver of Rs in the control plots, whereas microbial biomass carbon (MBC) was the dominant biotic driver of Rs in burned plots. Our findings demonstrated a significant discrepancy in the response of Rs components to fire disturbance. Forest fires can cause considerable losses of soil C in a cold temperate forest ecosystem, which suggests that proactive management of forest regeneration should be carried out after forest fire disturbances.

摘要：

森林火灾对调节森林生态系统土壤碳收支具有至关重要的作用。林火对土壤呼吸（Rs）及其组分（自养呼吸（Rh）和异养呼吸（Ra））影响的研究相对较少。本研究以中国东北地区兴安落叶松林为研究对象，探究林火干扰对Rs、Rh、Ra及其驱动因子的影响。研究发现，与对照相比，火干扰使Rh显著增加了约24%，Rh:Rs比率从未火烧样地的0.57增加至火烧样地的0.79。在生长季和春季冻融循环(FTC)期，火干扰导致火烧样地Rs碳通量累积量增加了约10%和28%。此外，结构方程模型表明，5 cm深度的土壤温度（T5）是影响对照和火烧样地Rs的主要非生物因子。细根生物量是对照样地Rs的主要生物驱动因子，但是在火烧样地，微生物生物量碳则是Rs的主要生物驱动因子。本研究结果表明，Rs组分对火干扰的响应存在显著差异。森林火灾会导致寒温带森林生态系统土壤碳的大量损失，这表明在林火干扰后应开展积极主动的林分管理更新措施。

以上摘要来自于公众号“林火科学”