Abstract The long-term effect of spruce stand decay on the CO 2 balance was studied in the taiga of Valdai (Russia, Novgorod oblast). The CO 2 emission from soil, the respiration of coarse wood debris, the total respiration, and the net fluxes of CO 2 and water vapor were evaluated. In areas of dead spruce forest affected by xylophages and saprotrophs, as well as by windfall, a noticeable decrease in specific gross respiration is absent. This is related to the fact that reduced CO 2 respiration of living trees is compensated by emission from coarse wood debris and a sharp (3- to 3.5-fold) and long-term (no less than six years long) rise in soil respiration (hotspots) under dead-standing spruce trees. The contribution to carbon emission from soil hotspots per unit area in dead spruce stands under dry standing trees is greater than the role of decomposition of coarse wood debris (14.4 and 9%, respectively). The observation period is characterized by a significant decrease in the annual net CO 2 sink in the area studied: from –300 to –95 g C m –2 year –1 , which is followed by reduced evapotranspiration (0.0116 g H 2 O m –2 s –1 in May–October 2018 as compared to 0.0142 g H 2 O m –2 s –1 in the same period of 2010). We assume that the observed decrease in carbon uptake is related both to the reduction in the primary spruce productivity and to an increase in gross respiration from larger areas of decomposed spruce trees. The calculations show that if the area of the dead spruce stands is further increased to 27%, the resulting net balance of the territory will switch to a CO 2 source for the atmosphere. This should be taken into account for remote forecasting.

中文翻译：

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云杉持续衰败对针叶林碳交换的长期影响

摘要 在瓦尔代（俄罗斯，诺夫哥罗德州）针叶林中研究了云杉林分腐烂对 CO 2 平衡的长期影响。评估了土壤中的 CO 2 排放、粗木屑的呼吸、总呼吸以及 CO 2 和水蒸气的净通量。在受到木噬菌体和腐生菌影响以及意外收获影响的死亡云杉林地区，特定总呼吸没有明显下降。这与以下事实有关，即通过粗木屑的排放和土壤呼吸的急剧（3 到 3.5 倍）和长期（不少于 6 年）增加来补偿活树 CO 2 呼吸减少的事实。热点）在枯死的云杉树下。枯死的云杉林下单位面积土壤热点对碳排放的贡献大于粗木屑分解的作用（分别为 14.4% 和 9%）。观察期的特点是研究区域的年净 CO 2 汇显着减少：从 –300 到 –95 g C m –2 年 –1 ，随后蒸发量减少（0.0116 g H 2 O m – 2 s –1（2018 年 5 月至 10 月），而 2010 年同期为 0.0142 g H 2 O m –2 s –1）。我们假设观察到的碳吸收减少与初级云杉生产力的降低和更大面积的分解云杉树的总呼吸增加有关。计算表明，如果将死云杉的面积进一步增加到27%，由此产生的领土净平衡将转换为大气的 CO 2 来源。远程预测应考虑到这一点。