Validating methodology for quantifying of carbon (C) loss from dead wood is critical for understanding C turnover in forest ecosystems. We compared estimates of CO2 fluxes with a closed dynamic chamber method using an infrared gas analyzer with: 1) small chambers installed on the downed woody debris (DWD) surface and 2) DWD segments placed in large chambers. The fluxes were measured from 6 intermediately decayed DWD fragments, wood and bark of Betula pubescens and Populus tremula and calculated on the surface area, volume and mass bases. For most DWD fragments, the tendency with an underestimation of CO2 flux in the first approach up to 90% was observed due to a barrier effect of a thick bark layer and possible gas leakages. Our results demonstrate the importance of taking into account contribution of bark into total DWD respiration rates especially in upscaling the piece-level results into ecosystem level.

中文翻译：

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比较用于量化倒下木本碎片中 CO2 通量的测量方法与动态室法

用于量化死木中碳 (C) 损失的验证方法对于理解森林生态系统中的碳周转至关重要。我们使用红外气体分析仪将 CO2 通量的估计值与封闭动态室方法进行了比较，其中：1) 安装在倒下的木质碎片 (DWD) 表面上的小室和 2) 放置在大室中的 DWD 段。通量是从 6 个中度腐烂的 DWD 碎片、桦木和杨树的木材和树皮测量的，并根据表面积、体积和质量进行计算。对于大多数 DWD 碎片，由于厚树皮层的屏障效应和可能的气体泄漏，观察到第一种方法中 CO2 通量被低估高达 90% 的趋势。