Two independent estimations of stand-level root respiration on clonal Eucalyptus stands in Congo: up scaling of direct measurements on roots versus the trenched-plot technique.
Two independent estimations of stand-level root respiration on clonal Eucalyptus stands in Congo: up scaling of direct measurements on roots versus the trenched-plot technique.
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DOI：
10.1111/j.1469-8137.2007.02300.x
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
C. Marsden;Y. Nouvellon;A. T. M'bou;L. Saint-André;C. Jourdan;Antoine Kinana;D. Epron
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文献类型：
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作者：
C. Marsden;Y. Nouvellon;A. T. M'bou;L. Saint-André;C. Jourdan;Antoine Kinana;D. Epron
林分层次的根系呼吸是生态系统碳平衡的一个重要组成部分，过去曾使用各种方法估算过，其中大多数是间接的，依赖于土壤呼吸测量。在刚果布拉柴维尔的一个3岁的桉树林，涉及到的方法，在原位根上直接测量的放大，进行了比较与一个独立的方法，使用控制和开沟地块（即没有活根）进行土壤呼吸测量。第一个估计是基于根直径分布的知识和根直径和比呼吸速率之间的关系。直接技术包括根上直接测量的放大，导致估计为1.53微摩尔m（-2）s（-1），c。比间接技术获得的平均估计值（1.05 μ mol m（-2）s（-1））高50%。蒙特-卡罗模拟结果表明，结果具有较高的不确定性，但这种不确定性并不高于直接法比沟槽图法。为了减少放大结果的不确定性，需要更广泛地了解温度敏感性，并对细根的呼吸速率和生物量有更多的信心和精度。
Root respiration at the level of a forest stand, an important component of ecosystem carbon balance, has been estimated in the past using various methods, most of them being indirect and relying on soil respiration measurements. On a 3-yr-old Eucalyptus stand in Congo-Brazzaville, a method involving the upscaling of direct measurements made on roots in situ, was compared with an independent approach using soil respiration measurements conducted on control and trenched plots (i.e. without living roots). The first estimation was based on the knowledge of root-diameter distribution and on a relationship between root diameter and specific respiration rates. The direct technique involving the upscaling of direct measurements on roots resulted in an estimation of 1.53 micromol m(-2) s(-1), c. 50% higher than the mean estimation obtained with the indirect technique (1.05 micromol m(-2) s(-1)). Monte-Carlo simulations showed that the results carried high uncertainty, but this uncertainty was no higher for the direct method than for the trenched-plot method. The reduction of the uncertainties on upscaled results requires more extensive knowledge of temperature sensitivity and more confidence and precision on the respiration rates and biomasses of fine roots.