Biometric and eddy-covariance-based estimates of carbon balance for a warm-temperate mixed forest in Japan
Biometric and eddy-covariance-based estimates of carbon balance for a warm-temperate mixed forest in Japan
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DOI：
10.1016/j.agrformet.2008.01.017
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发表时间：
2008-05-15
影响因子：
6.2
通讯作者：
Ohtani, Yoshikazu
中科院分区：
文献类型：
--
作者：
Kominami, Yuji;Jomura, Mayuko;Ohtani, Yoshikazu
为了估计位于复杂地形的森林中的净生态系统交换（NEE）和净生态系统生产（NEP），我们评估了NEE估计值对选择摩擦速度（u*）校正的敏感性，以估计平静夜晚的通量。并将这些估计值与基于日本暖温带落叶和万年青混交林生物特征数据的估计值进行了比较。生物计量方法的基础上分析的自养碳库和异养碳通量（NEP）与变化的两个主要的碳库（三角洲C）。为了估计Delta C，我们计算了凋落物和粗木质残体（CWD）对土壤碳库的贡献。从2000年到2002年的3年平均年NEE为-1.23 MgC ha（-1）year（-1）（负通量表示碳增益）。据估计，Delta C和NEP分别为1.73和0.91 MgC m（-2）年（-1）（正通量表示碳增益）。活生物量的增加贡献了总Delta C的76%。由于土壤呼吸的空间变化很大，估计的NEP变化很大。现实的u* 阈值为0.4 m s（-1）。估计的NEE值大于NEP。NEE作为u* 阈值的函数的变化是显著的，并且大多数测量数据（约80%）可以通过使用0.4ms（-1）u* 阈值来消除。这些结果似乎是由于水平平流造成的夜间呼吸的损失。或排水流（因为研究地点位于复杂地形上）。这种趋势是一致的塔位于山脊和山谷。(C)2008 Elsevier B. V.保留所有权利。
To estimate net ecosystem exchange (NEE) and net ecosystem production (NEP) in a forest situated on complex terrain, we evaluated the sensitivity of the estimates of NEE to the choice of a friction velocity (u*) correction for the estimation of flux on calm night. And compared these estimates with estimates based on biometric data using a warm-temperate deciduous and evergreen mixed forest in Japan. Biometric approaches were based on analyses of autotrophic carbon pools and heterotrophic carbon fluxes (NEP) versus changes in two major carbon pools (Delta C). To estimate Delta C, we calculated contributions to the soil carbon pool by litter and coarse woody debris (CWD) independently. The 3-year mean annual NEE from 2000 to 2002 was -1.23 MgC ha(-1) year(-1) (a negative flux indicates carbon gain). Estimated Delta C and NEP were 1.73 and 0.91 MgC m(-2) year(-1), respectively (a positive flux indicates carbon gain). The increment of live biomass contributed 76% of total Delta C. Estimated NEP varied widely due to large spatial variation in soil respiration. A realistic u* threshold was 0.4 m s(-1). The estimated NEE value was larger than NEP. The change in NEE as a function of the u* threshold was marked, and most of the measured data (about 80%) could be eliminated by using the 0.4 m s(-1) u* threshold. These results seem to be caused by the loss of most nocturnal respiration as a result of horizontal advection. or drainage flow (because the study site was located on complex terrain). This tendency was consistent for towers located on a ridge and in a valley. (C) 2008 Elsevier B.V. All rights reserved.