Delayed recovery of soil respiration after wetting of dry soil further reduces C losses from a Norway spruce forest soil
Delayed recovery of soil respiration after wetting of dry soil further reduces C losses from a Norway spruce forest soil
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DOI：
10.1029/2009jg000998
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发表时间：
2009-12
影响因子：
--
通讯作者：
J. Muhr;W. Borken
中科院分区：
文献类型：
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作者：
J. Muhr;W. Borken
[1]本试验研究了夏季干旱对德国南部挪威云杉山地森林土壤呼吸的影响。在三个操作图，我们排除了夏季穿透在2006/2007年和测量SR通量相比，三个控制地块。使用放射性碳测量，我们量化了根际（RR）和异养呼吸（HR）对总SR的贡献。穿透雨排除（TE）小区的平均CO2排放量（±SE）小于对照小区的平均CO2排放量（5.7tC ha-1（±0.3），而2006年为6.7 t C ha-1（±0.2），2007年为5.9 t C ha-1（±0.3），而2007年为7.0 t C ha-1（±0.4）。在控制条件下，CO2主要来源于HR（占SR的60-95%）.长期干旱降低HR，而RR不受影响，甚至略有增加。减少CO 2排放量的TE图被发现长达6周后，基质电位条件的差异消失，可能是因为防水性抑制均匀再润湿的有机层或因为严重损害微生物种群。没有证据表明，释放新的，以前受保护的基板之前的干旱。在2008年的连续测量（无操纵）没有显示增加的二氧化碳排放量的TE图，可以补偿在2006/2007年的减少。根据我们的研究结果，我们假设之间的负反馈增加的频率和幅度的夏季干旱和SR在挪威云杉的立场。
[1] This experiment investigated the effects of prolonged summer drought on soil respiration (SR) in a mountainous Norway spruce forest in south Germany. On three manipulation plots we excluded summer throughfall in the years of 2006/2007 and measured SR fluxes in comparison to three control plots. Using radiocarbon measurements we quantified the contribution of rhizosphere (RR) and heterotrophic respiration (HR) to total SR. In both manipulation years, mean CO 2 emissions (±SE) from the throughfall exclusion (TE) plots were smaller than from the control plots with 5.7 t C ha -1 (±0.3) compared to 6.7 t C ha -1 (±0.2) in 2006 and 5.9 t C ha -1 (±0.3) compared to 7.0 t C ha -1 (±0.4) in 2007. Under control conditions, CO 2 originated mainly from HR (60-95% of SR). Prolonged drought reduced HR, whereas RR was not affected or even increased slightly. Reduction of CO 2 emissions on the TE plots was found up to 6 weeks after differences in matric potential conditions disappeared, possibly either because water repellency inhibited homogeneous rewetting of the organic horizons or because of severe damage to the microbial population. No evidence was found for the release of new, formerly protected substrates by preceding drought. Continuous measurements in 2008 (no manipulation) did not reveal increased CO 2 emissions on the TE plots that could compensate for the reduction during the years 2006/2007. Based on our results, we postulate a negative feedback between increased frequency and magnitude of summer droughts and SR in Norway spruce stands.