Soil carbon changes: comparing flux monitoring and mass balance in a box lysimeter experiment
Soil carbon changes: comparing flux monitoring and mass balance in a box lysimeter experiment
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DOI：
10.2136/sssaj2000.643943x
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发表时间：
2000-05-01
影响因子：
2.9
通讯作者：
Bormann, BT
中科院分区：
文献类型：
--
作者：
Nay, SM;Bormann, BT
土壤表面呼吸的直接措施，需要评估地下生物过程，森林生产力和生态系统对全球变化的反应。尽管红外气体分析仪（IRGA）方法在实验室研究中跟踪参考CO2流量，但仍存在将IRGA方法外推到现场条件的问题。我们用桑迪壤土和牛粪的均质混合物建造了10个箱式蒸渗仪，并保持它们不含植物，以产生一系列CO2石灰。红气体分析仪测量，每两周一次，然后进行了比较，以质量平衡为基础的措施，在土壤中的C变化超过8个月。在10个箱中的9个箱中，用IRGA测量的CO2通量与质量平衡测量的CO2通量没有显著差异（P < 0.05）。唯一具有统计学显著性差异的是具有最高初始C含量的蒸渗仪;该箱在试验早期升高了土壤温度，表明堆肥效应可能干扰了IRGA措施。质量平衡估计值的变化高于预期，表明在实地研究中建立真正的参考是多么困难。我们的结论是，从土壤中的CO2通量可以监测与IRGA为基础的腔室系统在现场产生可靠的估计累积C损失。然而，这种实地测量可能比实验室测量的变化更大，因此需要广泛的取样。
Direct measures of soil-surface respiration are needed to evaluate belowground biological processes, forest productivity, and ecosystem responses to global change. Although infra-red gas analyzer (IRGA) methods track reference CO2 flows in lab studies, questions remain for extrapolating IRGA methods to field conditions. We constructed 10 box lysimeters with homogenized mixtures of sandy loam and cattle manure and kept them free of plants to create a range of CO2 limes. Infra-red gas analyzer measurements, applied biweekly, were then compared to mass balance-based measures of changes in soil C over 8 mo. The CO2 fluxes measured with IRGA were not significantly different (P < 0.05) from the mass balance measure in 9 of the 10 boxes. The only statistically significant difference was in the lysimeter with the highest initial C content; this box had elevated soil temperatures early in the trial, suggesting a composting effect that may have interfered with IRGA measures. Variations in the mass balance estimates were higher than expected, demonstrating how difficult establishing a true reference in field studies is. We conclude that fluxes of CO2 from soils can be monitored with an IRGA-based chamber system in the field to produce reliable estimates of cumulative C loss. Such field measures will likely be much more variable than laboratory measures, however, and thus will require extensive sampling.