A critique of the microbial metabolic quotient (qCO2) as a bioindicator of disturbance and ecosystem development
A critique of the microbial metabolic quotient (qCO2) as a bioindicator of disturbance and ecosystem development
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DOI：
10.1016/0038-0717(95)00093-t
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发表时间：
1995-12
影响因子：
9.7
通讯作者：
D. Wardle;A. Ghani
中科院分区：
文献类型：
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作者：
D. Wardle;A. Ghani
微生物代谢商（呼吸-生物量比）或qCO 2，概念上基于Odum的生态系统演替理论，越来越多地被用作生态系统发展（在此期间，它应该下降）和干扰（由于它应该增加）的指数。我们调查了qCO 2作为生物指示剂的适用性：（1）来自Franz Josef Glacier年表的数据，跨越22，000年;（2）从已发表的研究中重新计算的数据。在Franz Josef序列中，qCO 2在前250年中在L层和矿物质土壤层中都发生了可检测的下降。然而，在继承的后期阶段有一个急剧增加qCO 2表明降低微生物效率，这似乎是有关的应力（独立的干扰），导致稳态条件。计算qCO 2从以前的三个研究干扰和生态系统的发展表明，该指数的反应不可预测，并不一定会下降，在演替过程中。植物凋落物分解研究表明，虽然qCO 2通常最初下降，qCO 2的显着增加，最终可以遵循耐分解的凋落物类型。24个先前的研究的相关性分析表明，qCO 2往往随着pH值，粘土含量和微生物生物量的增加而下降，这三个土壤特性都表明不同的压力，而不是干扰水平。对16项先前研究数据的重新分析表明，某些干扰（如施肥和石灰）可以增加或减少qCO 2值，这取决于干扰是否加剧了压力（减少qCO 2）或比压力更极端（增加qCO 2）。虽然种植是一个严重的干扰，qCO 2是不可预测的增强这种扰动。虽然qCO 2无疑提供了一个有用的衡量微生物的效率，我们的数据表明，它有局限性，因为它可能是不敏感的干扰和生态系统的发展，不能区分干扰和压力的影响，并没有下降可预测的生态系统发展时，压力增加沿着演替梯度。
The microbial metabolic quotient (respiration-to-biomass ratio) or qCO2, conceptually based on Odum's theory of ecosystem succession, is increasingly being used as an index of ecosystem development (during which it supposedly declines) and disturbance (due to which it supposedly increases). We investigated the suitability of qCO2as an bioindicator using: (1) data from the Franz Josef Glacier chronosequence, spanning over 22,000 years; and (2) data recalculated from published studies. In the Franz Josef sequence, a detectable decline in qCO2occurred in the first 250 years in both the L-layer and mineral soil layer. However, in the later phases of the succession there was a sharp increase in qCO2indicating reduced microbial efficiency, which appeared to be related to stress (independent of disturbance) resulting from steady-state conditions. Calculation of qCO2from three previous studies on disturbance and ecosystem development indicated that this index responds unpredictably and does not necessarily decline during succession. Plant litter decomposition studies demonstrate that while qCO2usually declines initially, a significant increase in qCO2can eventually follow on litter types resistant to decomposition. Correlation analysis of each of 24 previous studies demonstrated that qCO2often declines with increasing pH, clay content and amounts of microbial biomass; these three soil properties are all indicative of varying stress rather than disturbance levels. Reanalysis of data from 16 previous studies indicated that some disturbances such as fertilization and liming can either increase or decrease qCO2values depending on whether the disturbance alleviates stress (reducing qCO2)or is more extreme than the stress it alleviates (enhancing qCO2). Although cultivation represents a severe disturbance, qCO2is not predictably enhanced by this perturbation. While qCO2undoubtedly provides a useful measure of microbial efficiency, our data suggests it has limitations because it can be insensitive to disturbance and ecosystem development, fails to distinguish between effects of disturbance and stress, and does not decline predictably in response to ecosystem development whenever stress increases along successional gradients.