Accurately quantifying soil base cation pool sizes is essential to interpreting the sustainability of forest harvests from element mass-balance studies. The soil-exchangeable pool is classically viewed as the bank of “available” base cations in the soil, withdrawn upon by plant uptake and leaching and refilled by litter decomposition, atmospheric deposition and mineral weathering. The operational definition of this soil bank as the exchangeable (salt-extractable) pools ignores the potential role of “other” soil nutrient pools, including microbial biomass, clay interlayer absorbed elements, and calcium oxalate. These pools can be large relative to “exchangeable” pools. Thus neglecting these other pools in studies examining the sustainability of biomass extractions, or need for nutrient return, limits our ability to gauge the threat or risk of unsustainable biomass removals. We examine a set of chemical extraction data from a mature Norway spruce forest in central Sweden and compare this dataset to ecosystem flux data gathered from the site in previous research. The 0.2 M HCl extraction released large pools of Ca, K, Mg, and Na, considerably larger than the exchangeable pools. Where net losses of base cations are predicted from biomass harvest, exchangeable pools may not be sufficient to support more than a single 65-year forest rotation, but acid-extractable pools are sufficient to support many rotations of net-ecosystem losses. We examine elemental ratios, soil clay and carbon contents, and pool depth trends to identify the likely origin of the HCl-extractable pool. No single candidate compound class emerges, as very strongly supported by the data, as being the major constituent of the HCl-extractable fraction. A combination of microbial biomass, fine grain, potentially shielded, easily weatherable minerals, and non-structural clay interlayer bound potassium may explain the size and distribution of the acid-extractable base cation pool. Sequential extraction techniques and isotope-exchange measurements should be further developed and, if possible, complemented with spectroscopic techniques to illuminate the identity of and flux rates through these important, and commonly overlooked, nutrient pools.

中文翻译：

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土壤库中的阳离子：不可交换的水池可能会持续数百年的林业和淋洗净损失

准确量化土壤阳离子池的大小对于从元素质量平衡研究解释森林采伐的可持续性至关重要。土壤可交换池在传统上被视为土壤中“可用的”基础阳离子库，通过植物吸收和浸出而撤出，并通过凋落物分解，大气沉积和矿物风化来补充。该土壤库作为可交换（可盐提取）库的操作定义忽略了“其他”土壤养分库的潜在作用，包括微生物生物量，粘土夹层吸收的元素和草酸钙。相对于“可交换”池，这些池可能很大。因此，在研究生物量提取的可持续性或营养返回需求的研究中忽略了这些其他资源，限制了我们评估不可持续生物质去除的威胁或风险的能力。我们检查了一组来自瑞典中部成熟的挪威云杉林的化学提取数据，并将此数据集与先前研究中从该地点收集的生态系统通量数据进行了比较。0.2 M HCl萃取释放出大量的Ca，K，Mg和Na，远远大于可交换池。如果从生物量的收获中预测碱性阳离子的净损失，可交换池可能不足以支持一个65年以上的森林轮换，但可酸提取的池足以支持许多轮换的生态系统净损失。我们研究了元素比，土壤粘土和碳含量以及池深度趋势，以确定可提取HCl的池的可能来源。没有单个候选化合物类出现，数据非常有力的支持，因为它是HCl可萃取馏分的主要成分。微生物生物量，细颗粒，可能被屏蔽的，易风化的矿物以及非结构性粘土夹层结合的钾的结合可能解释了可酸萃取的碱性阳离子池的大小和分布。应进一步开发顺序提取技术和同位素交换测量，并在可能的情况下，通过光谱技术加以补充，以阐明通过这些重要且通常被忽视的营养物库的特征和通量率。非结构性粘土层间键合钾可能解释了可酸萃取的碱性阳离子池的大小和分布。应进一步开发顺序提取技术和同位素交换测量，并在可能的情况下，通过光谱技术加以补充，以阐明通过这些重要且通常被忽视的营养物库的特征和通量率。非结构性粘土层间键合钾可能解释了可酸萃取的碱性阳离子池的大小和分布。应进一步开发顺序提取技术和同位素交换测量，并在可能的情况下，通过光谱技术加以补充，以阐明通过这些重要且通常被忽视的营养物库的特性和通量率。