We investigate the edaphic, mineralogical and climatic controls of soil organic carbon (SOC) concentration utilising data from 147 primary forest soils (0–30 cm depth) sampled in eight different countries across the Amazon Basin. Sampled across 14 different World Reference Base soil groups, our data suggest that stabilisation mechanism varies with pedogenetic level. Specifically, although SOC concentrations in Ferralsols and Acrisols were best explained by simple variations in clay content – this presumably being due to their relatively uniform kaolinitic mineralogy – this was not the case for less weathered soils such as Alisols, Cambisols and Plinthosols for which interactions between Al species, soil pH and litter quality are argued to be much more important. Although for more strongly weathered soils the majority of SOC is located within the aggregate fraction, for the less weathered soils most of the SOC is located within the silt and clay fractions. It thus seems that for highly weathered soils SOC storage is mostly influenced by surface area variations arising from clay content, with physical protection inside aggregates rendering an additional level of protection against decomposition. On the other hand, most of the SOC in less weathered soils is associated with the precipitation of aluminium–carbon complexes within the fine soil fraction, with this mechanism enhanced by the presence of high levels of aromatic, carboxyl-rich organic matter compounds. Also examined as part of this study were a relatively small number of arenic soils (viz. Arenosols and Podzols) for which there was a small but significant influence of clay and silt content variations on SOM storage, with fractionation studies showing that particulate organic matter may account for up to 0.60 of arenic soil SOC. In contrast to what were in all cases strong influences of soil and/or litter quality properties, after accounting for these effects neither wood productivity, above-ground biomass nor precipitation/temperature variations were found to exert any significant influence on SOC stocks. These results have important implications for our understanding of how Amazon forest soils are likely to respond to ongoing and future climate changes.

中文翻译：

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土壤化学和物理性质的变化解释了整个流域亚马逊森林土壤碳浓度

我们使用亚马逊河流域八个不同国家的147种原始森林土壤（0-30厘米深）的数据，研究了土壤有机碳（SOC）浓度的深层，矿物学和气候控制。我们对14个不同的世界参考基准土壤组进行了采样，我们的数据表明稳定机制会随着成岩水平的变化而变化。具体地说，尽管用粘土含量的简单变化最好地解释了铁铝和丙烯醛中的SOC浓度-大概是由于它们的高岭石矿物学相对均匀-对于风化较弱的土壤（例如Alisols，Cambisols和Plinthosols）之间的相互作用铝的种类，土壤的pH值和垃圾质量被认为更为重要。尽管对于风化程度较高的土壤，大部分SOC位于集料部分内，而对于风化度较低的土壤，大多数SOC位于粉土和粘土部分中。因此，似乎对于高度风化的土壤，SOC的储存主要受粘土含量引起的表面积变化的影响，骨料内部的物理保护提供了防止分解的附加保护等级。另一方面，风化较弱的土壤中的大多数SOC与土壤细小部分中铝-碳络合物的沉淀有关，并且由于存在大量芳香族，富含羧基的有机物而增强了这种机理。作为这项研究的一部分，还检查了相对较少数量的槟榔土壤（vi。（Arenosols和Podzols）的粘土和淤泥含量变化对SOM储存影响很小，但影响显着，分馏研究表明，颗粒有机物最多可占土壤土壤SOC的0.60。与在所有情况下对土壤和/或垃圾质量特性的强烈影响相反，在考虑了这些影响后，未发现木材生产力，地上生物量或降水/温度变化都不会对SOC储量产生任何重大影响。这些结果对我们了解亚马逊河森林土壤可能如何响应当前和未来的气候变化具有重要意义。砂土土壤SOC为60。与在所有情况下对土壤和/或垃圾质量特性的强烈影响相反，在考虑了这些影响后，未发现木材生产力，地上生物量或降水/温度变化都不会对SOC储量产生任何重大影响。这些结果对我们了解亚马逊河森林土壤可能如何响应当前和未来的气候变化具有重要意义。砂土土壤SOC为60。与在所有情况下对土壤和/或垃圾质量特性的强烈影响相反，在考虑了这些影响后，未发现木材生产力，地上生物量或降水/温度变化都不会对SOC储量产生任何重大影响。这些结果对我们了解亚马逊河森林土壤可能如何响应当前和未来的气候变化具有重要意义。