Soil development and mineral transformations along a 1‐million‐year chronosequence on the Galápagos Islands
Soil development and mineral transformations along a 1‐million‐year chronosequence on the Galápagos Islands
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加拉帕戈斯群岛一百万年的土壤发育和矿物转化
DOI：
10.1002/saj2.20317
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发表时间：
2021
影响因子：
2.9
通讯作者：
F. Zehetner
中科院分区：
文献类型：
--
作者：
I. Candra;M. Gerzabek;F. Ottner;K. Wriessnig;J. Tintner;Greta Schmidt;Maria V. Rechberger;N. Rampazzo;F. Zehetner
加拉帕戈斯群岛是研究土壤演变的理想生态系统模型。在这里，我们研究了加拉帕戈斯火山土壤的矿物转化和成土作用，以响应风化时间（1500 - 1070000年）和气候（潮湿与干燥）。结果表明，在湿润气候条件下，土壤pH值、电导率、有机碳含量、阳离子交换量（CEC）和持水性随土壤年龄的增加而降低，粘粒含量和容重随土壤年龄的增加而增加。Andic特性在≤ 4，300年的土壤中表现出来，但在成土作用中相对较早消失，在≥ 26，000年的土壤中不存在。年轻的冻土（≤ 4，300年）的粘粒组分主要是水铝英石和水铁矿。经过26，000年的成土作用，伊利石-蛭石相占主导地位，在较老的土壤（≥ 166，000年）中，高岭石，赤铁矿和三水铝石占主导地位。从最年轻到第二古老的网站的土壤顺序是Histosol-Andisol-Alfisol（蛭石）-Alfisol（parasesquic）-Ultisol。最古老的土壤的潮湿时序（1,070,000岁）符合所有的诊断标准的Oxisol除了所需的低CEC。在两个干燥的比较网站的土壤不太发达，低粘土含量和玻璃质材料在26,000年的年龄（风化土），主要是蒙脱石粘土矿物和明显的收缩膨胀功能在813,000年的年龄（变性土）。我们的研究结果突出了早期成壤过程中通过Andisol阶段的快速过渡以及加拉帕戈斯群岛湿润与干燥区的强烈分歧的成壤发展，这两者都对这个独特的群岛的土壤功能和生态系统演化具有重要意义。
The Galápagos archipelago is a well‐suited model ecosystem for investigating soil evolution. Here, we study mineral transformations and pedogenesis of the volcanic soils of Galápagos in response to weathering duration (1,500–1,070,000 yr) and climate (humid vs. dry). Our results show that soil pH, electrical conductivity, organic C content, cation exchange capacity (CEC), and water retention decreased whereas clay content and bulk density increased with soil age under humid climate. Andic properties were expressed in soils ≤4,300 yr old, but disappeared relatively early in pedogenesis and were absent in soils ≥26,000 yr old. The clay fraction of the young andic soils (≤4,300 yr old) was dominated by allophane and ferrihydrite. After 26,000 yr of pedogenesis, illitic–vermiculitic phases were predominant, and in the older soils (≥166,000 yr old), kaolinite, hematite, and gibbsite prevailed. The sequence of soil orders from the youngest to the second oldest site was Histosol–Andisol–Alfisol (vermiculitic)–Alfisol (parasesquic)–Ultisol. The oldest soil of the humid chronosequence (1,070,000 yr old) met all diagnostic criteria for an Oxisol except for the required low CEC. The soils at two dry comparison sites were less developed with low clay contents and vitric materials at 26,000 yr of age (Entisol), and dominantly smectitic clay mineralogy and pronounced shrink–swell features at 813,000 yr of age (Vertisol). Our results highlight a rapid transition through the Andisol stage during early pedogenesis as well as strongly divergent pedogenic development in humid vs. dry zones of the Galápagos Islands, both of which have important bearings on soil functioning and ecosystem evolution on this unique archipelago.