Pedogenesis of Volcanic Ash Soils in Andean Ecuador
Pedogenesis of Volcanic Ash Soils in Andean Ecuador
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厄瓜多尔安第斯火山灰土壤的成土作用
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
L. West
中科院分区：
文献类型：
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作者：
F. Zehetner;W. P. Miller;L. West
世界不同地区火山灰土的风化发育规律相似；然而，在特定地点的特定环境条件导致控制土壤形成的因素和过程的独特组合。本研究旨在研究厄瓜多尔北部安第斯山脉间山谷火山斜坡上的成土作用。在海拔2410 ~ 4050 m范围内选取了12个代表不同成土环境的土墩。在海拔3200 m以上的土壤中，胶体组分以磷矾和腐殖土复合体为主，表层土壤有机质含量高，土壤属于黑化表层的土类。在海拔2700 m以下的土壤中，高岭土是主要的胶体成分，表层土壤有机碳含量<1%，土壤类型为初始溶质和完整溶质。中等海拔高度的土墩是一个过渡带，在这个过渡带中，allophane和高岭土同时存在，土壤一般被分类为具有麻质土墩的Andisols。这种总体的海拔格局在不稳定的景观位置被改变了，在那里，随着表土物质的侵蚀，冰岛的土壤特性被移除了。在3000年前的土壤和埋藏的古土壤中观察到几乎相同的高度风化序列，古土壤被认为超过4万年。因此，不同的成土时间对胶体组分的组成没有明显的影响。气候被认为是通过影响淋滤制度和有机质分解而导致土壤发育高度差异的主要因素。
Weathering and development of volcanic ash soils show similar patterns in different regions of the world; however, the specific environmental conditions at a given location result in a unique combination of factors and processes governing soil formation. This research was conducted to study pedogenesis on volcanic slopes in the inter-Andean valley of northern Ecuador. Twelve pedons representing different pedogenic environments were sampled at elevations between 2410 and 4050 m above sea level (asl). In pedons above 3200 m asl, allophane and Al-humus complexes dominate the colloidal fraction, the topsoils are high in organic matter, and the soils classify as Andisols with melanic epipedons. In pedons below 2700 m asl, halloysite is the predominant colloidal constituent, the topsoils contain <1% organic C, and the soils are Inceptisols and Entisols. The pedons at intermediate elevations mark a transition zone, in which allophane and halloysite coexist and the soils generally classify as Andisols with umbric epipedons. This general altitudinal pattern was found to be altered in unstable landscape positions, where andic soil properties have been removed along with the erosion of topsoil material. Virtually the same altitudinal weathering sequence was observed in the 3000-yr-old soils and in buried paleosols, which are considered to be older than 40 000 years. Thus, different time of pedogenesis has not caused marked differences in the composition of the colloidal fraction. Climate is considered the overriding factor responsible for the observed altitudinal differences in soil development by affecting leaching regime and organic matter decomposition.