Physical and Chemical Characteristics of Soils Forming on Boulder Tops, Kärkevagge, Sweden

Recent pedologic studies in Kärkevagge, Swedish Lapland, have characterized soil distribution and confirmed the importance of chemical weathering in this arctic–alpine environment. However, these studies have overlooked soils that are forming on the uppermost surface of the boulders that give Kärkevagge its name, “Valley of the Boulders.” The physical and chemical characteristics of the soils forming on boulder tops are therefore examined herein. Soil samples were collected from 20 large boulder tops and analyzed according to standard procedures. The boulder‐top soils were weakly developed, <27‐cm deep, coarse‐textured, weak‐structured, and well‐drained. There was minimal horizonation. Physical characteristics of the boulder‐top soils are comparable with the alpine soils in the region. Soil reactions were very acidic, with low base saturation and low cation exchange capacity (CEC). Chemical characteristics are similar to soils in the rest of the watershed, whereby extractable Ca > Mg > K > Na in the soils, albeit the values are substantially lower overall in the boulder‐top soils than for the rest of the soils in Kärkevagge. Although the boulder‐top soils were weakly developed, there was incipient pedogenesis as exemplified by the presence of pedogenic Fe. The boulder‐top soils were classified as loamy‐skeletal, micaceous, acid Lithic Cryorthents. Results illustrated that, like the rest of Kärkevagge, chemical weathering is an important contributing process in boulder‐top soil formation, and that the boulder‐tops provided a unique opportunity to evaluate incipient pedogenesis in an arctic–alpine setting.