Single‐Tree Influence on Soil Properties in the Mountains of Eastern Kentucky

Abstract

The validity of the concept of "ingle—tree influence circles" was tested in a forest dominated by Tsuga canadensis and Liriodendron tulipifera on steep slopes in the Appalachian Mountains of the eastern USA. Samples of forest floors and the 0—5 cm depth of mineral soil were collected at 135 locations within plots 1.3 ha in total area. Examination of particle—size distribution and pH at 33 of these locations confirmed that parent material to a depth of 100 cm was uniform throughout the study area. Soils were sandy and generally low in nutrients. Levels of pH, Ca, Mg, K, and mineralizable N tended to be higher, and forest floor mass tended to be lower, under the crowns of L. tulipifera compared to T. canadensis. Differnces between tree species were better expressed on areas lacking Rhododendron maximum understories. These results indicate that single—tree influence on soil properties is detectable even in mixed stands on steep slopes, and that the soil landscape may be considered a mosaic of profiles reflecting the occurrence and chemical characteristics of the ground cover vegetation and of individuals of the various tree species present.