Aspen Root Studies on Three Sites in Northern Utah

Abstract

Aspen (Populus tremuloides Michx.) root distribution was studied on the, Davis County Experimental Watershed (DCEW) near Farmington, Utah, and at the head of Cowley Canyon, a secondary valley that drains into Logan Canyon near Logan, Utah. At the DCEW two groups consisting of 9 and 15 trees, respectively, in sandy loam soil and one of five trees in clay were identified by the use of eosin bluish dye as a tracer, and were then excavated to determine rooting habits. A single tree was excavated in Cowley Canyon. Nine of the 29 trees sampled had no vertical adventitious roots and 12 had no lateral root development. Seven trees had no root development whatsoever other than the parent root from which they originated; six others had only a single adventitious lateral or vertical root. Root development was similar in all soils except that small roots were nearly absent in the clay. Root depth at the DCEW exceeded 114 inches in sandy loam and 50 inches in the clay. At Cowley Canyon rooting depth in loam with a dense clay B horizon exceeded 60 inches for a tree of agfe 52 years. The, majority of roots in all soils were concentrated in the top 4 ft of soil. The total length of the parent root between terminal ramets was 113.2 and 56.8 ft, respectively, in the two clones in sandy loam and 20.5 ft in the clone growing in clay on the DCEW. Parent root depth varied from 0.2 to 3.3 ft. Lateral roots (one in Cowley Canyon and four from the two clones in sandy loam on DCEW) extended 26, 26.5, 10, 8 and 6 ft, respectively. All ramets appeared to originate at depths ranging from 2 to 12 inches. INTRODUCTION Quaking aspen (Populus tremuloides Michx.) in the Intermountain Region characteristically develop dense stands, from which transpiration losses are believed large enough to, be of economic significance in respect to water yields. For this reason, research concerning comparative water uses of aspen and other vegetation is needed. Knowledge of the rapidity of regeneration, depth of penetration, and the volume of soil occupied by the root system is requisite to an accurate and adequate determination of the water economy of aspen. Aspens have unique root systems. The lateral system of roots is widespread (Baker, 1925; Brown, 1935; Day, 1944; Smirnov, 1959). Although most roots are confined to the upper 2 or 3 ft of soil, sinkers or vertical roots descending from laterals may reach a considerable depth (Berndt and Gibbons, 1958; Brown and Thompson, 1965; Cook and Harris, 1950; Love, 1958; Stoeckeler, 1956). Depending on the site, lateral spread may exceed 100 ft and depth of penetration may exceed 8 ft. The rate of elongation of selected roots can be as much as 58 inches per year (Buell and Buell, 1959). ' Present address: College of Agriculture., Division of Plant, Soil and Water Science, University of Nevada, Reno 89507.