Soil heterogeneity and root distribution of mature loblolly pine stands in piedmont soils

Factors that influence rooting patterns in mature forest stands are poorly understood. We examined the distribution of loblolly pine (Pinus taeda L,) roots in trench profiles and related rooting to selected soil physical features along a moisture gradient on the Clemson University Experimental Forest, Clemson, SC, Root density was greater on xeric and subxeric sites than on intermediate sites. Root density declined exponentially with soil depth. Fine roots (<4 mm) accounted for 83 to 95% of all roots and averaged 17 fold higher in root channels than in the soil matrix. Root density Has also higher along rack-soil interfaces than in the soil matrix. Soil morphological and physical features, as well as the relative position of the site in the landscape, influence root growth and survival and markedly affect the distribution of roots in mature loblolly pine stands.