RELATIONSHIP BETWEEN XYLEM TRACE-METALS AND RADIAL GROWTH OF LOBLOLLY-PINE IN RURAL ALABAMA

This study was undertaken to evaluate the relationship between the metals Al, Cd, Cu, Mn, Pb, and Zn and the basal area increment (BAI) of loblolly pine (Pinus taeda L.) in an old growth stand in Alabama. The BAI is the annual stand average area increment at breast height, estimated from increment borer core samples at breast height. The sampled trees have inner annual ring dates ranging from 1843 to 1918. Significant negative linear relationships were found between concentrations of Cd, Pb, Zn, and the BAI series. Aluminum and Cu concentrations were inversely related to BAI. No significance was exhibited for Mn. These findings are discussed as potential contributing factors to forest decline. No correlation was found between the soil-extractable levels of the metals and the concentration in the most recent xylem tissue. A significant correlation was found between bark Zn and recent xylem Zn concentrations. No other metals exhibited correlations between recent xylem and soil or bark concentration.