The Response of a Southern Appalachian Forest to Waste Water Irrigation

The operational land treatment system at Unicoi State Park near Helen, Georgia was used for a period of 3 years to study the role of a mature Appalachian forest in renovating municipal waste water. Uptake of some of the nutrients in the waste water was occurring in the vegetation, but no systematic nutrient uptake by any one component of the stand was observed. Overstory trees failed to show any growth response to the irrigation in height or diameter at breast height (dbh), but did show increased stem diameter growth within the canopy. The irrigation was causing significant increases in diameter at 0.3 m and height of understory trees. A detailed stem analysis of 5 treated and 5 control white pine trees ( Pinus strobus L.) from the mature overstory showed that upper stem diameter growth was increased significantly as a result of the irrigation. This stem volume response to waste water irrigation would not be detected had breast height diameter and total height been the only stem measurements taken. The irrigation is decreasing the biomass, the diversity, and the number of individuals of the ground vegetation.