THE EFFECTS OF THE HEMLOCK WOOLLY ADELGID ON SOIL WATER CHEMISTRY

The hemlock woolly adelgid (HWA) is an invasive species which feeds on hemlock trees; resulting in mass tree mortality. Tree mortality can negatively affect a forest ecosystem by leading to an alteration in soil nutrients. The HWA was first introduced into the eastern United States in the 1950s from China and Japan. The non-native insect currently infests Mine Kill State Park (MK) and threatens to infest Robert V. Riddell State Park (RVR). In the Catskill region, hemlock trees are the third most abundant tree species. The likelihood of HWA spreading to RVR is high, as HWA is spread by means of wind, birds, and mammals. Within the next 30 years, the remaining hemlock stands in the eastern United States will likely be infested by HWA. The goal of this study is to investigate the effect of the hemlock woolly adelgid on soil water chemistry. Soil water samples were collected from samplers installed at MK located in North Blenheim, NY and RVR located in Davenport, NY. Three sampling sites were established at MK, a HWA infected site (HWA), a HWA uninfected site (NOHWA), and a HWA treated site (HWAT). The HWAT site was treated with insecticides for HWA remediation. At RVR surface water samples were also collected. Field parameters such as pH, electrical conductivity (EC), dissolved oxygen, temperature, and turbidity were measured. In the lab, the samples were analyzed for anion, cation, silica, and bicarbonate concentrations. Samples were collected through the summers of 2014 and 2015. Chloride and sulfate are the dominant anions in both the surface and soil waters. None of the water samples have detectable phosphate concentrations, while nitrate ranges between 0.180 and 2.61 mg/L at MK and non-detectable at RVR. The surface water samples have higher turbidity than the soil water samples. The pH values of the samples are around 7 at all sites. The EC and silica content are both higher in soil water samples than in the surface water samples. The silica concentrations at MK are about six times higher than at RVR. Soil water samples have about ten times more bicarbonate than surface water samples. This collected baseline data may provide information to determine any changes which may result from infection of HWA.