HEMLOCK WOOLLY ADELGID INFESTATION CAUSED CHANGES IN SOIL, SOIL WATER AND MICROBIAL COMMUNITY IN MINE KILL STATE PARK, NEW YORK

Hemlock woolly adelgid (HWA), an invasive species, was first introduced into the US during the 1950s from Asia. This fluid-feeding insect slowly kills hemlock trees by extracting carbohydrates and disrupting water movement at the base of the needles. The goal of this study is to monitor and quantify the effects of HWA induced hemlock productivity decline on soil microbial community, and nutrient content of the soil and soil water at Mine Kill State Park, Blenheim, New York, which was infested in 2011. Three sampling sites were established within the park, an HWA infected site, an uninfected site, and an infected and insecticide treated site. Soil water samplers were installed in 2014, and water samples are collected when available. Temperature, pH, and electrical conductivity are measured on site, then the samples are filtered, preserved and analyzed for anion and cation compositions. Three replicated soil cores were collected at each site and analyzed at three depth increments. Soil temperature, moisture, pH, total organic matter content, extractable cation and anion concentrations of the soils were measured. Additional soil cores were collected for microbial community determination and Illumina MiSeq next generation high-throughput sequencing was used to classify the microbial community present. Data analyses were completed using QIIME, Rstudio and Excel Analyse-it software packages.

Qualitative and quantitative differences are found between infected and uninfected sites for all parameters analyzed. Chloride, sulfate and bicarbonate are the dominant anions, and calcium, magnesium and sodium are the major cations in the water samples with neutral pH. Highest concentrations of extractable cations and anions are found in the top soil layers at each site. The infected sites have higher concentrations of extractable ions and higher acidity than the uninfected site. DNA concentrations decrease by depth at all sites with the highest values found at the uninfected site. However, species diversity is highest at the infected site. Declining productivity of hemlock trees has caused a shift in microbial community structure that has resulted in changes of the soil and soil water chemistry. This study provides insights to the biogeochemical response to a major ecological change in hemlock forests of New York State.