Wednesday, November 7, 2007
316-4

Biological and Soil Characteristics of Loblolly Pine Decline Sites in Alabama.

Emily Carter, USDA-FS (Forest Service), USDA - Forest Service, 520 Devall Dr., Auburn, AL 36849, Nolan J. Hess, Forest Health Protection, USDA Forest Service, 2500 Shreveport Highway, Pineville, LA 71360, Arthur J. Goddard, National Forest System, USDA Forest Service, 2946 Chestnut Street, Montgomery, AL 36107, and Lori G. Eckhardt, School of Forestry, Auburn University, 602 Duncan, Auburn University, AL 36849.

Loblolly pine(Pinus taeda L.) decline has been reported throughout central Alabama for years and was tentatively linked to the presence of Phytophora cinnamomiRands. Previous investigations identified specific site conditions of poor internal drainage and insufficient soil nutrient content as casual factors of decline. An examination of biological and soil characteristics of sites with evidence of decline was initiated in 2000 and compared with sites that were determined to be in a healthy condition. Soil samples were removed from decline and healthy plots for assessment of physical and chemical characteristics. Soil physical and chemical properties determined included bulk density (BD), soil texture (TEX), total soil porosity (TPOR), gravimetric water content (GMC), exchangeable bases (EB), pH, aluminum (AL), and manganese (MN). Biological properties determined included presence (INF) or absence (UNINF) of pathogenic fungi(Leptographium spp.), percent disease incidence in plots (DI), basal area of trees (BA), and 10 year growth increment (10YGI). Soil physical and chemical properties were segregated by INF or UNINF and results indicated BD and EB were elevated in INF sites in all 10 cm depth increment compared with UNINF. pH measurements ranged between 4.5 and 4.8 with INF sites slightly more acidic. Aluminum and MN contents were higher in INF sites at all depth increments compared to UNINF sites. Multiple regression analyses indicated biological factors of DI, BA and 10YGI were not related to site conditions selected for evaluation, but examination of data by management intensity indicated better agreement with specific site factors when management intensity was considered (e.g. fertilization).