PS 18-41 - Measurements of hydrologic and biogeochemical fluxes of streamflow and soil quality from southern pine beetle outbreaks in southern forests

Wednesday, August 10, 2016
ESA Exhibit Hall, Ft Lauderdale Convention Center
Jacob Landfield, College of Forest Resources, Mississippi State University, Starkville, MS and Courtney Siegert, Forestry, Mississippi State University, Mississippi State, MS

Widespread modern planting of loblolly pine (Pinus taeda) has greatly increased the suitable habitat for southern pine beetle. During winter southern pine beetles may impact whole stands of what could be marketable pine. This study aims to fill gaps of literature describing the biogeochemical and hydrological fluxes in stemflow from southern pine beetle elicited tree death. We hypothesize that affected trees will produce more stemflow than control trees. In this study we treated ten trees to simulate bark beetle impacts by girdling and treating five stems with blue stain fungus, and five stems with nutrient agar. Stemflow depths of the three treatment groups were taken within 24 hours of rainfall from the John W. Starr Memorial Forest (N 33.2627, W -87.1138). Stemflow volume was then calculated to quantify hydrological fluxes to give a better understanding of the impacts that bark beetles have on southern pine forests. Water and soil samples were collected, water was filtered, and assessed for dissolved organic matter, stemflow chemistry analysis, and to investigate interstorm variation. This research allows for a specific understanding of the impacts of the southern pine beetle on hydrological fluxes and biogeochemical fluxes in forested ecosystems. 


A two sample t-Test (α=0.05) done on preliminary data showed that there was no significant difference in stemflow output between treated trees and control trees within the first year after treatments. This is analogous with field observations noting a lag between infestations by bark beetles and displaying of indicators by the invaded organism such as crown death due to phloem interruptions. Closer investigation of biogeochemical fluxes are being conducted to measure the impact on tree physiology. Little is expected to show differences in such a short timeframe as the first year; however, these results could give evidence of an early warning which could be examined by forest and watershed managers.