UTILIZING NASA SATELLITE MISSIONS TO IDENTIFY BARK BEETLE INFESTATION IN SEQUOIA NATIONAL PARK

摘要

Bark beetle-induced tree mortality has increased over the last few decades, exacerbated by below-average precipitation and a loss of soil nutrients, forcing park managers to improve bark beetle monitoring techniques. Bark beetle dynamics were investigated during summer 2009 at 32 sites within Sequoia National Park, California with the aim of correlating field data with satellite imagery to provide forest managers with a more efficient methodology for tracking, monitoring, and forecasting bark beetle outbreaks. Field parameters included visual assessments of the presence and degree of bark beetle-induced mortality and percent canopy cover. Ancillary data such as relative leaf chlorophyll concentration and soil nutrient concentrations including sodium [Na~(+)], nitrate [NO_(3)~(-)], and potassium [K~(+)] were collected for each 15 X 15 meter site. The relationship between bark beetle attacks and potassium [K~(+)] shows higher concentrations of that nutrient in areas with healthy trees. Additionally, algorithms from three satellites were used to identify areas of moisture and vegetation stress; including the Ratio Vegetation Index (RVI) from ASTER, Enhanced Wetness Difference Index (EWDI) from Landsat Thematic Mapper (TM5), Disturbance Index (DI) from MODIS, and four other vegetation indices from Landsat TM5. Vegetation indices show uniform vegetation stress across various years.