Mapping Terpenes over the Teakettle Experimental Forest

Abstract:

Terpenes are a category of biogenic volatile organic compounds (BVOC) produced by many plants, most notably coniferous plants. Commonly, these terpenes are aromatic compounds. The intensity of terpene emission varies depending greatly on light and temperature. Through remote sensing data as well as ASD spectroradiometry data this study focuses on locating sources of terpene emissions in the Teakettle Experimental Forest. These emissions are of particular concern because of their influence on the chemical concentration of the lower troposphere, as well as being an indicator of tree health.

A novel approach has been designed through this study in order to locate and further understand these terpene emissions. Terpenes such as camphene have been reported to have subtle spectral features located at around 1.7 μm. For the first time, a map of terpene sources has been constructed by accentuating this particular feature. A continuum interpolated band ratio (CIBR) was used in order to compute a relative abundance of terpenes from the AVIRIS data. The CIBR equation showed promise, as terpenes were most strongly concentrated in areas of coniferous vegetation (a primary source of terpenes) and were less prominent over bodies of water or industrialized areas. The greatest concentrations were focused over treetops and other woody vegetation.

Although it is known that terpenes have weak absorption features in the SWIR, there is little information available regarding the mapping of terpene emissions. This project addresses a novel approach to observing biochemical components in the lower troposphere and could potentially give more information to explain the health of forest ecosystems.