Emerging Technologies for Measuring Tree Root Biomass in the Context of Global Greenhouse Gas Emissions Reductions Programs

Greenhouse gas emission reduction programs fundamentally rely on accurate carbon dioxide data. A large part of annual emission inventories that countries undertake involve assessing carbon stocks in forests and agricultural lands. Subsurface carbon quantification in these landscapes has primarily been roughly estimated on especially coarse data when dealing with large and cumbersome tree root systems. Root biomass makes up a portion of the subsurface carbon and is difficult, labor intensive, and costly to measure. The present research seeks to answer the question: What new methods offer promise for measuring tree root carbon via biomass, and how may they be applied in the context of national greenhouse gas inventories? Two very promising geophysical methods have emerged over other novel root measurement technologies. Ground penetrating radar and electrical resistivity tomography are better suited for use in national greenhouse gas inventories than electrical impedance and capacitance methods. Use of ground penetrating radar (GPR) and/or electrical resistivity tomography (ERT) enable large tracts of land to be surveyed under appropriate conditions, allowing for the acquisition of more expansive data resources on which to develop more representative allometric models. Ground penetrating radar detects coarse roots well in dry soil. Electrical resistivity tomography does best in detecting roots in moist soils, but is especially limited by electrode configuration (Mancuso 2012). Integration of these two technologies into a baseline protocol based on site-specific characteristics, especially soil moisture and plants species heterogeneity, may increase temporal efficiency of root biomass measurements for use in national greenhouse gas inventories.

This thesis assesses the applicability of novel geophysical and geoelectrical techniques to global greenhouse gas emissions reductions programs.