Relationships between fine root productivity and aboveground forest metrics

Understanding pools and fluxes of belowground living plant C in most ecosystems is a global priority (Clark et al. 2001). There is a pressing need for studies that address the variability of fine roots and to accurately describe the causes for variability of belowground plant C. This study addressed variability in fine root productivity as it is influenced by overstory productivity, overstory diversity, and variation of canopy height. We use imagery from a minirhizotron optical scanning device for estimates of fine root productivity, while overstory productivity and overstory diversity were assessed with traditional field-based methods. Aerial LiDAR was used for estimates of variation of canopy height, which provided an estimate of the standard deviation of upper canopy height. Estimates of fine root productivity were related to estimates of overstory productivity, overstory diversity and standard deviation of canopy height with the goal of finding the best predictor of variation in fine root production. We prioritize this research in terms of three hypotheses: 1) There is a relationship between overstory productivity and fine root productivity; 2) There is a relationship between overstory diversity and fine root productivity; 3) There are relationships between the standard deviation of canopy height and fine root productivity. A better understanding of relationships between aboveground plant metrics and variability of belowground plant C could allow for an increased understanding of causes for variation of belowground plant C, especially as there is a pressing need to accurately estimate whole system C in forest ecosystems (Toan et al. 2004; Hese et al. 2004; Boudreau et al. 2008).