COMMUNITY-LEVEL ALLOMETRIC RELATIONSHIPS AMONG LENGTH, PLANAR AREA, AND BIOMASS OF FINE ROOTS ON A COASTAL BARRIER-ISLAND

The most common techniques for quantifying fine root belowground bioma ss and production involve procedures which are extremely tedious and d isruptive to the site. An alternative and more desirable method to det ermine these parameters would be the use of a direct non-destructive o bservation system that collects quantitative data (i.e., root length o r planar area) that could predict biomass and biomass change. The obje ctive of this study was to determine if predictive community-level all ometric relationships between root length, planar area and biomass exi sted in a coastal barrier island dune ecosystem. Fine root samples wer e extracted monthly from four dune and swale areas along a chronoseque nce (6, 24, 36, and 120 years old) on Hog Island, part of the Virginia Coast Reserve-Long Term Ecological Research site. Dominant life forms were rhizomatous perennial grasses on the dunes and in younger swales and shrubs in the older swales. Root planar area in May and August yi elded the stronger regression relationships, with winter values exhibi ting greater variability. An analysis of covariance (ANCOVA) was used to examine the heterogeneity of regression slopes among sample dates. Both root length and area models exhibited significantly greater slope s during the course of the growing season. The regression slopes for t he oldest dune site displayed no significant differences with season f or either length or area. Data from the swales produced stronger predi ctive relationships than the dunes. These results provide a foundation for indirect root biomass estimates in this system.