THE EFFECT OF NITROGEN FERTILIZATION ON THE PHENOLOGY OF ROOTS IN
A BARRIER ISLAND DUNE ECOSYSTEM: A MINIRHIZOTRON ANALYSIS.
Little work has been done on the phenology of root growth
and senescence largely due to methodological difficulties. The
application of minirhizotron technology has enabled the tracking
of individual roots through an entire growing season. As a
result, direct measures of turnover, root growth, and senescence
are possible. Small plots on a 36 year old dune on Hog Island, a
barrier island in the Virginia Coast Reserve Long Term Ecological
Research Site, were fertilized with nitrogen. Minirhizotron tubes
were installed in each fertilized and control plot. Each tube was
sampled monthly for nine months, March through November.
Preliminary results showed an increase in root density from March
to June with the fertilized plots showing a higher root density
than the unfertilized plots for both March (256% greater) and
April (140% greater). Only 4% of the roots sampled in April were
present in the March sampling. The minirhizotron method allows a
high resolution perspective of the belowground environment and
direct monitoring of phenomena which previously were obtainable
only through indirect measures.