Synchronicity of fine root and soil fungal phenology: Response to disturbance, interannual variation in precipitation and temperature, and atmospheric [CO2] over 12 years
Principal investigator: Seth Pritchard, College of Charleston
Co-investigator: Allan Strand, College of Charleston
Objectives: 1) To explore the interactions among climatic variability (interannual and
monthly) and disturbance (drought, ice storm, and hurricane) and fine roots/soil fungal
processes over a 12 year period; 2) To link temporal patterns of allocation to fine roots
and associated fungal structures with soil CO2 efflux, leaf area dynamics, and stem
growth; and 3) Determine if interannual variation in mean or extreme climates will cause
differential shifts in phenology of roots compared to soil fungi resulting in temporal
asynchrony between fine root and soil fungal dynamics.
Hypotheses: 1) Seasonal fine root phenology will be linked to canopy temperatures
while soil fungal phenology will be more closely linked to soil moisture availability.
Temperature extremes will uncouple phenology of fine root and soil fungi; 2) Because
the temperature optimum for photosynthesis is higher with CO2-enrichment, warm years
will lead to a greater fine root production in CO2-enriched plots than ambient plots; 3)
Climatic extremes will result in asynchrony between roots and leaves; consequently, fine
root and mycorrhizal standing crop will shift out of phase with rhizomorphs (many of
which are saprotrophic).
Location of research activities: Charleston, SC and Durham, NC.
Methods: For over a decade, images of roots and associated fungal structures were
recorded at monthly sampling intervals (>200,000 images taken over 106 sessions)
using micro-video cameras at the Duke University FACE site, the longest continuous
running forest-scale CO2-enrichment experiment in the world. We propose to use
statistical techniques including time-series analysis to extract the changes in frequency
and magnitude of fine root and fungal activity occurring over a 12 year period and to
relate those to climatic variability over the same period. We also propose to determine
how interannual and monthly variation in temperature and precipitation, soil N fertility,
and atmospheric CO2 concentration influence the synchrony between above- with
belowground processes and between roots and soil fungi.
Expected deliverables: Integration of multiple long-term data-sets with a long term
record of fine root processes, analyzed in the context of interannual variability in climate,
will provide important information on controls of soil C flux. This information will be useful
for predicting the influence of climate change and variability on ecosystem dynamics and
will result in three refereed publications.