Carbon Measurement in Coarse Woody Debris in the LongTerm Plots of Black Rock Forest

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Carbon Measurement in Coarse Woody Debris in the
Long-Term Plots of Black Rock Forest

• By Emma Hoyt

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Black Rock Forest in Cornwall, NY

• A private, preserved forest in the Hudson
  Highlands (50 miles north of NYC, borders West
  Point)
• Originally preserved for timber production in
  1928 by the Consortium (Columbia included)

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Long-term plots

• 4 pairs of plots at 4 different sites that have
  been studied since 1931 - one of each pair
  thinned in 1931, one left alone (control) - over
  70 years of data!
• Diameter at Breast Height (DBH) in inches taken
  every year for every living tree
• Allometric equations used to calculate the dry
  biomass of each tree - from those numbers, the
  amount of carbon is calculated (49.8 of dry
  biomass) as well as the amount sequestered every
  year
• Plots are meant to be representative of BRFs
  dominant ecosystem (oak forest) - from plot data,
  one can calculate an average amount of carbon,
  and over time, the amount of carbon being
  sequestered by the forest

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But what about other carbon pools?

• Current study only accounts for the above-ground
  portion of living trees
• Soil, fine and coarse woody debris, and tree
  roots hold significant amounts of carbon
• One goal of the carbon study at BRF is to
  eventually be able to measure all significant
  carbon pools and calculate total ecosystem carbon

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Coarse woody debris on the long-term plots

• Harmon Sextons guidelines
• Defined as dead wood with a length of 1.5 meters
  or longer and a diameter of 10 cm or more
• Can be standing (snag) or on the ground (log)
• 5 decay classes
• 1) Mostly snags, very likely retains fine twigs
  and bark, died w/in last 2 yrs

• 2) Mostly snags, retaining the main branches and
  most bark, died for 2 - 5 yrs
• 3) Mostly logs, retaining cylindrical shape, all
  or most branches gone, bark mostly gone, wood
  mostly sound
• 4) Logs, may have an irregular shape, branches
  gone, bark gone, mostly soft and fragmenting wood
• 5) Too decayed to measure all soft and
  fragmenting wood, highly irregular shape,
  indistinguishable from the soil in some places

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GOALS

• To design a set of methods for measuring carbon
  amounts in coarse woody debris that others can
  use in the future.
• To measure the amount of carbon in the CWD on the
  long-term plots and what percent of each plots
  total carbon it makes up.

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Things to consider

• Study of living trees uses equations to calculate
  biomass but decaying wood loses biomass, so
  equations would not work for all but the newly
  dead
• used mass density volume
• Used Harmon Sextons equation to find volume
• Needed samples of specimens to determine
  densities but the long-term plots cannot be
  interfered w/ - must seek samples elsewhere

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Harmon Sextons equationV
L(AbaseAmidpointAtop)6

• roped off plots w/measuring tape to create an x-y
  axis and recorded coordinates of each specimen to
  map for later reference
• Took measurements for each specimen according to
  Guidelines volume equation

• Sometimes ran into irregular shapes, had to use
  other volume equations
• Equipment diameter tape, measuring tape,
  caliper, sonic height-measuring device

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Had volumes, now needed densities to eventually
calculate mass

• Wanted to create a table of densities for every
  decay class and species we worked w/
• Took samples to dry
• Could not take from plots, so took from nearby

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Methods for calculating densities

• Weighed wet samples and used equations to
  calculate their volume
• Cut a sub-sample from each sample (many were too
  big to fit in the labs oven) - calculated its
  wet wt. and vol. (calculated its of the larger
  sample for both wet wt. and vol.)
• Dried sub-samples in oven, obtained dry wt, then
  used sub-sample dry wts and values to calculate
  dry wt of original samples
• Dry wt dry mass used w/volume to calculate
  density of the sample

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Acknowledgements

• Many thanks to the BRF staff for their generous
  help Matt, John, Barbara, and especially Bill
• Professor Bower, my thesis mentor
• Susanna, my project partner-in-crime