How to measure carbon in different classes of biomass and different categories of forest

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How to measure carbon in different classes of
biomass and different categories of forest

• B. Turner and P. van Laake

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What are we covering this session?

• Forest categories
• Sampling, height and diameter measures, form
  factors, drying and weighing, wood density
• Allometric equations
• Use of GPS
• Equipment requirements
• Data formatting
• But first, some principles

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Carbon pools within ecosystems

• Carbon in above-ground living biomass
• Carbon in woody and other debris
• Carbon in root systems
• Carbon in the soil
• Here, just dealing with the first (above-ground
  biomass), but dont forget the others!

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Forest categories

• Different ways of classifying forests
• According to floristics (species mix)
• According to structure (growth stage, age,
  density)
• Structural classes more useful for C estimation
• But different floristic classes may have
  different biomass profiles, and may be easier to
  map (delineate spatially)

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Estimating above ground biomass requires

• Sampling
• Height and diameter measurements
• Consideration of tree form
• Drying and weighing of samples
• Measurement of wood density

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Measuring above-ground biomass (AGB)

• Measurement of above-ground biomass of a forest
  is impractical, so must sample.
• Some destructive sampling is inevitable, to
  develop allometric relations of oven-dry weight
  to more easily measured variables.
• Above-ground biomass consists of
• Overstorey
• Understorey

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Typical procedure for estimating AGB of a
project area

• Stratify forest area into classes (from remote
  sensing) and estimate land areas in each class
• Install plots according to valid sampling scheme
• Locate plots using GPS if possible
• Measure dbhob and heights (and bark thicknesses?)
  and note species of all trees on plot
• Measure understorey appropriately

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Use of GPS

• Global Positioning System (GPS) allows location
  of a ground point (latitude, longitude
  altitude) anywhere on Earth
• Constellation of satellites whose positions are
  constantly monitored
• Distance from ground instrument measured by speed
  of light
• Triangulation of 4 or more satellites distances
  gives precise position
• Accuracy varies, but about few metres
• Must have line of sight to satellites so doesnt
  work through dense canopies

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Measuring trees in tropical rainforests
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Allometric equations

• Allometry is about relationships between
  different measures of an organism (e.g., weight
  and height)
• Allometric equations represent this relationship
  mathematically
• Commonly of the form ln Y a b ln X
• To normalise residuals and provide linear form
• E.g., Y weight of a branch, X diameter of
  branch at base

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Calculating AGB

• Calculate total volume of each tree in plot using
  some model which relates dbhob, tree height and
  species to total volume of tree
• If these models dont exist then research will be
  needed.
• Multiply total volume of each tree by factor
  which converts total volume to above ground
  biomass
• Based on wood density but accounts for non-wood
  components.
• If this factor isnt available, research is
  needed to get it. Could use IPCC defaults in
  interim.
• Sum up biomasses for each tree and add in
  understorey biomass (calculated similarly) to get
  plot biomass
• Calculate area-weighted total AGB for project.

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Locating the biomass spatially

• Problem with above method is only gives single
  average or total value for forest (or stratum)
  ---but---
• Where is it? Where is it high and low?
• Alternative method
• Use plot biomass to establish relationship
  between stand biomass and spatial variables such
  as soil, climate, topography, NDVI from
  satellites, etc.
• Then use GIS power to predict biomass at any
  point (pixel, cell) in landscape.
• As used in Australian National Carbon Accounting
  System (NCAS).

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Equipment requirements

• Tree measurement instruments
• Tree diameter tapes or calipers
• Height measuring instruments, including laser
• Bark gauges
• Distance measuring instruments
• Tapes
• Laser instruments
• Weighing instruments (research level)
• Weigh bridges to balances
• Computers

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• What is the capacity of your country to estimate
  biomass?