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Computing tree above-ground biomass (AGB)

Source: R/computeAGB.R
computeAGB.Rd

This function uses Chave et al. 2014's pantropical models to estimate the above-ground biomass of tropical trees.

Usage

computeAGB(D, WD, H = NULL, coord = NULL, Dlim = NULL)

Arguments

D

Tree diameter (in cm), either a vector or a single value.

WD

Wood density (in g/cm3), either a vector or a single value. If not available, see getWoodDensity().

H

(optional) Tree height (H in m), either a vector or a single value. If not available, see retrieveH() and modelHD(). Compulsory if the coordinates coord are not given.

coord

(optional) Coordinates of the site(s), either a vector giving a single site (e.g. c(longitude, latitude)) or a matrix/dataframe with two columns (e.g. cbind(longitude, latitude)). The coordinates are used to account for variation in height-diameter relationship thanks to an environmental proxy (parameter E in Chave et al. 2014). Compulsory if tree heights H are not given.

Dlim

(optional) Minimum diameter (in cm) for which aboveground biomass should be calculated (all diameter below Dlim will have a 0 value in the output).

Value

The function returns the AGB in Mg (or ton) as a single value or a vector.

Details

This function uses two different ways of computing the above-ground biomass of a tree:

  1. If tree height data are available, the AGB is computed thanks to the following equation (Eq. 4 in Chave et al., 2014): $$AGB = 0.0673 * (WD * H * D^2)^0.976$$

  2. If no tree height data is available, the AGB is computed thanks to the site coordinates with the following equation, slightly modified from Eq. 7 in Chave et al., 2014 (see Réjou-Méchain et al. 2017): $$AGB = exp(-2.024- 0.896*E + 0.920*log(WD) + 2.795*log(D) - 0.0461*(log(D)^2))$$ where E is a measure of environmental stress estimated from the site coordinates (coord).

References

Chave et al. (2014) Improved allometric models to estimate the aboveground biomass of tropical trees, Global Change Biology, 20 (10), 3177-3190

See also

computeE()

Author

Maxime REJOU-MECHAIN, Ariane TANGUY, Arthur PERE

Examples

# Create variables
D <- 10:99
WD <- runif(length(D), min = 0.1, max = 1)
H <- D^(2 / 3)

# If you have height data
AGB <- computeAGB(D, WD, H)

# If you do not have height data and a single site
lat <- 4.08
long <- -52.68
coord <- c(long, lat)
# \donttest{
AGB <- computeAGB(D, WD, coord = coord)
# }

# If you do not have height data and several sites (here three)
lat <- c(rep(4.08, 30), rep(3.98, 30), rep(4.12, 30))
long <- c(rep(-52.68, 30), rep(-53.12, 30), rep(-53.29, 30))
coord <- cbind(long, lat)
# \donttest{
AGB <- computeAGB(D, WD, coord = coord)
# }