computeAGB {BIOMASS}

Computing tree above-ground biomass (AGB)

Description

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).

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).

Value

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

Author(s)

Maxime REJOU-MECHAIN, Ariane TANGUY, Arthur PERE

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()

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)

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)

AGB <- computeAGB(D, WD, coord = coord)