HoldridgePlot() creates a blank triangular plot, as proposed by Holdridge (1947, 1967), onto which potential evapotranspiration (PET) ratio and annual precipitation data can be plotted (using the AddToHoldridge() family of functions) in order to interpret climatic life zones.

HoldridgePoints(), HoldridgeText() and related functions allow data points to be added to an existing plot; AddToHoldridge() allows plotting using any of the standard plotting functions.

HoldridgeBelts() and HoldridgeHexagons() plot interpretative lines and hexagons allowing plotted data to be linked to interpreted climate settings.

# Load package and data
library("Ternary")

data(holdridge, holdridgeLifeZonesUp, package = "Ternary")

# Suppress plot margins
par(mar = c(0, 0, 0, 0))

# Create blank Holdridge plot
HoldridgePlot(hex.labels = holdridgeLifeZonesUp)
HoldridgeBelts()

# Plot data, shaded by latitude; darker = equitorial.
HoldridgePoints(holdridge$PET, holdridge$Precipitation,
                col = hcl.colors(91)[abs(holdridge$Latitude) + 1],
                lwd = 2)

References

Holdridge (1947), “Determination of world plant formations from simple climatic data”, Science 105:367–368.

Holdridge (1967), Life zone ecology. Tropical Science Center, San José.