Generic tree allometric models

This webpage contains supplementary information to the following article: Chave J, Rejou-Mechain M, Burquez A, Chidumayo E, Colgan MS, Delitti WBC, Duque A, Eid T, Fearnside PM, Goodman RC, Henry M, Martinez-Yrizar A, Mugasha WA, Muller-Landau HC, Mencuccini M, Nelson BW, Ngomanda A, Nogueira EM, Ortiz-Malavassi E, Pelissier R, Ploton P, Ryan CM, Saldarriaga JG, Vieilledent G. Improved allometric models to estimate the above ground biomass of tropical trees. 2014. Global Change Biology. DOI: 10.1111/gcb.12629


We have compiled tree harvest data for 58 sites around the tropics. Included trees had a diameter at breast height > 5 cm. Every felled tree had at least: (i) a trunk diameter measurement, in cm; (ii) a total tree height measurement, in m; (iii) an aboveground biomass measurement (oven-dry biomass, in kg); and (iv) an estimate of wood specific gravity. The file below (in csv format) contains five columns: the four tree-level variables reported in the database, plus an acronym describing the study site, and described in detail in Table S1 of Chave et al. 2014

Download the pantropical tree harvest database


The long-term climatic water deficit (CWD) is the water lost by the environment during dry months (defined as months where evapotranspiration exceeds rainfall). It is measured in mm/yr as the difference between rainfall and evapotranspiration during dry months only and is, by definition, negative. Sites such that CWD=0 are not seasonally water-stressed; in contrast, sites with very negative CWD values are strongly seasonally water-stressed. Several recent studies have emphasized the importance of CWD as a predictor of ecosystem response to climatic change. Here, we provide a global climate layer for the long-term average of CWD at 2.5 arc-minute resolution.

Download kmz layer for CWD (may be opened in Google Earth)
Download CWD in netCDF format (zipped)
Download CWD in generic grid (raster) format (zipped)
Download CWD in GeoTIFF format (zipped)


Environmental stress factor on the diameter-height tree allometry. During the analysis of a pantropical tree harvest compilation (Chave et al. 2014), we found that an environmental variable defined by E=1.e-3 x (0.178xTS-0.938xCWD-6.61xPS) is an important covariable of the diameter-height relationship of trees. In this equation, TS is temperature seasonality as defined in the Worldclim dataset (bioclimatic variable 4). CWD is the climatic water deficit (in mm/yr, measured as above). PS is the precipitation seasonality as defined in the Worldclim dataset (bioclimatic variable 15). The raster file for variable E is available below 2.5 arc-minute resolution.

Download kmz layer for E (may be opened in Google Earth)
Download E in netCDF format (zipped)
Download E in generic grid (raster) format (zipped)
Download E in GeoTIFF format (zipped)


Raster tools. For beginners in spatial grid data and/or R (for more information on the R project, see, you may obtain values for CWD or E at one or several geolocations by copying and pasting the following two lines in the R environment:



Here, 'raster' should be either "CWD" or "E", depending on the raster file to be selected; 'coord' is a R data.frame containing the coordinates of one or several sites; 'plot' option is set to "TRUE" only to plot the raster as a map (time-consuming); format is the format of the raster file: "nc" for netCDF format (default, faster in linux-based environments), or "bil" a file in raster format.
To check that the routine above works properly, please run the lines below in R (or RStudio):


The first value for CWD should return -117.7933. The second value (for E) should return -0.1287045. The coordinates in this test are those of the Nouragues Ecological Research Station.


Last update May 10th, 2014