A National, Detailed Map of Forest Aboveground Carbon Stocks in Mexico

A spatially explicit map of aboveground carbon stored in Mexico's forests was generated from empirical modeling on forest inventory and spaceborne optical and radar data. Between 2004 and 2007, the Mexican National Forestry Commission (CONAFOR) established a network of similar to 26,000 permanent inventory plots in the frame of their national inventory program, the Inventario Nacional Forestal y de Suelos (INFyS). INFyS data served as model response for spatially extending the field-based estimates of carbon stored in the aboveground live dry biomass to a wall-to-wall map, with 30 x 30 m(2) pixel posting using canopy density estimates derived from Landsat, L-Band radar data from ALOS PALSAR, as well as elevation information derived from the Shuttle Radar Topography Mission (SRTM) data set. Validation against an independent set of INFyS plots resulted in a coefficient of determination (R-2) of 0.5 with a root mean square error (RMSE) of 14 t.C/ha in the case of flat terrain. The validation for different forest types showed a consistently low estimation bias (<3 t.C/ha) and R(2)s in the range of 0.5 except for mangroves (R-2 = 0.2). Lower accuracies were achieved for forests located on steep slopes (>15 degrees) with an R-2 of 0.34. A comparison of the average carbon stocks computed from: (a) the map; and (b) statistical estimates from INFyS, at the scale of similar to 650 km(2) large hexagons (R-2 of 0.78, RMSE of 5 t.C/ha) and Mexican states (R-2 of 0.98, RMSE of 1.4 t.C/ha), showed strong agreement.