3.4 Mapping Mexico forests tree height and tree density
The models were used to generate a spatially continuous national map of
total tree height (Fig 4) and the total number of trees (Fig 5), both at
a 1000-m resolution, along with their associated uncertainties. At the
forest type level, maximum pixel values of tree height exist in
coniferous, coniferous-broadleaf forests and cloud mountain forests
(~36 m, 30 m and 21 m, respectively). These types of
forest ecosystems constitute Mexico’s mountain chains Sierra Madre
Oriental and Sierra Madre Occidental. Moreover, the smallest tree
heights were predicted in arid and semi-arid zones, having a mean of
~4 m. The model had the highest uncertainty when
predicting tree height in arid zones (60-80%), the latter could be
related to the limited sample size we had for that specific forest type
(Fig 4b). Lower uncertainty was observed for tropical forest, tropical
dry forest, coniferous and broadleaf forest.
Tropical forests had the maximum pixel values of tree density
(~1370 trees/ha), followed by tropical dry forest (1006
trees/ha), coniferous forest (988 trees/ha) and coniferous-broadleaf
forest (931 trees/ha) (Fig 5a). Uncertainty in predictions of tree
density was relatively low across all forest types (Fig 5b). Similar to
what we observed for tree height, the highest uncertainty estimates were
found for arid and semi-arid ecosystems but were of a higher magnitude
(>80%).