Remote Sensing, Vol. 8, Pages 494: Abiotic Controls on Macroscale Variations of Humid Tropical Forest Height

Spatial variation of tropical forest tree height is a
key indicator of ecological processes associated with forest growth
and carbon dynamics. Here we examine the macroscale variations of
tree height of humid tropical forests across three continents and
quantify the climate and edaphic controls on these variations.
Forest tree heights are systematically sampled across global humid
tropical forests with more than 2.5 million measurements from
Geoscience Laser Altimeter System (GLAS) satellite observations
(2004–2008). We used top canopy height (TCH) of GLAS footprints to
grid the statistical mean and variance and the 90 percentile height
of samples at 0.5 degrees to capture the regional variability of
average and large trees globally. We used the spatial regression
method (spatial eigenvector mapping-SEVM) to evaluate the
contributions of climate, soil and topography in explaining and
predicting the regional variations of forest height. Statistical
models suggest that climate, soil, topography, and spatial
contextual information together can explain more than 60% of the
observed forest height variation, while climate and soil jointly
explain 30% of the height variations. Soil basics, including
physical compositions such as clay and sand contents, chemical
properties such as PH values and cation-exchange capacity, as well
as biological variables s