Regional-scale drivers of forest structure and function in northwestern Amazonia

PLoS One. 2015 Mar 20;10(3):e0119887. doi: 10.1371/journal.pone.0119887. eCollection 2015.


Field studies in Amazonia have found a relationship at continental scales between soil fertility and broad trends in forest structure and function. Little is known at regional scales, however, about how discrete patterns in forest structure or functional attributes map onto underlying edaphic or geological patterns. We collected airborne LiDAR (Light Detection and Ranging) data and VSWIR (Visible to Shortwave Infrared) imaging spectroscopy measurements over 600 km2 of northwestern Amazonian lowland forests. We also established 83 inventories of plant species composition and soil properties, distributed between two widespread geological formations. Using these data, we mapped forest structure and canopy reflectance, and compared them to patterns in plant species composition, soils, and underlying geology. We found that variations in soils and species composition explained up to 70% of variation in canopy height, and corresponded to profound changes in forest vertical profiles. We further found that soils and plant species composition explained more than 90% of the variation in canopy reflectance as measured by imaging spectroscopy, indicating edaphic and compositional control of canopy chemical properties. We last found that soils explained between 30% and 70% of the variation in gap frequency in these forests, depending on the height threshold used to define gaps. Our findings indicate that a relatively small number of edaphic and compositional variables, corresponding to underlying geology, may be responsible for variations in canopy structure and chemistry over large expanses of Amazonian forest.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biodiversity
  • Ecosystem*
  • Forests*
  • Peru
  • Soil / chemistry
  • Tropical Climate*


  • Soil

Grants and funding

This work was supported by the Carnegie Institution for Science (USA;, Fellowship support to MAH. Grant number not available. This work was also supported by the National Science Foundation (USA;, Fellowship support to MAH. Grant number not available. This study was further supported by the American—Scandinavian Foundation (USA;, Fellowship support to MAH. Grant number not available. Finally, the study was supported by Duke University (USA;, Small travel grant to MAH. Grant numbers not available. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.