A Historical and Comparative Review of 50 Years of Root Data Collection in Puerto Rico

Data synthesis to enrich root database representation for the tropics, and ultimately better inform Earth System Models

The Science

Researchers synthesized and analyzed studies and raw data on root systems in Puerto Rican tropical forests, including data from Spanish-language publications not previously published in English. They compared these studies and data with other tropical studies and identified key knowledge gaps to be addressed for future studies.

The Impact

Studies including root data in Puerto Rico are representative for the tropics. However, fine-root functional trait data for tropical ecosystems have not been fully explored. The research team’s synthesis will be used to enrich root database representation for the tropics, and ultimately better inform broader Earth System Models.


Fine roots play an important role in plant nutrition, as well as in carbon, water and nutrient cycling. Fine roots account for a third of terrestrial net primary production (NPP), and inclusion of their structure and function in global carbon models should improve predictions of ecosystem responses to climate change. Unfortunately, studies focusing on underground plant components are less frequent than those on aboveground structure. This disparity is more marked in the tropics, where one third of the planet’s terrestrial NPP is produced. Available tropical forest fine root data in Puerto Rico is overrepresented considering its land cover. This Caribbean island’s biodiversity, frequency of natural disturbances, ease of access to forests, and long-term plots have created an ideal place for the study of tropical ecological processes. This literature review emphasizes 50 years of root research and patterns revealed around Puerto Rico. The data in this review were compiled from scientific publications, conference reports, symposiums, and include new raw data shared by some researchers. Emergent patterns for fine roots include the shallower distribution of fine roots compared to other tropical forests, the greater root:shoot ratio compared to other tropical meta-analysis, the little variation in root phosphorus concentrations among forest types, and the slow recovery of root biomass after hurricane disturbance. Because more than half of the data on roots come from the wet tropical Luquillo Experimental Forest, other habitat types are under-represented. Gaps in knowledge about fine roots in the Puerto Rico’s ecosystems, are noted as examples to promote and guide future studies.

Principal Investigator

Richard J. Norby
University of Tennessee-Knoxville, Department of Ecology & Evolutionary Biology
[email protected]

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]


This work was supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Program, Climate and Environmental Sciences Division. Oak Ridge National Laboratory (ORNL) is managed by University of Tennessee (UT)-Battelle, LLC, for the U.S. Department of Energy under contractDE-AC05-00OR22725.


Yaffar, D. and Norby, R. J. "A Historical and Comparative Review of 50 Years of Root Data Collection in Puerto Rico." Biotropica 52 (3), 563–76  (2020). https://doi.org/10.1111/btp.12771.