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

Knowledge gaps in fine-root data noted for future studies.

The Science

Studies and raw data on root systems in Puerto Rican tropical forests, including data from Spanish-language publications not previously published in English, were synthesized and analyzed in comparison with other tropical studies, and gaps were exposed 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. This synthesis will be used to enrich root database representation for the tropics and, ultimately, to better inform 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 much 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 are 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, and symposiums, and also include new raw data shared by some researchers. Emergent patterns for fine roots in Puerto Rico include the shallower distribution there 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 the data on roots come from the wet tropical Luquillo Experimental Forest, other habitat types are underrepresented. Gaps in knowledge about fine roots in Puerto Rico’s ecosystems are noted as examples to promote and guide future studies.

Principal Investigator(s)

Richard Norby
Oak Ridge National Laboratory


This work was supported by the Climate and Environmental Sciences Division (now Earth and Environmental Systems Sciences Division) of the Office of Biological and Environmental Research (BER), within the U.S. Department of Energy (DOE) Office of Science. Oak Ridge National Laboratory (ORNL) is managed by University of Tennessee (UT)-Battelle, LLC, for DOE under Contract No. DE-AC05-00OR22725.


Yaffar, D., and R. J. Norby. “A historical and comparative review of 50 years of root data collection in Puerto Rico.” Biotropica 98(2985), 283–97 (2020). DOI:10.1111/btp.12771