October 25, 2017

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Root and Rhizosphere Bacterial Phosphatase Activity Varies with Tree Species and Soil Phosphorus Availability in Puerto Rico Tropical Forest

Understanding the role of roots and bacteria in the phosphorus cycle.

The Science

Phosphorus is an important nutrient for plant growth, but its availability is often limited in tropical forests. While most studies focus on either roots or bacteria, scientists from Oak Ridge National Laboratory studied an important enzyme (phosphatase) in both roots and bacteria, showing that phosphatase release varies with tree species and soil phosphorus availability.

The Impact

Earth system models (ESMs) poorly represent tropical forests in part due to a lack of data on both the phosphorus cycle and the belowground processes that influence them. The results can be used to improve how models represent the influence that roots and microbes have on the phosphorus cycle in tropical forests.


ESMs simulate the global carbon cycle to predict how the world responds to and changes with perturbations to the carbon cycle. Tropical forests absorb a large amount of carbon in the atmosphere, making it important to understand how they grow and are influenced by environmental factors such as phosphorus. Roots and microbes interact to access nutrients and water from the soil environment. In tropical forests, roots and microbes must release phosphatase, an enzyme that breaks down phosphorus locked into organic material. Plant growth in future climates may be highly influenced by whether plants can release enough phosphatase to continue growing. Scientists from ORNL studied phosphatase activity in roots and bacteria collected from different tree species and soil phosphorus availabilities in tropical forests of Puerto Rico to better understand phosphatase activity. The influences of roots and bacteria on the phosphorus cycle are not usually included in ESMs. The study’s results can be used to help improve ESMs.

Principal Investigator

Richard Norby
Oak Ridge National Laboratory

Program Manager

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


This research was supported as part of the Next-Generation Ecosystem Experiments (NGEE)–Tropics, funded by Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science.

Related Links


Cabugao, K. G., C. M. Timm, A. A. Carrell, and J. Childs, et al. "Root and rhizosphere bacterial phosphatase activity varies with tree species and soil phosphorus availability in Puerto Rico tropical forest". Frontiers in Plant Science 8 1834  (2017). https://doi.org/10.3389/fpls.2017.01834.