Sustain Our Nation's Forests and Grasslands

In the aftermath of Hurricane Maria - Part 3: El Yunque National Forest


October 19, 2017 - Forest Service technician Humberto Robles and incident team member Raymond Escobar work at replacing litterfall baskets inside a research plot in a lowland moist forest in Canóvanas, PR. Forest Service photo by María M. Rivera.

PUERTO RICO — In September 2017, the Caribbean was battered by the combined force of two massive hurricanes; first came Irma followed two weeks later by Maria. The International Institute of Tropical Forestry began post-hurricane work within days of Hurricane Irma, which occurred on September 6, 2017. Hurricane Maria occurred on September 20th and the Institute began post-Maria work on September 23, 2017.

Since September 2017, after the passage of hurricanes Irma and Maria through Puerto Rico, local USDA Forest Service staff, interagency Incident Management Team members from across the U.S along with locally hired temporary employees and contractors have worked diligently to restore services and facilities to the El Yunque National Forest. To date over 125,000 person-hours have been logged in recovery work.

Damage assessments by biologists, engineers and operational staffs provided initial and ongoing information to formulate a strategy for recovery efforts. A small contingent of off-island resources remain to support the forest, mainly assisting with clean-up and rehabilitation of some remaining projects.  

To date, specific research and development projects and efforts in and around El Yunque National Forest include:

Comparison with experimental data (Luquillo Experimental Forest): The canopy trimming experiment was measuring the abiotic characteristics of a control forest and a forest under a simulated hurricane, before Hurricane Maria hit. These measured abiotic variables include beneath-canopy solar radiation; temperature of air and soil; moisture of leaves, litter, and soil; and relative humidity. The abiotic measurements will help to elucidate the driving forces and the timeline behind forest recovery from hurricanes.

The measurements continued through Hurricane Maria and the data is being compared to satellite proxy measurements of the recovery of Puerto Rican forests with solar radiation; temperature of air and soil moisture. Comparisons of the satellite data and the more fine scale CTE data are being used to understand how well satellites measure the forest recovery and the island is recovering as a whole.


View from El Yunque National Forest towards Municipality of Luquillo on the Northeast coast of Puerto Rico. Forest Service photo by Kathleen McGinley.


Landslide in El Yunque National Forest following Hurricane Maria. Forest Service photo by Kathleen McGinley.


More landslide devastation in El Yunque National Forest following Hurricane Maria. Forest Service photo by Kathleen McGinley.


Vegetative regrowth following Hurricane Maria in El Yunque National Forest on 1 February 2017. Forest Service photo by Kathleen McGinley.

Forest recovery – Bisley watersheds (Luquillo Experimental Forest): IITF is quantifying hurricane-induced changes to forest dynamics structure in the Bisley Experimental Watersheds, including continuation of long-term monitoring and focusing both onfrom trees and understory vegetation. Within 13 ha   hectares of the Bisley Experimental Watersheds, in a network of permanent forest plots, trees and understory vegetation have been consistently followed for 30 years, tracking forest dynamics associated to multiple hurricanes, droughts and storms. 

After hurricane Maria, field work was initiated to document forest vegetation responses to this event. Post-hurricane vegetation measurements at this long-term tropical research site include multiple forest structure variables and species composition.

Initial quantification of complex post-hurricane changes to understory vegetation in this forest, currently without a canopy, include changes in the dominant understory plant types (vines, herbs, forbs, shrubs), changes in stem density and stem size categories, aboveground biomass and identification of tree species topographic setting in relation to structural changes induced by the hurricane.


Panoramic view of El Yunque National Forest taken from the top of El Yunque Peak on April 8, 2018. Forest Service photo by María M. Rivera.


Forest Service hydrological technician Carlos Estrada re-establishing long term monitoring equipment inside a Palo Colorado stand in the Luquillo Experimental Forest / El Yunque National Forest. Forest Service photo by María M. Rivera.


Forest Service IITF technicians re-establishing a long term research plot in the tabonuco forest in the Luquillo Experimental Forest / El Yunque National Forest on October 27, 2017 after the passage of hurricanes Irma and Maria through Puerto Rico. FS personnel have been doing forest inventories in this area since 1940s. Forest Service photo by María M. Rivera.


Composite of three pictures showing the impact of hurricanes Irma and Maria, as well as the outcome of recovery efforts. Forest Service photo.

Tropical Responses to Altered Climate Experiment (Luquillo Experimental Forest): The goal of the Tropical Responses to Altered Climate Experiment is to evaluate the effects of warming temperatures on the tropical forest carbon cycle. At the time Hurricanes Irma and Maria passed over the island of Puerto Rico, the TRACE experimental areas had been successfully warmed by 7 °F (+ 4 °C) above ambient temperature for a full year. 

While experimental warming was “paused” due to damages to the infrastructure and loss of power, the majority of data collections associated with the project were rapidly re-established in order to capitalize on a once in a century opportunity to investigate interactions between increased temperatures and hurricane disturbance in a field setting. As such, TRACE is poised to be the only experiment in the world with the capacity to address the following two questions:

  • Are forests that have been exposed to stressful conditions, such as above average temperatures, more or less vulnerable to hurricane disturbance?
  • Will increased temperatures following major hurricane disturbance affect the trajectory of forest recovery?

Better understanding interactions between climate, disturbance and forest recovery is relevant to all coastal forests that are vulnerable to hurricane disturbance. Currently, TRACE has been cleared of dangerous trees, trails and fences have been re-established, repairs to the experimental infrastructure are almost complete and damaged scientific equipment and sensors are being replaced, repaired and/or re-calibrated. 

The site is being extensively studied to assess potential legacy effects of prior warming and to establish a new baseline prior to the re-initiation of experimental warming. IITF expects warming will be re-established by June 2018.

Forest management (El Yunque National Forest/Luquillo Experimental Forest): IITF is augmenting the El Yunque National Forest Land Management Plan Revision with Post-Irma and Maria information. Since 2012, IITF Scientists have worked closely with the El Yunque National Forest on the revision of its land and resource management plan, along with other collaborators, as directed by the NFS Land Management Planning Rule of 2012. 

By September 2017, EYNF had developed and released for public comment the final draft Revised LMP and draft Environmental Impact Statement, with scientific and interdisciplinary team support from IITF, along with extensive public participation and community collaboration. EYNF received and addressed public and internal comments and was prepared to release its final Revised LMP and EIS by October 2017. However, following Hurricanes Irma and Maria, EYNF was compelled to reassess the forest and its resources and services to account for the effects of the hurricanes and to determine if any additional revisions or modifications were necessary for the final Revised LMP and final EIS.  

Since December 2017, IITF personnel have worked with EYNF to assess the effects of Hurricanes Irma and Maria on the forest and surrounding social-ecological systems and to incorporate these findings into the draft plan direction and draft EIS. Post-hurricanes assessments resulted in some slight modifications, mostly to the EIS.  Yet very little was changed in the way of plan direction, given the existing knowledge of disturbances and their implications for management.  The final draft documents have been shared with agency leadership, key stakeholders, and the public at large.  Final revisions to the LMP and EIS are nearly complete and expected to be signed off by the Forest Supervisor and Institute Director and released to the public by or before mid-2018.


Fallen Dacryodes excelsa tree (tabonuco) encountered during post-hurricane assessments in the Bisley Experimental Watersheds/El Yunque National Forest, Luquillo, PR. Forest Service photo.


View of the effects on the forest canopy 5 months after hurricane María, with standing sierra palms (Prestoea montana) covered in climbing vegetation, Luquillo, PR. Forest Service photo.