Lter: luquillo lter VII: understanding ecosystem change in northeastern puerto rico

The National Science Foundation's Division of Environmental Biology awarded $1.275 million to the University of Puerto Rico-Rio Piedras for the Luquillo Long-Term Ecological Research (LTER) Program VII project (CFDA 47.074, Biological Sciences), effective August 1, 2025 through July 31, 2031. This Project Grant funds long-term ecological research examining how environmental variability—including intensified hurricanes and droughts—affects tropical forest ecosystems in the Luquillo Mountains of northeastern Puerto Rico. The research program combines long-term field measurements, experimental manipulations, and computer simulations to assess the effects of changing disturbance regimes on forest composition, species dynamics, and biogeochemical cycling. Drawing on a 90-year research history, the project tests hypotheses that combined increases in storm frequency and drought intensity may compromise ecosystem resilience, potentially resulting in novel species combinations and altered carbon and nutrient dynamics.

The award supports research activities implemented through collaborative sub-awards with five partner institutions. The University of California, Berkeley analyzes soil carbon cycling and isotope dynamics at depth profiles using field sensors and laboratory incubations. North Carolina State University provides overall project coordination and supervision under Principal Investigator Alonso Ramirez. Ciudadanos Del Karso, Inc. implements field experiments and manages the drought manipulation study in Puerto Rico. Columbia University supervises data analysis and tree demography modeling using the Ecosystem Demography (ED2) model to incorporate hurricane and drought damage data. The University of New Hampshire performs analytical chemistry on rainfall, throughfall, and stream samples to quantify organic matter, major ions, greenhouse gases, and nutrient concentrations. The integrated research effort supports workforce development across elementary through graduate educational levels while generating scientific data and methodologies advancing understanding of tropical forest resilience to compound disturbance events.

Abstract

The luquillo long-term ecological research program (luquillo LTER) studies how environmental variability, such as more severe hurricanes and droughts, affect the tropical forests in the luquillo mountains in eastern puerto rico, USA. Since the luquillo LTER began in 1988, multiple hurricanes and droughts have affected the site. This research looks at how ongoing changes in disturbance patterns and what has happened in the past could lead to new combinations of forest plants and animals. For example, species adapted to hot and dry conditions might expand into tropical forests where trees have been blown down following hurricanes. The program includes exciting experiments to investigate how increased droughts could change which plant and animal species remain in these forests and how carbon and nutrients are stored in the soil and streams. The luquillo LTER helps train the next generation of scientists, with student engagement from elementary to graduate levels. The luquillo long-term ecological research program (LTER) combines long-term measurements, experimental manipulations, and computer simulations to determine the effects of changes in the frequency and intensity of disturbance events on tropical forests. Building on a 90-year research history in natural and modified forests, research at this site has revealed that while tropical forests exhibit resilience to individual disturbance events, the potential combination of increased frequency of intense storms and more frequent drought may compromise ecosystem resilience in the long-term. This research tests hypotheses that changing environmental and disturbance regimes, interacting with the effects of past disturbance events, will result in new combinations of species and altered biogeochemical dynamics. The research will continue to characterize the spatial and temporal dynamics of biota and biogeochemical processes in native tabonuco forest and leverage temperature variation across elevation in the luquillo mountains for the purposes of field experiments. Two experiments, simulating drought and warming, will address hypotheses that increased drought frequency will alter species composition and distribution as well as soil carbon and nutrient storage along hill slopes and in streams. Computer models and data-model integration will provide predictive understanding of the combined effects of increased drought and hurricane frequency on tropical forests, as well as facilitate synthesis across scales and forecasting of future ecosystem states. The luquillo LTER will continue to train undergraduate and graduate students, as well as secondary school students and teachers, producing a cadre of new multidisciplinary scientists who have the skills and experiences to address the pressing environmental challenges of the 21ST century. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are planned for this award.