CREST-PRP: Ecohydrology in the Anthropocene: Hydrometeorological Controls of Physical and Biogeochemical Processes in Chronically Stressed Ecosystems

The CREST Postdoctoral Research Program (CREST-PRP) provides two years of support for research, training, and mentoring experiences for individual early career scientists at active CREST Centers. The goal of the CREST-PRP awards is to increase the STEM workforce presence of individuals who are members of groups underrepresented in STEM fields. CREST-PRP awards recognize investigators with significant potential and support their research experiences to broaden their perspectives, facilitate interdisciplinary interactions, and prepare CREST-PRP scholars for positions of leadership within the scientific community.

The research project, " CREST-PRP: Ecohydrology in the Anthropocene: Hydrometeorological Controls of Physical and Biogeochemical Processes in Chronically Stressed Ecosystems", is in direct alignment with the CREST-PRP goals. Submitted by a researcher affiliated with the CREST Center for Innovation, Research, and Education in Environmental Nanotechnology at the University of Puerto Rico, the project is designed to study impacts on ecosystems due to the combined effects of human-induced changes in land use and changing weather and climate patterns.

Two sites located in the Puerto Rico archipelago with a common semi-arid climate but contrasting land use will be the sites for this study: Mosquito Bay, a world-renowned touristic bioluminescent bay with mangrove vegetation where agriculture and military operations were carried out during the last three centuries, and Finca Atabey, a multi-cropping farm with a previous history of sugar cane production. Combining hydrology, ecology, plant ecophysiology and meteorological components, the research will aim to answer complex questions related to changing climate conditions, assessing ecosystems’ adaptability to present and future stressors.

Research outcomes include a model framework that can be used for studying the effects of anthropogenic and climate stressors at other sites in the Caribbean Basin and the Tropics. Findings from this type of work will also assist communities in developing informed public policies related to environmental conservation practices, benefitting local economies, and supporting food sovereignty as communities work to restore and develop environmentally sustainable ecosystems.

The Caribbean region is vulnerable to climate change-related factors and anthropic disturbances which are testing the environmental sustainability of ecosystems. Biophysical quantification of the system is crucial for a conservation approach to adaptive sustainability. This research study is based on an integrated, transdisciplinary ecohydrological-ecophysiology research framework within a terrestrial-aquatic-marine connectivity-based matrix.

The project will seek to answer the following overarching questions: 1) How does spatiotemporal variability and recurrent climate change impact ecophysiology plant responses and their tolerance to shifting climatic conditions? 2) How does weather and climate variability affect water source distribution and availability in the Puerto Rican semi-arid regions? 3) What are the past and present sources of soil organic matter and how spatiotemporal variability affects organic matter origin and distribution? 4) What are the spatiotemporal dynamics of anthropogenic N inputs in ecosystems with history of anthropogenic use? The research will assess hydrometeorological effects on the biogeochemical processes and plant tolerance in two contrasting ecosystems located in semi-arid regions in the Puerto Rico archipelago, where freshwater availability is the main stressor.

The study will use an ecohydrological and hydrometeorological approach where natural abundance of isotopes (δD, δ18O, δ15N and δ13C) will be indicators of environmental stressors and plant response. Structural (area, weight, Specific Leaf Area) and eco-physiological leaf functional traits (stomatal conductance, osmolarity, osmotic potential, elements) will be measured to assess plant physiological responses to hydric and salinity stress.

Soil and water will be sampled for biogeochemical analyses (Organic Carbon, SOM light fraction and heavy fraction, natural abundance of δ15N and δ13C for organic matter origin and nitrogen sources, pH, salinity, conductivity, volumetric water content, elemental analyses). A variety of water sources will be sampled to determine the natural abundance of δD and δ18O.

Plants will be sampled for natural abundance of δD and δ18O determinations. Water use efficiency (based on δ13C and δ18O) will be determined bi-monthly. An R-based Bayesian mixing model will be used to determine the relative proportions of the water sources in the plants.

Differences in plant water source, water availability, and physical and physiological plant characteristics between dry and wet weather are to be expected to reflect seasonal weather variability as well as climate change related to pulsing events in the Caribbean region.

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.