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Partnerships for enhanced engagement in research (PEER)
Cycle 4 (2015 Deadline)

Functional diversity of interrelated photosynthesis and water use of Central Amazonian trees

PI: Tomas Domingues (tdomingu@gmail.com), University of São Paulo
U.S. Partner: Pierre Gentine, Columbia University
Project Dates: November 2015 - October 2019

Project Overview

4-445 Tree Canopy Measurements
Team member Maquelle Garcia takes measurements at the top of the tree canopy (photo courtesy of Dr. Domingues).

This project will generate novel understanding on the diversity of plant traits related to water use and photosynthesis. The functional diversity present in a given community is a key dimension of biodiversity that effectively modulates how forests respond to disturbances, such as logging, precipitation, and temperature extremes or the increase in carbon dioxide concentration. It also determines the extent of the feedback between forest and climate, therefore informing us on possible consequences of forest mortality or land use change. To better predict the resilience of the forest and its capacity to provide ecosystem services, it is essential to evaluate the current spectrum of functional diversity, still a major unknown component in biodiversity research. Dr. Domingues and his colleagues will use a new approach looking at the carbon and water cycles as fundamentally coupled at both the leaf and tree level. In order to achieve a qualitative and quantitative assessment of water and carbon strategies by Amazonian trees, they will continuously monitor both the transport of water in tree trunks and the continuous expansion and contraction of the tree’s bole diameter, which relates to water storage, mobilization of photosynthetic products, and growth. This will be complemented by leaf-level measurements of photosynthetic apparatus and hydraulics to comprehend the individual link of photosynthesis with water usage. This novel dataset will demonstrate the coupling between transport of water and carbon within trees and how it relates to forest productivity. The new data will be applied to broader scales by using land-surface and ecosystem models to simulate the interaction between forest and atmosphere at different scenarios of functional diversity. This step will be achieved by collaboration with U.S. Government-supported partner Pierre Gentine, who is implementing a soil-plant-atmosphere-continuum model able to reproduce the carbon and water relationship in the Community Land Model. Brazilian students will also receive much-needed training in computational modeling.

The proposed research will shed light on the role of biodiversity not only in maintaining and improving quality of life for inhabitants of the Amazon region but also for improving water security in other areas. By characterizing current variability in water and carbon use strategies expressed by Amazonian trees, it is possible to assess how much biodiversity loss within this group is tolerable, without seriously compromising ecosystem functioning. The information to be generated by this project will help in evaluating ecosystem integrity in areas where disturbance has already occurred. For example, it will be possible to assess disparities between pristine forest and secondary vegetation, in terms of ecosystem response to water stress whether from bottom up (soil to leaves induced by dry soil conditions) or top down (from leaves to soil induced by dry or hot weather conditions), according to species composition of the community. As a result, plant communities can be evaluated in terms of resilience to further climatic extremes. The products of this research will also aid in guiding species selection for vegetation restoration efforts. For example, such information will be of great value to local community initiatives focusing on production of tree saplings for reforestation programs or ecosystem improvement actions.


Summary of Recent Activities

During the second and third quarters of 2018, Dr. Domingues and his group continued their ecophysiological data acquisition activities designed to monitor photosynthesis activity in trees in the Amazon, the movement of sap flow within tree trunks, and the variation of tree trunk sizes. Such measurements make it possible to gain a better understanding of how different tree species apply distinct strategies to capture carbon and use water. The team routinely visits their research area in the Amazon in order to make measurements and to download data recorded onto data loggers. New undergraduate and graduate students have joined the team in recent months and are planning additional auxiliary projects.

In addition to the field data gathering efforts, the PI and his colleagues and students have participated in two recent events intended to broadcast the aims and partial results of the PEER project. The first event was an Environmental Awareness Week, during which they interacted with the community in the city of Ribeirão Preto and discussed the importance of vegetation in general, but with a focus on the vast influence of the Amazon forest over climate, locally, regionally, and globally. This activity was associated with the efforts of a group of academic institutions, state agencies, and private sector organizations joining forces to plan activities related to public outreach and management of an important protected area within the city limits (see http://fflorestal.sp.gov.br/ribeirao-preto/home/). The second event was the participation of PhD student Maquelle Garcia in a postgraduate course on Amazon Ecology. Besides offering a chance to facilitate training and interactions with many interested students, the course provided an opportunity for Maquelle to demonstrate the gas exchange system purchased with PEER funds and to get the students involved in working on questions regarding the carbon cycle, primary productivity, and biodiversity in the Amazon biome. With support from PEER, Maquelle continues to make excellent progress on her own research. She will be doing more field work during the coming 12 months and will also begin disseminating project results at international conferences. Meanwhile, postdoc Sabrina Garcia is finishing her first manuscript, which describes the ecological relationships between the abiotic factors (light, wind, humidity, etc.) with ecophysiological traits related to carbon gain and water use by trees in the Amazon.

In early November 2018, Dr. Domingues will join other members of his group in a longer than usual field campaign in order to replace some of their sap flow sensors/data loggers, several of which were damaged due to lightning strikes but are now being repaired. They are also planning a manuscript writing workshop in Manaus November 20-25, during which the PEER group and the AmazonFACE group will gather (a total of about 30 researchers) for a focused effort to complete and submit several manuscripts for review. A report on the AmazonFACE project, which has some overlap with the PEER project in terms of personnel and research objectives, is available at https://interactive.pri.org/2018/10/amazon-carbon/science.html. A no-cost extension has been issued through October 2019 to allow the team more time to complete their complex set of research, capacity building, and outreach activities.

Dr. Domingues reports the publication of three recent papers based on his PEER-supported work:


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