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Partnerships for enhanced engagement in research (PEER) SCIENCE
Cycle 2 (2012 Deadline)

Tree isotope records of past rainfall variability in the Indonesian maritime region

PI: Sri Yudawati Cahyarini with co-PI Intan Suci Nurhati (Indonesian Institute of Science - Lembaga Ilmu Pengetahuan Indonesia)
U.S. Partner: Mike Evans (University of Maryland, College Park)
Project Dates: August 2013 to May 2018
2-409_Co-PI Dr. Intan Suci Nurhati explaining tree sampling method.bmp
Co-PI Dr. Intan Suci Nurhati explaining tree sampling method
This project focuses on applying techniques for tree isotope analysis to Indonesian trees in order to generate rainfall records over the past 300 years. These data would advance scientific understanding in two major areas of research. The first is the evolution of the El Niño-Southern Oscillation (ENSO) over the past centuries. As the strongest natural variability factor affecting our climate, ENSO modulates monsoonal rainfall variability in Indonesia, causing climate-related disasters. The effects of global warming on ENSO characteristics are still uncertain, and a 300-year high-resolution rainfall record from Indonesia, a region of strong ENSO impacts, is a key in better understanding ENSO. The second research area involved in this project is tropical dendroclimatology, or the reconstruction of climate records using trees, a field that has faced several challenges in the tropics. The inference of past rainfall variability via tree-ring widths has been hampered in the region due to indistinct annual growth rings in tropical trees. The majority of dendroclimate studies in Indonesia conducted by one of the research group’s collaborators at the Lamont-Doherty Earth Observatory have relied on teaks as semi-deciduous ring-producing trees, with the oldest sample retrieved from Muna (Sulawesi) extending back to 1565 AD. Recent works by the U.S. collaborator reveal the ability of the stable oxygen isotopic (δ18O) composition in tropical trees to capture wet-dry seasonality, implying the potential to improve the coverage of tropical dendroclimatology. 

Carrying out this project will not only add to the scientific knowledge base shared by researchers worldwide but also improve the infrastructure at Indonesian institutions and build the skills of the project participants. New lab equipment will be purchased and installed at the Indonesian Institute of Science (LIPI) to allow the researchers and their students to conduct sample preparation work and basic analysis on the tree samples collected. As a state research institution, LIPI also regularly reaches out to universities across Indonesia. Through this project, it will expand these outreach activities on tropical dendrochronology and expand them to include a university in Sulawesi near where their Muna tree sampling site is located. Selected scientists and students from LIPI will have the opportunity to receive training at the University of Maryland, and the U.S. collaborators based there will contribute to the development of a teaching workshop based on active-learning methods to be presented in Indonesia.
Summary of Recent Activities
Dr. Cahyarini and her co-PI Dr. Intan Suci Nurhati of Surya University worked with counterparts at Mulawarman University in East Kalimantan to organize a capacity building workshop on dendroclimatology, which was held at Mulawarman May 24 to June 2, 2014. One day of lectures and one day of technical training in the university’s forest were followed by a week of field work for selected participants to collect tree samples for further tree ring analysis. The goals of the event were (1) to build linkages among Indonesian paleoclimatologists and stakeholders in the local forestry sector to initiate dendroclimate studies at the university and (2) to create interest in paleoclimate studies among forestry undergraduates. As a follow up to this workshop, a Memorandum of Understanding between the Indonesian Institute of Science (LIPI) and Mulawarman University was signed on September 10, 2014, with the aim of facilitating expanded collaboration in educational and research activities. The PI Dr. Cahyarini presented a lecture on the use of trees and corals for paleoclimate studies during the visit. Later that year, they sent some tree core samples to the University of Maryland for chemical analysis, and Dr. Nurhati continued supervising her students as they prepared other samples for analysis.

Dr. Nurhati presented a poster at the Asia Dendrochronological Association meeting in Kathmandu, Nepal, March 9-12, 2015. From March 24 to 30, she visited Mahidol University in Thailand, with her primary objective being to receive training on tree ring width measurement from Prof. Natsuda Pumijumnong. Dr. Nurhati has now moved to LIPI from her previous position at Surya University. In the last quarter of 2015, she continued working on sample preparation techniques, and she and Dr. Cahyarini continued discussions with their U.S. partner Dr. Evans via e-mail. The PI has presented lectures on paleoclimate using geological archives (such as trees, coral, and sediments) at the Department of Oceanography at the Institut Teknologi Bandung. The team also made a poster presentation on their paleoclimate study using coral and tree rings at the annual meeting of the LIPI Research Center for Geotechnology, the Asia Oceania Geosciences Society annual meeting (August 2015 in Singapore), and the Small Islands Research in Tropical Regions conference (September 2015 in Makassar).

Several no-cost extensions have been approved for this project, most recently through May 2018, to allow Dr. Cahyarini and Dr. Evans more time to overcome issues with sample processing and complete their research activities.
2-409_Practical training session
PEER Workshop on Dendroclimatology at the University of Mulawarman, May 24-25, 2014 - Practical training session.
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