PREDICTING THE CHANGING DROUGHT VULNERABILITY OF NORTH AMERICAN FORESTS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1015399
• Grant No.: 2018-67012-28020
• Cumulative Award Amt.: $165,000.00
• Proposal No.: 2017-07164
• Project Start Date: May 1, 2018
• Project End Date: Oct 13, 2019
• Grant Year: 2018
• Program Code: [A7201]- AFRI Post Doctoral Fellowships

Recipient Organization
University of Utah
201 S President Circle RM 408
Salt Lake City,UT 84112-9023

Performing Department
(N/A)

Non Technical Summary
The economic and societal impacts of increasing drought stress on U.S. forests are numerous, ranging from direct consequences affecting timber productivity and water quality, to indirect impacts such as increased wildfire and insect activity. Recent "hot droughts" have driven large-scale declines in forest productivity and triggered tree mortality in multiple species in the western U.S. However, the overall impact that changing drought conditions may have on U.S. forests depends on how atmospheric CO2 fertilization stimulates forest growth and how this interacts with more frequent and severe drought conditions. Understanding how drought and CO2 fertilization impact forest productivity will enable better forecast efforts. Thus, this research will help illuminate key forests management strategies for maintaining productivity and sustainability of these systems in the future. In this research project, we will use model simulations, forest surveys, and previous studies of the impacts of CO2 fertilization on plant growth to a) understand how trees die from drought, b) quantify the impact of CO2 fertilization on tree growth, and c) estimate the combined effects of CO2 fertilization and drought on forests productivity, resilience, and sustainability in future conditions.This research is important because it directly assesses how drought and CO2 interactively affect tree physiology and water loss in future climates, which will inform future forest management plans. The research will provide 1) foundational research and model development that advances our scientific ability to forecast how climate change can influence agroecosystem processes, and 2) will facilitate improvements to forest management plans across U.S. forests. Broad-scale societal benefits include economic benefits of more resilient forests and improved forecasting abilities that will enable planning for changes in timber production, among others, to local communities.

Animal Health Component

20%

Research Effort Categories

Basic

80%

Applied

20%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
123	0699	1070	100%

Knowledge Area
123 - Management and Sustainability of Forest Resources;

Subject Of Investigation
0699 - Trees, forests, and forest products, general;

Field Of Science
1070 - Ecology;

Keywords

drought

forests

management

models

recovery

Goals / Objectives
The goal of the proposed research is to advance our understanding of how climate change will affect forest productivity and how the impacts of climate change might differ regionally within the U.S. based on environmental variability. The major objectives of the proposed research are to address the following three key questions: (1) How does a tree recover from drought? (2) How does increasing atmospheric CO2 change the hydraulic vulnerability of ecosystems through differential changes in leaf and sapwood allocation? (3) How will changes in hydraulic vulnerability resultant from increasing atmospheric CO2 interact with increasing drought stress to determine the future of forests productivity and resilience in the United States over the next century? This advance in our understanding of tree drought physiology will offer long-range improvements in the predictive ability necessary for forest managers and forestry/bioenergy stakeholders to optimize sustainability in production and natural resources under changing drought conditions with increasing atmospheric CO2 concentrations across the U.S.

Project Methods
1. Tree recover from droughtFirst, to understand the mechanisms governing the success and failure of tree recovery from drought-induced xylem embolism, I will use a tractable model of a single tree, with tree-level photosynthesis dependent on leaf area, functional xylem area, soil water, VPD, and atmospheric CO2. In my initial experiment phase, I will impose a drought event on trees of varying size that results in nonrecoverable xylem embolism and a partial crown loss in response to xylem damage (Carnicer et al. 2011). I will then use optimal control theory to constrain the best way for the tree to recover post drought to minimize recovery time, and to understand how recovery success and time varies across the continental U.S. depending on local environmental conditions. Next, I will incorporate processes-based leaf, fine root, and xylem loss using observed thresholds in stem water potential (Bartlett et al. 2016), processes-based recovery using my results from the tree-level model, and increased xylem vulnerability with drought based on observed thresholds into an ecosystem model. I will then test the tree recovery hypothesis developed from the optimality model by performing simulations at a wider spatial scales and evaluating model predictions of growth and mortality against the U.S. FIA datasets over the years 2000-2016. I will use the 0.5°, 3-hourly meteorology from the Princeton Global Forcing Dataset (Sheffield et al. 2006) as input for the models. Model vegetation will be initialized with the first inventory of the FIA census and I will compare the emergent vegetation dynamics in the model with the subsequent inventories at each site. This exercise will be performed at numerous sites across the U.S. and specifically tested at locations where increased mortality has been observed over the past few decades (van Mantgem et al. 2009). These simulations will serve both as rigorous tests of my hypotheses developed using optimal control theory, and will also evaluate the widespread applicability of the hypotheses to a range of environmental conditions. Importantly, incorporating drought recovery strategies into an ecosystem model represents a significant improvement on current drought recovery schemes in ecosystem models, as near-perfect recovery is often assumed and many models do not represent hydraulic damage to xylem during drought (Anderegg et al. 2015).2. Increasing atmospheric CO2 and changes in leaf and sapwood allocationI will carry out a meta-analysis of growth chamber experiments and the 12 large-scale Free-air CO2 enrichment (FACE) experiments to compile concurrent estimates of changes in leaf area normalized by tree sapwood area resulting from CO2 fertilization. Next, I will quantify the effects of increased CO2 on leaf-sapwood ratios using generalized non-linear mixed models incorporating plot/study location as a random effect and forest age, stand density, climate, and atmospheric CO2 as fixed effects (van Mantgem et al. 2009, Peng et al. 2011, Luo and Chen 2015, Zhang et al. 2015, Trugman et al. 2018). For the fixed effects associated with climate, I will use seasonal and annual-level climate variables such as VPD, temperature, and precipitation using 800 m resolution PRISM climatology (Daly et al. 2002). A number of studies indicate that growing season temperature and midsummer VPD may be the most important controls on tree demographic rates (Beck et al. 2011, Walker et al. 2015, Zhang et al. 2015, Trugman et al. 2018. Using these results, I will parameterize an allometric leaf/sapwood response function and incorporate the function into the ecosystem model to simulate adaptation of hydraulic vulnerability with CO2 fertilization.3. Drought, CO2 fertilization, and future forest productivity and sustainabilityI will perform four model experiments that project the future of U.S. forests to isolate the effects of changing hydraulic vulnerability and drought stress on forest productivity and sustainability in the U.S. The first experiment will include the tree drought response scheme from (1), but not the allometric response function to CO2 fertilization from (2). The second experiment will include the allometric response function but not the drought response scheme. The third experiment will include both, and the fourth experiment will include neither. These factorial simulations will be initialized with forests spun up from 1700-1950 using meteorology from the GFDL earth system historical meteorology for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Next I will run each of the four experiments using the highest greenhouse gas concentration pathway from CMIP6 to quantify the interaction effect between drought and CO2 fertilization on forest productivity and sustainability. The new drought recovery scheme and allometric response function to CO2 fertiliation will be readily adaptable for general ecosystem model development, enabling the community at large to better project how drought conditions will affect forest growth and sustainability throughout the U.S. in the 21st century.

Progress 05/01/18 to 04/30/20

Outputs
Target Audience:Over the last reporting period (7/2019 to 10/2019) I have continued to reach the following target audiences. Scientific audiences: I have published or have papers under review in multiple peer-reviewed, relevant, and top-notch journals in the field (Global Change Biology, PNAS, Science, Ecology, New Phytologist, and the Journal of Theoretical Biology) and presented initial project results to scientific researchers at research seminars at the Ecological Society of America Annual Meetingand American Geophysical UnionChapmanConferenceon Understanding Carbon Climate Feedbacks. General Public & Incoming Masters Students: I have continuedmy communication efforts to several segments of the general public. These efforts included a media/press release from the University of Utah following the publication of our PNAS paper in summer 2019, where we made text and multi-media (pictures and videos) available to journalists and the general public once this paper came out.In addition, I have done one guest lecture about the project and related research to incoming Masters students in the Bren School for Environmental Science and Management, University of California Santa Barbara. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The current project has provided me with numerous training and professional development opportunities. I participated in a professional development series for postdocs run by the University of Utah Global Change and Sustainability Center. The mentorship of my host, Dr. William Anderegg, and the Global Change and Sustainability Center professional development series provided the background and training needed for me to secure 4 campus interview invitations for tenure track positions at the University of California Santa Barbara, University of California Los Angeles, University of California Irvine, and Cornell University, which resulted in two job offers. I will start as a new tenure track Assistant Professor in the Geography Department at the University of California Santa Barbara in November 2019. In addition, the project enabled me to undergo mentorship training through the University of Utah Undergraduate Research Mentor Development Program and the opportunity to improve my teaching skills through developing a module based on my research and present a guest lecture for incoming freshman through the ACCESS Program for Women in Science & Mathematics at the University of Utah. Finally, the project provided me with the opportunity to establish a strong collaboration with the US Forest Service Forest Inventory and Analysis (FIA) group based at the Rocky Mountain Research Station in Ogden, UT. This collaboration will benefit me throughout my scientific career. How have the results been disseminated to communities of interest?Project results have been disseminated in the form of peer-reviewed scientific publications and research talks to scientific audiences at multiple universities and professional meetings throughout the United States. Following the publication of our Nature and PNAS papers, we further disseminated project results via a press release, multi-media material, and media coverage of the paper in venues like Scientific American. Finally, initial project results were also disseminated in several a general audience talks incoming freshmen women at the University of Utah and incoming masters students at University of California Santa Barbara. What do you plan to do during the next reporting period to accomplish the goals?I have formally request that the remainder of my USDA NIFA Postdoctoral Fellowship be converted to a standard research grant because I have accepted a tenure-track faculty position in the Department of Geography at the University of California Santa Barbara (UCSB) and the request has been approved by the National Program Director. My appointment at UCSB will begin November 1, 2019. My appointment as a NIFA Postdoctoral Fellow began May 1, 2018, and come October 31, 2019, I will have completed 18 months of my NIFA Postdoctoral Fellowship.Over the final reporting period, from November 1, 2019 onwards, I will continue to develop the datasets and models to address Objective 3. This will be undertaken in collaboration with USFS FIA scientists. Indeed, FIA researchers are coauthors on 2 of the 3 in review publications mentioned related to objective 3. We anticipate publishable results within the next 6-12 months. Overall, I believe progress on the project has been proceeding according to plan and am excited to see more results emerge over this 6-12 month time period.

Impacts
What was accomplished under these goals? For Objective 1, I published a foundational paper in Ecology Letters (Trugman et al. 2018b) that develops a model to explicitly address Objective 1 and applies the physiological insight from the model to understand drought recovery across numerous species throughout the US and other continents in addition to North America. I, along with coauthors, have also published multiple other studies examining how species-specific physiological strategies influence drought resilience (Anderegg et al. 2018; Anderegg et al. 2019b) and drought-climate feedbacks (Anderegg et al. 2019a). These papers will be critical for the addressing and carrying out the rest of the research proposed for Objective 3. For Objective 2, I published two foundational paper in Global Change Biology (Trugman et al. 2019a, Trugman et al. 2019b) that collectively review the current state of the science, develop a model and tests the model theory using tree observations across broad environmental and CO2 gradients. These papers will also be critical for the addressing and carrying out the rest of the research proposed for Objective 3. For Objective 3, I have had several meetings and established a strong collaboration with the US Forest Service Forest Inventory and Analysis (FIA) group based at the Rocky Mountain Research Station in Ogden, UT. Building on my results from Objectives 1-2 and this collaboration to analyze FIA data, the analysis for Objective 3 is well underway. This is the subject of three papers currently under review at PNAS, PNAS, and Science, respectively (Trugman et al. Under Review; Sperry et al. Under Review; Anderegg et al. Under Review). I have formally request that the remainder of my USDA NIFA Postdoctoral Fellowship be converted to a standard research grant because I have accepted a tenure-track faculty position in the Department of Geography at the University of California Santa Barbara (UCSB) and the request has been approved by the National Program Director. My appointment at UCSB will begin November 1, 2019. My appointment as a NIFA Postdoctoral Fellow began May 1, 2018, and come October 31, 2019, I will have completed 18 months of my NIFA Postdoctoral Fellowship. Over the final reporting period, from November 1, 2019 onwards, I will continue to develop the datasets and models to address Objective 3. This will be undertaken in collaboration with USFS FIA scientists. Indeed, FIA researchers are coauthors on 2 of the 3 in review publications mentioned related to objective 3. We anticipate publishable results within the next 6-12 months. Overall, I believe progress on the project has been proceeding according to plan and am excited to see more results emerge over this 6-12 month time period.

Publications

• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Yu K, WK Smith, AT Trugman, R Condit, DB Clark, P van Mantgem, SP Hubbell, J Penuelas, C Peng, J Sardans, WRL Anderegg. Pervasive decreases in vegetation turnover time across global forest biomes. Under review at PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Wang Y, JS Sperry, MD Venturas, AT Trugman, WRL Anderegg. The over-estimation of leaf diffusive conductance for CO2: causes and consequences. Under review at Journal of Theoretical Ecology.
• Type: Journal Articles Status: Submitted Year Published: 2019 Citation: Trugman AT, LDL Anderegg, JD Shaw, WRL Anderegg. Trait velocities reveal that mortality has driven widespread coordinated shifts in forest hydraulic trait composition. Submitted to PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Sperry JS*, MD Venturas*, HN Todd, AT Trugman, WRL Anderegg, Y Wang, X Tai. The impact of acclimation on the response of US forests to climate change. Under review at PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Anderegg WRL, AT Trugman, G Badgley, A Konings, J Shaw. Divergent ecosystem sensitivity to repeated climate extremes. Under review at Science.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Kulmatiski A, K Yu, S Mackay, C Staver, A Parolari, Y Liu, S Majumder, AT Trugman. Forecasting semi-arid biome shifts in the Anthropocene. Under review at New Phytologist
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Trugman AT, LDL Anderegg, Y Wang, M Venturas, JS Sperry, WRL Anderegg (2019). Leveraging plant hydraulics to yield predictive and dynamic plant leaf allocation in vegetation models with climate change. Global Change Biology.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Anderegg WRL, LDL Anderegg, KL Kerr, AT Trugman (2019). Widespread drought-induced tree mortality at dry range edges indicates climate stress exceeds species compensating mechanisms. Global Change Biology
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Kerr K, N Zenes, AT Trugman, WRL Anderegg. Competition and functional traits mediate trait allocation and drought response physiology. Under review at Ecology.

Progress 05/01/18 to 10/13/19

Outputs
Target Audience:Over the last reporting period (7/2019 to 10/2019) I have continued to reach the following target audiences. Scientific audiences: I have published or have papers under review in multiple peer-reviewed, relevant, and top-notch journals in the field (Global Change Biology, PNAS, Science, Ecology, New Phytologist, and the Journal of Theoretical Biology) and presented initial project results to scientific researchers at research seminars at the Ecological Society of America Annual Meetingand American Geophysical UnionChapmanConferenceon Understanding Carbon Climate Feedbacks. General Public & Incoming Masters Students: I have continuedmy communication efforts to several segments of the general public. These efforts included a media/press release from the University of Utah following the publication of our PNAS paper in summer 2019, where we made text and multi-media (pictures and videos) available to journalists and the general public once this paper came out.In addition, I have done one guest lecture about the project and related research to incoming Masters students in the Bren School for Environmental Science and Management, University of California Santa Barbara. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The current project has provided me with numerous training and professional development opportunities. I participated in a professional development series for postdocs run by the University of Utah Global Change and Sustainability Center. The mentorship of my host, Dr. William Anderegg, and the Global Change and Sustainability Center professional development series provided the background and training needed for me to secure 4 campus interview invitations for tenure track positions at the University of California Santa Barbara, University of California Los Angeles, University of California Irvine, and Cornell University, which resulted in two job offers. I will start as a new tenure track Assistant Professor in the Geography Department at the University of California Santa Barbara in November 2019. In addition, the project enabled me to undergo mentorship training through the University of Utah Undergraduate Research Mentor Development Program and the opportunity to improve my teaching skills through developing a module based on my research and present a guest lecture for incoming freshman through the ACCESS Program for Women in Science & Mathematics at the University of Utah. Finally, the project provided me with the opportunity to establish a strong collaboration with the US Forest Service Forest Inventory and Analysis (FIA) group based at the Rocky Mountain Research Station in Ogden, UT. This collaboration will benefit me throughout my scientific career. How have the results been disseminated to communities of interest?Project results have been disseminated in the form of peer-reviewed scientific publications and research talks to scientific audiences at multiple universities and professional meetings throughout the United States. Following the publication of our Nature and PNAS papers, we further disseminated project results via a press release, multi-media material, and media coverage of the paper in venues like Scientific American. Finally, initial project results were also disseminated in several a general audience talks incoming freshmen women at the University of Utah and incoming masters students at University of California Santa Barbara. What do you plan to do during the next reporting period to accomplish the goals?I have formally request that the remainder of my USDA NIFA Postdoctoral Fellowship be converted to a standard research grant because I have accepted a tenure-track faculty position in the Department of Geography at the University of California Santa Barbara (UCSB) and the request has been approved by the National Program Director. My appointment at UCSB will begin November 1, 2019. My appointment as a NIFA Postdoctoral Fellow began May 1, 2018, and come October 31, 2019, I will have completed 18 months of my NIFA Postdoctoral Fellowship.Over the final reporting period, from November 1, 2019 onwards, I will continue to develop the datasets and models to address Objective 3. This will be undertaken in collaboration with USFS FIA scientists. Indeed, FIA researchers are coauthors on 2 of the 3 in review publications mentioned related to objective 3. We anticipate publishable results within the next 6-12 months. Overall, I believe progress on the project has been proceeding according to plan and am excited to see more results emerge over this 6-12 month time period.

Impacts
What was accomplished under these goals? For Objective 1, I published a foundational paper in Ecology Letters (Trugman et al. 2018b) that develops a model to explicitly address Objective 1 and applies the physiological insight from the model to understand drought recovery across numerous species throughout the US and other continents in addition to North America. I, along with coauthors, have also published multiple other studies examining how species-specific physiological strategies influence drought resilience (Anderegg et al. 2018; Anderegg et al. 2019b) and drought-climate feedbacks (Anderegg et al. 2019a). These papers will be critical for the addressing and carrying out the rest of the research proposed for Objective 3. For Objective 2, I published two foundational paper in Global Change Biology (Trugman et al. 2019a, Trugman et al. 2019b) that collectively review the current state of the science, develop a model and tests the model theory using tree observations across broad environmental and CO2 gradients. These papers will also be critical for the addressing and carrying out the rest of the research proposed for Objective 3. For Objective 3, I have had several meetings and established a strong collaboration with the US Forest Service Forest Inventory and Analysis (FIA) group based at the Rocky Mountain Research Station in Ogden, UT. Building on my results from Objectives 1-2 and this collaboration to analyze FIA data, the analysis for Objective 3 is well underway. This is the subject of three papers currently under review at PNAS, PNAS, and Science, respectively (Trugman et al. Under Review; Sperry et al. Under Review; Anderegg et al. Under Review). I have formally request that the remainder of my USDA NIFA Postdoctoral Fellowship be converted to a standard research grant because I have accepted a tenure-track faculty position in the Department of Geography at the University of California Santa Barbara (UCSB) and the request has been approved by the National Program Director. My appointment at UCSB will begin November 1, 2019. My appointment as a NIFA Postdoctoral Fellow began May 1, 2018, and come October 31, 2019, I will have completed 18 months of my NIFA Postdoctoral Fellowship. Over the final reporting period, from November 1, 2019 onwards, I will continue to develop the datasets and models to address Objective 3. This will be undertaken in collaboration with USFS FIA scientists. Indeed, FIA researchers are coauthors on 2 of the 3 in review publications mentioned related to objective 3. We anticipate publishable results within the next 6-12 months. Overall, I believe progress on the project has been proceeding according to plan and am excited to see more results emerge over this 6-12 month time period.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Trugman AT, LDL Anderegg, Y Wang, M Venturas, JS Sperry, WRL Anderegg (2019). Leveraging plant hydraulics to yield predictive and dynamic plant leaf allocation in vegetation models with climate change. Global Change Biology.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Anderegg WRL, LDL Anderegg, KL Kerr, AT Trugman (2019). Widespread drought-induced tree mortality at dry range edges indicates climate stress exceeds species compensating mechanisms. Global Change Biology
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Kerr K, N Zenes, AT Trugman, WRL Anderegg. Competition and functional traits mediate trait allocation and drought response physiology. Under review at Ecology.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Yu K, WK Smith, AT Trugman, R Condit, DB Clark, P van Mantgem, SP Hubbell, J Penuelas, C Peng, J Sardans, WRL Anderegg. Pervasive decreases in vegetation turnover time across global forest biomes. Under review at PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Wang Y, JS Sperry, MD Venturas, AT Trugman, WRL Anderegg. The over-estimation of leaf diffusive conductance for CO2: causes and consequences. Under review at Journal of Theoretical Ecology.
• Type: Journal Articles Status: Submitted Year Published: 2019 Citation: Trugman AT, LDL Anderegg, JD Shaw, WRL Anderegg. Trait velocities reveal that mortality has driven widespread coordinated shifts in forest hydraulic trait composition. Submitted to PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Sperry JS*, MD Venturas*, HN Todd, AT Trugman, WRL Anderegg, Y Wang, X Tai. The impact of acclimation on the response of US forests to climate change. Under review at PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Anderegg WRL, AT Trugman, G Badgley, A Konings, J Shaw. Divergent ecosystem sensitivity to repeated climate extremes. Under review at Science.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Kulmatiski A, K Yu, S Mackay, C Staver, A Parolari, Y Liu, S Majumder, AT Trugman. Forecasting semi-arid biome shifts in the Anthropocene. Under review at New Phytologist

Progress 05/01/18 to 04/30/19

Outputs
Target Audience:Scientific audiences: I have published multiple peer-reviewed papers in relevant and top-notch journals in the field (Nature, Proceedings of the National Academy of Sciences of the United States of America, Ecology Letters, Global Change Biology, Geophysical Research Letters, Tree Physiology, and Ecosphere) and presented initial project results to scientific researchers at research and department seminars at the University of California at Irvine, University of California at Santa Barbara, Cornell University, University of California at Los Angeles, American Geophysical Union Fall Meeting, Ecological Society of America Annual Meeting, and Gordon Research Conference on Multiscale Plant Vascular Biology. General Public & Incoming College Freshman: I have begun my communication efforts to several segments of the general public. These efforts included a media/press release from the University of Utah following the publication of our Nature paper in fall 2018 and PNAS paper in the spring 2019, where we made text and multi-media (pictures and videos) available to journalists and the general public once this paper came out. This effort led to news coverage of our Nature paper in multiple online media websites and also Scientific American. In addition, I have done one guest lecture about the project and related research to incoming freshman for the ACCESS Program for Women in Science & Mathematics, University of Utah in the summer 2018. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The current project has already provided me with numerous training and professional development opportunities. I participated in a professional development series for postdocs run by the University of Utah Global Change and Sustainability Center. The mentorship of my host, Dr. William Anderegg, and the Global Change and Sustainability Center professional development series provided the background and training needed for me to secure 4 campus interview invitations for tenure track positions at the University of California Santa Barbara, University of California Los Angeles, University of California Irvine, and Cornell University, which resulted in two job offers. I will start as a new tenure track Assistant Professor in the Geography Department at the University of California Santa Barbara in March 2020. In addition, the project enabled me to undergo mentorship training through the University of Utah Undergraduate Research Mentor Development Program. Finally, the project provided me with the opportunity to improve my teaching skills through developing a module based on my research and present a guest lecture for incoming freshman through the ACCESS Program for Women in Science & Mathematics at the University of Utah. How have the results been disseminated to communities of interest?Project results have been disseminated in the form of peer-reviewed scientific publications and research talks to scientific audiences at multiple universities and professional meetings throughout the United States. Following the publication of our Nature paper, we further disseminated project results via a press release, multi-media material, and media coverage of the paper in venues like Scientific American. Finally, initial project results were also disseminated in several a general audience talks incoming freshmen women at the University of Utah. What do you plan to do during the next reporting period to accomplish the goals?Over the next reporting period, I will continue to develop the datasets and models to address Objective 3. This will be undertaken in collaboration with USFS FIA scientists and we anticipate some publishable results within the next 6-12 months. Overall, I believe progress on the project has been proceeding according to plan and am excited to see more results emerge in the next reporting period.

Impacts
What was accomplished under these goals? For Objective 1, I published a foundational paper in Ecology Letters (Trugman et al. 2018) that develops a model to explicitly address Objective 1 and applies the physiological insight from the model to understand drought recovery across numerous species throughout the US and other continents in addition to North America. I, along with coauthors, have also published multiple other studies examining how species-specific physiological strategies influence drought resilience (Anderegg et al. 2018; Anderegg et al. 2019). These papers will be critical for the addressing and carrying out the rest of the research proposed for Objective 3. For Objective 2, I published a foundational paper in Global Change Biology (Trugman et al. 2019) that develops a model and tests the model theory using tree observations across broad environmental and CO2 gradients. This is also the subject of a review paper currently under review at Global Change Biology (Trugman et al. Under Review). These papers will also be critical for the addressing and carrying out the rest of the research proposed for Objective 3. For Objective 3, I have had several meetings and established a strong collaboration with the US Forest Service Forest Inventory and Analysis (FIA) group based at the Rocky Mountain Research Station in Ogden, UT. Building on my results from Objectives 1-2 and this collaboration to analyze FIA data, the analysis for Objective 3 is well underway.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Trugman AT, LDL Anderegg, BT Wolfe, B Birami, NK Ruehr, M Detto, MK Bartlett, WRL Anderegg (2019). Climate and plant trait strategies determine tree carbon allocation to leaves and mediate future forest productivity. Global Change Biology.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Jiang Y, J Kim, AT Trugman, Y Kim, C Still (2019). Modeling carbon, water and energy fluxes in an old-growth forest: integrating physiology, structure, and demography. Ecosphere.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Wang Y, JS Sperry, MD Venturas, AT Trugman, DM Love, and WRL Anderegg (2019). The stomatal response to rising CO2 concentration and drought is predicted by a hydraulic trait-based optimization model. Tree Physiology.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Anderegg WRL, AG Konings, AT Trugman, K Yu, DR Bowling, D Karp, S Pacala, J Sperry, B Sulman (2018). Hydraulic diversity of forests mediates ecosystem resilience during drought. Nature, 561: 538-541.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Trugman AT, M Detto, MK Bartlett, D Medvigy, WRL Anderegg, C Schwalm, B Schaffer, S Pacala (2018). Tree carbon allocation explains forest drought-kill and recovery patterns. Ecology Letters, 21: 1552-1560.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Trugman AT, D Medvigy, JS Mankin, WRL Anderegg (2018). Soil moisture drought as a major driver of carbon cycle uncertainty. Geophysical Research Letters, 45: 6495-6503.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Tree carbon allocation strategy mediates terrestrial productivity in the Anthropocene. American Geophysical Union Fall Meeting (2018), Walter E. Washington Convention Center, Washington, D.C. Invited.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Plant allometric constraints and hydraulic-carbon coupling govern tree drought mortality. Ecological Society of America Annual Meeting (2018), New Orleans Ernest N. Morial Convention Center, New Orleans, LA. Invited.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Tree carbon allocation explains forest drought-kill and recovery patterns. Gordon Research Conference on Multiscale Plant Vascular Biology, Mount Snow in West Dover, VT. Poster.
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Anderegg WRL, LDL Anderegg, KL Kerr, AT Trugman (2019). Widespread drought-induced tree mortality at dry range edges indicates climate stress exceeds species compensating mechanisms. Global Change Biology
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Anderegg WRL, AT Trugman, DR Bowling, S Tuttle (2019). Plant functional traits and climate influence drought intensification and land-atmosphere feedbacks. PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Trugman AT, LDL Anderegg, Y Wang, M Venturas, JS Sperry, WRL Anderegg. Leveraging plant hydraulics to yield predictive and dynamic plant leaf allocation in vegetation models with climate change. Under review at Global Change Biology.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Kerr K, N Zenes, AT Trugman, WRL Anderegg. Competition and functional traits mediate trait allocation and drought response physiology. Under review at New Phytologist.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Yu K, WK Smith, AT Trugman, R Condit, DB Clark, P van Mantgem, SP Hubbell, J Penuelas, C Peng, J Sardans, WRL Anderegg. Pervasive decreases in vegetation turnover time across global forest biomes. Under review at PNAS.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Wang Y, JS Sperry, MD Venturas, AT Trugman, WRL Anderegg. The over-estimation of leaf diffusive conductance for CO2: causes and consequences. Under review at Plant, Cell, and Environment.