Progress 06/01/20 to 05/31/23
Outputs
Target Audience:There were two primary target audiences for this reporting period: Forests ecologists, plant ecophysiologists, and ecohydrologists The general public Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Over the course of the project, training was provided for one technician (now doctoral student), one postdoctoral scholar (now faculty) six summer undergraduate research students (now transitioning into the workforce), and 25 undergraduate students engaged in a course-based undergraduate research experience. In addition, collaborators from across more than a dozen institutions engaged in field sampling to carry out the project and almost universally included trainees in these experiences. These training opportunities led to conference presentations led by those trainees at the Ecological Society of America, the American Geophysical Union and the Schmid College of Science and Technology summer undergraduate research conference. How have the results been disseminated to communities of interest?To date, the project has produced one peer-reviewed publication (Diao et al. 2023 HESS), one publication in review (Felton et al.) and two additional publications in preparation. Conference presentations were made at the Ecological Society of America, the American Geophysical Union and the Schmid College of Science and Technology summer undergraduate research conference. Invited talks were given at the Luxembourg Institute for Science and Technology (LIST), University of Aarhus, and Chapman University. In addition, a project focused on public engagement in science distributed 200 pins featuring wood anatomy images from the project as "science conversation starters." What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Trees have adopted a number of structural and functional traits to withstand drought. Understanding these traits is critical to our ability to conserve our nation's existing forests, as well as to plant new forests, particularly in the context of a rapidly changing climate. Our project focused on the ability for trees to store water in their wood, how much stored water can be mobilized when water supply is low and demand is high, and the speed at which water transits through trees. This included 1) field collection and laboratory measurement of wood cores from 51 common tree species at 22 sites across the United States, 2) experimental laboratory approaches to measuring the turnover of water in trees, and 3) a remote sensing-based evaluation of the storage and turnover time of wood in trees on a global scale on a seasonal basis at 9 km resolution. The key outcomes are as follows: The generation of the largest tree wood water capacitance data set ever assembled. The data inform our understanding of how species identity and predominant climate characteristics inform our ability to improve forest management. The data will also inform our ability to better incorporate tree-water relations into land surface models. Foundational insights into wood water isotope fractionation and exchange processes that will inform our ability to use this tool for asking questions of plant water sourcing, plant water storage, and plant water use. The first spatially and temporally resolved global maps of aboveground vegetation water storage and turnover time. Such maps will inform our understanding of the flow of water across the soil-plant-atmosphere continuum among land cover types in the context of climate and land-use, with implications for improved forest management. Key results from each objective of the project include the following: We collected cores from up to 4 different species from each of 22 sites across the United States. Sites ranged in mean annual temperature from - 4.2 to 24.1°C and mean annual precipitation from 445 to 1532 mm. We measured wood water storage, capacitance, and wood anatomy among 51 common tree species at sites around the United States. Mean wood water capacitance across sites was 510 ± 86 kg H2O m-3 MPa-1, with an inter-site variation of 271 kg H2O m-3 MPa-1 and an average intra-site variation of 513 kg H2O m-3 MPa-1. Gymnosperms had a significantly higher capacitance than angiosperms. There was no relationship between tree size and capacitance. For each of the cores, we measured a number of different wood anatomy traits. We find an inverse curvilinear relationship between capacitance and average conduit diameter. No other traits (including wood density, conduit area, and conduit density) were related to capacitance. However, it is clear that gross anatomy, as defined in the comparison between angiosperm vs. gymnosperm, still governs significant differences in capacitance. Needle-leafed species consistently have a greater capacity to use stored water than broad-leafed species. Our results indicate that the identity of the tree species is far more important than the location in which it is growing in governing the ability for trees to use water stored in wood. This indicates that climate does not play as large a role in the ability for trees to use stored water than was originally expected. We complement our measurement of storage and capacitance on the basis of individual trees with a global study of the water stored in aboveground vegetation and its transit time. We estimate global aboveground vegetation water storage to be 379 km3, 37% of which is in evergreen broadleaf forests. We then combine these estimates with estimates of transpiration to find that the global median annual transit time of water through vegetation varies from ~2.5 days in savannas to ~12 days in evergreen needleleaf forests, with a global median of 5.4 days. In land cover types with comparatively low water storage and high seasonal water use (e.g., croplands), the water stored in biomass may be turning over several times per day. Our spatially and temporally resolved maps of vegetation water storage and transit time provide a new means of assessing the complex and interactive effects of global change on the time it takes for water to move through the terrestrial water cycle.
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2023
Citation:
Felton, A.J., J.B. Fisher, A.J. Purdy, S.A. Spawn-Lee, L.F. Duloisy, & G.R. Goldsmith. In Review Global estimates of the storage and transit time of water through vegetation. Nature Water
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Progress 06/01/21 to 05/31/22
Outputs
Target Audience:Target Audiences: We sought to engage with 1) students from groups historically underrepresented in STEM and from disciplines historically not involved in agricultural sciences/forestry and 2) academic scientists. Efforts: We engaged 25 students engaged in an upper-division plant biology laboratory using project-based learning over the course of eight weeks. Students 1) learned about wood anatomy, 2) brainstormed wood anatomical traits that they expected would correlate with wood functional traits such as capacitance, 3) developed methods for analyzing these traits using computer software, and 4) visualized the results. The project culminated with small groups of students presenting their results in a class presentation. In addition, we engaged 5 students (4 computer science majors and 1 biology major; 3 from underrepresented groups) in paid summer internships addressing project objectives. Research is ongoing, however, preliminary results were presented in a poster presentation by students at the college-wide summer research symposium. We engaged with academic audiences by presenting preliminary results of our research in a poster presented at the Ecological Society of America's annual conference in Montreal, Canada and in an oral presentation at the American Geophysical Union's annual conference in New Orleans, Louisiana. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The research has resulted in training for one postdoctoral research associate, one technician, five paid summer undergraduate student interns and 25 undergraduate students in a classroom setting. The postdoctoral research associate, technician, and one undergraduate student intern all attended scientific conferences as a result of their participation in the project. In addition, the technician participated in an advanced course in data visualization and analysis in support of the research. The postdoctoral research associate, technician and summer undergraduate student interns were all mentored by the project director with contributions from the project co-director. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?Our plans for the next reporting period to accomplish the goals outlined in the project include the following activities: -Complete manuscript reporting primary results of project objectives 1+2, as well as a second manuscript reporting on methodology used in project. -Publish database of wood water capacitance traits and associated wood anatomical traits for each site. -Carry out experiment focused on objective 3 to determine proportion of water actively participating in transpiration as originally planned. -Complete outreach project on wood anatomy focused on introducing a broader public audience to the future of forests. -Write outreach article focused on the role of water stored in wood as a means of drought resistance in trees for forestry industry audience.
Impacts
What was accomplished under these goals?
Summary Trees have adopted a number of structural and functional traits to withstand drought. Understanding these traits is critical to our ability to conserve our nation's existing forests, as well as to plant new forests, particularly in the context of a rapidly changing climate. Our project is particularly focused on the ability for trees to store water in their wood and use it at times of when the supply of water is low (drought) and the demand for water is high (high temperatures). We have adopted a unique approach to measuring wood water storage and the ability for trees to use that stored water by engaging collaborators around the United States to sample the most common tree species in their backyards. Samples are sent back to our lab for standardized measurement. To date, we have collected data from 51 common tree species occurring at 22 sites from Alaska to Florida. Our results show that the identity of the tree species is far more important than the location in which it is growing in governing the ability for trees to use water stored in wood. This indicates that climate does not play as large a role in the ability for trees to use stored water than was originally expected. In fact, we find no strong relationships between the ability for plants to use water stored in wood and either temperature of the hottest month or precipitation of the driest month in the location in which the trees were sampled. It would suggest that vulnerability to drought, with respect to this particular set of structural and functional traits, can be predicted by species alone. For example, needle-leafed species consistently have a greater capacity to use stored water than broad-leafed species. The results will contribute to our ability to make informed decisions about which tree species to plant in a given a location and ensure the long-term sustainability of our forestry, agroforestry, and agricultural systems. Specific Accomplishments Objective 1: Determine how wood water storage and capacitance varies within and among key tree species in the United States. We completed the second year of data collection, resulting in data on 51 common tree species from 22 sites around the United States. We originally planned to sample 25 species from 8 sites. We have measured wood water capacitance and associated wood anatomical traits from all of these species using standardized methodology. Mean wood water capacitance across sites was 510 ± 86 kg H2O m-3 MPa-1, with an inter-site variation of 271 kg H2O m-3 MPa-1and an average intra-site variation of 513 kg H2O m-3 MPa-1. Capacitance was significantly higher in gymnosperms than angiosperms, (t-test, P < 0.01). The variation we observed within sites was as high as the continental-scale variation, suggesting that gross differences in climate do not drive capacitance. Moreover, capacitance did not correlate well with measures of climate. Species identity drives capacitance within a site. We expect the results of this research to enable significantly better decision making for those engaged in forestry, particularly with respect to decisions on which species to plant at any given location. We presented these preliminary results in a poster presentation at the annual meeting of the Ecological Society of America and are now preparing a manuscript for submission. In addition, because we have carried out significant methods development in support of the project, we have now prepared a draft of a manuscript reporting the methods we have adopted for making these measurements in the lab. The completion of this research was carried out, in part, by a research technician who has recently departed to begin a doctoral degree in forest ecophysiology at Montana State University. Objective 2: Establish the relationship between capacitance and wood structural traits. We correlated measurements of wood structural traits (conduit diameter, conduit density, conduit area per unit wood area) with wood wood water capacitance. In contrast to previous studies, we do not observe a significant relationship between tree size and capacitance. Capacitance decreases non- linearly with increasing conduit diameter, but was not related to other traits. These results were reported in the poster presentation at the annual meeting of the Ecological Society of America as described above. We expect the results of this research to further our foundational understanding of the relationships between plant structure and function, thereby facilitating better decision-making by those engaged in forestry. The completion of this research was supported by students participating in a plant biology laboratory class and a paid student summer intern. In addition to work on wood water storage as measured through capacitance, we have also been exploring novel methods for using satellite remote sensing for measurement of wood water storage. In particular, we are using vegetation optical depth (an L-Band microwave data product provided by NASA's SMAP mission) to infer vegetation water storage and correlate it with ground-based measures of water storage as a means of validation. Our results show a strong correlation (Spearman's rho = 0.7) between ground- and satellite-based measures of vegetation water storage among different plant functional types (e.g., trees, grasses). Preliminary results were presented in an oral presentation at the annual meeting of the American Geophysical Union. We expect the results of this research to enable the use of satellite remote sensing for measuring plant water storage and vulnerability to drought at a global scale not previously feasible due to sampling constraints. The completion of this research is supported by four paid student summer interns and was initiated by a postdoctoral research associate. Objective 3: Quantify the proportion of xylem water actively participating in the transpiration stream. We completed a study to systematically test the uncertainties associated with methods commonly used for determining the source of water in xylem. In particular, differences in the stable isotope composition of hydrogen and oxygen isotopes in water are commonly used as tracers for natural processes. In this project, we proposed leveraging this tool to quantify the proportion of xylem water actively participating in the transpiration stream. However, recent developments in the field have made it necessary to conduct further methodological tests. In an international collaboration, we have systematically tested uncertainties in the isotopic composition of water extracted from wood using the common cryogenic vacuum distillation method. To do so, we conducted a series of incubation and rehydration experiments using isotopically depleted water, water at natural isotopic abundance, and organic materials with and without exchangeable hydrogen. We show that the offsets between hydrogen and oxygen isotope ratios and expected reference values (Δ2H and Δ18O) have inversely proportional relationships with the absolute amount of water being extracted. These results demonstrate the validity of the method we originally proposed to use, but that samples must be large. As such, we will now proceed with quantifying the proportion of xylem water actively participating in transpiration using live trees in the field. We expect the results of this research to enable additional, more accurate applications of the stable isotopes of water to a number of different environmental research applications. Preliminary results of this research were presented at the annual meeting of the European Geophysical Union and posted as a preprint now in review at Hydrology and Earth Systems Science.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Duloisy, L., D.M. Johnson, S.T. Allen, C. Doughty, D. Grose, J.L. Reid, J. Wason, & G.R. Goldsmith. 2022. Developing a continental-scale perspective on wood water storage and capacitance. Annual Meeting of the Ecological Society of America.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Felton, A., J.B. Fisher, A.J. Purdy, S. Spawn & G.R. Goldsmith. 2021. The storage and transit time of water moving through vegetation. Annual Meeting of the American Geophysical Union.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2022
Citation:
Diao, H., P. Schuler, G.R. Goldsmith, R.T.W. Siegwolf, M. Saurer, & M.M. Lehman. In Review On uncertainties in the plant water isotopic composition following extraction by cryogenic vacuum distillation. Hydrology and Earth Systems Science https://doi.org/10.5194/hess-2022-178
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Diao, H., G.R. Goldsmith, & M.M. Lehman. 2022. On uncertainties in the plant water isotopic composition extracted with cryogenic vacuum distillation. Annual Meeting of the European Geophysical Union.
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Progress 06/01/20 to 05/31/21
Outputs
Target Audience:
Nothing Reported
Changes/Problems:Due to COVID-19, we delayed the beginning of field data collection by one year. This approach allowed us to minimize risk to those engaged in the project, including collaborators from field sites all over the United States. Instead, we adopted an alternative approach based on satellite remote sensing. We are now deeply engaged in field data collection; however, we anticipate requesting a one year, no-cost extension in order to complete the project. We have been in consistent contact with the sponsored projects office to apprise them of our progress and to facilitate communications with USDA-NIFA where appropriate. What opportunities for training and professional development has the project provided?This project has provided training to two undergraduate students, one graduate student, one early career technician, and one postdoctoral research associate to date. How have the results been disseminated to communities of interest?We have not yet begun to disseminate results. We expect our first results will be presented at the annual meeting of the American Geophysical Union in December with the submission of our first manuscript for peer review before the end of the year. What do you plan to do during the next reporting period to accomplish the goals?We are very excited to be deeply engaged in the collection of the field data for Objectives 1+2 over the course of an extended summer field season (June-September). In the fall (October-November), we will collate this data and plan for the experimentation in support of Objective 3 to take place in the winter (December-February). Finally, in the spring (March-May), we expect to focus our efforts on analysis of data collected for Objective 3, including efforts to present the results to various audiences through a number of different outlets. Finally, we will request a one-year no-cost extension; we expect that with this extension, we will be able to accomplish all of the proposed goals.
Impacts
What was accomplished under these goals?
In recognition of the challenges imposed by the pandemic, we focused our efforts on using an alternative approach to addressing Objectives 1+2. In particular, we hired a postdoctoral research associate (Dr. Andrew Felton) with expertise in satellite remote sensing to develop a map of water stored in vegetation using radar-based sensing of vegetation optical depth. We have a preliminary 9 km global map with monthly resolution. We then calculated transit time, which is the age, since entry, of water leaving vegetation. Transit time of water in vegetation is an important measure of the rate at which water stored in wood is used by the plant (i.e. capacitance; Objective 1) and the estimation of the amount of water participating in transpiration (Objective 3) has important implications for the interpretation of transit time. We have supported these estimates by assembling estimates of seasonal changes in relative water content from the literature. This work has been carried out by an undergraduate research assistant (Alex Guerrero) under supervision from Dr. Andrew Felton. This alternative approach allowed us to delay the start of field sampling and the intensive sample processing associated with the proposed project. However, we recently hired a technician (Lou Duloisy; July 1 start date) and have begun collecting the data to complete Objectives 1+2 as originally proposed. To date, we have collected data on wood water capacitance, wood water content, wood density, and wood anatomy from 8 collaborators and more than 20 tree species across the United States, putting us on track to complete the proposed data collection for Objective 1+2 by the end of the summer. We expect to continue this data collection (past the original proposed work) in summer 2022. In parallel, Dr. Dan Johnson, a graduate student (Justine Rojas), and an undergraduate (Kentrell Richardson) at the University of Georgia have been advancing new methods for the measurement of wood water capacitance. They are planning a significant methods comparison this fall.
Publications
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