Progress 01/01/23 to 12/31/23
Outputs
Target Audience:We targeted syrup producers, scientists (including other tree physiologists and syrup researchers), natural resource managers, interested landowners, and the general public (especially syrup consumers) with our research and outreach activities, as described in detail below. Changes/Problems: During this past reporting cycle, we experienced four problems that required minor changes to our planned activities. The pressure sensors (Omega Engineering, Norwalk, CT) that were used to monitor vacuum levels were recommended to us by other well-established syrup researchers. However, our experience with these sensors has been mixed, possibly due to these sensors not being specifically calibrated for negative (below-atmospheric) pressures. This is important, because a large percentage of the pressures in deciduous, woody angiosperms during winter dormancy are below atmospheric pressure. Thus, further lab validation is needed to determine how accurate they are at measuring low pressures so we can be confident in the claims we will make about how tap barrel lengths affect vacuum levels. To address this issue, we plan to conduct a rigorous lab validation and calibration of these pressure sensors once the 2024 field season ends using known vacuum levels. Second, our axial (vertical) measurement positions for the wood temperature and stem pressure sensors were located at ground level, at breast height, and in the canopy. For some species of trees, the distance between the breast height measurements and the canopy measurements was about 1 m, but for others, this distance was as large as 20 m. Thus, there is quite a bit of uncertainty in our calculated values of wood temperature and stem pressure axial gradients when these distances were large due to these gaps in the measurements. Future studies should include more regular axial measurement intervals with more numerous sensors located across shorter distances. Third, we were not able to obtain any xylem sap osmolality measurements in 2023. The 'jet-discharge' method of extracting xylem sap from wood cores using a pressure bomb, described in several peer-reviewed journal articles, did not work on our wood cores, and attempts to communicate with the authors of these journal articles were not successful. Twig samples also did not yield as much sap as we had expected. To address this issue, we have developed and tested a more effective approach for extracting xylem sap that we are using during the 2024 field season.This approach involves drilling small holes at the ground, breast-height, and canopy positions along the tree stem and using a syringe to extract sap from each hole. Putty is used to seal where the syringe needle enters the hole, and a manual pneumatic vacuum pump (used in the automotive industry for bleeding brake lines) is connected to the syringe and used to generate enough negative pressure for sap to be extracted under most conditions. This technique is currently being used during the 2024 field season with a high degree of sucess. Fourth, in assessing maple syrup producers' willingness to adopt the production of novel tree syrup, we face the usual problem of low response rates by producers. Currently, we are contracting with a survey firm to supply us with the mailing address of maple syrup producers. However, the sample size is too small. To address this, we plan to augment our sampling approach by incorporating email addresses of maple syrup producers. This expansion will help increase the sample size at the risk of increasing selection bias. What opportunities for training and professional development has the project provided?Ph.D. candidate David Moore enhanced his professional development by participating in an international maple syrup producer conference an academic conference (a sap flow workshop). At the maple syrup producer conference, interacted with several preeminent maple syrup researchers (e.g., Adam Wild, Cornell University; Matthew Watson, University of Canterbury, NZ), building his professional network, sharing ideas and learning from others, and exploring opportunities for future collaboration. This past year, Moore also improved his R coding skills, his CRBasic coding skills, his ability to craft an effective public oral presentation, and his understanding of canopy access techniques. Furthermore, while working on a manuscript for publication, David learned about freezing-point-depression measurement techniques and will apply these techniques to his sap samples this year to understand more completely how freeze-thaw dynamics affect sap flow, stem pressure, and wood water content, thereby strengthening the interpretation of his results for future publication. Additionally, four undergraduate students and one high-school volunteer learned how to assemble sap flow and stem pressure sensors for field monitoring of sap flow dynamics, including soldering techniques and basic electrical engineering principles. One graduate student and a high-school volunteer got experience and instruction on safe chainsaw operation. Graduate student Tanner Frost gained valuable experience climbing trees to help with the installation and removal of canopy wood temperature and stem pressure sensors. Ph.D. student Yizun Yan enhanced her skills in choice experiment design, econometric estimation, software proficiency, and survey framing throughout the project. Yizun crafted the choice experiment survey utilizing a D-optimal design approach and conducted a pretest of this survey at the 2023 North American Maple Conference. Using pretest data, she skillfully applied conditional logit model and mixed logit model to obtain initial estimates, which were then used as Bayesian priors to generate the final choice design. From this process, she learned how to use and to cross-validate among different software tools, including R, Stata, JMP and Ngene in discrete choice model and data analysis. Furthermore, Yizun learned how to frame survey questions in a way that elicits meaningful insights from producers' perceptions and preferences in decision-making. How have the results been disseminated to communities of interest?The primary target audience for the agroforestry-related research is landowners, farmers, producers, and other stakeholders interested in implementing diverse agroforestry systems on their lands, as well as natural resource managers and policy makers who need science-based information on which to base their decisions, and consumers who are interested in learning more about different agroforestry products and where they can be obtained. We disseminated results to scientists at the 12th International Workshop on Sap Flow, to syrup producers at a professional conference (the 2023 International Maple Syrup Conference), five media appearances, five taste-testing events, and informally, through interactions with our team's extensive network syrup producers in the region. The taste tests and the media appearances were especially important, as many consumers had never realized that syrup production from trees other than maples was possible. When taste test participants were asked about their syrup preferences, approximately 50% stated a non-maple syrup as their favorite, with beech, sycamore, and birch syrups being the three top choices after maple. Increasing consumer awareness of and preferences for alternative syrups is an important first step towards creating new markets for diverse tree syrup products. Finally, as part of an international exchange visit whereby UNH hosted a group of forestry researchers and professionals from Bangladesh, PhD student Moore gave a presentation and facilitated discussion about his syrup diversification research. In Bangladesh, date palm syrup is an important product, and the similarities between maple syrup production and date palm syrup production may open opportunities for future collaboration. Both syrup producers and consumers have benefited directly from PhD student Moore's research on diversification of the syrup industry--producers have obtained information regarding techniques for producing syrup from sap extracted from trees other than maples, while consumers have had opportunities to taste diverse syrups and received information on where they can purchase these syrups throughout the region. The interest among these stakeholders in this research is reflected by them actively reaching out to PhD student Moore for information, with the result that Moore communicated with approximately 25 maple syrup producers and interested landowners on how to produce syrup from different types of trees, and about 40 interested consumers on where to obtain syrups from different tree species. As both producers and consumers become more knowledgeable about the potential for diverse tree species to produce interesting and flavorful syrups and to contribute to forest conservation and climate resilience, this should lead to growing market opportunities for producers to diversify their income base, as well as an increase in incentives for landowners and other forest managers to conserve and sustainably manage different types of forests and for consumers to directly support local industries and climate adaptation. What do you plan to do during the next reporting period to accomplish the goals?Goal #1. During 2024, we plant to collect data on xylem sap osmolality, while continuing to collect measurements of bark respiration, sap flow, wood temperature, stem pressure, and wood water content measurements. Combined, these data will allow for a more complete analysis of the drivers of sap flow dynamics across our study species. We will also perform chemical analyses, including both gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), on all the sap and syrup samples collected during the first two years of the project. These analyses will allow us to identify the different compounds and their amounts present in all our sap and syrup samples. During the coming field season, we will fell 35 of the study trees that were tapped in 2022 and 2023 and cut cross-sections ('cookies') that include the area of each stem affected by tapping. Each cookie will be planed, sanded, photographed, and analyzed with image-analyzing software to estimate the size of the nonconductive wood columns above and below old tap holes. Additionally, the cookies will be used to quantify annual radial growth rates to determine whether radial growth rates are compensating for the loss of hydraulically conductive wood each year due to tap hole wounds. Combined, these results will be used to generate tapping guidelines for these novel species. Goal #2: We will implement our final Bayesian choice design with a representative sample of maple syrup producers. We are now contracting a survey firm to supply us with the mailing addresses of maple syrup producers. In the final survey, we include two information treatments where we randomly provide respondents information about projected declines in syrup yields across most of the U.S. range under future climate scenarios and about the premium consumers are willing to pay for syrup produced from diversified forests. The survey includes perception questions that will help us better understand producer preferences and the extent to which they are driven by the market or by environmental considerations. Analysis of these incentives and barriers to adoption is needed to predict where and how many producers might adopt production of novel tree syrup, providing vital insights for the industry and policymakers interested in increased diversification for the purpose of increased resilience in agriculture and forestry. Willingness-to-adopt estimates are useful to policymakers and stakeholders to develop targeted interventions and support mechanisms, promoting sustainable practices and enhancing the industry's resilience against environmental challenges.
Impacts
What was accomplished under these goals?
This project addresses the need to understand the potential for diversifying the maple syrup industry to include other non-maple tree species as a strategy for adapting to future climate change by increasing the biodiversity of sugarbushes while also developing new opportunities for market expansion and income diversification for producers and landowners. Diversification of the maple syrup industry also has the potential to enhance climate mitigation by promoting conservation of forest ecosystems and increases in total carbon sequestration and storage. In the absence of diversification, the long-terms sustainability of the maple syrup industry, which comprises and important cultural, economic, and ecological land use practice in New England, is threatened by climate change-induced rising temperatures and increasing drought frequency, given the high sensitivity of sugar maple to environmental change. Goal #1: Patterns and drivers of dormant season sap flow. To determine the drivers of winter-dormant-season sap flow, and sap pressurization, we collected continuous (15-min) data during the winter and spring of 2023 when study species were dormant. In three trees of each of the study species (i.e., sugar maple, paper birch, American beech, American sycamore, hophornbeam, basswoods, speckled alder), we monitored wood water content, sap flow, and wood temperature and stem pressure at ground level, breast height, and in the canopy. We calculated axial (vertical) and radial gradients of wood temperature and axial gradients of stem pressure, and analyzed the degree of correlation between these variables. Sap was harvested from these species to produce syrup used in taste-testing events to understand consumer preferences. Sap and syrup samples will be analyzed for chemical composition. This past year, we also focused our efforts on analyzing and interpreting data collected over the past 5 years and developing and writing manuscripts. Preliminary results thus far suggest that, contrary to our hypothesis, freeze-thaw events appear to drive sap flow events during winter dormancy in nearly all study species, despite differences in the timing of their maximum sap yield. This suggests that stem pressure may be a stronger driver of sap yield than sap flow--a hypothesis that will be tested this coming year. Goal #3. Assess consumer preferences and willingness to pay. To assess maple syrup producers' willingness to adopt production of novel tree syrups, we designed a choice experiment (CE) that elicits maple syrup producers' preferences and their willingness to adopt maple forest diversification. Our CE asked maple syrup producers to make choices over different diversification programs, characterized by seven attributes (e.g., diversification intensity, annual syrup yield reduction from competition, increased resilience, neighbor's adoption rates, equipment needs, contract length, and payment). Our preliminary findings from the pilot study indicate that diversity intensity, yield reduction, and contract length significantly influence producers' preferences. We identify a nonlinear preference for diversification intensity, with a favored range of 25% to 50% non-maple species. This aligns with ecological studies indicating a non-linear link between biodiversity and ecosystem functionality, due to diminishing marginal benefits of diversity in ecological systems shaped by complex interspecies interactions. Our findings on contract length diverge from the existing literature on annual systems, as we found that producers prefer a 15-year contract but are less likely to enroll in a 10-year contract, suggesting that for perennial systems, forest diversification is characterized by longer-term planning and slower maturation of environmental benefits. To assess maple syrup producers' willingness to adopt production of novel tree syrups, we designed a choice experiment for maple syrup producers that elicits maple syrup producers' preferences and their willingness to adopt maple forest diversification. We conducted a pretest with 144 participants at the 2023 North American Maple Conference: Quality from Tree to Table. Our preliminary findings from the pilot study indicate that diversity intensity, yield reduction, and contract length significantly influence producers' preferences. Combined, these accomplishments during the 2023 reporting cycling have advanced our understanding of the drivers of sap flow and the potential for syrup production from seven non-maple tree species, as well as the potential for developing economically viable markets for diverse tree syrups based on consumer preferences and willingness to pay. This information will help inform decision making and management approaches by producers interested in expanding their syrup production systems to enhance their future sustainability, climate resilience, and profitability.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Moore, D.B., M.A. Vadeboncoeur, J. Gutierrez Lopez, T. Frost, and H. Asbjornsen. 2023. Modeling Winter-Dormant-Season Sap Flow in Deciduous, Woody Angiosperms in New England. 12th International Workshop on Sap Flow. Nov. 3, 2023. Rotorua, New Zealand.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Moore, D.B., M.A. Vadeboncoeur, J. Gutierrez Lopez, T. Frost, J. Ehmett, and H. Asbjornsen. 2023. Sap Flow, Stem Pressure, and Sap Yield: Using Tree Physiology Data to Draw Conclusions About Syrup Production. 2023 International Maple Syrup Conference. Oct. 27, 2023. Sturbridge, MA.
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Progress 01/01/22 to 12/31/22
Outputs
Target Audience:The target audience for this project includes diverse stakeholdersthroughout the northeast region who are interested in the syrup industry, including syrup producers, woodland owners, and farmers, as well as consumers and the general public. Given the important cultural, ecological, economic, and historical importance of thesyrup industry in New England, this project has the potential to attract braod interest in the region. Changes/Problems:The biggest challenge faced with Goal #2 in 2022 was that the datalogger script not working properly - we were not able to collect and data on sap flow, wood temperature, wood water content, or stem pressure. This problem was fixed and data is currently being collected (we had a second field season as part of the project), so we will ultimately end up with plenty of data to analyze. These data are being collected to determine what drives sap flow and sap pressurization (and thus sap yield) during winter dormancy. For Goal #3, due to Covid-19, the study was modify to a lab-based experiment. It was very challenging to meet the Covid-19 guidelines, requiring volunteers to help with the process. To make sure we were controlling for Covid-19 related taste impairments,we also included a separate question in our survey regarding the taste buds. Giventhese challenges, we are currently considering the possibility of conducting a follow up field-based consumer survey during the third project year that would include more diverse consumers and tree syrups, as well as new information about the health and ecosystem service benefits of diversified sugarbushes, which we anticipate becoming available after the upcoming second project year. What opportunities for training and professional development has the project provided?This project partially supported Mr. Muhammad Jawad Khan to complete his PhD dissertation at UNH focused on understanding consumer willingness to pay for diversified tree syrups.The research results were shared among the public through, seminars, and conference publications. This project is currently providing partial support for Mr. David Moore to conduct his PhD dissertation research on the plant biological, physiological, and phytochemical aspects of syrup production from diverse tree species. Three undergraduate research assistantslearned how to construct sap-flow sensors and the theory behind how sap-flow sensors work. Graduate student Tanner Frost received training in tree climbing, which allowed him to provide invaluable assistance with intalling the sap flow sensors in the tree canopies forthisproject. Mr. Frost has also providing training to two other graduate students in our lab in tree climbing techniques and safety measures. Graduate studentDavid Moore learned how to operate the two NMR spectrometers owned by the University of New Hampshire's Instrumentation Center, and he also audited a spectroscopy course (CHEM 808 - Spectroscopic Investigations of Organic Molecules) at UNH during the fall 2022 semester as well. This skills enabled him to conduct the phytochemical analysis of his tree syrups. How have the results been disseminated to communities of interest?Four of the syrups produced as part of this project (maple, birch, beech, and sycamore) were featured in the University of New Hampshire's 'Taste of COLSA' event on Oct. 7th, 2022, which served as an outreach opportunity to teach students, faculty, and the public about the potential for producing syrup from non-maple tree species. Graduate student David Moore gave a tour of an AFRI study site to a high-school FFA group (led by their teacher, Audra Leach) from Housatonic Valley Regional High School on Mar. 27th, 2022. Graduate student David Moorespoke with about half a dozen syrup producers informally about producing syrup from different tree species other than sugar maple. Graduate student Moore presented his research resultson how to harvest sap and produce syrup from trees other than maples at the New England Society of American Foresters annual meeting in Portland, ME on Mar. 24th, 2022. He also gave a presentation onhis sap-flow modeling techniques at a departmental seminar on Apr. 26th, 2022. The results from our study on consumer willingness to pay for tree syrupsderived from diversified forests were presented atthree different conferences (see details above). These conferences included people from academia, industry, students, and other researchers. What do you plan to do during the next reporting period to accomplish the goals?Goal #1: We are currently collecting (and will later analyze) sap flow, stem pressure, wood temperature, and wood water content data (as well as environmental data) to determine the factors that drivesap flow and sap pressurization during winter dormancy. Wood temperature and stem pressure are being monitored at three heights in each study tree (in the root flare, at breast height, and in the canopy), and sap flow and wood water content are being monitored at breast height only. Goal #2: We plan to analyze all of the sap and syrup samples produced from this study thus far using both gas chromatography and liquid chromatography for their phytochemical properties. We will corroborate these data with the data we have already produced from NMR spectroscopy during the first project year. Goal #3: We will draft a choice experiment (CE) survey to be deployed with syrup producers. We will conduct two focus groups of syrup producers, one in New Hampshire and one in Illinois, to identify the major determinants of producer's potential decision to adopt novel syrups. We will use a shortlist of these adoption determinants to define the attributes and the attribute levels to be used in a survey-based choice experiment (CE). In addition to identifying the attributes, we will ask the focus group participants to help review a draft survey questionnaire aimed at understanding producers' preferences regarding syrup diversification. The survey will elicit information in four areas: (1)forestcharacteristics, (2) choice experiment, (3) attitudes, beliefs, and cultural values, and (4) individual socio-economic information. The CE will consist of asking respondents to choose among hypothetical choice options described in terms of their attributes and a given cost of adoption. The attributes, to be confirmed in the focus groups, are likely to include the specific technology adoption method (e.g., species, syrup yield, syrup extraction technology; Obj. #1), changes in ecosystem service outcomes as a result of adoption (e.g., increases in biodiversity, carbon storage, sawtimber; Obj. #4), whether neighbors are adopters, and a given adoption cost or subsidy (Obj. #1).
Impacts
What was accomplished under these goals?
Objective #1: Due to technical problems, work related to this Objective was deferred to the second project year (see details provided below). Objective #2: We performed nuclear magnetic resonance (NMR) spectroscopy on sap and syrup samples from sugar maple (Acer saccharum), paper birch (Betula papyrifera), American beech (Fagus grandifolia), American sycamore (Platanus occidentalis), alder (Alnus spp.), American basswood (Tilia americana), and American hophornbeam (Ostrya virginiana). Although the sugar in sap and syrup from sugar maple is primarily sucrose, the sugar in all the other 6 species is primarily fructose and glucose. Refractive index and pH data were measured for all sap and syrup samples as well. Preliminary results are currently being analyzed and compiled into a manuscript and outreach materials. Objective #3: We completed initial data collection and analysis of consumer willingness to pay for different tree syrups relative to syrups produced from sugar maple. This analysis included an assessment of information on the benefits of diversified forests affects willingness to pay. The results indicate that consumer preferences might support the future diversification of maple forests, especially if labeling can successfully deliver the information on the ecological benefits of forest diversification. Objective #4: Work on this project component has not been started yet, as we first need the results from Objectives #1-3.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Moore, D., T. Frost, M. Vadeboncoeur, and H. Asbjornsen. 2022. Harvesting Sap and Producing Syrup From Trees Other Than Maples. New England Society of American Foresters annual meeting. Portland, ME.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Moore, D., and J. Gutierrez Lopez. 2022. Using an n = 1 Hermite Function to Model the Relationship Between Sugar Maple Winter-Dormant-Season Sap Flow and Wood Temperature. University of New Hampshire Department of Natural Resources and the Environment Seminar Series. Durham, NH.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Khan, M.J., S. Atallah, M.H. Kalaitzandonakes, B. Ellison. 2022. Consumer willingness to pay for tree syrups derived from diversified forests. Agricultural & Applied Economic Association (AAEA) Annual Meeting, Anaheim, CA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Khan, M.J., S. Atallah, M.H. Kalaitzandonakes, B. Ellison. 2022. Consumer willingness to pay for products derived from diversified forests: the case of tree syrups. Northeast Agricultural and Resource Economics Association (NAREA), Mystic, CT.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Khan, M.J., S. Atallah, M.H. Kalaitzandonakes, B. Ellison. 2022. Consumer willingness to pay for products derived from diversified forests: the case of tree syrups. Heartland Workshop, Urbana IL.
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