Examining Sustainable Diets for Planetary Health: A Mixed Methods Study of Sustainable Diets Knowledge Creation, Reproduction, and Recommendations

Food systems are a vital component of planetary health, or the inextricably linked health of humans and the environment, with the capacity to both threaten and support all dimensions of sustainability. Sustainable diets are recognized as both a driver and outcome of a sustainable food system needed to support the well-being of people and the planet. Although attention to sustainable diets as both a lever for change and result of complex food system dynamics is growing both within academia and beyond, there have been limited efforts to comprehensively review and synthesize the evolution and current state of sustainable diets research. Similarly, few studies have systematically examined how and what kinds of sustainable diets research is created, reproduced, and recommended for future study and food systems change. This comprehensive understanding of sustainable diets knowledge is essential in determining whether and how this research acknowledges and accounts for the full suite of sustainability dimensions and broader food systems dynamics. It is critical in accurately and thoroughly assessing system trade-offs and designing just, effective strategies for a sustainable food system transformation. Without it, research and solutions run the risk of inhibiting and contradicting planetary health goals. This three article mixed methods dissertation aims to address these gaps in knowledge and analysis through a thematic scoping review, bibliometric and altmetric analysis, and content analysis. Each chapter in this dissertation builds layers of detail and depth to our understanding of sustainable diets research and its implications for future study and food systems change. The first chapter presents a thematic scoping review of sustainable diets literature. This chapter uses topic modeling, a natural language processing method, to identify research gaps, trends, and themes over time and across disciplines, and examines how these themes align with components of sustainable diets described by the Food and Agriculture Organization of the United Nations. Chapter 2 studies how the literature considered in the thematic scoping review is created and reproduced. Drawing from the mutual aims of science of science and research impact evaluation, it examines the practice of science through a citation and altmetric analysis and evaluation of whether and how research characteristics and indicators of power are linked with impact metrics. Chapter 3 takes a closer look at the objectives and recommendations of the most highly cited sustainable diets literature through a content analysis. It also reviews how the literature aligns with upstream and downstream food system influences as described by the Food Systems Dashboard’s Food Systems Framework to identify strengths and gaps in the research. The dissertation concludes with a summary of the findings and a critique of the ability of sustainable diets research to adequately address systems trade-offs necessary to designing solutions for a sustainable food system

Room to Grow: Agritourism Opportunities in Vermont Agriculture and Food System Plan: 2020 (Part One)

This analysis demonstrates that there is signficant unrealized potential to advance agritourism within the Vermont Agriculture and Food System Plan: 2020 (Part One)1 strategic plan and that applying an agritourism lens allows for the identification of a wide range of additional opportunities that can support Vermont farmers and agritourism goals. While agritourism is recognized in the report with a dedicated issue brief, this subsector of Vermont agriculture is otherwise largely overlooked in the other opportunities identified in Vermont’s strategic plan, particularly for the agritourism activities of hospitality, recreation, and entertainment. While direct-to-consumer sales, agricultural education, and farm diversification were referenced within the strategic plan’s opportunities, there is substantial room for increased attention to these activities as well. - 3/22 (14%) of the briefs explicitly mention agritourism activities within their respective opportunities sections (Apples, Dairy, and Direct Markets) - 18/22 (82%) of the briefs have the potential to incorporate agritourism, or could do so to a greater extent, according to our analysis - 6/157 (4%) of all opportunities across all briefs are explicitly related to agritourism, while 27/157 (17%) are implicitly related to agritourism (Table 1) - We identify 57 potential but overlooked agritourism opportunities across the report briefs and agritourism categories (Table 1) - Hospitality, recreation, and entertainment activities are absent from the opportunities (Table 1) - Farm diversification, recreation and agricultural education hold the greatest potential for future agritourism growth and investment (Table 1

Scoping review of sustainable diets research reveals a thematic and disciplinary emphasis on nutrition and environment

Sustainable diets have been identified as an important component of a food systems transformation that is urgently needed to meet global sustainability and development goals. This study addresses the lack of a comprehensive synthesis and overview of the sustainable diets literature, including its evolution over time and across disciplines, and sheds light on whether and how this body of work addresses dimensions of sustainability as defined by the Food and Agriculture Organization of the United Nation’s (FAO) sustainable diets framework. Topic modeling, a type of natural language processing, was used to perform a thematic scoping review of 855 articles published between 2000–2022 to identify trends and themes in a way that was rapid, transparent, reliable, and reproducible. This research finds demonstrated growth in the field of sustainable diets research, with the majority (66%) of sustainable diets articles considered in this study published in the last three years of the study period. Sixty-three percent of the sustainable diets research articles can be characterized by two topics, ‘sustainability impacts of dietary patterns’ and ‘sustainable diets and food system policy.’ FAO components of sustainable diets related to local and seasonal foods, culture, and equity receive relatively little research attention, whereas components of health, environment, and food security each align with approximately a third of the research literature. This is also reflected in the subject classification analysis, in which nearly half of the research (44%) was classified as Nutrition and Dietetics and/or Environmental Studies. This research highlights the need for more transdisciplinary research that addresses areas of equity, culture, social processes, and context as well as the intersections of sustainability dimensions to better understand the need for, implications, and directions of sustainable diets to support a sustainable food systems transformation

Leaf photosynthesis, respiration and stomatal conductance in six Eucalyptus species native to mesic and xeric environments growing in a common garden

Trees adapted to mesic and xeric habits may differ in a suite of physiological responses that affect leaf-level carbon balance, including the relationship between photosynthesis (A) and respiration at night (Rn). Understanding the factors that regulate physiological function in mesic and xeric species is critical for predicting changes in growth and distribution under changing climates. In this study, we examined the relationship between A and Rn, and leaf traits that may regulate A and Rn, in six Eucalyptus species native to mesic or xeric ecosystems, during two 24-h cycles in a common garden under high soil moisture. Peak A and Rn generally were higher in xeric compared with mesic species. Across species, A and Rn covaried, correlated with leaf mass per area, leaf N per unit area and daytime soluble sugar accumulation. A also covaried with g s, which accounted for 93 of the variation in A within species. These results suggest that A and Rn in these six Eucalyptus species were linked through leaf N and carbohydrates. Further, the relationship between A and Rn across species suggests that differences in this relationship between mesic and xeric Eucalyptus species in their native habitats may be largely driven by environmental factors rather than inter-specific genetic variation

Examination of pre-industrial and future [CO2] reveals the temperature-dependent CO2 sensitivity of light energy partitioning at PSII in eucalypts

We grew faster-growing Eucalyptus saligna Sm. and slower-growing Eucalyptus sideroxylon A. Cunn ex Woolls tree seedlings in sunlit glasshouses at all combinations of 290 µL L–1 (pre-industrial), 400 µL L–1 (modern) or 650 µL L–1 (future) global atmospheric CO2 ([CO2]), and ambient or ambient + 4°C temperature. To assess photosynthetic performance, we simultaneously measured light-saturated CO2 assimilation (Asat) and chlorophyll fluorescence emission along with the capacity for photosynthetic O2 evolution and leaf pigment composition. Photosynthetic response to [CO2] was similar between species. Increasing [CO2] but not temperature increased Asat. The response of photosynthetic electron transport to [CO2] was temperature-dependent and manifested through adjustments in energy partitioning at PSII. Increasing [CO2] resulted in greater PSII operating efficiencies at the elevated temperature. We observed no associated acclimatory adjustments in the capacity for photosynthetic O2 evolution or changes in leaf chlorophyll content. Photoprotective energy dissipation responded to increasing [CO2] and temperature. Across species and treatments, increased energy partitioning to electron transport was always associated with decreased partitioning to energy dissipation. Our results suggest that in response to increasing [CO2] and temperature, E. saligna and E. sideroxylon meet increased demands for the products of electron transport via adjustments in energy partitioning, not through acclimation of the capacity for photosynthetic electron transport or light absorption

Impact of eastern dwarf mistletoe (Arceuthobium pusillum) on host white spruce (Picea glauca) development, growth and performance across multiple scales

Infection by eastern dwarf mistletoe (Arceuthobium pusillum) modifies needle and branch morphology and hastens white spruce (Picea glauca) mortality. We examined potential causal mechanisms and assessed the impacts of infection-induced alterations to host development and performance across scales ranging from needle hormone contents to bole expansion. Needles on infected branches (IBs) possessed higher total cytokinin (CK) and lower abscisic acid contents than needles on uninfected branches (UBs). IBs exhibited greater xylem growth than same-aged UBs, which is consistent with the promotive effect of CKs on vascular differentiation and organ sink strength. Elevated CK content may also explain the dense secondary and tertiary branching observed at the site of infection, i.e. the formation of ‘witches’ brooms’ with significantly lower light capture efficiencies. Observed hormone perturbations were consistent with higher rates of transpiration, lower water use efficiencies (WUEs) and more negative needle carbon isotope ratios observed for IBs. Observed reductions in needle size allowed IBs to compensate for reduced hydraulic conductivity. Severe infections resulted in dramatically decreased diameter growth of the bole. It seems likely that the modifications to host hormone contents by eastern dwarf mistletoe infection led white spruce trees to dedicate a disproportionate fraction of their photoassimilate and other resources to self-shaded branches with low WUE. This would have decreased the potential for fixed carbon accumulation, generating a decline in the whole-tree resource pool. As mistletoe infections grew in size and the number of IBs increased, this burden was manifested as increasingly greater reductions in bole growth