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Societal Impact Statement: Trees are an important part of many ecosystems. The Global Tree Assessment data can be used to focus conservation and restoration efforts for the circa 30% of tree species that are threatened worldwide. The conservation status for the tree flora of Limahuli Valley on Kaua'i Island and a restoration plan for 11 endangered tree species is evaluated in the Global Tree Assessment framework. Lessons learned from Limahuli Valley, one of the most biodiverse valleys in the Hawaiian Islands, provide recommendations for developing long-term sustainable restoration projects. Summary: Based on conservation status assessments of the world's circa 60,000 trees, the Global Tree Assessment (GTA) report revealed that 30% (17,500) of known tree species are currently at risk of extinction. This study aims to evaluate the conservation status for the tree flora of Limahuli Valley and a restoration plan for 11 endangered tree species, in the Global Tree Assessment framework. Of the 117 tree taxa found in Limahuli Valley, 83 (71%) have been assessed for the International Union for the Conservation of Nature (IUCN) Red List and 90% of the assessed tree taxa are threatened. However, only 19 (21%) of these are federally listed and nine tree taxa were not found under their current name or at all in the GlobalTree Portal, suggesting a need for additional curation as well as a conservation status assessment gap. Progress has been made in Limahuli Valley on most restoration goals suggested by the GTA framework, but challenges remain related to both access to material for restoration, mitigation of threats, and understanding correlates of survivorship. Furthermore, trees only constitute about 40% of the flora in Limahuli Valley, and it is important to also consider nontrees including ferns and allies to strive for restoration of an ecosystem as well as the targeted species.

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mayfield, K. K., Eisenhauer, A., Santiago Ramos, D. P., Higgins, J. A., Horner, T. J., Auro, M., Magna, T., Moosdorf, N., Charette, M. A., Gonneea, M. E., Brady, C. E., Komar, N., Peucker-Ehrenbrink, B., & Paytan, A. Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba. Nature Communications, 12(1), (2021): 148-020-20248-3, doi:10.1038/s41467-020-20248-3., Groundwater-derived solute fluxes to the ocean have long been assumed static and subordinate to riverine fluxes, if not neglected entirely, in marine isotope budgets. Here we present concentration and isotope data for Li, Mg, Ca, Sr, and Ba in coastal groundwaters to constrain the importance of groundwater discharge in mediating the magnitude and isotopic composition of terrestrially derived solute fluxes to the ocean. Data were extrapolated globally using three independent volumetric estimates of groundwater discharge to coastal waters, from which we estimate that groundwater-derived solute fluxes represent, at a minimum, 5% of riverine fluxes for Li, Mg, Ca, Sr, and Ba. The isotopic compositions of the groundwater-derived Mg, Ca, and Sr fluxes are distinct from global riverine averages, while Li and Ba fluxes are isotopically indistinguishable from rivers. These differences reflect a strong dependence on coastal lithology that should be considered a priority for parameterization in Earth-system models., We thank A. Beck, H. Dulai, I. Santos, C. Benitez-Nelson, W. Moore, A. Martin, and H. Windom for sample access. We also thank A. Kolevica, A. Heuser, H. Pryer, J. Middleton, R. Franks, F. Lon, N. Slater, and O. Šebek for their laboratory and analytical assistance. This material is based upon research supported by the National Science Foundation Graduate Research Fellowship Program and an internship provided through the U.S. Geological Survey Graduate Research Internship Program (GRIP). This research was also supported by grants from: the German Academic Exchange Service (DAAD), Northern California chapter of the Achievement Rewards for College Scientists Foundation, International Association of GeoChemistry, Geological Society of America, Northern California Geological Society, Myers Trust, Friends of Long Marine Lab, and UC MEXUS (to K.K.M.). We acknowledge funding from EU-ITN Horizon project 643084 (to A.E. and T.M.) and NSF grant Award Number 1259440 (to A.P.). We also acknowledge funding from NSF grant award number OCE-1736949 (to T.J.H.). Any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.