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Federal Register / Vol. 86, No. 106 / Friday, June 4, 2021 / Proposed Rules
recognizable taxon and represents a distinct species. Tiehms buckwheat is a low-growing perennial herb, with blueish gray leaves and pale, yellow flowers that bloom from May to June and turn red with age. Seeds ripen in late-June through mid-July. Tiehms buckwheat is a narrow-ranging endemic known only from one population, comprising eight subpopulations, in the Rhyolite Ridge area of Silver Peak Range in Esmeralda County, Nevada. The single population of Tiehms buckwheat is restricted to approximately 10 acres 4
hectares across a 3-square-mile area, located entirely on public lands administered by the Bureau of Land Management BLM. The subpopulations are separated by a rural county unpaved road where subpopulations 1, 2, and 8 occur north of the road, and subpopulations 3, 4, 5, 6, and 7 occur south of the road. A 2019
survey estimated that the total Tiehms buckwheat population is 43,921
individual plants. Surveys have not detected additional populations of Tiehms buckwheat.
Tiehms buckwheat is a soil specialist specifically adapted to grow on its preferred soil type. The species is restricted to dry, open, relatively barren slopes with light-colored rocky clay soils derived from an uncommon formation of interbedded claystones, shales, tuffaceous sandstones, and limestones. Vegetation varies from pure stands of Tiehms buckwheat to sparse associations with a few other lowgrowing herbs and grass species. The abundance and diversity of arthropods insects, mites, and spiders observed in Tiehms buckwheat subpopulations is especially high 1,898 specimens from 12 orders, 70 families, and 129 species were found in 2020 for a plant community dominated by a single plant species. Primary pollinator visitors to Tiehms buckwheat include wasps, beetles, and flies. Tiehms buckwheat benefits from pollinator services and needs pollination to increase seed production.
Threats The naturally occurring Tiehms buckwheat population represented by one population with eight subpopulations and a seedling transplant experiment suffered detrimental herbivory in 2020. All of the naturally occurring subpopulations experienced greater than 50 percent damage or loss of individual plants, while almost all transplants were lost to rodent herbivores in a 2-week period.
An environmental DNA analysis i.e., trace DNA found in soil, water, food items, or other substrates with which an
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organism has interacted conducted on damaged Tiehms buckwheat roots, nearby soils, and rodent scat strongly linked small mammal herbivory to the widespread damage and loss of the naturally occurring Tiehms buckwheat population. This was the first time herbivory was documented on the species, although, prior to 2019, surveys of the population were infrequent. The significance of herbivory in the naturally occurring population depends not only on its frequency and intensity, but whether damaged plants can recover and survive, as we are uncertain if the species will be able to recover from this damage and loss. Rodent herbivore pressure precluded seedling survival in experimental plots. Further studies and monitoring need to be conducted to determine if management to reduce rodent herbivory is necessary to maintain Tiehms buckwheat individuals and subpopulations, or if it was just a random catastrophic event that is not likely to occur on a regular basis.
The specialized soils on which Tiehms buckwheat occurs are high in lithium and boron, making this location of high interest for mineral development. In May 2020, Ioneer USA
Corporation Ioneer submitted a plan of operations to BLM for the proposed Rhyolite Ridge Lithium-Boron project.
The proposed project is awaiting BLM
permitting and approval for mineral development in the areas where the Tiehms buckwheat population occurs.
Ioneers proposed Rhyolite Ridge Lithium-Boron project, if permitted by BLM, would result in the loss of habitat and subpopulations 4, 5, 6, and 7, even with the voluntary protection measures included in Ioneers s project proposal.
The potential impact from the proposed project, combined with the loss resulting from the recent herbivory event, would reduce the total Tiehms buckwheat population by 70 to 88
percent, or from 43,921 individuals to roughly 5,2898,696 individuals. The number of individuals estimated to survive is a range because we do not know yet if the plants damaged from herbivory will be able to recover and survive. The low end of this range is based on permanent loss of damaged plants, while the high end represents conditions if all the herbivore-damaged plants recover. Dust deposition, generated from increased vehicle traffic associated with mine operations, may also negatively affect the overall health and physiological processes of the subpopulations remaining 1, 2, 3, and 8 after full implementation of the project.

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Ioneer is proposing to salvage all remaining plants in subpopulations 4, 5, 6, and 7 by transplanting them to another location. However, we are uncertain whether the salvage operation will succeed because current research indicates that Tiehms buckwheat is a soil specialist, that adjacent unoccupied sites are not suitable for all early lifehistory stages, and there has been no testing and multiyear monitoring on the feasibility of successfully transplanting the species. The impact to Tiehms buckwheat from mining, salvage operations, or both would be permanent and irreversible under the proposed project because the plants and the land on which they are currently growing, including any existing seed bank in the soil, would be completely removed, and in place of that site there would be a terminal quarry lake. The terminal quarry lake would develop when the mining operation ceased pumping out the anticipated groundwater that would infiltrate the quarry. Elimination of these subpopulations may remove corridors for pollinator movement, seed dispersal, and population expansion.
There is strong evidence that subpopulation 6 is the most resilient of the eight Tiehms buckwheat subpopulations. This subpopulation contains multiple life stages of individual plants, including the majority of older and larger plants across all populations. In addition, subpopulation 6 has the most variety in size classes of individual plants, indicating it is likely experiencing the most recruitment. Loss of subpopulation 6, in particular, may have an immense impact on the overall resiliency and continued viability of the entire Tiehms buckwheat population.
In addition to the direct impacts from the physical removal of subpopulations as a result of the project, road development and vehicle traffic associated with the proposed mine, as well as livestock grazing which currently occurs within the Tiehms buckwheat population as part of the BLMs Silver Peak allotment, may create conditions that further favor the establishment of nonnative invasive species within Tiehms buckwheat habitat. Mineral exploration has already impacted Tiehms buckwheat habitat by contributing to the spread of saltlover Halogeton glomeratus, a nonnative invasive plant species, within all subpopulations of the species. Mineral exploration activities can result in disturbance to natural soil conditions that support Tiehms buckwheat and encourage spread of saltlover, which alters the substrate by making the soil
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