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Federal Register / Vol. 86, No. 166 / Tuesday, August 31, 2021 / Rules and Regulations 12 different mountain ranges in southern Arizona and northern Mexico.
Although this may imply some level of redundancy across the range of Bartrams stonecrop, 43 of the 50 extant populations contain fewer than 150 total individual plants. Further, 29
populations have 50 individuals or fewer, and 3 populations have been extirpated over recent approximately 10 years. Given the distance of the mountain ranges with Bartrams stonecrop populations from each other, natural gene exchange or reestablishment following extirpation of populations within a mountain range is unlikely. In addition, the Mule Mountains contain a large number of Bartrams stonecrop individuals, but are represented by a single population approximately 38 kilometers 23.6
miles away from the nearest population, making natural reestablishment of populations unlikely.

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Future Condition of Bartrams Stonecrop We used the best available information to forecast the future viability of Bartrams stonecrop.
Maintaining multiple resilient populations over time viability depends on moisture in the microenvironment maintained by shade from overstory vegetation, spring and winter precipitation, proximity to water, and vegetation litter. We expect all extant Bartrams stonecrop populations to experience changes to these habitat characteristics to varying degrees. In addition, direct impacts to Bartrams stonecrop through being dislodged, buried, or collected will continue to impact the species.
We note that, by using the SSA
framework to guide our analysis of the scientific information documented in the SSA report, we have not only analyzed individual effects on the species, but we have also analyzed their potential cumulative effects. We incorporate the cumulative effects into our SSA analysis when we characterize the current and future condition of the species. Our assessment of the current and future conditions encompasses and incorporates the threats individually and cumulatively. Our current and future condition assessment is iterative because it accumulates and evaluates the effects of all the factors that may be influencing the species, including threats and conservation efforts.
Because the SSA framework considers not just the presence of the factors, but to what degree they collectively influence risk to the entire species, our assessment integrates the cumulative
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effects of the factors and replaces a standalone cumulative effects analysis.
Acknowledging inherent uncertainties regarding the scope of the stressors manifesting and the species response, we forecasted future conditions of Bartrams stonecrop under four plausible future scenarios see chapter 6
of the SSA report; Service 2020a, pp.
104124. The scenarios span a range of potential stressors that are occurring or will occur in the future that will influence the future status of the species and the effects of those stressors on the species. We analyzed future projections in 10-year and 40-year timeframes because this is within the range of predictions of available hydrological and climate change model forecasts and is within the period of the Rosemont Mine effects. Forty years represents eight generations of Bartrams stonecrop, which allows us to assess reproductive effects on the species and allows populations to have opportunities to rebound. The 10-year time step also represents a reasonable timeframe to judge the species shortterm vulnerability to stressors at the current level, without projecting changes to stressors that longer timeframes would provide. Thus, the future scenarios forecast the viability of Bartrams stonecrop over the next 40
years. The following stressors were considered at different levels of impact for each scenario:
Mining activitywater extraction, excavation, burial, shade reduction;
Altered fire regimelightning, recreation, cross-border human activity, nonnative plants;
Climate effects waterreduction in available water including precipitation, soil moisture, humidity, surface water, aquifer recharge, reduction in riparian vegetation, increased number of days without water;
Climate effects otherdislodging from flooding events, seedling desiccation, flowering halt, shade removed; and Effects to individual plants applied to populations with fewer than 50
individualsrecreation, collection, trampling, livestock or wildlife grazing and herbivory.
The levels of stressors assessed in each scenario are described in greater detail in chapter 6 of the SSA report Service 2020a, pp. 104124.
The first scenario continuation evaluates the condition of Bartrams stonecrop if impacts from drought, climate change, and other stressors continue as in the near past, while the other scenarios evaluate the response of the species to changes in those risks.

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Scenario 1 is evaluated at the 10-year time step. The second scenario conservation assumes impacts from drought, climate change, and other stressors continue as in the near past and also takes into account realistically possible additional protective measures, which may or may not happen.
Scenarios 2, 3, and 4 are evaluated at the 40-year time step. The third scenario moderate effects assesses an increase in stressors to populations with changes in climate as projected in a lower RCP 4.5 emissions scenario along with increases in other stressors.
The final scenario major effects assesses a further increase in stressors to populations, with changes in climate projected at a higher RCP 8.5
emissions scenario, and with additional increases in other stressors. These scenarios are described in more detail in chapter 6 of the SSA report Service 2020a.
In scenario 1, we assess impacts to Bartrams stonecrop from drought, climate change, and other stressors that continue as in the near past. Based on climate change projections, emissions will continue at the same rate as the near past, resulting in continued impacts to the species. In this scenario, we expect the viability of Bartrams stonecrop to be characterized by a loss of resiliency, representation, and redundancy from the current levels. At the 10-year time step, no populations would exhibit high resiliency, 9
populations would exhibit moderate resiliency, 41 populations would exhibit low resiliency and be more susceptible to loss, and no additional populations would be extirpated.
In scenario 2, we assess impacts to Bartrams stonecrop from drought, climate change, and other stressors that continue as in scenario 1 but with conservation measures implemented that provide a benefit to the species e.g., nonnative control, forest thinning, and prevention of human-caused wildfire. Climate change impacts are projected to continue at the current rate, and no conservation measures address drying of habitat. In this scenario, we expect the viability of Bartrams stonecrop to be characterized by similar levels of representation and redundancy and slightly lower levels of resiliency than it exhibits under the current condition. Because current stressors remain in place, conservation measures improve the resiliency of populations, but this effect is overshadowed by the impact of continued climate change and drought at the current level.
The third scenario assesses moderate effects to Bartrams stonecrop with impacts to the species evaluated at the
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