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Federal Register / Vol. 86, No. 166 / Tuesday, August 31, 2021 / Rules and Regulations
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under changing environmental conditions. Using these principles, we identified the species ecological requirements for survival and reproduction at the individual, population, and species levels, and described the beneficial and risk factors influencing the species viability.
The SSA process can be categorized into three sequential stages. During the first stage, we evaluated the individual species life-history needs. The next stage involved an assessment of the historical and current condition of the species demographics and habitat characteristics, including an explanation of how the species arrived at its current condition. The final stage of the SSA involved making predictions about the species responses to positive and negative environmental and anthropogenic influences. This process used the best available information to characterize viability as the ability of a species to sustain populations in the wild over time. We use this information to inform our regulatory decision.
Summary of Biological Status and Threats In this discussion, we review the biological condition of the species and its resources, and the threats that influence the species current and future condition, in order to assess the species overall viability and the risks to that viability. Bartrams stonecrop occurs between elevations of 3,500 to 6,800 ft in Madrean woodlands with oaks, junipers, pines and species found in more mesic wet areas including sycamores, cottonwoods, and willows.
The species typically occurs on rocky outcrops in deep, narrow canyons in heavy cover of litter and shade; and typically within 10 meters m; 32.8 feet ft of flowing or intermittent water.
Bartrams stonecrop requires adequate precipitation to maintain soil moisture, cooler temperatures, and humidity in the microenvironment and for germination, growth and reproduction.
Based on microhabitats in which the species is typically found, species needs include crevices with or without soil for seeds to lodge and germinate, shade and deep leaf litter to help maintain soil moisture, and a humid microhabitat in this arid environment. In addition, the habitat must support sufficient Bartrams stonecrop pollinators e.g., flies, bees, and butterflies including plants for pollinator foraging and nesting within pollinator flight distance of Bartrams stonecrop populations. To maintain the species viability, populations with multiple subpopulations and overall high abundance must be distributed across
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the species range and represent a range of environmental conditions. These populations must experience recruitment that exceeds mortality.
Several stressors influence whether Bartrams stonecrop populations will grow to maximize habitat occupancy, which increases the resiliency of a population to stochastic events. We evaluated the past, current, and future stressors i.e., negative changes in the resources needed by Bartrams stonecrop that influence the viability of the species. We describe these stressors on viability in detail in chapter 4 of the SSA report Service 2020a, entire.
Stressors that have the potential to affect Bartrams stonecrops population resiliency include:
Loss of water in nearby drainages from climate change drought and mining;
Altered fire regime resulting from fires ignited by recreationists, crossborder human activity, and lightning and exacerbated by nonnative plants;
Altered precipitation, drought, flooding, and freezing regime from current and future climate change;
Erosion, sedimentation, and burial from mining, recreation trails and roads, cross-border human activity, and postwildfire runoff;
Trampling from humans, and trampling and herbivory from wildlife and livestock;
Illegal collection; and Small population size exacerbating all other stressors.
The largest risk to viability of the species is caused by the loss of habitat and includes: 1 Groundwater extraction and prolonged drought that reduce nearby water levels and humidity within Bartrams stonecrop habitat; and 2 altered fire regimes leading to erosion of Bartrams stonecrop habitat, sedimentation and burial of individuals by post-fire runoff, and loss of overstory shade trees. These stressors play a large role in the future viability of Bartrams stonecrop, especially for smaller populations.
These stressors are currently reducing and are expected to continue to reduce nearby water levels, shade, and humidity within Bartrams stonecrop habitat or directly impact individuals.
Loss of Water Dewatering of streams from mining operations may lead to overstory canopy losses and subsequent loss of shade, as well as reductions in spring and stream flow and humidity in nearby Bartrams stonecrop populations. The Rosemont Mine Final Environmental Impact Statement Statement notes that no Bartrams stonecrop individuals were
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found in the project area or the footprint of the associated actions; however, individuals growing in the analysis area could experience indirect impacts from groundwater drawdown USFS 2013a, p. 676. According to the Statement, the proposed mine pit would create a permanent drawdown of the water table, and groundwater would flow toward the pit and be lost to evaporation USFS
2013a, p. 339. The Bartrams stonecrop plants growing just southwest of the proposed Rosemont Mine were analyzed in the Rosemont Final Environmental Impact Statement USFS 2013a, pp.
346350. The predicted groundwater drawdown in the affected population at the end of active mining is 0.15 feet, depending on the site assessed and the model used. At 20 years from the mine closure, the predicted drawdown increases to a maximum of 1520 feet.
The water would be perpetually replenished in part by groundwater from the regional aquifer, and the pit would act as a hydraulic sink. Given that Bartrams stonecrop is consistently found in locations with nearby springs or other water sources, the loss of groundwater and changes in soil moisture and humidity are expected to negatively affect the plant. For example, loss of groundwater in the unmapped spring in Box Canyon/Sycamore Canyon confluence, between Ruelas Spring and the Singing Valley Road residences, could substantially impact Bartrams stonecrop plants growing nearby just southwest of the proposed Rosemont Mine.
Mining claims, trenching and exploration drilling activities, and a few active and proposed mines are present in Bartrams stonecrops range. Many currently undeveloped areas of locatable mineral deposits may be explored and/
or mined in the future. We do not know the full extent of future mine activity within the range of Bartrams stonecrop;
however, a number of proposed mines are identified for development within Bartrams stonecrop habitat. The range of current and projected mining activities varies from 1 to 10 per sky island mountain range with Bartrams stonecrop occurrences USFS 2012, entire. The loss or reduction of groundwater, stream flow, or spring flow in or near a Bartrams stonecrop population due to mining-related activities could lead to extirpation of that population.
Altered Fire Regime Wildfire frequency in western forests from the mid-1980s to the present has nearly quadrupled compared to 1970
1985. The timing, frequency, extent, and destructiveness of wildfires are
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