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Federal Register / Vol. 86, No. 155 / Monday, August 16, 2021 / Rules and Regulations
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2018, pers. comm.. Eight years after initial outplanting, the genetic variation in this population, which was established in 2005 from seven genetic lines, was approaching levels of genetic diversity comparable to the source population Philpott et al. 2014, entire.
The Missouri Botanical Garden MBG
has seeds in storage from BSF and PSP
that were collected in 1991, 1994, 2005, and 2014 Dell 2018, pers. comm..
Collections were made at multiple points in time to maintain seed viability in storage. While a cultivated source of plants is not currently maintained ex situ, the need for doing so is mitigated by the development of methods to micropropagate the species from cuttings and by availability of seeds in ex situ collections, providing two potential methods for propagating the species should it become necessary to do so.
Available data support the determination that Cumberland sandwort is not likely to become endangered in the foreseeable future due to limited distribution or small population sizes.
Effects of Climate Change Our analyses under the Act include consideration of ongoing and projected changes in climate. The terms climate and climate change are defined by the Intergovernmental Panel on Climate Change IPCC. The term climate change thus refers to a change in the mean or variability of one or more measures of climate e.g., temperature or precipitation that persists for an extended period, typically decades or longer, whether the change is due to natural variability, human activity, or both IPCC 2014, pp. 119120. A recent compilation of climate change and its effects is available from reports of the IPCC IPCC 2014, entire.
The IPCC concluded that evidence of warming of the climate system is unequivocal IPCC 2014, pp. 2, 40.
Numerous long-term climate changes have been observed including changes in arctic temperatures and ice, widespread changes in precipitation amounts, changes in ocean salinity, and aspects of extreme weather including heavy precipitation and heat waves IPCC 2014, pp. 4044. Since 1970, the average annual temperature across the Southeast has increased by about 2
degrees Fahrenheit F, with the greatest increases occurring during winter months. The geographic extent of areas in the Southeast region affected by moderate to severe spring and summer drought has increased over the past three decades by 12 and 14 percent, respectively Karl et al. 2009, p. 111.

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These trends are expected to increase.
Rates of warming are predicted to more than double in comparison to what the Southeast has experienced since 1975, with the greatest increases projected for summer months. Depending on the emissions scenario used for modeling change IPCC 2000, entire, average temperatures are expected to increase by 2.5 degrees Celsius C 4.5 F scenario B1 to 5 C 9 F scenario A2 by the 2080s Karl et al. 2009, p. 111. While there is considerable variability in rainfall predictions throughout the region, increases in evaporation of moisture from soils and loss of water by plants in response to warmer temperatures are expected to contribute to increased frequency, intensity, and duration of drought events Karl et al.
2009, p. 112.
We used the National Climate Change Viewer NCCV, a climate-visualization tool developed by the U.S. Geological Survey USGS, to generate future climate projections across the range of Cumberland sandwort. The NCCV is a web-based tool for visualizing projected changes in climate and water balance at watershed, State, and county scales USGS 2017. This tool uses air temperature and precipitation data from 30 downscaled climate models for two Representative Concentration Pathway RCP scenarios, RCP 4.5 and RCP 8.5, as input to a simple water-balance model to simulate changes in the surface water balance over historical and future time periods, providing insight into potential for climate-driven changes in water resources. To evaluate the maximum effects of climate change in the future, we used projections from RCP 8.5, which is the most aggressive emissions scenario wherein greenhouse gases GHGs rise unchecked through the end of the century, to characterize projected future changes in climate and water resources, averaged across the five counties encompassing the range of Cumberland sandwort. The projections estimate change in mean annual values, comparing the period 1981 through 2010 with 2050 through 2074, for maximum and minimum temperature, monthly precipitation and runoff, snowfall, soil water storage, and evaporative deficit.
Within the range of Cumberland sandwort, the NCCV projects that, under the more extreme RCP 8.5 scenario, maximum temperature will increase by 3.2 C 5.7 F, minimum temperature will increase by 3.1 C 5.6 F, precipitation will increase by 5.36 mm 0.2 in per month, soil water storage will decrease by 12.2 mm 0.5 in annually, and evaporative deficit will increase by 4.6 mm 0.2 in per month.

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Projected changes in snowfall are negligible. These estimates indicate that, despite projected minimal increases in annual precipitation, anticipated increases in maximum and minimum temperatures will offset those gains, leading to a net loss in projected runoff and soil water storage. The most notable change with respect to water balance between the two time periods is that soil storage projections are projected to be significantly reduced during the months of June through November for the period 2050 through 2074. Based on these projections, Cumberland sandwort will on average be exposed to increased temperatures across its range, which, despite limited increases in precipitation, are expected to decrease soil water available during the growing season.
Assessments of vulnerability of federally listed plants in Tennessee to projected climate change have been conducted by two different groups Glick et al. 2015, entire; Kwit 2018, pers. comm. using version 2.1 of NatureServes Climate Change Vulnerability Index CCVI Young et al.
2015, entire. The CCVI is an assessment tool that combines results of downscaled climate predictions, characterizing direct exposure to projected climate change, with readily available information about a species natural history, distribution, and landscape circumstances, which together influence sensitivity to change, to predict whether it will likely suffer a range contraction and/or population reductions due to the effects of climate change. For these assessments using the CCVI, climate change projections were based on ensemble climate predictions, representing a median of 16 major global circulation models and using a middle of the road scenario i.e., emission scenario A1B of the IPCC
IPCC 2000, entire for GHG emissions Young et al. 2015, p. 14 instead of the more extreme scenario that we used in the NCCV to project the climate and water balance changes reported above.
From these two assessments, Cumberland sandwort was ranked as either presumed stable Glick et al.
2015, p. 40 or moderately vulnerable Kwit 2018, pers. comm., the latter indicating the species abundance and/
or range extent within the geographical area assessed would likely decrease by 2050 Young et al. 2015, p. 45.
The disparate results between these two assessments conducted using the same tool illustrate that there is some subjectivity involved in evaluating aspects of a species biology and ecology as they relate to CCVI sensitivity factors used to model potential vulnerability to
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