Appendix 5
Reference Document 5-3
damage if temperatures drop again (Schaberg 1996) . Red spruce appears especially vulnerable to frost injury compared to other trees in the same forest, taking significantly longer durations to re-harden following a midwinter thaw (Strimbeck et al. 1995; Jordan 2018) . The Fraser fir appears flexible in its heat tolerance but is extremely limited in distribution and exhibits potentially weak competitive ability at lower elevations, as well as its high seedling mortality rate in exposed areas may prevent it from moving further upslope into new habitat (Berry et al. 2015; Johnson and Smith 2005; Jordan 2018) . Red spruce may be more capable of migrating farther north due to warming, as it is more successful in warmer habitats and is much more common than the Fraser fir. Within the Southern Spruce-Fir Forest, red spruce could displace Fraser fir as it moves upslope and the Fraser fir loses its competitive advantage, but hardwood tree species could also migrate upslope and potentially displace the conifer populations altogether (Beckage et al. 2008; Jordan 2018) . While many populations of Fraser fir are projected to recover well in higher- elevation sites in the southern Appalachians, population density at lower elevations suggests a high risk of local extinction from lower-lying areas (Kaylor et al. 2016) . It seems a possibility that, given sufficient warming, the Fraser fir and red spruce could be extirpated altogether from the southern Appalachian Mountains (Jordan 2018) .
Higher cloud ceilings and less snowpack
In the central and southern Appalachian Mountains, sites experience frequent cloud immersion, immersed in clouds for part of the day on ~70% of all days (Reinhard and Smith 2008; Berry and Smith 2012) . This cloud immersion is due to frequent fog from having a cloud ceiling (the height of the lowest layer of clouds) at the height of the mountain peaks and buffers temperatures during the growing season so that daytime temperatures in the area rarely exceed 72 °F (Corey et al. 2017) . These cloud conditions and cool temperatures improve plant water status, maintain high soil moisture, and contribute to foliar uptake from cloudwater (Berry et al. 2013, 2014, Berry and Smith 2014) . Fraser fir ( Abies fraseri ) is endemic to only seven high-elevation peaks in the SAM above 4920 ft and are adapted to these unique microclimatic conditions (Corey et al. 2017; NCWRC 2025) . Cloud ceilings in the SAM are predicted to rise, and as this occurs and temperatures continue to increase, this may further shift the timing of the growing season for Fraser fir (Richardson et al. 2003; Berry and Smith 2012) . Research is needed to better understand and project future changes in cloud base elevations and other microclimate conditions important to red spruce and Fraser fir (Medlock 2014) . Cloud ceilings play a crucial role in determining the type, intensity, and duration of snowfall. Lower cloud ceilings are generally more favorable for significant snowfall, while higher ceilings can limit precipitation amounts. However, even with evidence of rising cloud ceiling in the SAM, a recent study analyzing historical snowfall data in the southern Appalachians from 1910 to 2017 found no statistically significant trends throughout the region since 1910 (Eck et al. 2018) . Yet they observed that the majority of eastward-facing slopes experienced a general decline in snowfall over time (Eck et al. 2018) . A major caveat is that there are several complexities associated with the development and measuring of snow in montane environments (Eck et al. 2018) . Nonetheless, future winter snowpack in the Central Appalachians is projected to decrease
2025 NC Wildlife Action Plan
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