Succession and disturbance in an endangered red spruce−Fraser fir forest in the southern Appalachian Mountains, North Carolina, USA

Abstract

Red spruce−Fraser fir forests are geographically limited to high elevations in the Appalachian Mountains (USA) and are considered to be endangered in the USA. We investigated the successional status and radial growth patterns in the heavily disturbed red spruce Picea rubens Sarg. and Fraser fir Abies fraseri (Pursh) Poir. forest of Roan Mountain, Tennessee and North Carolina. This study elucidates the complexity of second-growth red spruce development after logging and disturbances by balsam woolly adelgid Adelges piceae Ratz. We documented precise temporal information of stand age, disturbance regimes, recruitment patterns, and the successional trajectory of the spruce−fir forest community. We used radial growth patterns of red spruce samples to detect the frequency and magnitude of disturbance. Red spruce was the oldest dominant canopy species, although Fraser fir had high recruitment rates over the past 80 yr. Changes in forest structure and species richness coincided with stand-wide disturbance events such as balsam woolly adelgid infestation and widespread early twentieth-century logging. The competitive advantage of Fraser fir over red spruce has resulted in an even-aged Fraser fir-dominant forest that occupies a relatively early stage of successional development. This study provides a 130 yr environmental history to assist land managers in the southern Appalachian Mountains as they develop long-term restoration plans for this unique ecosystem.

Habitat fragmentation influences genetic diversity and differentiation: Fine‐scale population structure ofCercis canadensis(eastern redbud)

“…Human disturbances in forest ecosystems include land conversion for agriculture and settlements (Foster et al, 1998; Weir & Ott, 1997), logging (Hayes, Moody, White, & Costanza, 2007; Pyle, 1984), and fragmentation by building infrastructure (Kwak et al, 1998). In the 1800s and 1900s, human disturbances greatly affected the forest area in the southern Appalachian region and altered the ecosystem by logging, forest clearing, and burning, thus creating poor soil conditions and erosion (McLaughlin, Andersen, Hanson, Tjoelker, & Roy, 1991; Pyle, 1984; Wear & Greis, 2002; White, Gevel, & Soulé, 2012). Despite anthropogenic disturbances and habitat fragmentation, many forest trees were able to maintain high genetic diversity at population levels (Brunet, Zalapa, & Guries, 2016; Chang et al, 1998; Hamrick & Godt, 1996; Hamrick, Godt, & Sherman‐Broyles, 1992; Marquardt & Epperson, 2004; Nybom, 2004; Petit & Hampe, 2006; Wang et al, 2014).…”

Late winter and early spring home range and habitat use of the endangered Carolina northern flying squirrel in western North Carolina

“…We concur with Weigl (2007) that many of the direct causal relationships between required habitat components and the presence of both CNFS and VNFS remain poorly elucidated. Accordingly, we believe the weight of evidence from this study and that of preceding research does suggest that both CNFS and VNFS foraging habitat use is linked to red spruce occurrence and abundance (Hackett 2002, Menzel et al 2006b, Ford et al 2007a, and that overall squirrel occurrence and occupancy are higher with an increasing red spruce component at the forest stand and landscape scales (Ford et al 2004, 2010, 2012, Menzel et al 2006a). …”

“…However, it has been well documented that the area dominated by red spruce, and presumably the area of mixed red spruce− northern hardwood forests, is greatly reduced relative to pre-European settlement and prior to forest exploitation (White et al 2012). Mast production from beechnuts and maple samaras in northern hardwood stands in some years is not dissimilar to caloric values reported from oak-dominated stands (Jensen et al 2012) that are capable of supporting the southern flying squirrel, a competitor of the CNFS.…”

“…Mast production from beechnuts and maple samaras in northern hardwood stands in some years is not dissimilar to caloric values reported from oak-dominated stands (Jensen et al 2012) that are capable of supporting the southern flying squirrel, a competitor of the CNFS. Therefore it would seem reasonable that efforts to promote and increase red spruce should benefit both subspecies of northern flying squirrels in the Appalachians (and possibly decrease suitability for southern flying squirrels) as well as potentially increase this vulnerable forest type's resilience to perturbations such as ongoing climate change (Nowacki et al 2010, White et al 2012. Few forest stands outside of the very highest elevations of the southern Appalachians (>1900 m) are devoid of any hardwood species at the local scale.…”

Tree-Ring Reconstruction of Bark Beetle Disturbances in the Picea schrenkiana Fisch. et Mey. Forests of Southeast Kazakhstan

“…A disturbance is inferred when the forward 5-or 10-year running mean of the series exceeds the backward 5-or 10-year running mean by a given percent; changes on the order of 50 to 200% are commonly used. More conservative rule sets (requiring greater growth increases) detect dramatic release events that result from overstory removal, and less conservative rule sets detect stand-thinning events in addition to severe events [48,49]. Both the lengths of the running means and the required proportional growth increase affect the dates that inferred disturbances are associated with, requiring passage of several years before surging growth exceeds previous trends.…”