Table Mountain Pine

The importance of Table Mountain pine lies in its ecological, not economic, value: increasing landscape diversity, protecting areas prone to erosion, and providing food and cover to a number of wildlife species (Gray 2001). Table Mountain pine plays a critical role in the regeneration of mountain forests after major fire occurrences (Zobel 1969; Williams and Johnson 1990; Armbrister 2002). Deterioration of xerophytic Table Mountain pine and mixed pine-oak stands has prompted concern about their continued survival in the central Appalachian Mountains. Fire ecologists and forest researchers predict that fire-intolerant species will eventually dominate traditional pine sites unless fire is restored to these ecosystems (Farrar 1998, Brose et al. 2001).

Table Mountain pine was historically prevalent on the xeric ridgetops and on south to southwest facing slopes of the Appalachian Mountains. This species does not maintain a continuous distribution, but occurs in isolated, high elevation stands (Sanders 1992) from Pennsylvania to Georgia (Zobel 1969). Table Mountain pine is a fire-adapted species, dependent on repeated fires to open serotinous cones for seed dispersal, prepare seed beds, increase sunlight reaching the forest floor, and eliminate hardwood

competitors. Like other fire-dependent pines, Table Mountain pine evolved during periods of frequent lightning-ignited fires. Before the arrival of humans in the

Appalachian Mountains, these fires would have been the only disturbance with enough frequency and intensity to influence the evolution and distribution of pines (Keeley and Zedler 1998).

For several thousand years, Table Mountain pine had benefited from Native Americans who augmented the natural fire regime until Euro-American settlement in the

18th century. Euro-American fires of the late 19th and early 20th centuries helped maintain populations of Table Mountain pine, but these fires were more destructive and eventually led to policies of fire suppression. The abundance and distribution of living pines and fire-tolerant hardwoods, as well as remnant fire-scarred materials, indicate that fire was a frequently occurring disturbance and primary influence on vegetation before the 1930s. In the past, fire acted as a natural disturbance process that altered successional dynamics, but after several decades of fire suppression, ridgetop pine communities of the central Appalachian Mountains are entering the later seral stages of forest succession and are disappearing (Waldrop et al. 2002). In 1996, the Southern Appalachian Assessment listed Table Mountain pine ecosystems as one of the 31 rare communities in the southern Appalachian Mountains (SAMAB 1996; Gray 2001). This is also the case in the central Appalachians where management agencies struggle to maintain Table Mountain pine-oak stands through the reintroduction of fire.

Understanding the complex relationships between climate, tree growth, and wildfire will further guide the management of Table Mountain pine. Knowledge of how Table Mountain pine responds to different climate variables is virtually nonexistent and therefore so is the ability to predict the response of this species to future changes in climate. Sutherland et al. (1995) conducted a limited climate analysis on Table Mountain pine in the central Appalachian Mountains and this is the only climatic research that involved Table Mountain pine to date. This research focused only on the relationship between fire years and climate, and not specifically on the influence of climate on tree growth. Later, Copenheaver et al. (2002) found that small-scale environmental variables, such as soils and land-use history, had more impact on vegetation distribution in Virginia

pine-pitch pine stands in Virginia than climate. It is possible that no association exists between climate and tree growth in Table Mountain pines because of the stronger influence of competition and topography on the stands.

Over the last 25 years, interest in the relationship between fire and Table Mountain pine has increased (Harmon 1982, Turrill 1998, Waldrop et al. 1999, Welch and Waldrop 2001, Waldrop et al., 2002, 2003; Brose et al. 2002, Lafon and Kutac 2003), but only a few studies have used dendrochronology to examine the age structure and fire regimes in mixed hardwood-Table Mountain pine stands (e.g., Sutherland et al. 1995, Armbrister 2002, Pfeffer 2005). A need exists to thoroughly and comprehensively evaluate the dendrochronological potential of Table Mountain pine as it gains increasing importance for understanding past successional trends and past fire regimes, especially in light of anticipated future changes in climate.

The purpose of this study is to evaluate the dendrochronological potential of Table Mountain pine for use in ongoing fire history studies, climate analyses, and studies of stand dynamics. Specific objectives include (1) determine the crossdating potential of Table Mountain pine; (2) develop tree-ring chronologies for Table Mountain pine; (3) determine when climate exerts the most influence on growth of Table Mountain pines; and (4) develop a model of Table Mountain pine tree growth using climatic variables to eventually gain a better understanding of fire-climate relationships within these stands.

3.3 Study Sites

The four research sites are located in the Ridge and Valley Province in the Appalachian Mountains, Jefferson National Forest, Virginia. The central Appalachian Mountains are characterized by a humid continental climate (Bailey 1978; Lafon et al. 2005). Soils of southern Appalachian pine forests are sandy-loam Ultisols and Inceptisols (Welch 1999). The geology of all sites is sandstone and shale. Deep, dendritic fissures created by water erosion have formed valleys and spurs on the ancient Appalachian tablelands (Hufford 2002) with distinct vegetation communities that vary with

topography and microclimate. Yellow pine stands cover the south-, west-, and southwest- facing sides of these spurs in narrow strips that alternate with hardwood-dominated areas in drainages and on north- and northwest-facing slopes (Lafon and Kutac 2003).

Sites on North Mountain (37º25’N, 80º10’W) are located on the northwest side of the mountain, which is located in Craig County, adjacent to Craig Creek Valley. Sites are between 670 and 760 m (2200 and 2500 ft) in elevation. North Mountain receives

approximately 83 cm (32.6 in) of precipitation annually (NOAA 2005). The northwest slope is heavily dissected by tributaries of Craig Creek, which create northwest-running ridges and breaks in the otherwise continuous vegetation. The understory on North

Mountain contains a thick cover of mountain laurel, blueberry, huckleberry, bear oak, and greenbrier. Understory trees included serviceberry, black gum, red maple, and hickory. Chestnut oak, black gum, Table Mountain pine, and to a much lesser extent Virginia pine, scarlet oak, black oak, northern red oak, and black locust, are present in the canopy.

Brush Mountain (37º19’N, 80º20’W) is located in Montgomery County adjacent to the Craig Creek Valley (Figure 2.1). The sites on Brush Mountain lie between 850 and

900 m (2800 and 2900 ft) in elevation. Brush Mountain receives approximately 86 cm (34 in) of precipitation annually (NOAA 2005). Samples were collected from the northern side of Brush Mountain, on the upper west- and southwest-facing slopes. The yellow pine stands on this mountain are fairly open with an understory sparsely populated with mountain laurel, serviceberry, black gum, red maple, white pine, and white oak. Table Mountain pine and chestnut oak, and to a lesser extent black gum, red maple, scarlet oak, Virginia pine, and black oak, are present in the canopy.

Griffith Knob (37º1’N, 81º13’W) is located between Little Walker and Brushy Mountains in Bland County, adjacent to Reed Creek Valley. The sites on Griffith Knob are located on the western face between 1100 and 1150 m (3600 and 3782 ft) in

elevation. Griffith Knob receives approximately 94 cm (37 in) of precipitation annually (NOAA 2005). Griffith Knob is very steep with continuous vegetation. Table Mountain pine dominates the overstory along with chestnut oak, scarlet oak, black gum, northern red oak, and white oak. The understory is dominated by blackgum, Virginia pine, Table Mountain pine, bear oak, and mountain laurel, with a thick cover of blueberry. This is the only site that has any significant yellow pine regeneration.

The Little Walker Mountain (37°03’N, 80°56’W) sites are located on the north face of the mountain, itself located in Bland County, adjacent to Little Walker Creek. Sites are between 800 and 920 m (2625–3018 ft) elevation. Annual precipitation is approximately 81.5 cm (32 in) (NOAA 2005). The understory on Little Walker Mountain contains numerous oak and American chestnut seedlings. The midstory is dominated by mountain laurel and striped maple, while Table Mountain pine and chestnut oak dominate

the canopy along with black gum, white pine, red maple, scarlet oak, and northern red oak.