Vegetation Change in a Former Chestnut Stand on the Cumberland Plateau of Tennessee during an 80-year Period (1921-2000)

Castanea, Jun 2004 by Myers, Brenda R, Walck, Jeffrey L, Blum, Kurt E

ABSTRACT

A former chestnut stand on the Cumberland Plateau of Tennessee was sampled in 1952/53, 1979, and 2000. The site was clear-cut in 1921/22, and has remained unburnt and relatively undisturbed. Chestnut stumps are present, but sprouts are not. Liriodendron tulipifera remained important in the canopy since 1952/53. Acer rubrum and A. saccharum increased in the canopy, but only A. rubruin did so in the subcanopy. Quercus rubra/velutina increased in the canopy, and decreased in the subcanopy. Shade-intolerant (Juglans nigra, Liquidambar styraciflua, Ulmus rubra, Fraxinus americana) and shade-tolerant (Tilia americana, Aesculus flava) species declined, perhaps due to absence of large-scale disturbance needed for regeneration. Juglans cinerea and Cornus florida were impacted by fungal pathogens. Although J. cinerea was an important replacement species, no individuals are currently present. Cornus florida is present in the canopy, but not in the subcanopy. Lindera benzoin and Viburnum acerifolium increased, apparently in response to C. florida's decline.

INTRODUCTION

The American chestnut [Castanea dentata (Marsh.) Borkh.] was once a dominant (or codominant) species in forest communities of eastern North America. The natural range of the American chestnut extended from Maine to Michigan and south to Mississippi and Georgia, encompassing over approximately 80 million ha. The species accounted for about 25%, and in some instances 40%, of the standing timber in some stands of the eastern deciduous forest (Keever 1953, Kuhlman 1978, Russell 1987). These rapidly growing trees could attain a height of 37 m and a diameter of 2 m (Woods and Shanks 1959). American chestnut trees had long, straight, branch-free boles up to 15 m in length. The characteristics of the bole and the decay resistance of the wood, attributed to high tannin levels, made the species a valuable timber tree used for various construction purposes. The tannin extracted from the bark and wood was important in the leather industry. The fruit of the tree had a fine, sweet flavor, making it a highly prized item for both humans and wildlife. Moreover, the fruit was a much-needed cash crop for many Appalachian families (Beattie and Diller 1954; Rice et al. 1980; Anagnostakis 1987, 1995).

In 1904, a fungus [Cryphonectria parasitica (Murr.) Barr] was discovered on American chestnut trees in the New York Zoological Garden by forester Herman Merkel. The fungus had entered the United States on an Asian species of chestnut (Castanea crenata Sieb. & Zucc.), which was imported in an attempt to crossbreed and improve the quality of the native chestnut (Anagnostakis 1987, 1995). The folly of this endeavor was soon realized as the fungus rapidly spread. Foresters tried to control the fungus by pruning, cutting, and spraying, but all attempts failed. Within half a century the chestnut had virtually disappeared from the eastern deciduous forest (Beattie and Diller 1954, Anagnostakis 1987). Today, remnants of the American chestnut can be found as understory sprouts. Occasionally, a large specimen may be observed, but it rarely survives to the fruiting stage, virtually eliminating sexual reproduction from populations (Paillet 1993). The sprouts usually become infected before attaining a dbh (diameter at breast height) of 15 cm (Jaynes and Elliston 1982).

The introduction of C. parasitica changed the composition and structure of the eastern deciduous forest dramatically as other species of trees replaced chestnut in areas once dominated (or co-dominated) by this tree. The recovery of forests following the removal of chestnut has been examined in several physiographic provinces (sensu Fenneman 1938): Blue Ridge (Aughanbaugh 1935; Keever 1953; Nelson 1955; Woods and Shank 1957, 1959; Day and Monk 1974; Karban 1978; Johnson and Ware 1982; Busing 1989), Ridge and Valley (Korstian and Stickel 1927; Aughanbaugh 1935; Thor and Summers 1971; Skeen 1973; Stephenson 1974, 1986; Shugart and West 1977; McCormick and Platt 1980; Agrawal and Stephenson 1995), Allegheny Plateaus (Aughanbaugh 1935, Mackey and Sivec 1973), and New England (Korstian and Stickel 1927, Good 1968). The majority of these studies have focused on forests that were mapped in the oakchestnut region of Braun (1950). However, American chestnut also was an important member in some association segregates (communities) of the mixed mesophytic forest. On the Cumberland Plateau of the Appalachian Plateaus Province, the species was more prominent in the gorges than the upland (Aughanbaugh 1935, Braun 1950, Caplenor 1965, Hinkle 1989, Hinkle et al. 1993).

The forests in the gorges of the Cumberland Plateau and elsewhere have been subjected to several other impacts since the chestnut blight, e.g., dogwood anthracnose, butternut canker, and oak decline (Hoffard et al. 1997). Cornus florida has suffered due to the introduction of a fungus: Discula destructiva Redlin, the cause of dogwood anthracnose (Daughtrey and Hibben 1994). juglans cinerea is being killed throughout its range by butternut canker, caused by the introduced fungus Sirococcus clavigignenti-juglandacearum Nair, Kostichka & Kuntz (Ostry 1997, Furnier et al. 1999). Lastly, the decline oiQuercus spp. has been suggested to be caused by disease, drought, fire suppression, and/or differential herbivory (Abrams 1998, McDonald et al. 2002).