Late Quaternary Vegetation of Central Appalachia and the New Jersey Coastal Plain

Abstract

Pollen and plant macrofossil studies at 11 sites in New Jersey, southern and eastern Pennsylvania, West Virginia, and Virginia, USA reveal the character of the stable vegetation of the unglaciated eastern United States while the Wisconsin ice sheet was still at its outer limit. Grass—dominated tundra with dwarf shrubs was present 60 km south of the ice front at Longswamp, Pennsylvania. Sedge tundra covered the higher mountains of central Appalachia. In southern Pennsylvania, New Jersey (including the Pine Barrens), and northern Virginia, Picea (black or white spruce) was common, with Betula glandulosa (dwarf birch) and tall herbs, especially Sanguisorba canadensis (burnet). This is interpreted as forest tundra. In North and South Carolina and in northwest Georgia, forests of Picea and Pinus banksiana (jack pine) were present, with few deciduous trees. No site is yet known where broad—leaved trees formed the predominant vegetation cover anywhere on the Coastal Plain or in the Florida peninsula. With climatic warming, dwarf birch and spruce expanded into the tundra in unglaciated Pennsylvania. At Crider's Pond in southern Pennsylvania a Picea/Betula glandulosa assemblage with tall herbs was present from 15 000 to 13 000 yr BP. The associated aquatic flora was species poor. About 13 000 yr BP Abies balsamea (fir), Pinus banksiana, and Alnus cf. rugosa (speckled alder) invaded, together with diverse tree and shrub species, an assemblage like the southern boreal forest today. Betula populifolia (grey birch) occurs in this assemblage at Longswamp; there the aquatic flora is species rich. The increase in species diversity is evidence of marked climatic warming about 13 000 yr BP in southern and eastern Pennsylvania. Picea rubens (red spruce) arrived at Crider's Pond shortly before 11 500 yr BP, followed soon after by Pinus strobus (white pine). At Tannersville in glaciated eastern Pennsylvania an invasion series Picea—Abies—Pinus banksiana—Betula papyrifera (paper birch)—Larix laricina (tamarack)—Pinus strobus—Betula populifolia—Pinus rigida (pitch pine) can be demonstrated between 13 000 and 9000 yr BP. The stable flora of the periglacial region was different from the pioneer flora of the deglaciated area and from the vegetation of the modern tundra. As the ice withdrew, Tsuga (hemlock) and other tree species for which there is little or no fossil record at the height of the glaciation appeared in large populations in central Appalachia and the northern coastal plain, from which they invaded the deglaciated region at different rates. Castanea (chestnut), a slow migrant, took 5000 yr to reach southern New England from central Appalachia. Persistent tundra made the higher mountains of central Appalachia an important phytogeographical barrier to tree migration until about 12 500 yr BP. It explains differences in forest history west and east of the mountains. Tamarack seems to have migrated eastward from a glacial refuge south of the Great Lakes region. The distinctive modern vegetation of the Pine Barrens was assembled aft...

Roadlog and site description for the 1989 Southeast Friends of the Pleistocene field excursion; surficial geology of the New River valley, southwest Virginia

“…indicates that the rock block slide and subsequent formation of a small sedimentary basin behind it occurred prior to Holocene time. This date does not correspond well with the pollen age obtained by comparison of the pollen profile at this site to the pollen profiles at Delcourt and Delcourt's (1986) dated Saltville site (middle to late Holocene), but does correlate well with the Potts Mountain Pond site (Watts, 1979). The assumption is thus made that local site differences may indeed mask regional vegetation patterns.…”

“…The following comments are paraphrased from Thompson's report: He found that both the surface and the basal samples were similar in overall compositon but had minor differences in minor taxa and in relative proportions. Since the basal sample included a very low abundance of pine pollen and completely lacked spruce and fir pollen, an age later than earliest Holocene is suggested because fir, spruce, and pine pollen are common in regional pollen spectra of late Wisconsin and earliest Holocene age (according to Craig, 1969;Maxwell and Davis, 1972;Watts, 1979;and Delcourt and Delcourt, 1986). At the nearest previously studied site (Potts Mountain Pond, Va.), spruce and fir disappear by approximately 9,000 yrs B.P.…”

Inferences about the origin of a field cricket hybrid zone from a mitochondrial DNA phylogeny

“…Pollen evidence suggests that when the Wisconsin glaciation was at its maximum, tundra vegetation extended considerably south of the glacial margin (Maxwell & Davis, 1972;Watts, 1979Watts, , 1983, and that spruce and pine forests (indicative of a climate that crickets would tolerate) did not return to New England until 12 000-10 000 years ago. Clearly the northern field cricket populations have been established since the glaciers retreated.…”

Distribution, historical development and ecophysiological attributes of oak species in the eastern United States

“…In contrast, Quercus species now represent a significant proportion of northern hardwoodconifer forests, and Q rubra in particular has developed prominence (Whitney and Davis, 1986;Crow, 1988). We studied the presettlement forest records and current forest composition and structure of 46 Q rubra forests along an edaphic gradient in northcentral Wisconsin to gain an understanding of their historical development and current and future ecological status (Nowacki et al, 1990 (Crow, 1988 (Day, 1953;Watts, 1980;Lorimer, 1985;Patterson and Sassaman, 1988;Abrams, 1992 (Keever, 1953) (tables II and III). In southwestern Virginia, Q rubra represented 69% importance in forests where C dentata formerly comprised up to 85% of the canopy (Stephenson, 1986 (Braun, 1950 Interestingly, the increase in P strobus was followed by a wave of Q rubra and Q velutina recruitment, suggesting possible facilitation of these red oaks by P strobus (cf Crow, 1988;Abrams, 1992 (fig 4; Abrams, 1986).…”

“…For (Horsley and Marquis, 1983;Crow, 1988;Steiner et al, 1993). It (Watts, 1980;Davis, 1985;Webb, 1988).…”