Showing papers in "Castanea in 1998"

A Flexible, Multipurpose Method for Recording Vegetation Composition and Structure

Abstract: We present a flexible protocol for recording vegetation composition and structure that is appropriate for diverse applications, is scale transgressive, yields data compatible with those from commonly used methods, and is applicable across a broad range of terrestrial vegetation. The protocol is intended to be flexible in the intensity of use and commitment of time, and sufficiently open in architecture as to be adaptable to unanticipated applications. The standard observation unit is a 10 x 10 m (0.01 ha) quadrat or "module." Where the extent of homogeneous vegetation is sufficient, multiple modules are combined to form a larger, more representative sample-unit. All vascular species are recorded by cover class and in intensively sampled modules as present or absent in sets of nested quadrats. For each module, tree stems are tallied by diameter class; species with exceptionally high or low stem density can be sub- or supersampled to allow efficient collection of data and assessment of population structure. The most common plot configuration consists of 10 modules arranged in a 2 x 5 array with four modules sampled intensively; this size is often necessary to capture the complexity of a forest community. For rapid reconnaissance or inventory purposes, fewer modules are typically employed, and less information is collected.

The Influence of Prehistoric Human-set Fires on Oak- Chestnut Forests in the Southern Appalachians

Abstract: Fossil pollen and charcoal in peat deposits and pond sediments from three sites in the southern Appalachians yielded evidence for a direct relationship between prehistoric Native American use of fire and increases in the importance of oak-chestnut forest between about 3,000 and 1,000 years ago. At Cliff Palace Pond on the Cumberland Plateau of southeastern Kentucky, Tuskegee Pond, in the Ridge and Valley of East Tennessee, and Horse Cove Bog in the Blue Ridge Mountains of western North Carolina, increases in fire frequency corresponded with the change in Native American activities from hunting and gathering in the Late Archaic cultural period toward more sedentary lifestyles and cultivation of native plants in the Woodland cultural period. Forests of oak and chestnut became dominant on upper slopes, with fire-adapted pines establishing on ridge tops and disturbance-adapted hardwoods invading abandoned Indian old fields. We speculate that prehistoric Native American use of fire would have been an intermediate-scale disturbance regime that would have heightened ecotonal contrast across plant community boundaries and would also have increased biological diversity across the landscape.

An Assessment of the Allelopathic Potential of the Invasive Weed Alliaria petiolata (Brassicaceae)

Abstract: Alliaria petiolata (M. Bieb.) Cavara & Grande (garlic mustard) is a non-indigenous member of the Brassicaceae that is invading woodlands throughout eastern North America. Previous work has demonstrated that this species is having a negative effect on the diversity of understory communities and is actively displacing native species. The purpose of this study was to evaluate the extent to which allelopathy might be acting as the mechanism of interference. Extracts of garlic mustard root and shoot tissues were applied to seeds and seedlings of four target species used as bioassays: radish, winter rye, hairy vetch, and lettuce. While seed germination rates varied by species and extract concentration, total germination after 5-7 d was largely unaffected by any extract concentration. Only radish seeds treated with the most concentrated root solution exhibited a depressed germination relative to the water control. Likewise, seedling biomass was generally unaffected by any extract treatment. Only shoot biomass for rye was significantly depressed with the highest concentration of leaf extract. Our data provide little evidence that allelopathy is involved in the invasive success or community interference of this non-indigenous species, even though the Brassicaceae are well known to possess potentially biologically active compounds with allelopathic effects.

Changes in Xeric Forests in Western Great Smoky Mountains National Park, 1936-1995

Abstract: Yellow pines (Pinus rigida, P. virginiana, P. echinata, and P. pungens) and oaks (Quercus spp.) dominate xeric slopes and ridges in western Great Smoky Mountains National Park (GSMNP). In the late nineteenth and early twentieth centuries, these sites burned frequently. Since about 1940, the Park Service has suppressed fire, prompting concerns over possible changes in forest composition and structure. This study documents changes in xeric forests using non-permanent plots sampled in 1936-37, permanent plots established in 1977-79, and a subset of those permanent plots resampled in 1995. Some permanent plots burned just prior to sampling in the 1970s, while others have not burned since before 1940. Between the 1930s and 1970s, canopy density, basal area, and canopy richness increased dramatically on fire-suppressed sites. W7hile high-intensity fires reduced canopy density and basal area to low levels, low-intensity fires did not significantly reduce canopy density or basal area relative to fire-suppressed sites. Between the 1970s and 1995, canopy density on fire-suppressed and low-intensity fire sites remained relatively stable, while that on sites of high-intensity fires increased rapidly. During this period, abundant regeneration of yellow pines occurred on some burned sites. On fire-suppressed sites, densities of Acer rubrum, Nyssa sylvatica, Pinus strobus and Tsuga canadensis have increased. Changes in the canopies of xeric forests since the onset of fire suppression may alter response to future fire events and complicate the restoration of historical composition and structure in these communities.

Forest Patch Size, Land Use, and Mesic Forest Herbs in the French Broad River Basin, North Carolina

Abstract: The effect of forest fragmentation on cove-forest herbs was studied in the Southern Blue Ridge Province. Patches of mesic forests were sampled with 4 ha study plots. The coverage and density of herb species were greater in large patches (>200 ha) than in small patches (<10 ha). Several ant-dispersed species, such as Disporum maculatum and Uvularia grandiflora, were more likely to be absent from small patches than from large patches. Wind-dispersed species, such as ferns and composites, were not affected by patch size and isolation. Small patches had reduced amounts of organic matter in the soil, suggesting that small patches have experienced more disturbance than large patches. Otherwise, there were no other differences in soil characteristics between patch sizes. Mechanisms hypothesized to have affected these populations include (a) disruption of population dynamics due to habitat fragmentation, (b) habitat degradation, and (c) anthropogenic disturbance via land use. Disturbances may have affected herb populations directly by increasing mortality rates and by degrading habitat. These habitat changes were confounded by the small size and isolation of small forest patches.

Vegetation of Linville Gorge Wilderness, North Carolina

Abstract: Species composition and vegetation-environment relationships are described for Linville Gorge Wilderness, a rugged landscape straddling the Blue Ridge escarpment of the southern Appalachian Mountains. A hierarchical classification is presented for 28 community types, which span eight broad vegetation classes. Vegetation classes associated with infertile conditions are most widespread. THERMIC OAK-PINE FORESTS dominate ridgelines and upper-slopes. ACIDIC COVE AND SLOPE FORESTS are prominent on sheltered, midand lower-slopes. MONTANE OAK FORESTS and RICH COVE AND SLOPE FORESTS are present, but are limited in distribution. The atypical concentrations of the latter class on high-elevation ridgelines results from underlying nutrient-rich bedrock. Vegetation composition is most strongly associated with soil nutrients, soil texture, and topographic position. The combination of rugged topography, infertile soils, relatively low annual rainfall levels, and lack of anthropogenic disturbance is responsible for the unusual combination of southern Appalachian vegetation communities that characterize Linville Gorge Wilderness.

Vegetation of Great Smoky Mountains National Park, 1935-1938

Abstract: During the establishment of Great Smoky Mountains as a National Park in the mid 1930's, the National Park Service hired Frank H. Miller as an assistant forester to conduct a vegetation survey of the proposed park area. At that time, Miller and his crews sampled over 1,378 plots. This data set is the only known sampling effort that has occurred across the park's entire landscape. This paper quantitatively summarizes and classifies the overstory data collected by Miller. At the time of the sampling, Castanea dentata was the dominant species even though the chestnut blight had become established in the area of the park between 1925 and 1936. Sixteen vegetation types were identified ranging from the low elevation, xeric Pinus rigida type to the high elevation, mesic Abies fraseri type. Comparison of the whole park classification derived from the Miller data with those of other, less inclusive, studies illustrates the importance of whole park analysis for a complete understanding of the park's vegetation.

Changes in forest overstory composition on the southwest-facing slope of Beanfield Mountain in southwestern Virginia

Abstract: A former oak-chestnut forest community on the southwest-facing slope of Beanfield Mountain in the Mountain Lake area of southwestern Virginia, previously sampled in 1939 and 1969-70, was resampled during the summer of 1993 to assess the successional changes in forest overstory composition that have taken place following the chestnut blight. In 1939, an oak complex dominated by white oak (Quercus alba), chestnut oak (Q. prinus), and red oak (Q. rubra) had replaced the original oak-chestnut forest. The 196970 study found that pignut hickory (Carya glabra) had become the leading dominant on the slope, with red oak and chestnut oak the most important codominants. However, by 1993 hickory had decreased in importance, and red maple (Acer rubrum) had become a canopy codominant. Red oak and chestnut oak were still the dominant oaks, but black birch (Betula lenta) also had become a consistent component of the community. As such, nearly seventy-five years following the blight, oaks have maintained their codominant status. Hickory is less important than in 1969-70, whereas red maple and black birch are more important.

The Genus Rubus L. in Iowa

Abstract: Morphological features were examined from more than 5,000 Rubus specimens to prepare the first comprehensive revision of the native and naturalized Rubus of Iowa. Twenty-eight species (one with two varieties) and one interspecific hybrid have been collected in the state. They are described in this revision, which contains keys to subgenera and species designed specifically for field researchers in Iowa and nearby states. Synonymy, distribution, phenology, habitat, associated plants, and taxonomic treatment by past researchers are also discussed. Range-wide county distribution maps are presented for 22 species representing Rubus subgenus Rubus (the blackberries and dewberries), and Iowa county distribution maps have been included for R. idaeus L. var. strigosus (Michx.) Maxim., R. occidentalis L., R. parvifolius L., and R. pubescens Raf. The findings of this study are discussed in the context of the putative reticulate phylogeny among species of Rubus subgenus Rubus, and potential subjects for future molecular and cytological research are proposed.

Pollination of the Miccosukee Gooseberry (Ribes echinellum)

Abstract: To determine the extent to which pollinator scarcity and/or specificity may account for the rarity of Ribes echinellum, and to provide information for protection, pollinators and pollinator behavior were observed. The primary pollinators at both Florida and South Carolina stations were large bees including species of Bombus, as well as Habropoda laboriosa. The pollinators are widespread, at least locally common, and are not host-specific, apart from an association with pendent blossoms in Habropoda laboriosa. Although neither pollinator rarity, nor pollinator specificity, appear to provide an adequate explanation for the rarity of Ribes echinellum, high floristic diversity in relicts of mesophytic forest may contribute to the persistence of the rare shrub by maintaining the large bee populations necessary for cross-pollination. The bees land on the pendent flowers immediately assuming an inverted position while grasping the reflexed calyx lobes and petals with hindlegs, and stamens and style with forelegs. In this position the anthers and style tips are brought into contact with the ventral thorax and abdomen, while the bee probes the floral tube. Protandry and circumstantial evidence suggest a reliance on pollinators for fruit development.

A new species of Echinodorus (Alismataceae) from the United States of America

Abstract: A new species, Echinodorus floridanus, from extreme western panhandle Florida, USA is described, and characteristics to separate it from the other species of Echinodorus are discussed. The new species is known only from the type locality.