Botany Commons^™

Distribution Of Foraminifera And Pollen In Coastal Depositional Environments Of The Southern Delmarva Peninsula, Virginia, U.S.A., Han Jun Woo

OES Theses and Dissertations

The coastal zone of the southern Delmarva Peninsula exhibits a wide variety of barrier island system subenvironments. This study investigates whether 20 a priori subenvironments can be distinguished from each other on the basis of abiotic environmental variables, pollen assemblages, living foraminiferal populations, and total (living plus dead) foraminiferal assemblages.

The physical data collected from the coastal zone were subjected to canonical variate analysis which discriminated 83% of the stations in 19 groups. These groups were clustered into two internally overlapping sets which represented the inside and outside of the inlet.

Twenty-two pollen types were found in low-energy marsh and …

Root Biomass And Production In Four Communities Within The Great Dismal Swamp, Susan West Powell

Biological Sciences Theses & Dissertations

A biomass difference approach was used to measure biomass and production over eleven months in four different communities within the Great Dismal Swamp. On all sites, fine roots were the moat dynamic root component. Both biomass and production were highest on the mixed hardwood site, the least flooded site, and second highest on the cedar site, the site with the longest duration of saturation. The maple-gum and cypress sites had lower amounts of biomass and rates of production. Environmental parameters that influenced production included frequency and duration of flooding, density of the stand, and soil type.

A second method, an …

An Autecological Study Of Pyxidanthera Barbulata In The Blackwater Ecologic Preserve Virginia, John Marc Lowenthal

Biological Sciences Theses & Dissertations

Pyxidanthera barbulata (pyxie moss), a rare and endangered subshrub, has been found in decreasing numbers in it's "pine barren" habitat. An autecological study encompassing vegetation association analysis and environmental measurements was performed in the Blackwater Ecologic Preserve, its only known location in Virginia. The preserve is being subjected to controlled burning and the effect of burning on the species was evaluated. A multivariate analysis of variance was performed to identify species associations, and simple analysis of variance was done to find trends in the environmental data. Four taxa were positively associated with P. barbulata, Gaultheria procumbens, Vaccinium tenellum, Cladonia spp., …

A Study Of Striga Chromosome Numbers With A Comparison To Those Of Some Genera In The Rhinathoideae And The Orobanchaceae, Cynthia White

Biological Sciences Theses & Dissertations

New chromosome counts are given for nine species of Striga including S. elegans (n=18), S. asiatica (n=19), S. forbesii (n=22), S. densiflora (n=26), S. aspera (n=27), S. passargei (n=28), and S. hermonthica (n=30). Previous counts reported for S. gesnerioides (n=20) and S. angustifolia (n=20) are verified. Evidence from the base number (x=10), chromosome counts, and differences in chromosome size (bimodality) suggests that the genus is an allotriploid with a descending aneuploid series. Genomic change appears to occur by different mechanisms in the Rhinanthoideae; some genera display a euploid series, others show aneuploidy, and some are very stable. Genera examined …

Decomposition Of Roots In The Great Dismal Swamp, Edward G. Tupacz

Biological Sciences Theses & Dissertations

The decomposition rates of roots to a depth of 40 cm were estimated by two methods in four plant communities in the periodically flooded Great Dismal Swamp. Modified litter bags and a core method were simultaneously employed on three flooded sites and an unflooded mixed hardwood site. Reciprocal samples (litter from each of the other sites) were placed on each site to examine the effects of litter composition.

For the litter bags, the cedar and maple - gum sites displayed the lowest mean decay rate. However, reciprocal samples showed that roots from the cedar and mixed hardwood sites decayed the …

Evaluation Of Two Methods For Estimating Belowground Production In The Great Dismal Swamp, Millie Symbula

Biological Sciences Theses & Dissertations

Two methods were used to estimate belowground production in a maple-gum stand in the seasonally flooded Great Dismal Swamp of Virginia. The first was an auger method which involved sequential core sampling. The second method was an implanted soil mass technique. Nylon mesh bags were filled with peat and buried at the study site. New growth into these implants was taken to be production.

Mean annual lateral root biomass and necromass to 40 cm, determined from soil cores, were 583 g·m^-2 and 281 g·m^-2, respectively. Production estimates for roots ≤ 5 mm in diameter, using soil cores, …

The Effect Of Pre-Sterile Medium Ph Photoperiod And N6-(2-Isopentenyl)-Adenine (2ip) On Shoot Production During Stage Ii Micropropagation Of Rhododendrons, Lori Longo Smith

Biological Sciences Theses & Dissertations

The number of shoots produced during a six week subculture of two Rhododendron sp., cultivars Rocket and Gibraltar was the same for both 16 and 24 hour photoperiods under cool white fluorescent lights, whereas significantly fewer shoots were produced under a 10 hour photoperiod for ‘Rocket.' Increasing concentrations of N₆- (2-isopentenyl)- adenine (2iP) from 0 to 32 μMin Anderson's medium resulted in proportional increases in shoot number. When shoots were cultured in the presence of indole-3-acetic acid (IAA) and 2iP, shoot multiplication was increased significantly over shoots cultured with 2iF alone. No interaction affecting shoot multiplication was …

Organic Matter Budgets And Models For Four Plant Communities In The Great Dismal Swamp, J. Patrick Megonigal

Biological Sciences Theses & Dissertations

Budgets and models of organic matter dynamics were developed for one mesic and three seasonally flooded plant communities in the Dismal Swamp. Components included aboveground parts, belowground parts, litter and soil organic matter (SOM).

Net primary- production was significantly greater on them flooded sites. Comparisons show that the Dismal Swamp is highly productive despite relatively low nutrient inputs.

Budget calculations showed that over 65% of the total input to SOM comes from roots. Leaves contributed about 70% of the aboveground inputs.

The model predicted that species composition, aboveground biomass and turnover rates on the cedar site will become quite similar …

Morphological Variation Of The Foraminifer Elphidium Excavatum (Terquem) On Crumps Bank And Willoughby Bank, Chesapeake Bay, Virginia, Pamela Kay Painter

OES Theses and Dissertations

Six variants of the highly variable foraminiferal species, Elphidium excavatum (Terquem) were recognized in the Crumps Bank and Willoughby Bank areas of the southern Chesapeake Bay. Measurements of the size of the test, the number of chambers, the number of umbilical bosses, and the number and average length of the sutural bridges on the last formed chamber, and opaqueness or translucence of the test were made on 30 specimens from each of 36 stations selected for differences in environmental parameters. The measurements were statistically analyzed by discriminant analysis to test the hypothesis that the variants are distinct morphotypes and to …

Variation In Leaf Macronutrients Of Overstory Trees As Influenced By Species Season And Soil Type In The Great Dismal Swamp Of Virginia, Bruce J. Bandle

Biological Sciences Theses & Dissertations

Leaf macronutrient variation was studied in four plant communities in the Dismal Swamp of Virginia. composition differed markedly between these sites. Soils and species Eight important overstory trees were studied in August 1980; whereas red maple (Acer rubrum L.} and black gum (Nyssa sylvatica Marsh.}, which occurred on all four sites, were sampled seasonally. Significant differences (p .05) were found in the nutrient concentrations of the leaves between species, seasons, and sites. These differences may be attributed to inherent species characteristics, leaf expansion, nutrient translocation, and differences in soil organic matter content, pH, and degree of …

The Use Of Microscopic Vegetative Characteristics And Leaf Characteristics And Leaf Deterioration Rates In The Formulation Of Keys Of Some Wetland Plants, Bruce Foy Williams

Biological Sciences Theses & Dissertations

Leaves of Spartina alterniflora, Spartina patens, Spartina cynosuroides, Distichlis spicata, Phragmites communis, Juncus roemerianus, Scirpus robustus, Typha latifolia, Iva frutescens, and Baccharis halimifolia were examined microscopically. Characteristics of each species were then used to develop identification keys. In addition, leaf fragments were buried in the marsh substrate to simulate a dredging and/or filling operation. At weekly intervals during each season of the year, a leaf fragment of each species was processed and examined to see if it could be identified.

Decay Rates And Nutrient Dynamics In Confines And Nonconfined Leaf Litter In The Great Dismal Swamp, R. Frederick K. Yates

Biological Sciences Theses & Dissertations

This study was designed to quantitatively compare decay rates and nutrient dynamics by the confined and unconfined litter techniques in a seasonally flooded swamp. In this study both methods indicated the same order of decay rates among sites (cedar>maple-gum>cypress> mixed hardwood), but the unconfined method showed faster decay rates at all sites. As in two years of previous data collection, the stands exhibiting some seasonal flooding showed greater decay rates than the mixed hardwood stand which was not inundated. Nutrient dynamics were not different between litter bag and leaf pack methods.

This study included a preliminary investigation of …

Germination And Haustorial Development In Orobanche Minor Smith (Orobanchaceae), David L. Spelce

Biological Sciences Theses & Dissertations

Orobanche minor Smith is an introduced root parasite that is known to attack some commercial crops. Germination occurs only after a preconditioning period involving moisture which must be followed by a chemical stimulant produced by the host root. Strigol and strigol analogs (GR-compounds} have been reported to germinate some species of Orobanche. Statistical tests indicate a significant difference between the effectiveness of strigol, GR-7 and GR-45 (P = 0.001).

The embryo is an undifferentiated mass of cells. During germination, the radicular pole of the embryo differentiates into the radicle, while the plumular pole remains undifferentiated. The radicle forms the primary …

Studies On The Anatomy Of The Parasitic Gymnosperm Parasitaxus Ustus (Podocarpaceaea), Evelyn Wilkinson

Biological Sciences Theses & Dissertations

An anatomical study of the parasitic gymnosperm Parasitaxus ustus was conducted. Material was collected in New Caledonia, embedded in paraffin or celloidin, sectioned and stained. The apical meristem consists of apical initial cells, central mother cells, the peripheral zone, and rib meristem. Leaves are scale-like, triangular and broadly decurrent at their bases. Resin ducts and prominent sclereids are present in leaves and the cortex of the stem. The parasite-host connection is in the form of a xylem to xylem connection in which the tracheids are connected by bordered pits.

Plant Distribution And Succession Within Interdunal Depressions On A Virginia Barrier Dune System, Robert Wayne Tyndall

Biological Sciences Theses & Dissertations

A unique series of interdunal depressions was recognized on the barrier dune system of southeastern Virginia. Plant distribution and succession, and environmental factors controlling them, were studied in the series. Plant community distribution appears to be predominantly controlled by soil moisture, interspecific competition, and feral hog disturbance. Both biotic and physiographic succession are apparent with Quercus virginiana probably climax for both. Salt spray and feral hog and migratory waterfowl activity are important controlling factors of plant succession. Results indicate that the zonal appearance of shrubs and trees on the Virginia and North Carolina coasts is due to the absence of …

Structural Comparisons Of Four Plant Communities In The Great Dismal Swamp, Claire Virginia Dabel

Biological Sciences Theses & Dissertations

Four plant communities in the Great Dismal Swamp, located on the coastal plain in southeastern Virginia, were sampled and estimates of density, basal area and aboveground standing crop biomass were determined, Biomass was estimated as 229,800 kg/ha in the Chamaecyparis thyoides community and as 344,500 kg/ha in the Taxodium distichum community. Biomass for the two hardwood communities, the

Acer-Nyssa community and mixed hardwood (Quercus-Nyssa-Acer-Liriodendron-Liquidamber) community was estimated as 195,700 kg/ha and 194,600 kg/ha respectively and did not differ significantly (P

Vegetative Study At The Duck Field Research Facility, Duck, North Carolina, Gerald F. Levy

Biological Sciences Faculty Publications

The Duck Field Research Facility is located on the Outer Banks of North Carolina, a series of offshore sandbars extending from the Virginia- North Carolina border southward about 200 miles to Bogue Inlet, North Carolina. These bars lie almost parallel to the mainland and are separated from it by shallow sounds of varying widths.

The study area is included in Currituck Bank (North Bank), which extends from the Virginia-North Carolina boundary southward to the town of Nags Head, a distance of about 45 miles (Fig. 1). The bank was originally demarcated by two inlets; Old Currituck Inlet, which was located …

Measurement Of Transpiration In Pinus Teada L. And Liquidambar Styraciflua L. In A Closed Environment Growth Chamber Using Tritiated Water, Jean K. Czoch

Biological Sciences Theses & Dissertations

Transpiration rates of loblolly pine (Pinus taeda L.) and sweetgum (Liguidambar styraciflua L.) were measured at two different water vapor pressure deficits (V.P.D.) in a controlled environment growth chamber using tritiated water as a tracer. The trees were maintained in a sealed plant bed containing a hydroponic nutrient solution. Samples of leaves, chamber air, spiked nutrient and control solutions were assayed for activity using liquid scintillation techniques. The transpiration rate of sweetgum (4.95 ml/hr/gm) was found to be 5 times greater than that of loblolly pine (1.03 ml/hr/gm) at the lower V.P.D. and 8 times greater at …

Community Structure And Production In A Marsh On The Southern Branch Of The Elizabeth River, Virginia, Michael Bassett Robblee

Biological Sciences Theses & Dissertations

Four different plant communities occur on the Southern Branch of the Elizabeth River, Virginia, 1. Spartina alterniflora, 2. Distichlis spicata - Spartina patens - Juncus roemerianus, J. Baccharis halimifolia - Iva frutescens and 4. Spartina cynosuroides. The cordgrasses s. alterniflora and S. cynosuroides dominate the marsh.

Based-on standing crop estimates S. alterniflora produced 1218.6 grams dry wt/m² and S.cynosuroides 1681.3 grams dry wt/m², which is much higher than generally assumed for Virginia marshes. Evidence for the presence of two crops of S. alterniflora on the marsh during the growing season is-presented.

Two animal associations, composed …

Plant Succession In The Great Dismal Swamp Of Virginia, Susan Woodward Walker

Biological Sciences Theses & Dissertations

Vegetational composition and environmental parameters were analyzed. for 14 stands. Cluster diagrams based on index of similarity values illustrated interstand relationships. The Index of Fluctuation was developed for the analysis of intrastand dynamics. Based on the densities and numbers of species of trees and saplings within a stand, it indicated degree of compositional stability. It was concluded that present vegetation is divided into relatively distinct communities which have resulted, at least in part, from disturbance.