Botany Commons^™

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 …

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 …

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.

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

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.