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Factors Restricting Recruitment Of Ascophyllum Nodosum L (Le Jolis), Paula K B Philbrick

Doctoral Dissertations

Ascophyllum nodosum dominates a wide zone on the shore. Juveniles occur high in the zone where canopy is continuous and grazing animals few. Settlement could account for the restricted range if it were enhanced under canopy or on the upper shore. Settlement was monitored under canopy and in the open at four shore levels during spring 1983. Propagules settled everywhere. Settlement does not restrict plant establishment. Germlings caged and not caged were placed under canopy and in the open through the zone to evaluate the effects of animals and the physical environment (shore level x frond cover) on survival and …

A Study Of Basidiomycetes Isolated From Coarse Woody Debris And Contiguous Soil Horizons In A Mixed Deciduous-Conifer Forest In New Hampshire, United States Of America, Therese Ann Thompson

Doctoral Dissertations

The wood decay fungus Hypholoma sublateritium (Fr.) Quel., links the mineral (BC & E) and organic (Oe) soil layers to decomposing coarse woody debris (CWD) in a northern hardwood forest. This link supports the possibility that energy stored in woody debris can facilitate the vertical transfer of elements and compounds within the soil profile. This potential transfer implies new pathways for biogeochemical cycling within forests. H. sublateritium was isolated from basidiocarp fruiting bodies (October 1997 & 1998), Acer rubrum L. bole wood (June 1999), and three soil horizons (October 1999 and October 2000) from one of six research sites in …

An Investigation Of Genetic Variation Within Northwest Atlantic Porphyra (Bangiales, Rhodophyta) With Specific Phylogeographic Analysis Of The Common, Rocky Intertidal Species, Porphyra Umbilicalis, Brian William Teasdale

Doctoral Dissertations

To investigate the phylogeography of the rocky intertidal red alga, Porphyra umbilicalis Kutzing, a restriction fragment polymorphism assay (RFLP) of the ribulose bisphosphate carboxylase large subunit ( rbcL) was developed to accurately distinguish P. umbilicalis from the other morphologically similar species in the North Atlantic. Initial screening of ∼800 Porphyra specimens resulted in the additional discovery of a cryptic Porphyra taxon.

The presence and variability of group-I introns of the ribosomal small subunit (SSU) were screened in North Atlantic species of Porphyra in order to assess whether they could be biogeographically informative. In an initial screening for the helix 50 …

A Comparison Of Floristic Diversity In Old-Growth Versus Mid-Successional Secondary-Growth Hardwood Forests Of The White Mountain National Forest, New Hampshire, United States, Leslie Marie Teeling-Adams

Doctoral Dissertations

There is currently debate over whether managed forests will ever regain the species diversity of old-growth stands. While succession and response to disturbance of tree species has been extensively researched, little similar effort has focused on understory herbaceous communities. This study conducted large-scale, comprehensive botanical inventories of three old-growth and three mid-successional (80--100 year old) secondary forest stands in New Hampshire's White Mountain National Forest (WMNF). Cluster analysis and TWINSPAN grouped the secondary sites within two steps. Old-growth floras were significantly richer in total, total herbaceous, woodland herbaceous, and unique herbaceous species. Abundance distributions of the two treatment groups were …

Spatial Modeling And Visualization Of Habitat Response To Hydrologic Restoration In New England Salt Marshes, Raymond Anthony Konisky

Doctoral Dissertations

Anthropogenic alterations that restrict tidal flows negatively impact 20% of New England salt marshes, but management attempts to restore tides to these sites can be met with unexpected or less than optimal results. Restoration planners may be hindered by a lack of synthesized information regarding important biotic and abiotic factors that determine the distribution of dominant salt marsh plants and invasive species. An ecosystem model was developed to better predict salt marsh habitat response to hydrologic modification as a synthesis of existing models for biomass production, marsh elevation, tidal hydrology, and plant succession. A field experiment was conducted to provide …

Factors Associated With Atlantic White -Cedar Seedling Recruitment On Microtopographic And Landscape Scales, Brown Mill Pond, Rye, New Hampshire, Lara Megdane Gengarelly

Doctoral Dissertations

The decline of Atlantic white-cedar (Chamaecyparis thyoides) throughout its range has motivated researchers to investigate cedar seedling recruitment. In this study, conducted at Brown Mill Pond in Rye, New Hampshire, the distribution pattern of cedar seedlings was studied in order to identify which, if any, biological or physical factors observed at a microtopographic scale were associated with seedling presence. On a landscape scale, five previously identified cedar communities were measured for differences in water table level and soil moisture in order to determine associations between stand dynamics and hydrology.

A field survey showed that cedar seedlings were (1) absent from …

Calcium -Dependent Protein Kinases Are Myristoylated And Associated With Different Membranes In Arabidopsis Thaliana, Sheen Xun Lu

Doctoral Dissertations

In plants, calcium-dependent protein kinases (CDPKs) are the predominant calcium-stimulated kinases and are known to be involved in many cellular processes. CDPK enzymatic activity previously has been detected in many locations in plant cells, including the membrane fraction. However, little is known about the subcellular locations of individual CDPKs or the mechanisms involved in targeting them to those locations. Arabidopsis contains 34 genes that are predicted to encode CDPKs and 28 of the predicted CDPK proteins have potential myristoylation motifs at their amino termini. Myristate is a 14-carbon saturated fatty acid that is attached co-translationally to the amino-terminal glycine of …

Factors Affecting Plant Community Composition And Dynamics In The Ossipee Pine Barrens, New Hampshire, Lauren Fredrick Howard

Doctoral Dissertations

Forty-one 0.25 ha sites were sampled in the Ossipee Pine Barrens to identify and describe tree community types and investigate factors controlling forest composition and dynamics. Every site had three site-time assemblages (STA's) representing past, present, and future trees. Past (1952) vegetation was calculated based on reverse growth estimates of current stems and stumps. Future (2052) vegetation was predicted by current sapling (<10 cm dbh and ≥1 m tall) relative densities.

Cluster analysis produced three community types from 121 STA's: pitch pine, mixed pine-hardwoods, and red maple. Pitch pine communities comprised 63% of sites in 1952, but declined since. Mixed pine-hardwoods peaked at 58% in 2002, but were …

Biodiversity And Phytogeography Of Bolivia's Wetland Flora, Nur Paul Ritter

Doctoral Dissertations

The composition, diversity, and phytogeographic affinities of the vascular flora of Bolivia's wetlands were examined and compared with wetland floras from the other Neotropical countries and the New World Temperate region. Forty-six wetlands distributed throughout Bolivia and ranging in elevation from 90 in to >4400 m were established as study sites. Regional and national wetland floras were compiled from field research, the literature, herbarium specimens, and available databases.

Two thousand and sixty species in 149 families and 666 genera were identified as associated with wetlands in Mesoamerica and tropical and subtropical South America. Of these, 1026 species in 126 families …

Reproductive Ecology Of Canada Mayflower (Maianthemum Canadense Desf), Michael Todd Ganger

Doctoral Dissertations

Canada mayflower (Maianthemum canadense var. canadense Desf.), a rhizomatous perennial herb, was the subject of field experiments investigating the role of several factors on the sexual reproduction of ramets. Mayflower ramets may be either flowering (with 2-3 leaves and a terminal inflorescence consisting of 4-35 perfect flowers) or vegetative (1 leaf).

Pollen addition increased the number of seeds matured by ramets in three out of four years in which pollen level was experimentally manipulated. The lack of compatible pollen is thought to be a major factor limiting seed maturation by ramets.

The act of severing the rhizomes, such that ramets …

Eelgrass (Zostera Marina L) As A Sentinel Accumulator Of Lead In Portsmouth Harbor, New Hampshire - Maine, Heidi Morrill Hoven

Doctoral Dissertations

The potential of eelgrass, Zostera marina L., as a sentinel indicator of lead (Pb) pollution in the water column was investigated. Eelgrass was grown in mesocosms that contained ambient sediment collected from sites near the Portsmouth Naval Shipyard Jamaica Island Landfill (JIL) of Kittery, Maine, to test viability of eelgrass in the Shipyard's marine sediment. Eelgrass was also grown in mesocosms at three shoot densities in marine sediment of three Pb concentrations to determine to what extent Pb affects eelgrass growth and whether Pb uptake by eelgrass is affected by plant density. Additionally, eelgrass was used to detect water-borne sources …

A Biosystematic Monograph Of The Genus Nuphar Sm (Nymphaeaceae), Donald Jay Padgett

Doctoral Dissertations

The genus Nuphar (Nymphaeaceae) comprises 10 perennial species native to freshwaters of the Northern Hemisphere. This taxonomic assessment utilizes morphometric analyses, cladistic analyses of morphology, nuclear and chloroplast DNA sequences, evaluation of randomly amplified polymorphic DNA, and pollen fertility estimations. Evolutionary reconstructions position Nuphar at the base of the family, most closely allied to Barclaya. Phylogenetic estimates within Nuphar indicate two major evolutionary lines, largely congruent with present biogeographical distributions that indicate an Old World/New World divergence. Accordingly, the genus is subdivided into two sections, Nuphar and Astylata. Section Nuphar includes the type of the genus, N. lutea, as well …

Systematics Of The Hamamelidaceae Based On Morphological And Molecular Evidence, Jianhua Li

Doctoral Dissertations

The Hamamelidaceae are a plant family of 31 genera and more than 140 species distributed in both the Old and New worlds. There has long been debate about the subfamilial, tribal, as well as generic, relationships within the family.

Parsimony analysis was performed to examine the relationships in the Hamamelidaceae based on morphology, and DNA sequences of the Internal Transcribed spacers (ITS) of nuclear ribosomal DNA, and the chloroplast matK gene. The morphology-based phylogeny shows weak support for all clades except for the Altingioideae, and differs greatly from the molecular phylogenies. Phylogenies based on the matK and ITS data are …

Relationship Of Critical Photoperiod Of Short-Day Parents To Frequency Of Day-Neutral Progeny In Short-Day X Day-Neutral Crosses Of Fragaria X Ananassa, Christina Marie Cundari

Doctoral Dissertations

Critical photoperiod for flowering was determined for short-day (SD) and day-neutral (DN) genotypes of strawberry used in SD x DN crosses to investigate whether variation in critical photoperiod contributes to variation in frequency of DN progeny and, hence, may be an effective selection criterion for screening SD genotypes for use as parents in breeding regionally-adapted DN cultivars. Twelve SD and four DN genotypes were grown in controlled environments under eight photothermal regimes (four photoperiods (9, 11, 13, 15 hr) x two day/night temperatures (19/14 and 24/19$\sp\circ$C)). Among the SD genotypes, critical photoperiod varied more under cool than warm regimes. Under …

Competition And Dispersal In The Regulation Of Plant Species Richness On Carex Stricta Tussocks, Leonard Alexander Lord

Doctoral Dissertations

Many wetland plant species can be found growing on Carex stricta Lam. (tussock sedge) tussocks in freshwater marshes. Based on Grime's model of plant species richness, the objectives of this research were to: (1) examine if dispersal characteristics vary among C. stricta marshes in a manner that could potentially influence species richness on individual tussocks, and (2) examine how variation in propagule availability may interact with standing crop and leaf litter to regulate species richness on individual tussocks. All of the research was conducted in southeastern New Hampshire.

Dispersal characteristics were quantified in five wetlands representing a broad range of …

Chilling Photoinhibition In Zea Mays L And Zea Diploperennis Iltis, Doebely And Guzman: The Role Of Oxygen And Antioxidants, Kajal Bose Ghoshroy

Doctoral Dissertations

Light absorbed by photosynthetic pigments must be distributed either for chemical work, reemitted as fluorescence or safely dissipated as heat. Adverse environmental conditions reduce the dissipation capacity of plants and the excess energy leads to damage to the photosynthetic mechanism, termed photoinhibition. Low, non-freezing temperatures cause such photoinhibition, especially in tropical plants grown in the temperate zone. This damage occurs in the photosystem II and is triggered by highly reactive radicals or reactive forms of dioxygen. Numerous studies point to the involvement of oxygen and antioxidant enzymes and substrates in amelioration of these damages. In C$\sb3$ plants, dioxygen is thought …

A Study Of Floral Development In Asparagus Officinalis L, Heather G. Miller

Doctoral Dissertations

Asparagus officinalis L. is typically classified as a dioecious species. However, in all-male hybrid cultivars, a percentage of individuals within a population exhibit a persistent perfect flowering (hermaphrodite) phenotype. Floral meristem development was divided into eight distinct stages of development and those developmental stages were compared in UC157 male, UC157 female, and 32/83 hermaphrodite individuals using scanning electron microscopy (SEM). In females, anthers abort between stages five and six. In males, style development is halted at stage eight. Hermaphrodites exhibit normal development of both anthers and styles. Within the 32/83 cultivar, the number of developing carpels can vary and some …

Light Detection System In Higher Plant Chloroplasts: Pigment Mediated Or Overall Photon Flux Density Related, Soumitra Ghoshroy

Doctoral Dissertations

Plants adapt to short term changes in irradiance and quality of the light environment by modulating the structure of the thylakoid membranes to make the best use of the available light energy. Shade-acclimated chloroplasts develop more thylakoid surface area as compared to those growing in full sunlight. Conversion of sun-type chloroplasts to shade-types and vice versa on the basis of total thylakoid membrane surface area can occur quickly. However, the response mechanism of chloroplasts to changes in light levels is yet to be understood. This short term light detection mechanism may be mediated by a pigment system other than photosynthetic …

Environmental And Biological Factors Affecting Tissue Composition Of Marine Macrophytes, Zhanyang Guo

Doctoral Dissertations

The tissue nitrogen and phosphorus composition of 59 marine macrophytes from the Great Bay Estuarine System, NH-Maine and adjacent coast is affected by a variety of environmental and biological factors; by contrast, tissue carbon is more consistent. The overall mean CNP ratio of these plants was 612:29:1, which deviated significantly from that previously recorded for phytoplankton.

The C:N:P ratios within seaweeds were more closely related to functional forms than phylogenetic relationships. Brown algae had higher C:N ratios than green and red algae. This pattern primarily resulted from the very high C:N ratios within thick bladed and coarsely branched species, which …

The Biosystematics Of Carex Section Scirpinae (Cyperaceae), Debra Ann Dunlop

Doctoral Dissertations

Carex section Scirpinae is a small group of North American sedges that possess a dioecious breeding system, unispicate inflorescences and pubescent perigynia. Historically, ten different taxa had been recognized at the specific or infraspecific levels based primarily on morphological characters. Taxonomic problems in the group were related to the lack of a comprehensive monographic treatment. Floristic treatments were limited and focused only on a few regional taxa. Descriptions were often incomplete, lacking descriptions of staminate material or complicated by the inconsistent use of the terms phyllopodic and aphyllopodic. Patterns of variation in morphological characters across a wide geographic range were …

Ecology Of Gracilaria Tikvahiae Mclachlan (Gigartinales, Rhodophyta) In The Great Bay Estuary, New Hampshire, Clayton Arthur Penniman

Doctoral Dissertations

The reproductive phenology, growth and variation of chemical composition of Gracilaria tikvahiae from the Great Bay Estuary, N.H. were evaluated. A major objective was an analysis of the chemical composition, particularly agar content and properties, of plants separated into reproductive categories. The net photosynthetic responses of G. tikvahiae to several irradiance, temperature and salinity regimes were determined.

Gracilaria tikvahiae plants from the Great Bay Estuary were vegetative throughout most of the year. However, discrete maxima of tetrasporic and spermatangial plants occurred during June-July and for cystocarpic plants during July-August. The in situ growth of Gracilaria tikvahiae was highest during June-September, …

Anatomical And Physiological Aspects Of A Host-Pathogen Interaction: Cytospora Canker On Prunus Persica (L) Batsch, Michael Edward Wisniewski

Doctoral Dissertations

A multifaceted program which examined several aspects of the host-pathogen interaction was conducted. Investigations were conducted in the following areas:

Developmental Anatomy of Wound Response in Current Year Shoots. Shoots wounded in mid-June developed a suberized necrophylactic periderm (NP) within two weeks. Both diffuse and delimited wound responses were observed. Normal xylem and phloem production was replaced by parenchymatous tissue in samples exhibiting a diffuse wound response. Within four weeks, NP acted as a center for, and instigated, premature exophylactic periderm development. Formation of gum cysts in the xylem and an accumulation of calcium oxalate crystals in cortical cells was …

Variation, Adaptation And Reproductive Biology In Ruppia Maritima L Populations From New Hampshire Coastal And Estuarine Tidal Marshes, Frank David Richardson

Doctoral Dissertations

Ruppia maritima L. populations in coastal and estuarine tidal marshes in New Hampshire exhibit considerable variation in morphology, reproductive strategy and pollination ecology in response to a range of environmental conditions. Variation among the populations correlates with seasonal changes in environmental conditions recorded at various sites. A comparison of coastal and estuarine habitats of Ruppia has shown them to differ significantly with respect to such factors as: origin and development, substrate, epibiota, floristic and faunistic components and seasonal patterns in water depth, temperature and salinity. The three varieties Ruppia maritima L. occurring in New Hampshire are phenotypically plastic in response …

Exophylactic And Necrophylactic Periderm Development In American Beech, William Dow Ostrofsky

Doctoral Dissertations

American beech (Fagus grandifolia Ehrh.) in forest stands of North America are threatened by a destructive disease commonly known as the beech bark disease. Investigations on bark structure and on response of bark tissues to mechanical injury and pathogen invasion would increase our understanding of the etiology of this disease. The objectives of this investigation were to provide descriptions of the development and anatomy of bark of American beech, with emphasis on bark periderms. Investigations were made of the ontogeny of the first exophylactic periderm, and on characteristics and development of the necrophylactic periderms resulting from the beech bark disease …

Photoadaptive Responses In The Tropical Brown Seaweed, Lobophora Variegata (Lamour) Womers, Christopher David Neefus

Doctoral Dissertations

A study was undertaken to determine if natural growth irradiance regimes influence the pigment content and/or photosynthesis-irradiance relationships of the tropical brown seaweed, Lobophora variegata. Pigment analyses were performed on samples collected from a series of depths between 9 and 49m. Chlorophyll a, chlorophyll c, and fucoxanthin were constant on a thallus weight basis, but showed small decreases when expressed in terms of thallus area. The beta-carotene content of L. variegata was much greater in shallow than in deep-water samples regardless of the pigment units employed. Experimental reduction of the light regime of the shallow population, produced a significant decrease …

Ecology And Genecology Of Fucus Distichus (L) Powell, Eric Joseph Sideman

Doctoral Dissertations

Growth rates, reproductive phenology, and longevity of Fucus distichus ssp. edentatus and F. distichus ssp. evanescens were evaluated in natural populations in New England. Both subspecies exhibited maximum growth during early summer, a slight decline in late summer, and a brief resurgence in the early fall. The maximum growth rates (in terms of elongation) for ssp. edentatus and ssp. evanescens was 3.5 cm/mo and 3.7 cm/mo, respectively. Populations of both subspecies showed a distinct bimodal reproductive periodicity, with maximums in the spring and fall. Individuals within natural populations were reproductive in either the spring or fall but never both seasons. …

The Seasonal And Spatial Distribution Of The Marine Benthic Algae Of Tunisia, Ernani Guingona Menez

Doctoral Dissertations

A detailed study of the marine flora of Tunisia was conducted by assessing the seasonal variation of seaweed populations along a 35 m transect at one site (La Marsa), as well as by qualitatively describing the species composition throughout the country, and comparing the floristic affinities of the Tunisian flora with other Mediterranean and northeastern Atlantic areas. The occurrence and distribution of the Tunisian flora were correlated with a variety of parameters, including water temperature, salinity, substrata and currents. The seasonal studies at La Marsa, which is within the Gulf of Tunis, were undertaken monthly between October, 1974 and August, …

Correlation Of Selected Dissolved Substances And The Distribution Of Potamogeton In New England, Carl Barre Hellquist

Doctoral Dissertations

No abstract provided.

An Ecological Study Of Fucus Spiralis Linnaeus, Richard Albert Niemeck

Doctoral Dissertations

No abstract provided.

Cell Proliferation And Elongation In Normal, Dwarf And Gibberellin-Treated Dwarf Watermelon Seedlings, Peter Bao-Wei Liu

Doctoral Dissertations

No abstract provided.