scholarly journals The Status of Carex elongata (Cyperaceae) in Yorkshire

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Alastair Fitter ◽  
Martin Hammond ◽  
Meg Huby ◽  
Kevin Walker ◽  
Phillip Whelpdale
Keyword(s):  
Seed Viability ◽  
Rare Plant ◽  
Local Distribution ◽  
Historic Sites ◽  
The Status ◽  
Winter Flooding ◽  
Colonisation Event

Gingerbread or Elongated Sedge Carex elongata L. is a rare plant in eastern England and the Yorkshire populations are isolated from the main distribution. It has only ever naturally occurred at five sites and is extant at two of them, one of which probably results from a recent colonisation event. It has been re-introduced near another of its historic sites. At its principal site, Askham Bog near York, the plant has expanded its population considerably over the last 40 years. Its local distribution appears to be strictly limited by topography and winter flooding. Its ability to colonise new sites and to expand populations show that earlier concern about seed viability was misplaced.

Depauperate seed banks in urban tropical seagrass meadows

2020 ◽  
Vol 71 (8) ◽  
pp. 935
Author(s):  
Glendon Hong Ming Ong ◽  
Samantha Lai ◽  
Siti Maryam Yaakub ◽  
Peter Todd
Keyword(s):  
Seed Bank ◽  
Large Scale ◽  
Seed Viability ◽  
Seed Banks ◽  
Dormant Seed ◽  
Seagrass Meadows ◽  
Halophila Ovalis ◽  
The Status ◽  
Cymodocea Rotundata

Seagrasses need to be resilient if they are to persist in the long term. Being able to build up a dormant seed bank in sediments is a key strategy that some species employ to regenerate from large-scale degradation. Much of the research on seed banks has focussed on temperate species, and little is known regarding the status of seed banks in tropical meadows. In the present study, we examined the seed bank status of three common seagrass species at six sites in Singapore and attempted to identify potential drivers of seed abundance. Our results indicated depauperate seed banks with few species setting viable seed and low seed densities. Halophila ovalis seeds were found at four sites and Halodule uninervis seeds at two sites, but Cymodocea rotundata seeds were absent from all six sites. Whereas H. ovalis seed viability ranged from 20% to 68.8%, none of the H. uninervis seeds was viable. Halophila ovalis seed densities (33–334m–2) were much higher than those of H. uninervis (9–21m–2). Of the variables examined, only H. ovalis cover was positively correlated with the number of seeds. Our study has highlighted the vulnerability of seagrass meadows in Singapore’s urban waters to future disturbances.

Seed ecology ofSynthyris bullii(Plantaginaceae), a rare endemic of the midwestern USA

Botany ◽  
2013 ◽  
Vol 91 (12) ◽  
pp. 884-889 ◽  
Author(s):  
Marnelle Curtis ◽  
Katherine Chi ◽  
Brenda Molano-Flores
Keyword(s):  
Seed Germination ◽  
Plant Species ◽  
Seed Viability ◽  
Seed Storage ◽  
Habitat Destruction ◽  
Rare Plant ◽  
Rare Plant Species ◽  
Seed Ecology ◽  
Midwestern Usa ◽  
Management Plans

Many rare plant species are declining owing to habitat destruction and degradation. Because many populations of rare species suffer low recruitment, a good understanding of seed ecology is crucial for developing effective conservation and management plans. In this study, we examine the effects of shading, seed longevity, and soilless mixes on seed germination for the rare midwestern USA endemic Synthyris bullii (Eaton) A. Heller. Seed germination studies were conducted in a greenhouse environment utilizing seeds from populations collected in Illinois in 2008, 2009, and 2010. In the shading study, both control (66.7% ± 1.3%) and green wrap (63.7% ± 1.3%) had similar and greater percent seed germination than the solid white wove paper (59.5% ± 1.3%). Percent seed germination was similar for seeds collected in 2010 and 2009 (59.5% ± 3.3% and 55.1% ± 4.4%, respectively) in the longevity study, but germination was lower for seeds collected in 2008 (27.1% ± 4.0%) compared with both of the other years. For the soilless mixes study, seeds sown in only one of the three media, Fafard Super-Fine Germinating Mix, emerged (3.5% ± 1.0%). Results from these studies suggest that for S. bullii, (i) seeds may be shade tolerant, (ii) seed viability lessens with age, and (iii) seedlings require a special soilless mix to grow. The information generated by this study can provide guidelines for better seed storage and germination protocols for the conservation of this rare plant species.

scholarly journals Estimation of Seed Bank and Seed Viability of the Gulf of Saint Lawrence Aster, Symphyotrichum laurentianum, (Fernald) Nesom

2004 ◽  
Vol 118 (1) ◽  
pp. 105 ◽  
Author(s):  
Joni F. Kemp ◽  
Christian R. Lacroix
Keyword(s):  
Seed Bank ◽  
Prince Edward Island ◽  
Seed Viability ◽  
Management Plan ◽  
Seed Banks ◽  
The Family ◽  
The Status ◽  
Viable Population ◽  
Tetrazolium Staining ◽  
Persistent Seed Bank

The Gulf of St. Lawrence Aster, Symphyotrichum laurentianum, is a member of the family Asteraceae and is listed as “threatened” by COSEWIC (Committee on the Status of Endangered Wildlife in Canada). This rare and vulnerable halophyte grows in only a few locations in New Brunswick, Prince Edward Island, and the Magdalen Islands, Quebec. As an annual, S. laurentianum relies exclusively on its seeds to survive to the next generation. The goal of this study was to estimate the quantity of viable S. laurentianum seeds in the persistent and transient seed banks at selected sites in Prince Edward Island. Overall, the number of seeds in the transient and persistent seed banks is low. The greatest concentration of seeds was found near the surface of the soil. In addition, only a small proportion of those seeds tested positive for viability based on Tetrazolium staining. Of the seeds in the persistent and transient seed banks combined, 53% were viable whereas only 2% of the seeds in the persistent seed bank were viable. Population surveys were also completed at the five known sites (both extinct and extant) in Prince Edward Island National Park. All sites showed signs of decline based on population estimates dating back to 1993. The Covehead Pond site showed the greatest decline: from 250-300 individuals in 1993 to only 10 individuals in 2002. The population at Dune Slack also showed a dramatic decrease from approximately 65 000 in 1999, to 2 200 individuals in 2002. Monitoring of this plant and the development of a management plan for the species are critical to its survival.

scholarly journals Dactylorhiza kalopissii (Liliopsida: Orchidacea) in Bulgaria: Distribution and conservation status

2019 ◽  
Vol 2 ◽  
Author(s):  
Antoaneta Petrova ◽  
Diana Venkova ◽  
Irina Gerasimova
Keyword(s):  
Endangered Species ◽  
Vascular Plants ◽  
Conservation Status ◽  
Natura 2000 ◽  
Red List ◽  
Local Distribution ◽  
Council Directive ◽  
The Status ◽  
Population Numbers ◽  
Single Locality

The Balkan sub-endemic species Dactylorhiza kalopissii E. Nelson is distributed in Bulgaria, Greece and North Macedonia. It has a local distribution and inhabits alkaline fens, wet meadows, and mountain rivulet banks. This orchid is a globally endangered species, included in Annex IIb of the Council Directive 92/43 EEC. It was first reported for Bulgaria in 1991 and until 2008 it was known only from this single locality in the country. Here we summarize the recent data on the distribution of the species in Bulgaria, the population numbers and their fluctuation in time. During the period 2008 - 2019 the species was found in more than ten localities of six floristic regions. Populations usually number less than 250 individuals. For some of the populations, data from recurrent observations are provided. We discuss the habitats and their management. The negative changes of the habitat quality during the last years for some of the localities are described as well. The species was evaluated as CR B1ab (iii) + 2ab (iii) according to the Red List of Bulgarian vascular plants. We reevaluate the status based on the improved knowledge. The species is still Critically Endangered in Bulgaria, but В2ab (iii, v) status better corresponds with recent data. Five of the known localities fall within the boundaries of Natura 2000 SCIs.

scholarly journals Factors affecting the local distribution of Polystigma rubrum stromata on Prunus spinosa

2018 ◽  
Vol 151 (2) ◽  
pp. 278-283
Author(s):  
Hattie R. Roberts ◽  
Sara E. Pidcock ◽  
Sky C. Redhead ◽  
Emily Richards ◽  
Kevin O’Shaughnessy ◽  
...  
Keyword(s):  
Leaf Surface ◽  
Early 20Th Century ◽  
Local Distribution ◽  
Factors Affecting ◽  
Prunus Spinosa ◽  
Gall Mite ◽  
Western Ireland ◽  
Winter Flooding ◽  
Individual Trees ◽  
Field Location

Background and aims – Polystigma rubrum forms orange-red stromata on the surface of living leaves of Prunus spinosa and P. domestica. Records suggests that this fungus now has a much more limited distribution in Britain than recorded in the 19th and early 20th century. Methods – We studied the local distribution of the fungus in the Burren Hills of western Ireland where it remains very common. Key results – Assessment of the local distribution of the fungus over two years found stromata to occur more frequently on P. spinosa leaves in hedgerows than woodlands. On individual trees in areas of open limestone pavement, the frequency of stromata was ten times higher in 2016 than 2015, possibly related to interannual rainfall differences. On hedgerow trees subjected to winter flooding, stromata were much less abundant, whereas stromata were more abundant on leaves also infected by the gall mite Eriophyes prunispinosae. The identity of Po. rubrum was confirmed by ITS sequencing.Conclusion – At a field location where Po. rubrum stromata are present in unusually high abundance, the distribution of stromata on trees in different habitats showed high levels of variation linked to both habitat and the presence of gall mites. Further work is required to determine whether variation in leaf surface and soil moisture are the key determinants of the observed distribution. Such investigations may reveal why Po. rubrum, once common in northern Europe is now restricted mainly to westerly, coastal locations.

The study of interfacial reactions of nickel thin films on GaAs

1983 ◽  
Vol 41 ◽  
pp. 156-157
Author(s):  
L.J. Chen ◽  
Y.F. Hsieh
Keyword(s):  
Thin Films ◽  
Integrated Circuits ◽  
Interfacial Reactions ◽  
Metal Contacts ◽  
Nickel Thin Films ◽  
Thin Foils ◽  
The Status ◽  
Si Doped ◽  
Electron Microscopes

One measure of the maturity of a device technology is the ease and reliability of applying contact metallurgy. Compared to metal contact of silicon, the status of GaAs metallization is still at its primitive stage. With the advent of GaAs MESFET and integrated circuits, very stringent requirements were placed on their metal contacts. During the past few years, extensive researches have been conducted in the area of Au-Ge-Ni in order to lower contact resistances and improve uniformity. In this paper, we report the results of TEM study of interfacial reactions between Ni and GaAs as part of the attempt to understand the role of nickel in Au-Ge-Ni contact of GaAs.N-type, Si-doped, (001) oriented GaAs wafers, 15 mil in thickness, were grown by gradient-freeze method. Nickel thin films, 300Å in thickness, were e-gun deposited on GaAs wafers. The samples were then annealed in dry N2 in a 3-zone diffusion furnace at temperatures 200°C - 600°C for 5-180 minutes. Thin foils for TEM examinations were prepared by chemical polishing from the GaA.s side. TEM investigations were performed with JE0L- 100B and JE0L-200CX electron microscopes.

Fate of sperm membrane in fertilized ova

1993 ◽  
Vol 51 ◽  
pp. 40-41
Author(s):  
Frank J. Longo
Keyword(s):  
Electron Microscopy ◽  
Electrical Activity ◽  
Sea Urchins ◽  
Morphological Changes ◽  
Integrated System ◽  
Electrophysiological Recording ◽  
Experimental Conditions ◽  
The Status ◽  
Sperm Membrane ◽  
Temporal And Spatial

Measurement of the egg's electrical activity, the fertilization potential or the activation current (in voltage clamped eggs), provides a means of detecting the earliest perceivable response of the egg to the fertilizing sperm. By using the electrical physiological record as a “real time” indicator of the instant of electrical continuity between the gametes, eggs can be inseminated with sperm at lower, more physiological densities, thereby assuring that only one sperm interacts with the egg. Integrating techniques of intracellular electrophysiological recording, video-imaging, and electron microscopy, we are able to identify the fertilizing sperm precisely and correlate the status of gamete organelles with the first indication (fertilization potential/activation current) of the egg's response to the attached sperm. Hence, this integrated system provides improved temporal and spatial resolution of morphological changes at the site of gamete interaction, under a variety of experimental conditions. Using these integrated techniques, we have investigated when sperm-egg plasma membrane fusion occurs in sea urchins with respect to the onset of the egg's change in electrical activity.

Revisiting the status of dental ethics instruction

2000 ◽  
Vol 64 (11) ◽  
pp. 772-774 ◽  
Author(s):  
JG Odom ◽  
PL Beemsterboer ◽  
TD Pate ◽  
NK Haden
Keyword(s):  
Ethics Instruction ◽  
The Status

The status of cosmology

2002 ◽  
Vol 110 (2) ◽  
pp. 9-15 ◽  
Author(s):  
W Freedman
Keyword(s):  
The Status

Multicultural Assessment of Personality and Psychopathology in the United States: Still Art, Not Yet Science, and Controversial

1998 ◽  
Vol 14 (1) ◽  
pp. 62-70 ◽  
Author(s):  
Richard H. Dana
Keyword(s):  
United States ◽  
Racial Identity ◽  
The United States ◽  
Therapeutic Assessment ◽  
Culturally Competent ◽  
Research Attention ◽  
The Status ◽  
Training Research ◽  
Multicultural Assessment ◽  
Personality Description

This paper describes the status of multicultural assessment training, research, and practice in the United States. Racism, politicization of issues, and demands for equity in assessment of psychopathology and personality description have created a climate of controversy. Some sources of bias provide an introduction to major assessment issues including service delivery, moderator variables, modifications of standard tests, development of culture-specific tests, personality theory and cultural/racial identity description, cultural formulations for psychiatric diagnosis, and use of findings, particularly in therapeutic assessment. An assessment-intervention model summarizes this paper and suggests dimensions that compel practitioners to ask questions meriting research attention and providing avenues for developments of culturally competent practice.

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