Conservation Evaluation of the Seaside Birds-foot Trefoil, <em>Lotus formosissimus</em>, in Canada

George W. Douglas; Michael Ryan

doi:10.22621/cfn.v120i2.279

Conservation Evaluation of the Seaside Birds-foot Trefoil, Lotus formosissimus, in Canada

The Canadian Field-Naturalist ◽

10.22621/cfn.v120i2.279 ◽

2006 ◽

Vol 120 (2) ◽

pp. 153

Author(s):

George W. Douglas ◽

Michael Ryan

Keyword(s):

Fire Suppression ◽

Vancouver Island ◽

Habitat Destruction ◽

Range Limits ◽

Limiting Factors ◽

Herbaceous Species ◽

Conservation Evaluation

In Canada, Seaside Birds-foot Trefoil, Lotus formosissimus, is restricted to the Victoria area on southeastern Vancouver Island and two adjacent islands. Populations at five sites are extant and have been recently inventoried, whereas populations at two or more sites in Victoria are extirpated. Existing populations represent the northern range limits of L. formosissimus. Although known populations are protected to a certain extent from direct habitat destruction, introduced herbaceous species may pose a serious threat to the continued existence of most populations and may prevent the establishment of L. formosissimus at other sites. Fire suppression, grazing, encroachment and low survivorship are also limiting factors.

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Conservation Evaluation of the Prairie Lupine, Lupinus lepidus var. lepidus, in Canada

The Canadian Field-Naturalist ◽

10.22621/cfn.v120i2.278 ◽

2006 ◽

Vol 120 (2) ◽

pp. 147

Author(s):

George W. Douglas ◽

Michael Ryan

Keyword(s):

Seed Bank ◽

Fire Suppression ◽

Vancouver Island ◽

Habitat Destruction ◽

The Other ◽

Herbaceous Species ◽

Remote Location ◽

The Status ◽

Conservation Evaluation ◽

Lupinus Lepidus

In Canada, Prairie Lupine, Lupinus lepidus var. lepidus, is restricted to southeastern Vancouver Island. Of the nine sites where it has been collected, five are extirpated and the status of two of the populations is uncertain. There are two extant populations; some of the other sites may contain the species in the seed bank. Some of the sites are protected to a certain extent from direct habitat destruction by their remote location, although introduced herbaceous species may pose a serious threat by preventing the establishment of the species at other sites. Fire suppression or the lack of other types of disturbance also likely plays a role in discouraging emergence of Lupinus lepidus.

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Conservation Evaluation of Howell's Triteleia, Triteleia howellii, an Endangered Lily in Canada

The Canadian Field-Naturalist ◽

10.22621/cfn.v118i2.906 ◽

2004 ◽

Vol 118 (2) ◽

pp. 174

Author(s):

George W. Douglas ◽

Jenifer L. Penny

Keyword(s):

British Columbia ◽

Introduced Species ◽

Vancouver Island ◽

Habitat Destruction ◽

Range Limits ◽

Quercus Garryana ◽

Potential Threat ◽

General Biology ◽

Conservation Evaluation

In Canada, Triteleia howellii is restricted to Quercus garryana stands and grass-dominated meadows on southeastern Vancouver Island in southwestern British Columbia. Nine sites have been confirmed in recent years while three other sites are considered extirpated. These Canadian sites represent the northern range limits of T. howellii. Threats to existing populations vary in intensity. Although most populations are protected to a certain extent from direct habitat destruction, introduced species pose a serious potential threat to the continued existence of most populations. Managing sites for T. howellii is difficult because little information is available regarding the general biology of this species.

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Secret of Owls

When Birds Are Near ◽

10.7591/cornell/9781501750915.003.0020 ◽

2020 ◽

pp. 177-182

Author(s):

K. Bannerman

Keyword(s):

Urban Development ◽

Vancouver Island ◽

Habitat Destruction ◽

Barred Owls

This chapter looks at the author's experience hiking in the Cumberland Forest, which stretches up from swamps and wetlands, along ridges of hemlocks and pines, into a series of canyons that contain frozen rivers and a couple of small, ice-locked lakes. For three nights, the author had heard the sounds of Vancouver Island northern pygmy-owls. It is not uncommon to hear barred owls or great horned owls in Cumberland Forest, but the unique call of a pygmy-owl is relatively rare, and they had been more active than usual. Northern pygmy-owls were once numerous on the island, but since the 1920s, their numbers have been declining fast due to logging, urban development, and other activities leading to habitat destruction and so the fragmentation of their population.

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Conservation Evaluation of the Pacific Population of Tall Woolly-heads, Psilocarphus elatior, an Endangered Herb in Canada

The Canadian Field-Naturalist ◽

10.22621/cfn.v118i2.905 ◽

2004 ◽

Vol 118 (2) ◽

pp. 169

Author(s):

George W. Douglas ◽

Jeanne M. Illingworth

Keyword(s):

British Columbia ◽

Vernal Pools ◽

Vancouver Island ◽

Pacific Population ◽

Large Numbers ◽

The Pacific ◽

The Status ◽

Conservation Evaluation

In Canada, Psilocarphus elatior occurs in British Columbia, Alberta and Saskatchewan. This paper examines the status of the Pacific populations located on southeastern Vancouver Island in southwestern British Columbia. The Pacific population consists of 12 recorded sites of which only five have been confirmed since 1993. In British Columbia, P. elatior is associated with dried beds of vernal pools and other open, moist depressions at lower elevations. In British Columbia, P. elatior populations occur in large numbers at only two of the seven locations.

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Conservation Evaluation of Pacific Rhododendron, Rhododendron macrophyllum, in Canada

The Canadian Field-Naturalist ◽

10.22621/cfn.v120i2.282 ◽

2006 ◽

Vol 120 (2) ◽

pp. 169

Author(s):

George W. Douglas ◽

Julie Desrosiers

Keyword(s):

At Risk ◽

British Columbia ◽

Protected Areas ◽

Vancouver Island ◽

Coniferous Forests ◽

Northern California ◽

River Watershed ◽

River Drainage ◽

Skagit River ◽

Conservation Evaluation

In Canada, Pacific Rhododendron (Rhododendron macrophyllum) is restricted to the Skagit River drainage and southeastern Vancouver Island in southwestern British Columbia. These populations represent the northern limits of the species, which ranges south to northern California. In British Columbia, Rhododendron macrophyllum is usually associated with coniferous forests. Until recently this species was considered to be rare. Results of this study indicate that the populations in the Skagit River watershed are large, extensive and mostly contained in protected areas, thus the species is not considered to be at risk in Canada at this time.

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Effects of sterilization modes on the mechanical strengths of plaster of paris implants

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156432 ◽

1989 ◽

Vol 47 ◽

pp. 890-891

Author(s):

K. Cowden ◽

B. Giammara ◽

T. Devine ◽

J. Hanker

Keyword(s):

Gamma Radiation ◽

Calcium Sulfate ◽

Significant Loss ◽

Potassium Sulfate ◽

Limiting Factors ◽

Radiation Sterilization ◽

Plaster Of Paris ◽

Hardness Tester ◽

Dry Heat ◽

Calcium Sulfate Hemihydrate

Plaster of Paris (calcium sulfate hemihydrate, CaSO4. ½ H2O) has been used as a biomedical implant material since 1892. One of the primary limiting factors of these implants is their mechanical properties. These materials have low compressive and tensile strengths when compared to normal bone. These are important limiting factors where large biomechanical forces exist. Previous work has suggested that sterilization techniques could affect the implant’s strength. A study of plaster of Paris implant mechanical and physical properties to find optimum sterilization techniques therefore, could lead to a significant increase in their application and promise for future use as hard tissue prosthetic materials.USG Medical Grade Calcium Sulfate Hemihydrate Types A, A-1 and B, were sterilized by dry heat and by gamma radiation. Types A and B were additionally sterilized with and without the setting agent potassium sulfate (K2SO4). The plaster mixtures were then moistened with a minimum amount of water and formed into disks (.339 in. diameter x .053 in. deep) in polyethylene molds with a microspatula. After drying, the disks were fractured with a Stokes Hardness Tester. The compressive strengths of the disks were obtained directly from the hardness tester. Values for the maximum tensile strengths σo were then calculated: where (P = applied compression, D = disk diameter, and t = disk thickness). Plaster disks (types A and B) that contained no setting agent showed a significant loss in strength with either dry heat or gamma radiation sterilization. Those that contained potassium sulfate (K2SO4) did not show a significant loss in strength with either sterilization technique. In all comparisons (with and without K2SO4 and with either dry heat or gamma radiation sterilization) the type B plaster had higher compressive and tensile strengths than that of the type A plaster. The type A-1 plaster however, which is specially modified for accelerated setting, was comparable to that of type B with K2SO4 in both compressive and tensile strength (Table 1).

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Mosaic Mapping: A Means of Tiling Images to Shorten Acquisition Speed for Lower - Magnification SEM Images and Wavelength Dispersive Spectrometers (WDS) X-Ray Maps

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164659 ◽

1996 ◽

Vol 54 ◽

pp. 438-439

Author(s):

J.D. Geller ◽

C.R. Herrington

Keyword(s):

Limiting Factors ◽

X Rays ◽

Angular Range ◽

Acceptance Angle ◽

Sem Images ◽

Worst Case ◽

X Ray ◽

Focusing Distance ◽

Layered Crystals ◽

Working Distance

The minimum magnification for which an image can be acquired is determined by the design and implementation of the electron optical column and the scanning and display electronics. It is also a function of the working distance and, possibly, the accelerating voltage. For secondary and backscattered electron images there are usually no other limiting factors. However, for x-ray maps there are further considerations. The energy-dispersive x-ray spectrometers (EDS) have a much larger solid angle of detection that for WDS. They also do not suffer from Bragg’s Law focusing effects which limit the angular range and focusing distance from the diffracting crystal. In practical terms EDS maps can be acquired at the lowest magnification of the SEM, assuming the collimator does not cutoff the x-ray signal. For WDS the focusing properties of the crystal limits the angular range of acceptance of the incident x-radiation. The range is dependent upon the 2d spacing of the crystal, with the acceptance angle increasing with 2d spacing. The natural line width of the x-ray also plays a role. For the metal layered crystals used to diffract soft x-rays, such as Be - O, the minimum magnification is approximately 100X. In the worst case, for the LEF crystal which diffracts Ti - Zn, ˜1000X is the minimum.

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