No abstract

Fifty-two species of lichens were found on Larix lyallii Parl. and Pinus albicaulis Engelm. trees in 31 stands in the subalpine zone of the mountains of southwestern Alberta. The species belong to the following North American distributional elements: 25, Pan Boreal; 13, Arctic Boreal; 8, Cordilleran or Western Boreal; 2, Pan North American; 2, Eastern Boreal; and 1, uncertain.In Larix lyallii, quadrats occupying the lower 30 cm of the trunk were characterized by a Parmeliopsis hyperopta – P. ambigua – Cetraria pinastri union whereas quadrats in a region 40 cm deep, centered at 1.3 m from the base, were occupied by a Letharia californica – Alectoria glabra union. In Pinus albicaulis, the lower quadrats were characterized by a Parmeliopsis ambigua – Cetraria pinastri – Parmeliopsis hyperopta – Lecidea fuscescens union whereas the upper were occupied by a Parmelia sphaerosporella – Letharia californica – Lecanora varia – Alectoria glabra union.Forty-eight species occurred on the smooth to rough, more absorbent, bark of Pinus albicaulis compared with 32 found on the rough bark of Larix lyallii.Succession followed four stages: (1) the invasion of appressed foliose lichens on the tree bases, (2) the appearance of crustose species on the lower four feet of the trunk, (3) the invasion of foliose species on the trunk and branches, and (4) the appearance of fruticose species.

The distribution and general ecology of 249 macrolichen taxa is described for 230 000 km2 of coniferous forest, open fens, and alpine terrain along the Mackenzie River in the District of Mackenzie, Northwest Territories, and the Peel River, a major tributary which rises in the Yukon Territory. Permafrost plays a major role in determining the plant communities that are present. Fire and man-made disturbances initiate succession. There are 45 new reports for the District of Mackenzie and 30 for the Yukon. Of the taxa, 86% are found in Europe, Asia, and North America, 9% are known from Asia and North America, whereas only 4% are restricted to North America. Pilophorus robustus is new to Canada. High mountains in the western part of the area, generally nonglaciated during the Wisconsinian, support a flora that contains many Arctic and Arctic–Alpine taxa. Amphi-Beringian species occur primarily in the north.

Haddock (Melanogrammus aeglefinus) eggs from an experimental culture were examined by electron and light microscopy to determine the structure of the egg envelope as preserved by various fixatives and to observe the effects on the envelope of microbial colonization during incubation. The egg envelope consisted of a featureless thin surface coating that readily dissociated into globules and was lost under standard fixation; a thin homogeneous surface layer penetrated by pores; a well-defined intact outer lamella 0.5-1.0 µm thick immediately beneath this; then about three more vaguely defined lamellae of similar thickness beneath which were several broader fibrillar layers. The total envelope thickness was 6.5-8.5 µm. Different fixatives primarily affected the appearance of the thin surface layer, which was well-preserved only by freezing or by fixation in glutaraldehyde with Alcian blue. Egg surfaces were colonized by microorganisms, regardless of early disinfection by various agents, and eggs at hatching were densely populated by bacteria, notably the filamentous genus Leucothrix. However, bacteria did not penetrate the egg envelope beyond the outer layers, where their presence was associated with surface erosion. A dense epiflora did not necessarily prevent normal development of the embryo, although very heavy infestations, as seen on eggs that failed to hatch, may cause suffocation. The envelope structure is compared with that of another gadoid which has been extensively studied and cultured, the Atlantic cod (Gadus morhua).

The relative abundance and ecology of 123 lichens, 12 liverworts, 1 peat moss, 59 mosses, and 40 vascular plants are described from the southeastern part of Prince Patrick Island, 76° N latitude. One hundred and three of the lichens, 25 of the bryophytes, and 6 of the vascular plants are first reports for the island. One lichen, Blastenia arctica, is reported for the first time from North America. One hundred and seventy of the species were found on the ground, 51 on rock, 9 on decaying plant material, 9 on bone, 5 on fossil wood, 4 on caribou dung, and 2 on mosses. Sixteen habitat types are described, based upon a relevé analysis of 31 different sites. A percentage of the lichens (95.1%), of the bryophytes (95.8%), and of the vascular plants (60.0%) encountered have a Circumpolar distribution. A percentage of the lichens (3.3%), of the bryophytes (1.4%), of the vascular plants (22.5%) have an American distribution. Eight species have an Amphi-Beringian distribution: lichens, 1.6%; bryophytes, 1.4%; vascular plants, 12.5%. One bryophyte (1.4%) and two vascular plants (5.0%) have an Amphi-Atlantic distribution.