Terrestrial Lichens Research Articles

Canopy, snow, and lichens on woodland caribou range in southeastern Manitoba

I examined the relationships among snow cover (api), lichen abundance, and canopy composition on the range of the Aikens Lake population of woodland caribou (Rangifer tarandus caribou) in southeastern Manitoba. Percent cover of forage lichens (Cladina spp.) was positively correlated with maximum total thickness and with maximum vertical hardness of api. Mixed communities of trembling aspen (Populus tremuloides), spruce (Picea spp.), and balsam fir (Abies balsamea) showed the most favourable nival conditions for caribou but had low lichen abundance; those dominated by jack pine (Pinus banksiana) were the converse. The results suggest an energetic compromise for woodland caribou when foraging for terrestrial lichens. During winter, caribou exhibited significant selection for jack pine communities whereas mixed communities were avoided.

Cadmium, lead, mercury and 137 cesium in fruticose lichens of northern Québec

Cadmium, lead and mercury concentration averaged 0.171, 4.09 and 0.09 μg · g −1 (dry wt.) respectively, in terrestrial lichens over a 640 000-km 2 study area of Northern Quebéc; the average cesium level reached 378 B1 · kg −1 (dry wt.). Cadmium and lead were the most closely related pollutants in lichens, while there was little relationship between 137cesium and the three trace metals. The distribution of the elements over the territory was not uniform and the altitude influenced three of them. The cesium concentration increased along with this variable, while lead levels were higher in the middle altitude class (200–400 m) than in the two other classes. There was a significant interaction between altitude and biome for mercury concentration, this element being almost twice more abundant in the tundra below 400 m than in the forest tundra and the boreal forest. The mercury level was related to percent ground cover by Alectoria ochroleuca, Cornicularia divergens and Cetraria nivalis, three lichen species typical of a wind-exposed habitat. Lead concentration was related only to Cornicularia divergens ground cover. In general, the concentrations of cadmium, lead and mercury were higher in the northwest quarter of the study area than elsewhere, while cesium contamination was highest in the southeast quarter. It seems preferable that caribou should be harvested at low elevation when they are taken in winter in order to minimize the risk associated with cesium consumption by humans.

Biomasse et espèces de lichens terrestres disponibles pour le caribou dans le nord du Québec

Following a two-stage sampling plan, 44 1-km2 primary units were systematically allocated between 53 and 59 ° latitude throughout northern Québec to estimate the biomass of terrestrial lichens. Lichens were collected in two secondary units (0.25 m2) located in parts of each primary unit where lichens were visible from a helicopter (lichen stratum). Overall, the lichen stratum covered 51% of the study area and lichen biomass averaged 1223 kg/ha (dry weight; SE = 201; n = 44). Almost 85% of the variance of this mean was attributable to variability between primary units. The biomass in the west was greater than in the east; it was the highest in the [Formula: see text]700-mm precipitation zone and the lowest in the 500- to 599-mm zone. Data on percent plant cover indicated mat mosses increased in importance over lichens in the east. There was a clear relationship between lichen biomass in secondary units on one hand and mat thickness and percent lichen ground cover on the other. Cladinia stellaris (Opiz) Brodo was the most common species; Alectoria ochroleuca (Hoffm.) Mass. and Cornicularia divergens Ach. were typical of the north, whereas Cladina mitis (Sandst.) Hustich characterized the south of the study area. The annual consumption of lichens by caribou was probably 0.5-0.9% of the available biomass in 1987. Key words: biomass, caribou, Cladina, lichens, Quebec.

Lichens as indicators of fluoride emission from a phosphorus plant, Long Harbour, Newfoundland, Canada

Fluoride concentrations in the terrestrial lichens Cladina rangiferina (L.) Harm, and Cladina stellaris (Opiz.) Brodo. were correlated inversely with distance from an industrial plant producing elemental phosphorus at Long Harbour, Nfld., in the direction (NE) of the prevailing wind. The fluoride concentrations ranged from 2830 ppm dry weight in a severely damaged area close to the emission source to 15.5 ppm (dry weight) 12 km NE of the industrial plant. Control samples from unpolluted areas had an average fluoride content of 6.4 ppm dry weight. The minimum observed damage symptoms occurred when these lichens had a fluoride content of 25 ppm dry weight. Damage symptoms included discolouration and structure loss. Discolouration effects were not as pronounced as observed on Abies balsamea (L.) Mill, or on Polytrichum commune (Hedw.) but combined with structure loss allowed the degree of damage to be readily identified in the field. Fluoride concentrations in these terrestrial lichens are compared with levels in soil humus, A. balsamea and some terrestrial bryophytes in four damage zones. The lichen tissue had, on average, twice as much fluoride as occurred in soil humus from the same site and about one half the amount of fluoride found in the terrestrial bryophyte P. commune. The effects of fluoride emissions on the epiphytic lichens Hypogymnia physodes (L.) W. Wats, and Alectoria sarmentosa (Ach.) Ach. in this area are also discussed.

Lipid and Fatty Acid Composition of Tree‐Growing and Terrestrial Lichens

AbstractA comparison of lipid and fatty acid composition was made of the tree‐growing lichens Evernia prunastri (L.) Ach., Parmelia saxatilis (L.) Ach. and Hypogymnia physodes (L.) Ach. and the terrestrial species Cetraria islandica (L.) Ach. and Cladonia impexa Harm.In the terrestrial species the total lipid content varied strongly during spring, while the tree‐growing species showed much less variation. Phospholipid and sterol content of all lichens was unusually low. Monoglycosyl diglyceride was absent from Parmelia saxatilis. Fatty acids common to higher plants as palmitic, stearic, oleic, linoleic and linolenic acid were invariably present in all lichen species. In addition large quantities of extra‐long chain fatty acids like behenic acid, eicosadienoic acid and cyclic aliphatic lichen acids were present in the terrestrial species. The degree of (poly) unsaturation decreased in the order Evernia prunastri, Parmelia saxatilis. Fatty acids common to higher plants as palmitic, stearic, impexa, which decrease was compensated by an increase in extralong chain fatty acids and lichen acids. It is suggested that the lichen acids are of adaptive value for lichen species growing in the terrestrial habitats, which were characterized by extreme diurnal temperature variations. Just as the polyunsaturated fatty acids, lichen acids guarantee at lower temperatures a high flexibility of the membranes involved, at the same time as they are less susceptible to photo‐oxidation at the high daytime temperatures.

Lichen Biomass in Acadian and Boreal Forests of Cape Breton Island, Nova Scotia

Lichen Biomass in Acadian and Boreal Forests of Cape Breton Island, Nova Scotia

Relative Abundance of Food in Winter for Newfoundland Caribou

Information on the winter feeding behaviour of caribou Rangifer tarandus Bangs in Newfoundland and the relative abundance of food available to them in winter are presented. Sight and smell were used to locate food beneath the snow. Tall shrubs showing above the snow appeared to increase lichen availability by providing air vents. A comparison of absolute abundance of food, based on percentage of ground surface covered with plants, and the relative abundance of food in winter, based on species composition in feeding craters, indicated that shrubs were consumed more than the absolute abundance suggested. Shrubs and terrestrial lichens were consumed more on a lichen woodland range than on a subalpine range, even though caribou densities were similar. Snow was softer and shrubs taller on the lichen woodland range than the subalpine; these factors probably increased the relative abundance of shrubs and lichens in winter.

EFFECTS OF CHRONIC GAMMA IRRADIATION ON LICHEN COMMUNITIES OF A FOREST

Chronic gamma irradiation of an oak‐pine forest on Long Island reduced populations of corticolous and terrestrial lichens in approximate proportion to the rate of irradiation. The decline in species diversity was approximately linearly related to logarithmic increases in daily radiation exposure. While a daily exposure of 2700 R/day was estimated to have reduced diversity to 50% in the first year, a linear extrapolation of diversity, coefficient of community and similarity curves to zero suggested that certain lichens would survive 3 years' exposure at daily rates of 5,000–10,000 R, possibly more. There was an apparent threshold at 300 R/day for radiation effects on the composition of lichen communities; changes in relative density occurred at lower exposures. The crustose forms were more resistant than foliose or fruticose forms, an observation which parallels previous observations that the most radio‐resistant higher plants tend to be of short, stature.