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

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Abstract
Following a two-stage sampling plan, 44 1-km2 primary units were systematically allocated between 53 and 59.degree. latitude throughout northern Quebec 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 .gtoreq. 700-mm precipitation zone and the lowest in the 500- to 599-mm zone. Data on percent plant cover indicated that 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. Cladina 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.