Effects of summer grazing by caribou on composition and productivity of vegetation: Community and landscape level
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Authors: M. Manseau, J. Huot, and M. Crete
Date: 1996
Journal: Journal of Ecology
Volume: 84
Number:
Pages: 503 - 513
Summary of Methods: To determine how a migrating caribou (Rangifer tarandus) herd influences plant community and productivity of summer range, authors compared grazed (in previous years) and ungrazed sites on two plant communities, the shrub tundra and stands of dwarf birch (Betula glandulosa) on the Riviere George in Northeast Quebec. Grazing on the tundra reduced lichens cover. Ground cover of shrubs not eaten by caribou was lower in grazed sites than in ungrazed sites, and coverage of graminoids, forage shrubs, and forbs did not differ significantly between grazed and ungrazed sites. In stands of dwarf birch, caribou have primarily modified ground cover and biomass of dwarf birch. Grazing and trampling have opened the closed canopy of dwarf birch and decreased leaf biomass by 60%. In contrast, ground cover and biomass of ground species have neither increased in response to thinning of the canopy nor decreased in response to grazing and trampling. Caribou have had a significant impact on plant biomass and indirectly on distribution of the food source at the landscape level. The serious negative impact of migratory ungulates on plant productivity of their summer range may be explained by characteristics of the vegetation and the high carrying capacity of winter compared to summer ranges. Significant factors related to the vegetation are its low resilience and productivity and the absence of a response of vascular plants following removal of lichens.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: caribou, rangifer tarandus, herbivory, overgrazing, plant-animal interaction, ungulate
Annotation: Plants were cut at one cm above the ground at each sampling site. ,Grazing defined as "ungrazed" and "grazed".
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