Using a grazing pressure index to predict cattle damage of regenerating tree seedlings
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Authors: M. D. Pitt, R. F. Newman, P. L. Youwe, B. M. Wikeem, and D. A. Quinton
Date: 1998
Journal: Journal of Range Management
Volume: 51
Number: 4
Pages: 417-422
Summary of Methods: Pitt et al. measured the effects of cattle grazing on lodgepole pine (Pinus contorta) seedlings in seeded clearcut areas at different stocking rates (AU days/ha) and grazing pressures (AU/Mg per ha). Most damage to lodgepole pine seedlings occurred during the first and second years of the study. After this time cattle browsed and trampled significantly less tree seedlings, possibly because of the increased size of the trees in these later years. During the first year of the study, as stocking rate and grazing pressure increased, basal scarring and browsing of tree seedlings increased, however, only grazing pressure was still related to seedling damage after the first year of the study. The authors concluded that grazing pressure (AU/Mg per ha) was a better predictor of lodgepole pine seedling damage in this system and that grazing pressures greater than 12.0 AU/Mg per ha caused significant damage to seedlings, however, they caution that grazing pressure thresholds may not be the same for all systems and that these should be determined before grazing is applied in timber production areas.
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: lodgepole pine, pinus contorta, cutblocks, forest grazing, british columbia
Annotation: Period of cattle grazing was 7,14, 21, and 30 days. Cows were grazed from mid-July to mid-August from 1989 to 1992. Cow-calf pairs were established to annually to achieve 50 and 80% use of available forage in each pasture. The number of cow-calf pairs in each pasture varied annually from 3 to 32. 10 plots were clipped in the grazed area to a 5-cm stubble height and 10 plots were also clipped to 5-cm in the ungrazed exclosure.
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