Effects of Grazing Intensity,Precipitation, and Temperature on Forage Production |
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| Institution: | 1. Assistant Range Scientist, Central Grasslands Research Extension Center, North Dakota State University, Streeter, ND 58483;2. Range Scientist and Director, Central Grasslands Research Extension Center, North Dakota State University, Streeter, ND 58483;3. Administrative Officer, Central Grasslands Research Extension Center, North Dakota State University, Streeter, ND 58483;1. Research assistants, Hulunber Grassland Ecosystem Research Station, Laboratory of Grassland Science, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, People’s Republic of China;2. Researcher, Hulunber Grassland Ecosystem Research Station, Laboratory of Grassland Science, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, People’s Republic of China;3. Research Associate, Hulunber Grassland Ecosystem Research Station, Laboratory of Grassland Science, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, People’s Republic of China;4. Professor, School of Animal Biology and Institute of Agriculture, The University of Western Australia, Crawley WA 6009, Australia;5. Doctor, Gansu Agricultural University, Lanzhou 730070, People’s Republic of China;6. Professor, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093;1. Assistant Project Scientist, Department of Plant Sciences, University of California, Davis, CA, 95616, USA;2. Assistant Professor, Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA;3. Supervisory Research Rangeland Management Specialist and Research Leader, USDA-ARS Rangeland Resources Research Unit, Cheyenne, WY 82009, USA;4. Professor, Department of Environmental Science and Policy, University of California, Davis, CA, 95616, USA;5. Professor and Rangeland Watershed Cooperative Extension Specialist, Department of Plant Sciences, University of California, Davis, CA, 95616, USA;1. Research Ecologist, USDA-ARS Grassland, Soil and Water Research Laboratory, Temple, TX 76502, USA;2. Professor, Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, USA;3. Plant Physiologist, USDA-ARS Crops Research Laboratory, Fort Collins, CO 80526, USA;4. Research Associate, National Oceanic and Atmospheric Administration, Earth Systems Research Laboratory, Boulder, CO 80305, USA;5. Professor, Animal and Range Sciences Department, New Mexico State University, Las Cruces, NM 88003, USA;6. Rangeland Management Specialist, USDA-NRCS Jornada Experimental Range, New Mexico State University, Las Cruces, NM 88003, USA. |
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| Abstract: | Questions have been raised about whether herbaceous productivity declines linearly with grazing or whether low levels of grazing can increase productivity. This paper reports the response of forage production to cattle grazing on prairie dominated by Kentucky bluegrass (Poa pratensis L.) in south-central North Dakota through the growing season at 5 grazing intensities: no grazing, light grazing (1.3 ± animal unit months AUM] · ha-1), moderate grazing (2.7 ± AUM · ha-1), heavy grazing (4.4 ± AUM · ha-1), and extreme grazing (6.9 ± AUM · ha-1; mean ± SD). Annual herbage production data were collected on silty and overflow range sites from 1989 to 2005. Precipitation and sod temperature were used as covariates in the analysis. On silty range sites, the light treatment produced the most herbage (3 410 kg · ha-1), and production was reduced as the grazing intensity increased. Average total production for the season was 545 kg · ha-1 less on the ungrazed treatment and 909 kg · ha-1 less on the extreme treatment than on the light treatment. On overflow range sites, there were no significant differences between the light (4 131 kg · ha-1), moderate (4 360 kg · ha-1), and heavy treatments (4 362 kg · ha-1; P &spigt; 0.05). Total production on overflow range sites interacted with precipitation, and production on the grazed treatments was greater than on the ungrazed treatment when precipitation (from the end of the growing season in the previous year to the end of the grazing season in the current year) was greater than 267.0, 248.4, 262.4, or 531.5 mm on the light, moderate, heavy, and extreme treatments, respectively. However, production on the extreme treatment was less than on the ungrazed treatment if precipitation was less than 315.2 mm. We conclude that low to moderate levels of grazing can increase production over no grazing, but that the level of grazing that maximizes production depends upon the growing conditions of the current year. |
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