Grazing Management in Tropical Savannas: Utilization and Rest Strategies to Manipulate Rangeland Condition |
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| Authors: | Andrew J Ash Jeff P Corfield John G McIvor Taoufik S Ksiksi |
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| Institution: | 1. Director, CSIRO Climate Adaptation Flagship, GPO Box 2583, Brisbane, QLD 4001, Australia;2. Research Project Officer, CSIRO, Private Mail Bag, PO Aitkenvale, QLD 4814, Australia;3. Research Scientist, CSIRO, GPO Box 2583, Brisbane, QLD 4001, Australia;4. Associate Professor, Department of Biology, United Arab Emirates University, PO Box 15551, Al-Ain, United Arab Emirates;1. College of Agriculture, Hawassa University, P.O. Box 05, Hawassa, Ethiopia;2. International Livestock Research Institute (ILRI), P.O. Box 30709, 00100 Nairobi, Kenya;3. School of Veterinary Medicine, Hawassa University, P.O. Box 05, Hawassa, Ethiopia;4. World Agroforestry Centre (ICRAF), P.O. Box 30677, 00100 Nairobi, Kenya;5. Botswana University of Agriculture and Natural Resources, Department of Animal Science and Production, Private bag 0027, Gaborone, Botswana;1. Departments of Environmental Studies and Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA;2. Earth Research Institute, University of California, Santa Barbara, CA 93106, USA;1. Research Scientist, Colegio de Postgraduados, Campus Veracruz, Predio Tepetates, Municipio de Manlio Fabio Altamirano, Veracruz, Mexico, C.P. 91690.;3. Professor, Colegio de Postgraduados, Campus Veracruz, Predio Tepetates, Municipio de Manlio Fabio Altamirano, Veracruz, Mexico, C.P. 91690.;2. Professor, Centro de Enseñanza, Investigación y Extensión en Ganaderia Tropical (CEIEGT), FMVZ-UNAM, Tlapacoyan, Veracruz, Mexico, C.P. 93600. |
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| Abstract: | Grazing management is important for sustaining the productivity and health of rangelands. However, the effects of grazing management on herbage growth and species composition in the tropical savannas of northern Australia are not well known. In this eight-year study the influences of utilization rate and resting pastures from grazing on vegetation dynamics were measured at three sites in northeast Queensland, Australia. The sites had high, medium, and low soil fertility, and there were two land condition classes (States I and II) at each site. Severe drought occurred during the first four years, but above-average rainfall was received in the second half of the study. High utilization rates reduced biomass, perennial grass basal area, and ground cover. The reduction in biomass was due to both higher consumption and decreased primary production. State I condition plots at the high and medium soil fertility sites were initially dominated by decreaser perennial grasses, but these declined at all utilization levels, particularly the high rate. They were largely replaced by exotic perennial grasses. At the low fertility site there were no exotic grasses, and the decreaser grasses increased in all treatments, with the increases greatest in plots with low utilization or medium utilization plus resting. In the State II condition plots at the high and medium fertility sites, low or moderate utilization, led to an increase in both decreaser and exotic perennial grasses; with high utilization the decreaser perennial grasses declined and were replaced largely by exotic perennial grasses. This study clearly demonstrated that either conservative stocking with year-round grazing or a grazing system that includes some wet-season resting will help maintain land in a desirable state or help facilitate the transition from a less desirable ecological state to one more desirable for pastoral production and rangeland condition. |
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