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. Resumen El manejo del pastoreo es importante para mantener una productividad sostenida y la salud de los pastizales. Sin embargo, el efecto del manejo del pastoreo en el crecimiento del forraje y la composición de las especies en las sabanas tropicales del norte de Australia se desconocen. En este estudio de 8 añ os se consideró la influencia de la tasa de utilización y el descanso del pastoreo en potreros en la dinámica de la vegetación. El estudio se llevó a cabo en tres sitios en el noroeste de Queensland Australia. Los sitios tenían niveles de fertilidad en el suelo altos, mediano y bajo, y se tenían dos clases de condición (Estado I y II) en cada sitio. Se presentó una sequía muy severa durante los primeros 4 añ os pero durante la otra mitad del estudio la precipitación fue por arriba del promedio. Las altas tasas de utilización redujeron la biomasa y el área basal y cobertura ae´rea de las gramíneas perenes. La reducción en la biomasa se debió tanto al alto consumo y la reducción de la producción primaria. Las parcelas en el estado de condición I en los suelos con fertilidad mediana y alta estuvieron domin...
Beef cattle grazing is the dominant land use in the extensive tropical and sub-tropical rangelands of northern Australia. Despite the considerable knowledge on land and herd management gained from both research and practical experience, the adoption of improved management is limited by an inability to predict how changes in practices and combinations of practices will affect cattle production, economic returns and resource condition. To address these issues, past Australian and international research relating to four management factors that affect productivity and resource condition was reviewed in order to identify key management principles. The four management factors considered were stocking rates, pasture resting, prescribed fire, and fencing and water point development for managing grazing distribution. Four management principles for sound grazing management in northern Australia were formulated as follows: (1) manage stocking rates to meet goals for livestock production and land condition; (2) rest pastures to maintain them in good condition or to restore them from poor condition to increase pasture productivity; (3) devise and apply fire regimes that enhance the condition of grazing land and livestock productivity while minimising undesirable impacts; and (4) use fencing and water points to manipulate grazing distribution. Each principle is supported by several more specific guidelines. These principles and guidelines, and the supporting research on which they are based, are presented.
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