ABSTRACT
Excessive grazing affects plants directly by altering their physiology and morphology and indirectly by altering microclimate, soil properties, and the competitive interactions among plants.[3] Without sufficient leaf surface area, plants cannot efficiently capture the energy from sunlight via photosynthesis and root growth will be reduced. Over time, the composition of the vegetation changes, rainfall infiltration declines (Fig. 1), surface runoff increases, and plant production decreases. Grazing management involves balancing the number of animals with the forage supply, selecting the appropriate kinds and classes of animals to be grazed, controlling the timing of grazing, and distributing grazing evenly across the landscape.[7] Achieving the proper level of utilization of plants and maintaining an acceptable minimum amount of litter is the most important management decision, regardless of whether rangeland is grazed continuously or in a complex grazing system. The minimum amounts of litter needed to sustain productivity of shortgrass, mid-grass, and
tall-grass rangelands are 340-560 kg/ha, 840-1120 kg/ ha, and 1350-1680 kg/ha, respectively.[8] ‘‘Take half and leave half’’ is the guiding principle for determining stocking rates. Under most management systems, 50% of the forage produced during the year should remain ungrazed. Twenty-five percent of the year’s forage growth will be lost to trampling, insects, and other
R ainfall-S
atellite
animals, or rendered ungrazable due to livestock dung or urine. The remaining 25% of plant growth can be utilized by livestock.[8] Rangeland vegetation and precipitation records should be continually monitored, and livestock and wildlife numbers should be adjusted annually or even seasonally to achieve proper use.
