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. 2003. Cattle herbage utilization patterns under highdensity rotational grazing in the Aspen Parkland. Can. J. Anim. Sci. 83: 541-550. Native Aspen Parkland landscapes consist of a complex mosaic of plant communities, including riparian meadows, upland grasslands, and forests. Sustainable livestock production in this environment depends on an understanding of livestock grazing behavior among communities, particularly under contemporary, intensive management rotational grazing systems. This study examined seasonal patterns of absolute (kg . ha -1 ) and relative (%) herbage utilization, as well as plant community visitation, across a Parkland landscape by 150 heifers in two rotations of a high-intensity, low-frequency grazing system. Graminoids constituted more than 92% of the total herbage utilized. Absolute graminoid utilization within each grazing period was greater (P < 0.05) throughout the growing season from riparian meadows (2003 to 2114 kg . ha -1 ) than from upland grasslands (762 to 1041 kg . ha -1 ) or forests (782 to 800 kg . ha -1 ). In contrast, relative graminoid utilization remained similar (P > 0.05) among communities in either rotation, suggesting heifers grazed in proportion to graminoid availability (57-61% in first rotation, 44-54% in second rotation). Although riparian meadows represented a small fraction of the landscape (~ 4%), and provided up to 9.5% of the total forage used, the majority of herbage removal at the paddock level continued to originate from upland grasslands and forests. Patterns of visitation indicated heifers initially visited riparian meadows more often within each 3-4 day grazing period, regardless of entry date. While upland grasslands were least visited in June, forests were least visited in August. Based on these utilization and visitation patterns, we discuss the implications of using high-density, rotational livestock grazing for the sustainable management of Aspen Parkland rangelands. Les prairies-parcs de trembles naturelles consistent en une mosaïque complexe de peuplements végétaux comprenant des prés riverains, des prairies sèches et des forêts. Élever du bétail de façon durable dans un tel environnement exige une solide connaissance du comportement des animaux qui se nourrissent des divers peuplements végétaux, surtout avec les régimes contemporains de gestion intensive des pâturages par rotation. L'étude portait sur des programmes saisonniers d'utilisation absolue (kg par hectare) ou relative (%) d'herbages et sur la fréquentation des écotypes par 150 génisses dans une région de prairies-parcs, en deux rotations, dans le cadre d'un régime de paissance à faible fréquence et à densité élevée. Les graminoïdes représentaient plus de 92 % des herbages consommés. Pendant la période végétative, les animaux ont consommé une plus grande quantité absolue (P < 0,05) de graminoïdes dans les prés riverains (de 2 003 à 2 114 kg par hectare) que dans les prairies sèches (de 762 à 1 041 kg par hectare) ou les forêts (de 782 à 800 kg par hectare) durant chaque période de pai...

. Seasonal herbage dynamics on Aspen Parkland landscapes in central Alberta. Can. J. Anim. Sci. 84: 149-153. We evaluated the temporal dynamics of herbage biomass and protein within riparian meadows and upland grasslands of native Aspen Parkland rangeland to understand the contribution of each to livestock foraging. For the growing season monitored, meadows were greater in forage yield and crude protein (P < 0.05), leading to important implications for sustainable livestock production and rangeland conservation.

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