In perennial grassland dominated systems, belowground bud banks regulate plant community dynamics. Plant community responses to disturbance are largely driven by the ability to generate future aboveground growth originating from belowground axillary buds. This study examined bud bank dynamics for Bouteloua gracilis, Hesperostipa comata, and Pascopyrum smithii following fire in northwestern mixed-grass prairie in eastern Montana, USA. Belowground axillary buds were counted and classified for three growing seasons to determine immediate and short-term effects of summer, fall, and spring prescribed burns on patterns of bud bank activity, dormancy, and mortality. Prescribed burns did not result in immediate mortality of B. gracilis, H. comata, or P. smithii buds. Surprisingly, spring prescribed burns immediately increased the number of active B. gracilis buds. Summer fire, however, reduced B. gracilis active bud numbers. Fall burns immediately activated P. smithii buds, whereas fire did not influence any immediate bud dynamics for H. comata. Reduced bud numbers of H. comata may limit the ability to respond to fire. Season of fire directly manipulated bud activity, dormancy, and mortality for these species throughout the growing and dormant seasons following fire. Using season of fire to manipulate bud bank dynamics illustrates potential to improve post-fire management strategies based on known bud development trajectories and bud dynamics following fire.

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Aristida purpurea (purple threeawn) is a competitive native perennial grass with monoculturistic tendencies and poor palatability. We examined effects of fire, defoliation, and interspecific/intraspecific planting for 1) threeawn responses in the presence of threeawn, Bouteloua gracilis, or Pascopyrum smithii, and 2) B. gracilis and P. smithii response with threeawn. Biomass, aboveground production, tillers, and axillary buds were analyzed following two fire and four clipping treatments applied to three species-pair combinations in a completely randomized factorial design with nine replications. Fire killed 36% of threeawn. Fire reduced surviving threeawn biomass 61% and reduced production 27%. Threeawn production was greatest when neither plant was clipped and least when competing species were moderately clipped, or when both plants were severely clipped. Tiller counts of burned threeawn were similar among clipping treatments, and less than non-clipped or moderately clipped plants not burned. Fire decreased threeawn axillary buds on average by 25%. Moderately clipped plants had greater production than those from other clipping treatments across species. Average threeawn percentage of pot biomass was greater with B. gracilis (46 6 3% SE) than P. smithii (38 6 3% SE). Fire reduced threeawn from 60 6 3% to 23 6 3% of pot biomass, indicating good potential for rapid reductions in threeawn dominance and restoration of plant diversity with fire.

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Grazing distribution can be improved by using adapted cattle breeds that travel to distant areas of extensive pastures. A 2-yr study was conducted to evaluate grazing distribution and diet quality of Angus, Brangus, and Brahman cows (seven cows per breed group) in the Chihuahuan Desert during three seasons (winter, early summer, and late summer) using three pastures. Two GPS collars were randomly assigned to each breed group and cow positions were logged every 10 min for 10-to 14-d periods in each pasture (3 periods Á season À1 ). In 2008, breed groups were evaluated in separate pastures and data were analyzed as a 333 Latin square design. In 2009, all breed groups were evaluated at the same time in the same pastures. Fecal samples were collected in 2008 and analyzed using near infrared spectroscopy (NIRS) to estimate diet quality. If positions recorded when cows were resting were excluded, Brahman cows traveled greater distances per day than Angus cows throughout the study and greater (P 0.10) than Brangus cows in all but one season during 2009. No differences in average distance to water were detected (P . 0.10) among breed groups. During early summer in 2008 and early and late summer in 2009, Angus cows maintained a more linear grazing path (P 0.10) than Brangus or Brahman cows. Brahman cows displayed more sinuous grazing paths (P 0.10) than other breeds during early and late summer seasons in 2009. In 2008, no differences in crude protein content of diets were detected (P . 0.10) among breed groups during all seasons. Spatial movement patterns of Brahman cows appeared to differ from Angus and Brangus cows; however, there was no evidence to suggest that there was any advantage in use of areas far from water by any breed group. ResumenLa distribución del pastoreo puede ser mejorada usando razas de ganado que se adapten a caminar largas distancias en potreros grandes. Se realizó un estudio de dos años para evaluar la distribución del pastoreo y calidad de la dieta de vacas Angus, Brangus, y Brahman (siete vacas por grupo racial) en el Desierto Chihuahuense durante tres temporadas (invierno, inicio, y finales de verano) usando tres potreros. Dos collares con GPS fueron asignados aleatoriamente a cada grupo racial y la posición de las vacas fue anotada cada 10 minutos por periodos de 10 a 14 días en cada potrero (tres periodos por temporada). En 2008, los grupos raciales fueron evaluados en porteros separados y los datos fueron analizados en un diseño de cuadro latino de 333. En 2009, todos los grupos raciales fueron evaluados al mismo tiempo en los mismos potreros. En 2008 se recolectaron muestras fecales y se analizaron usando espectroscopia infrarroja (NIRS) para estimar la calidad de la dieta. Sí se excluye el tiempo registrado de cuando las vacas estuvieron descansando, las vacas Brahman recorrieron mayores distancias por día que las vacas Angus a través del estudio y mayor (P 0.10) que las vacas Brangus en todos pero una temporada durante el 2009. No se encontró diferencia (P . 0.10) en distancia a el agua e...