Browsing Journal of Range Management, Volume 51, Number 4 (July 1998) by Subjects
Now showing items 1-2 of 2
Growth responses of warm-season tallgrasses to dormant-season managementA study on Conservation Reserve Program (CRP) land was established in southeastern Nebraska to determine the effect of dormant-season management on subsequent-year growth rates and yields of tallgrasses. The purpose of the management practices was removal of standing dead material and litter that negatively impact plant growth and grazing efficiency. Treatments consisted of a control with no residue manipulation and 5 residue manipulation practices including (1) October shredding and leaving residue; (2) October haying; (3) October intensive grazing; (4) March intensive grazing; and (5) spring prescribed burning. The study was conducted in 1994/95 and 1995/96 on a switchgrass (Panicum virgatum L.) monoculture and mixed stand of warm-season tallgrasses dominated by big bluestem (Andropogon gerardii Vitman) and little bluestem [Schizachyrium scoparium (Michx.) Nash]. The manipulation treatments effectively removed standing dead material without reducing yields in the growing season following application. Marked switchgrass tillers on the control plots increased (P < 0.1) in height at a more rapid rate than switchgrass on other treatments until late summer in both years. Rate of morphological development was similar (P > 0.1) for all treatments in 1995 and 1996. Rate of height increase and morphological development in big and little bluestem on the mixed grass site generally was comparable or slower on the manipulation treatments than the control in both years; however, big and little bluestem tillers grew relatively rapidly at the end of the 1995 growing season. Because the manipulation treatments generally did not increase tiller growth rates of the dominant grass species, potential harvest dates would be similar to those of untreated areas.
Morphological development of 2 warm-season grasses in the Nebraska SandhillsMorphological development of grasses has numerous implications to rangeland management including the timing and amount of herbivory. The objective of this study was to quantify the developmental morphology of prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.] and sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.] tiller populations. Tiller populations of these 2 grasses were studied for 2 years in the Nebraska Sandhills. Plant development was evaluated using a growth staging system which quantifies the development of tiller populations. A morphological growth index for each species was calculated from either the weighted average of tiller numbers reported as mean stage count (MSC) or tiller weight reported as mean stage weight (MSW) and correlated with the independent variables of growing degree days (GDD) and day of year (DOY). Correlation coefficients with the independent variables were greater than 0.97 for MSC and MSW within years and greater than 0.90 between years. Greater rainfall and warmer temperatures in 1991 increased the number of tillers in the more advanced morphological stages in prairie sandreed, but tiller weight rather than tiller number increased in more advanced stages of sand bluestem. A majority of the harvested tillers were vegetative throughout the sampling period but by the end of the growing season, a wide range of morphological stages were present. The use of grazing to prevent the formation of culmed tillers in these grasses may be unnecessary because of the high proportion of vegetative tillers and the wide range of morphological stages available for selection by livestock.