Grazing Ecology Rangeland Conservation Defoliation Physiological Effects of Defoliation Palatability, Preference, and Selective Defoliation Physical Effects of Grazing Animals Energy Flow and Nutrient Cycling Redistribution of Minerals by Plants and Animals Distribution of Plants by Animals Fire as an Environmental Factor Rangeland Synecology Grazing Management Numbers of Animals Utilization of Forage Animal Distribution Mixed Species Grazing Mixed Species Management Seasonal Management Grazing Plans Responses to Seasonal Grazing Plans Vegetation Management Modification of Vegetation Mechanical Control of Rangeland Plants Chemical Control of Rangeland Plants Prescribed Fire in Rangeland Management Biological Control Seeding of Rangelands Rangeland Fertilization Soil and Water Conservation Managing Rangeland Complexity Reclamation of Damaged Rangeland Riparian Areas and Pollution: Best Management Practices Multiple-Use Planning for Rangeland Management Decision Support Systems

Rangeland ecology and management

The mixed prairie represents the most arid region of the Northern Great Plains in Canada. Approximately 6.5 M ha of the original total of 24 M ha have retained their native character. The native pr...

Production characteristics of the mixed prairie: constraints and potential

. Our overall objective was to use a soil water model to predict spatial patterns in germination and establishment of two important perennial C4-bunchgrasses across the North American shortgrass steppe and desert grassland regions. We also predicted changes in establishment patterns under climate change scenarios. Bouteloua gracilis dominates the shortgrass steppe from northeastern Colorado to southeastern New Mexico. Bouteloua eriopoda dominates desert grasslands in central and southern New Mexico. Germination and establishment for each species were predicted at 16 sites along the gradient using a daily time step, multi-layer soil water model (SOILWAT) to determine the percentage of years that temperature and soil water criteria for germination and establishment were met. Percentage of years with predicted establishment decreased from north to south for B. gracilis, but increased from north to south for B. eriopoda, comparable to observed dominance patterns. The 95 % confidence interval around the point at which simulated establishment were equal for the two species was near the location of the shortgrass steppe-desert grassland ecotone where both species are abundant. The intersection in percentage of years with establishment for the two species was predicted to move further north when climate was scaled using three Global Circulation Models (GCMs), indicating a possible northward expansion of B. eriopoda. Our results suggest that recruitment by seed may be an important process in determining, at least in part, the geographic distribution of these two species. Changes in climate that affect establishment constraints could result in shifts of species dominance that may or may not be accompanied by changes in species composition.

Geographic patterns of simulated establishment of two Bouteloua species: implications for distributions of dominants and ecotones

The effects of seeding depth (1.5, 3, or 6 cm) on seedling emergence, morphology, and anatomy were examined in cool-season (Agropyron dasystachyum, Agropyron desertorwn, Agropyron smithii, Elymus a...

Impacts of seeding depth on emergence and seedling structure in eight perennial grasses

originated in the USA and led to cultivar development of these species. Blue grama and little bluestem are Inadequate seed supplies of adapted blue grama [Bouteloua gracioutcrossing species (Anderson and Aldous, 1938; Rielis (H.B.K.) Lag. ex Steud.] and little bluestem [Schizachyrium scoparium (Michx.) Nash.] cultivars limits the use of these two species in gel, 1941; Miller, 1967) in which populations with high the northern Great Plains of Western Canada. This study examined levels of genetic diversity are found across a broad geovariation in seed yield traits of 11 blue grama and 14 little bluestem graphical range. McGinnies et al. (1988) found that blue plant collections obtained from southern Manitoba, Canada to facili- grama plants from a single pasture in Colorado showed tate development of improved germplasm of these species. Measure- high levels of variability in number and height of reproments of seed yield traits including harvested air-dried biomass, culm ductive culms, plant biomass, basal diameter, and anthenumber, seedhead number, seed yield, caryopsis weight, and kernel sis date. Coffin and Lauenroth (1992) found that differindex were taken from randomized complete block spaced-plant nurs- ences in seed yield of blue grama between range sites eries. Tests were conducted for 2 yr at Winnipeg and 1 yr at Carman, in north-central Colorado were greatly influenced by MB, Canada. Collections within both species differed significantly for soil texture and animal grazing. McMillan (1956) evaluall traits. Significant collection 3 year (Winnipeg) and collection 3 location interactions were present for biomass and seed yield, and ated 16 little bluestem ecotypes in Kansas and found many of the seed yield-component traits. While significant, the interac- differences in morphology and seed yield between poputions resulted in few changes in rank among collections. Generally, lations obtained from sites ranging from North Dakota the most northern collection in both species showed earlier anthesis, and Colorado to Kansas. He found that the local Kansas produced less biomass, and had lower seed yield than more southern ecotypes produced the highest seed yield; northern ecocollections. These findings indicate that indigenous plant collections types from near Waterton, ND showed earlier anthesis of blue grama and little bluestem show high levels of genetic diversity and low seedset; and southern ecotypes with late matufor biomass, seed yield, and seed yield components, which provide ration succumbed to autumn frosts. Selection in blue opportunity for development of adapted cultivars with enhanced for- grama has improved different seed yield traits such as age and seed production capability for the region. culms per plant (Lovington and Hachita), spikes per culm (Lovington), spikelets per spike (Hachita), and fertility (PM-K1482) (Wilson et al., 1981). Similar stud

Seed Yield Variation in Blue Grama and Little Bluestem Plant Collections in Southern Manitoba, Canada

Blue grama [Boute~ouugrociris(H.B.K.) Lag. ex Steud.] has not been able to establish itself, or to be successfully planted, from seed on abandoned croplands of the Central Plains. The objectives of this study were to test blue grama phmt material under limited moisture and develop methods for improving emergence and establishment of blue grama seedlings. Experiments were conducted in the greenhouse and at the Central Plains Experimental Range near NUM, Colorado, with 3 accessions. Under limited moisture conditions in the greenhouse, seedlings emerged better from planting depths of 2.0 and 2.5 cm than from depths of 0.5,l.O or 1.5 cm. Higher caryopsis weight was associated with a significant increase in percentage emergence at all planting depths. Accession PM-K-1483 had greatest emergence, followed by ‘Hachita’ and ‘Lovington’. Under favorable soil moisture conditions in the field (2 cm of water applied at planting dates in June and July 1981), deep planting resulted in decreased emergence. Averaged over all planting depths, percentage emergence increased nearly 2-fold with an increase in caryopsis weight from 39 to 59 mg/lOO. When soil moisture conditions were marginal (only 1 cm water added), satisfactory emergence was obtained only when highweight seeds were planted at a depth of 2 cm. Soil at a planting depth of 1 cm dried quickly and prevented emergence. Genetic improvement of caryopsis weight combined with planting at depths of about 2.0 cm should improve the emergence and establishment of blue grama seedlings.

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Caryopsis Weight and Planting Depth of Blue Grama. II. Emergence in Marginal Soil Moisture

Blue grama [Bouteloua grads (H.B.K.) Lag. ex Steud.] has been diicult to establish from seed on disturbed areas of the Central Plains. The objective of this study was to investigate the relationship of caryopsis weight, planting depth, and genetic variability on seedling emergence of blue grama. Two experiments were conducted in the greenhouse under favorable moisture conditions with 3 accessions and various combinations of caryopsis weight and planting depth. Measurements included rate of germination and emergence as an index, percentage emergence, shoot length, shoot weight, seminal root length, coleoptile length, subcoleoptile internode length and weight, adventitious root weight, and longest adventitious root length. The length of the subcoleoptile internode increased in response to greater planting depth but weight per unit length deereased. If this indicates a decrease in internode diameter it could decrease the rate of water transport through the internode. Deep plantings were not advantageous to emergence or seedling growth under favorable soil moisture conditions and caused a delay in emergence and decreased percentage emergence, shoot weight, and adventitious root weight. High crryopsisweight was associated with an increase in emergence, weight per unit length of the subcoleoptile internode, coleoptile length, shoot weight, and adventitious root weight. Therefore, high caryopsis weight is advantageous in the deep plnnting of blue grama seeds and allows seeds to be planted deeper to take advantage of moisture for germination and emergence.

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A.M. Wilson

Papers

Caryopsis Weight and Planting Depth of Blue Grama. II. Emergence in Marginal Soil Moisture

Caryopsis weight and planting depth of blue grama. I. Morphology, emergence, and seedling growth.