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The use of aminopyralid combined with metsulfuron for western snowberry control was evaluated with field trials conducted near Rushville, NE. Herbicides treatments consisted of aminopyralid plus metsulfuron, aminopyralid plus metsulfuron plus 2,4-D, 2,4-D alone, and metsulfuron plus chlorsulfuron plus 2,4-D plus dicamba. All treatments were applied in May and June. Sixty days after treatment (DAT) western snowberry control with aminopyralid plus metsulfuron at 0.073 + 0.012 kg ai ha−1 applied in May was 64%, whereas when applied in June, control was 97%. Meanwhile control with 2,4-D was 99 and 78% for the May and June applications, respectively. No major differences between application timings were observed 60 DAT for the rest of the treatments, with control levels ranging from 85 to 99%. One year after application, differences in control between application timings only persisted for 2,4-D. At 365 DAT, western snowberry control with aminopyralid plus metsulfuron at 0.073 + 0.012 kg ai ha−1 was 76 and 78% for May and June applications, respectively. The addition of 2,4-D at 1.1 kg ai ha−1 to aminopyralid plus metsulfuron provided excellent control and was similar to the combination of metsulfuron, chlorsulfuron, 2,4-D, and dicamba for both May and June applications. Grass production and animal carrying capacity were higher after western snowberry control with the majority of the treatments. Aminopyralid plus metsulfuron applied at the lower rate was the exception. The increase in the carrying capacity after western snowberry control ranged from 2.2 to 4.5 animal unit month (AUM). The control of western snowberry resulted in an increase in net income per hectare when compared with the untreated checks, ranging from $4 to $47.9 ha−1. Several options are available for effective western snowberry control during a broader time of application with increased grass production.

Historically, fires occurred throughout the year in the Fescue Prairie of Canada, but little is known about plant community responses to burning at different times of the year. Composition of plant communities was determined annually for 6 years after burning one or three times in a remnant Fescue Prairie in central Saskatchewan. A multiple-response permutation procedure indicated that plant community composition was different in the two burning histories (P

Standing crop and species composition in semiarid grassland are linked to long-term patterns of water availability, but grasslands are characterized by large single-season variability in rainfall. We tested whether a single season of altered water availability influenced the proportions of grasses and shrubs in a semiarid grassland near the northern edge of the North American Great Plains. We studied stands of the clonal shrub snowberry (Symphoricarpos occidentalis) and adjacent grassland dominated by the native grasses Stipa spartea and Bouteloua gracilis. Rain was excluded and water supplied in amounts corresponding to years of low, medium, and high rainfall, producing a 2 − 4-fold range in monthly precipitation among water supply treatments. There were ten replicate plots of each water treatment in both snowberry stands and grassland. Grass standing crop increased significantly with water availability in grassland but not inside snowberry stands. Total standing crop and shrub stem density increased significantly with water supply, averaged across both communities. In contrast, water had no effect on shrub standing crop or light penetration. In summary, our finding that water has significant effects on a subset of components of grassland vegetation is consistent with long-term, correlational studies, but we also found that a single season of altered water supply had no effect on other important aspects of the ecosystem.

Aspen poplar, balsam poplar, prickly rose and western snowberry species grow together in pastures of the aspen parkland and reduce the grass and forb production available for grazing. Two 7-yr studies were conducted in east central Saskatchewan to evaluate metsulfuron-methyl (metsulfuron), 2,4-D and a mixture of metsulfuron + 2,4-D for the long-term control of these woody species. Metsulfuron applied at 60 g a.i. ha−1 effectively controlled the four woody species for 7 yr. Control was not improved when 2,4-D at 2 kg a.i. ha−1 was added to the 60 g ha−1 rate of metsulfuron. Aspen poplar control was improved when sucker regrowth was 2-yr old rather than 3-yr old. Grass and forb production was increased 50% from 1023 kg ha−1 in the untreated areas to 1619 kg ha−1 following application of 60 g ha−1 metsulfuron in two experiments averaged over 5 yr. Forbs production decreased from 44% on the untreated area to 8% on areas treated with metsulfuron. Key word: Aspen poplar, balsam poplar, prickly rose, western snowberry, metsulfuron-methyl, 2,4-D

Two 6-yr studies were conducted in southeastern Saskatchewan to evaluate 2,4-D, Metsulfuron methyl (Metsulfuron) and a mixture of 2,4-D + Metsulfuron for the long-term control of western snowberry. Western snowberry is a small shrub that grows in dense stands in rangelands and pastures and acts as a physical barrier to grazing. At the study site, the shrub was growing with native grasses and forbs. Metsulfuron applied at 15 g a.i. ha−1 effectively controlled western snowberry for 6 yr. Control with Metsulfuron was better than with 2,4-D because Metsulfuron killed the crown of the shrub. Control was not improved when 2,4-D was added to Metsulfuron, and at low levels of Metsulfuron the presence of 2,4-D in the mixture rendered Metsulfuron less effective, resulting in a higher canopy cover. Grass production averaged over years and experiments was 788 kg ha−1 for the check and increased to 1328 kg ha−1 after Metsulfuron was applied at 15 g ha−1. Forb production was not affected by the treatments. Key words: Western snowberry, Symphoricarpos occidentalis, metsulfuron methyl, 2,4-D

Seven- and nine-year studies were conducted in northeastern Saskatchewan to compare the long-term control of aspen poplar (Populus tremuloides Michx.) and western snowberry (Symphoricarpos occidentalis Hook.) following single and multiple applications of 2,4-D ester (2,4-DE) or amine (2,4-DA) mixed with dicamba. The area was bulldozed free of trees and was subsequently invaded by aspen poplar and western snowberry regrowth, native forbs and grasses. Herbicides were applied to 2- and 4-yr-old regrowth of aspen poplar, growing with a small uniform stand of western snowberry. A single application of dicamba with either 2,4-DE or 2,4-DA applied at 1.5 + 2.2 kg (a.i.) ha−1 was as effective as two or three consecutive yearly applications for the control of aspen poplar. In one experiment, two consecutive applications of dicamba + 2,4-D controlled western snowberry whereas in the other experiment a single application was adequate. The highest forage production of grasses and forbs occurred following dicamba + 2,4-DE treatments. Following a single dicamba + 2,4-DE application, grass production, averaged over 7 and 9 yr, increased from 38 to 98 g m−2 and from 31 to 83 g m−2, whereas forb production decreased from 48 to 25 g m−2 and from 58 to 48 g m−2, respectively. Key words: Aspen poplar, Populus tremuloides, western snowberry, Symphoricarpos occidentalis, 2,4-D dicamba

traits, and survival status of this taxonomic variety are the subjects of this study. Native Humulus populations were typically associated with only a few tree and shrub species, notably Acer negundo L. [box elder], Crategus spp. [hawthorn], Fraxinus nigra Marsh. [black ash], F. pennsylvanica Marsh. [green ash], Populus balsamifora L. [balsam poplar], P. deltoides Marsh. [cottonwood], Prunus americana Marsh. [wild plum], P. pensylvanica L. [pin cherry], P. virginiana L. [choke cherry], Quercus macrocarpa Michx. [bur oak], Ribes spp. [wild currant], Rosa spp. [wild rose], Salix spp. [willow], Sambucus canadensis L. [elder], Symphoricarpos occidentalis Hook. [snowberry], and Viburnum opulus var. americanum Ait. [highbush cranberry]. Cone (strobilus) variations, exceeding those of leaves and vines, included size (15 mm to 45 mm long), shape (globose to ovoid-conical), and compactness (loose vs. imbricated bracts). Trait diversity of seedling progenies exceeded that of each native population from which they originated. Traits of genetically potential usefulness included dwarf plant habit, precocious cone production, early season flowering, pest repellence, frost resistance, potential drought resistance, and commercially desirable cone structure. Both native-plant and progeny populations were generally free of diseases common to commercial hops, thus offering germplasm that is compatible with institutional hop breeding programs. Persistence of native hop populations from 1989 to 1999 was problematic, with five of 11 selected study sites sustaining complete loss or serious damage. Protection of sensitive riparian habitats occupied by this genetic resource may be warranted, particularly until adequate germplasm sources are secured and reposited for further investigation and use.

Spring fires were conducted in Symphoricarpos occidentalis Hook, stands to determine the effect of fire on the shrub and associated species. The canopy cover of Symphoricarpos had recovered to the level of unburned stands 3 months after fire. Stem density increased three to five times in the first 3 months and then gradually declined during the 2nd and 3rd year. Rubus strigosus increased in cover and stem density when burned and remained at higher levels for the 3 years studied. Forbs increased after fire with the cover of most annuals peaking the first growing season while perennials maintained a higher cover. The density of woody stems and coverage of the shrub, perennial forb, and grass and sedge groups continued to be higher 3 years after burning. There were substantial changes in one or more of frequency, cover, or density of major species.

Annual early spring burning has markedly altered the physiognomy and species composition of aspen parkland vegetation of east-central Alberta. Burning was conducted in April for at least 24 years when soil moisture was normally high. The number of herbaceous species per quadrat doubled while a number of woody species declined slightly. Forest cover declined while grassland increased. In the grass and shrublands, cover of the shrub Symphoricarpos occidentalis and the cool season grass Festuca scabrella declined greatly. Major increases in Calamovilfa longifolia, Carex obtusata, C. heliophylla, and Solidago missouriensis were noted. While the cover of Festuca scabrella and Stipa spartea var. curtiseta decreased; frequency of these species increased. Cover of all shrubs decreased, Populus tremuloides suckers excepted, while density of the fire adapted Elaeagnus commutata, Amelanchier alnifolia, Prunus virginiana, and Populus tremuloides suckers increased. Burning reduced the leaf blade length of all major grasses and sedges. Effect of burning on inflorescence production varied from species to species. Annual herbage production was reduced by burning with the grass and sedge component experiencing about a 50% reduction. Burning caused an increase in organic matter and phosphorus content of the Ah horizon. Burning did not appear to detrimentally affect the nitrogen status of the Ah horizon.

A carpet-covered roller was used to apply 2,4-D, 2,4-D+picloram (9:1 a.i.), and glyphosate at several concentrations to regrowth of aspen and balsam poplars (Populus tremuloides Michx., P. balsamifera L.), and willow (Salix spp.) growing with an understory of rose (Rosa woodsii Lindl.) and saskatoon (Amelanchier alnifolia Nutt.) and to western snowberry (Symphoricarpos occidentalis Hook.). A concentration of 2.25% a.i. of 2,4-D amine controlled aspen poplar for 3 yr, but was not satisfactory on the other species. A concentration of 0.60% + 0.07% a.i. of 2,4-D+picloram controlled both poplars and willow. A concentration of 0.53% a.i. of glyphosate controlled both poplar species adequately, but a 1.6% concentration was needed for good control of willow. None of the treatments was satisfactory on western snowberry because of poor coverage. The percentage of leaf area wetted was low, about 10%, and evidence is presented that better coverage will result in better brush control with more dilute herbicide. Brush too short to be wiped by the roller can rapidly replace the brush killed. Forage species suffered only minor and temporary damage.Key words: Glyphosate, 2,4-D, picloram, roller-applicator, poplar, willow, western snowberry

Bromegrass (Bromus inermis Leyss. cult Carlton) was grown alone or with aspen (Populus tremuloides Michx.), silverberry (Elaeagnus commutata Bernh.), or western snowberry (Symphoricarpos occidentalis Hook.) in the greenhouse for 90 days. Competition reduced the yields of grass and woody plants compared with yields obtained when either was grown alone. Bromegrass grown alone or with aspen or snowberry produced similar total yields, but when grown with high density silverberry, the total yields were significantly greater. The yield of oat forage obtained from soil that had grown a previous crop of woody plants was reduced by previous high production of aspen or snowberry, but oat yield increased with previous high production of silverberry. It is known that another species of the genus Elaeagnus is a nitrogen-fixer and the silverberry plants used in this study were nodulated. The beneficial effects of silverberry on the grass may have been due to nitrogen fixation.

Quantitative data were collected in 101 vegetational stands in two regions considered to be representative of dune sand vegetation within the grassland zone of Saskatchewan. The purpose was to ascertain species distributional patterns and to attempt to relate these distributions to environmental factors. The data were used to establish two ordinations, one based on physiographic types and the other on compositional similarities between the stands. Areas of active erosion and deposition are dominated by rhizomatous species, particularly Agropyron spp. and Psoralea lanceolata. Juniperus horizontalis is prominent in stabilized blowouts, while stabilized dunes support grassland dominated by Stipa comata, Carex eleocharis, and Koeleria cristata. The most mesic sites, dune depressions and sand flats, are occupied by Carex heliophila and Agropyron spp. with a shrubby overstory of Symphoricarpos occidentalis, Rosa woodsii, and Prunus virginiana. Factorial gradients involved in the distributional patterns include a moisture gradient ranging from xeric to mesic and a stability gradient ranging from active complexes to stabilized areas. The existence of these gradients and the intergradation of the species behavioral patterns offer strong evidence of the continuous nature of dune sand vegetation in Saskatchewan.