Dry grasslands in Wood Buffalo National Park: reply

In examining dry grassland areas of Wood Buffalo National Park (WBNP), we used vascular plant indicators commonly found in the grassland landscapes in the southern and central parts of the Prairie Provinces. With distance northward the landscapes become increasingly tree-dominated and the dry grasslands have fewer dry grassland indicator species (about 40 in the area of WBNP) and become smaller in size (about 1 ha in WBNP). Key species are Stipa comata Trin & Rupr., Stipa curtiseta (A.S. Hitchc.) Barkworth, and Stipa columbiana Macoun on the drier sites. Paleontological records and historical documents suggest that these remnant dry grasslands must expand during decades of drought and must contract during decades of higher summer rainfall. We hypothesize that fires might enhance dry grassland expansion by stressing and killing trees and shrubs. Southern dry grassland vascular plant species represent over 7% of the total in WBNP. It is reasonable to hypothesize that these represent special ecotypes that deserve special protection through prescribed burning.Key words: remnant grasslands, Stipa spp., climate change.

Slope, aspect, and slope position as factors controlling grassland communities in the coulees of the Oldman River, Alberta

Vegetation and environmental variables were examined in some coulees of the Oldman River near Lethbridge, Alta. Principal components analysis of environmental variables indicated that solar energy, aspect, soil Mg2+, [Formula: see text], and moisture were related to the first axis of variation. Slope position, soil [Formula: see text], moisture, K+, [Formula: see text], and amount of bare ground were related to a second axis of variation. There was a large range in species diversity among plots; most diverse plots were on north-facing slopes. Direct ordination of vegetation data indicated that slope position and aspect were most important in describing distribution of species. Koeleria macrantha, Bouteloua gracilis, Stipa comata, and Artemisia frigida were found on most coulee positions. Hymenoxys richardsonii, Machaeranthera grindeloides, Astragalus spatulatus, and Eriogonum flavum were mostly restricted to summit and upper slope positions. Anemone patens, Geum triflorum, Thermopsis rhombifolia, and others were most abundant on north- and east-facing slopes. Fewer species (e.g., the C4 Aristida longiseta and the cactus Coryphantha vivipara) were mostly confined to south-facing positions.

The influence of a weedy habitat on the seed bank of an adjacent cultivated field

Seed traps positioned 1 to 100 m into a cultivated field were used to assess the seed rain from an adjacent weedy pasture. The cultivated field was in the fallow phase of a crop-fallow rotation. Two sets of traps were used: one set contained steampasteurized soil and the other contained untreated soil from the field. Traps were left in the field for 12 months and then transported to a greenhouse where they were kept for 12 additional months. Seed content was determined by field and greenhouse emergence of seedlings. The pasture was dominated by grasses, the most abundant being Poa pratensis, Stipa comata, Bromus inermis, and Agropyron repens. Seeds of pasture species were found in decreasing numbers in the fallow field, with few found more than 7 m from the fence line in traps of both sterilized and nonsterilized soil. The fallow field was dominated by species such as Setaria viridis, Thlaspi arvense, Descurainia sophia, and Salsola kali which were not found in abundance in the pasture. It was concluded that seed rain from the pasture had a significant influence on the germinable seed content of the soil of the cultivated field (at the edge only). The incursion of pasture species into cultivated land presumably has been restricted by cultural practices.

Tebuthiuron Effects on Artemisia Spp. and Associated Grasses

Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} was evaluated on three Wyoming soil types for control of big sagebrush (Artemisia tridentata Nutt.), silver sagebrush (Artemisia cana Pursh.), and phytotoxic effects on associated vegetation. Big sagebrush was controlled with tebuthiuron at application rates of 0.6 to 1.1 kg ai/ha, whereas silver sagebrush was not completely controlled. Prairie junegrass [Koeleria pyramidata (Cam.) Beauv.], western wheatgrass (Agropyron smithii Rydb. ♯3 AGRSM), needleandthread (Stipa comata Trin. ♯ STDCO), and green needlegrass (Stipa viritdula Trin. ♯ STOVI) were not significantly reduced with tebuthiuron up to 1.1 kg ai/ha. Blue grama (Bouteloua gracilis H.B.K. ♯ BOBGR), downy brome (Bromus tectorum L. ♯ BROTE), plains pricklypear (Opuntia polyacantha Haw. ♯ OPUPO), and broom snakeweed [Gutierrezia sarothrae (Pursh.) Britt. and Rugsby, ♯ GUESA] were tolerant to tebuthiuron at rates up to 1.1 kg ai/ha.

NUTRITIVE CHARACTERISTICS OF GRASSES ON SPRING RANGE IN SOUTH CENTRAL BRITISH COLUMBIA IN RELATION TO TIME, HABITAT AND FALL GRAZING

Bluebunch wheatgrass (Agropyron spicatum), crested wheatgrass (Agropyron desertorum), Sandberg bluegrass (Poa sandbergii), cheatgrass (Bromus tectorum), needle-and-thread (Stipa comata) and Junegrass (Koeleria cristata) forage samples were collected from 14 Feb. to 31 May 1974. The samples were analyzed for crude protein, phosphorus, calcium, magnesium, neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin. Polynomial regressions were used to describe the change of chemical constituents over time. Bluebunch wheatgrass, crested wheatgrass and needle-and-thread were relatively high in crude protein, phosphorus and ADF while Sandberg bluegrass was relatively high in magnesium and calcium but low in NDF, ADF and lignin. In both bluebunch wheatgrass and Sandberg bluegrass, lignin was higher on the open range than on the treed range while NDF was higher in Sandberg bluegrass but lower in bluebunch wheatgrass on the open range. Cheatgrass displayed fewest differences between habitats. Few significant differences occurred between fall grazed and fall ungrazed bluebunch wheatgrass or crested wheatgrass plants. Crude protein, NDF and lignin tended to be higher but calcium lower in grazed plants.

ALKALINE CUPRIC OXIDE OXIDATION OF ROOTS AND ALKALINE-EXTRACTABLE ORGANIC MATTER OF CHERNOZEMIC SOILS

Alkaline cupric oxide oxidation was performed on roots of three grass species, on humic substances from three Chernozemic soils, and on three known compounds. The three grass species were Stipa comata Trin. & Rupr., Stipa spartea Trin. var. curtiseta Hitchc, and Festuca scabrella Torr., the three Chernozemic soils were Brown, Dark Brown and Black, and the three known compounds were vanillin, p-hydroxybenzaldehyde, and syringaldehyde. The intent of the study was to obtain a qualitative overview of the set of ethyl ether-soluble products. The gas chromatographic patterns were, therefore, qualitatively assessed and only some of the major peaks were tentatively identified. The ethyl ether-soluble fraction represented only up to 5.7% of the total root C. Most of the compounds identified in the root digests were also present in digests of the alkaline-soluble humic substances. There were quantitative differences for each chromatographic peak among root species, among time of sampling and growth location, and among extraction procedures of humic substances. The oxidation of the three known compounds in turn led to a number of compounds. The CuO-NaOH oxidation may thus cause alterations in similar compounds released from the original structure which will lead to either inflated or deflated yields of compounds that were part of the original structure.

A taxonomic study of the large-glumed species of Stipa (Gramineae) occurring in Canada

The morphology and awn anatomy of the large-glumed species of Stipa occurring in Canada were examined. Numerical analysis of the data indicates that S. spartea var. spartea and S. spartea var. curtiseta are very distinct taxa differing not only in many of their quantitative characters but also in nodal pubescence, ligule shape, and pubescence of the leaf margin. It is proposed that they be treated as separate species, S. spartea and S. curtiseta. Some evidence was found for differentiation within S. spartea s.s. but it was deemed insufficient for the recognition of infraspecific taxa. Stipa comata var. comata and S. comata var. intermedia are very similar in all morphological characters examined. Cross sections of their distal awn segments do, however, show consistent distinguishing characters; those of var. intermedia are more heavily lignified and tend to be square in outline compared with those of var. comata. Although similar to each other, cross sections of the varieties of S. comata are distinct from those of S. spartea and S. curtiseta. The possibility that certain specimens were hybrids between S. comata var. comata and S. curtiseta was explored and rejected. Distribution maps and a key to the accepted taxa are given.

EFFECTS OF INITIAL CHEMICAL COMPOSITION ON DECOMPOSITION OF ROOTS OF THREE GRASS SPECIES

Grass root production is a major source of C entering Chernozemic soils. The influence of the initial chemical composition of the roots of three grass species on decomposition was studied in a laboratory incubation experiment. Roots of Stipa comata Trin. and Rupr., Stipa spartea Trin. var. curtiseta Hitchc., and Festuca scabrella Torr. were incubated at 28 C for 47 wk. Carbon dioxide production and percent loss of carbohydrate were inversely related to [(C:N) (% lignin)] (% carbohydrate−½). Percent loss of lignin, however, was directly proportional to this factor. This relationship was also found to fit data in the earlier literature. Decomposition rate appeared to be slower in the laboratory in the absence of soil than has been reported for decomposition rates in field soils. The data are discussed with reference to the dynamics of plant residues and organic matter in soil systems. It is postulated that the effect of soil in controlling decomposition may be as great as the effect of the substrate.

SOIL PROPERTIES AFFECTING THE VEGETATIVE COMPOSITION OF AGROPYRON COMMUNITIES AT KAMLOOPS, BRITISH COLUMBIA

The dominant range grass species of climax stands in the Kamloops area of British Columbia is Agropyron spicatum, but throughout this area there are localized regions where Stipa comata is dominant. It was believed that certain edaphic factors influenced the composition of the two grassland stand types. Stipa comata was observed to be growing on gravelly and coarse textured soils with low available water storage capacity, while Agropyron spicatum grew on finer soils with higher water storage capacities. At the beginning of the growing season, soils supporting Agropyron had a higher field moisture content than did nearby soils supporting Stipa. However, Stipa was observed to develop faster and is believed to be more highly adapted to droughty soil conditions.

GERMINATION AND EARLY GROWTH OF GRASSES AT FOUR ROOT-ZONE TEMPERATURES

Six native grass species, Bouteloua gracilis, Stipa comata, Koeleria cristata, Festuca scabrella, Andropogon scoparius, and Danthonia parryi, and six introduced grass species, Elymus junceus, Bromus inermis, Agropyron cristatum, Agropyron tricophorum, Festuca rubra, and Dactylis glomerata, were germinated and grown for 90 days at root-zone temperatures of 7, 13, 18, and 27 °C. In general, the introduced species were superior to the native species in percentage germination and speed of germination and germinated, emerged and grew more readily at lower root-zone temperatures. Introduced species produced about 10 times as much weight of leaf and about eight times as much weight of root as did the native species at comparable growth stages. The chances of establishment and successful early growth of seeded stands appeared to be better with introduced grass species than with native grass species.