Campestris Rydb Research Articles

Grass Yields Under Clipping and Watering Explain Varied Efficacy of Management Intensive Grazing on Rangelands

Management intensive grazing (MIG) may not maximize plant productivity on rangelands because of morphophysiological traits of grassland vegetation. We examined defoliation and moisture effects on the biomass yield of rhizomatous and caespitose grass pairs that were either phylogenetically similar or of similar agroclimatic adaptation, including two agronomic grasses. From relatively low to high moisture regime adaptation, species pairs included western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) and needle-and-thread (Hesperostipa comata [Trin. & Rupr.] Barkw.), northern wheatgrass (Elymus lanceolatus [Scribn. & J.G. Sm.]) and western porcupine grass (H. curtiseta [Hitchc.] Barkw.), plains and foothills rough fescue (Festuca hallii [Vasey] and F. campestris Rydb.), and smooth and meadow brome (Bromus inermis Leyss. and B. riparius Rehm). Response variables were shoot yield, root-shoot ratio, and water-use efficiency. We hypothesized that caespitose grasses, regardless of their origin or adaptation to agroclimate regime, would respond more determinately in biomass accumulation. Defoliation effects on shoot biomass were more pronounced under high moisture. Low intensity−high frequency defoliation yielded similarly to deferred controls in all grasses, and the same was true for high-intensity−low-frequency (HILF) defoliation in 1 rhizomatous grass. Three of the 4 rhizomatous grasses and 1 caespitose grass yielded greater under HILF defoliation compared with high-intensity−high-frequency defoliation. Caespitose grasses allocated more biomass to roots under low moisture conditions. Water-use efficiency decreased under high moisture conditions and more intense and/or frequent defoliation and peaked in agronomic grasses. Overall, our results suggested that growth patterns corresponded more with phylogenetic similarity as opposed to growth form. A conceptual model from these results showed that across all species, only the introduced bromes generated greater biomass under HILF defoliation, and this may explain why past research consistently concludes that MIG does not enhance plant productivity on rangelands.

Long-term grazing effects on rough fescue grassland soils in southern British Columbia

Krzic, M., Lamagna, S. F., Newman, R. F., Bradfield, G. and Wallace, B. M. 2014. Long-term grazing effects on rough fescue grassland soils in southern British Columbia. Can. J. Soil Sci. 94: 337–345. Rough fescue (Festuca campestris Rydb.) is a highly palatable forage species with little resistance to continuous grazing. The objective of this study was to evaluate the effects of long-term cattle grazing on soil properties, above-ground biomass, and canopy cover of key grass species on rough fescue grasslands in the southern interior British Columbia. Soil and vegetation properties were determined on a total of six open grassland sites located at the Lac du Bois and Hamilton Mountain. At all sites, grazing use has decreased over time, with the heaviest grazing occurring prior to 1960. The long-term (25–75 yr) elimination of grazing on these semi-arid grasslands has led to greater above-ground biomass and canopy cover of rough fescue, as well as increased soil polysaccharides; however, no differences in total soil C, N, and aggregate stability were found between pastures with and without grazing. Both soil bulk density and mechanical resistance were greater on grazed plots compared with those without grazing, with differences being more pronounced at the Hamilton Mountain location. The current grazing regime has not allowed for the elimination of negative effects of overgrazing on soil compaction on these rough fescue grasslands, especially at the location that continued to be grazed more heavily (i.e., Hamilton Mountain). Our findings suggest that soils in these grazing-sensitive grasslands need more than 75 yr to fully recover from the impacts of overgrazing.

Long-term grazing effects on rough fescue grassland soils in southern British Columbia

Krzic, M., Lamagna, S. F., Newman, R. F., Bradfield, G. and Wallace, B. M. 2014. Long-term grazing effects on rough fescue grassland soils in southern British Columbia. Can. J. Soil Sci. 94: 337-345. Rough fescue (Festuca campestris Rydb.) is a highly palatable forage species with little resistance to continuous grazing. The objective of this study was to evaluate the effects of long-term cattle grazing on soil properties, above-ground biomass, and canopy cover of key grass species on rough fescue grasslands in the southern interior British Columbia. Soil and vegetation properties were determined on a total of six open grassland sites located at the Lac du Bois and Hamilton Mountain. At all sites, grazing use has decreased over time, with the heaviest grazing occurring prior to 1960. The long-term (25-75 yr) elimination of grazing on these semi-arid grasslands has led to greater above-ground biomass and canopy cover of rough fescue, as well as increased soil polysaccharides; however, no differences in tot...

Effects of long-term protection from grazing on phenotypic expression in geographically separated mountain rough fescue populations

Thompson, D. J. and Willms, W. D. 2014. Effects of long-term protection from grazing on phenotypic expression in geographically separated mountain rough fescue populations. Can. J. Plant Sci. 94: 33–39. Whether or not long-term grazing or protection from grazing alters the genetic makeup of grass populations has been debated. Mountain rough fescue [(Festuca campestris (Rydb.)], which is highly sensitive to summer grazing, and becomes dominant in plant communities with long-term protection, was chosen to address this question. Plants from three geographic sites (Stavely in AB, Milroy in the Kootenay trench, BC and Goose Lake on the BC interior plateau) with divergent grazing histories were vegetatively propagated from tillers. Daughter plants were planted into two field nurseries (at Kamloops, BC, and Stavely, AB) and morphological measurements were taken in two field seasons post-establishment. Plants from all three populations were taller, flowered earlier, and were more productive at the Kamloops nursery site. Of the three geographic sources, plants from the Goose Lake site were most distinct with narrower leaves, later flowering, and greater yield. Plants with a long history of grazing had slightly shorter fertile tillers and leaves than plants with a history of long-term protection.

Responses of herbage and cattle tail switch hair δ15N value to long-term stocking rates on a rough fescue grassland

The purpose of this study was to investigate the response of δ15N in herbage and cattle tail switch hair to long-term grazing pressure on a rough fescue grassland (Festuca campestris Rydb.) near Stavely, Alberta, Canada. Cattle have grazed the paddocks from 15 May to 15 November annually since 1949. Stocking rates were 0, 2.4 and 4.8 animal unit months ha−1 for non-grazing (Control), moderate grazing (MG) and heavy grazing (HG), respectively. Green standing crop (GSC) was sampled monthly throughout the grazing season in 2007. The GSC was fractioned into neutral detergent fiber (NDF), acid detergent fiber (ADF), and their total nitrogen (TN) concentration and δ15N values in NDF, ADF and GSC were determined. Tail switch hair samples from cows (>2 years old) and calves (<1 year) were collected at the end of the grazing season in 2007 and 2008 and analysed for δ15N values. The TN concentrations in NDF and δ15N values in herbage NDF and ADF fractions were higher (P < 0.05) in MG and HG than the Control, and decreased over the grazing season. The δ15N values in tail hair also decreased (P < 0.05) over the grazing season but were not affected by grazing intensity. However, as expected, δ15N values in tail hair increased with herbage δ15N values. The δ15N values in tail hair were enriched by +5.2‰ compared to herbage δ15N values in 2007. Changes in δ15N value in GSC and cattle hair reflect the influence of grazing practices on N cycles through the animal/plant/soil system on this rough fescue grassland.

Changes in soil C, N, and P with long‐term (58 years) cattle grazing on rough fescue grassland

AbstractWe investigated soil response to long‐term cattle grazing at stocking rates 0 (CK), 2.4 (MG), and 4.8 (HG) animal unit months ha–1 on a Rough Fescue (Festuca campestris Rydb.) grassland. Soil organic C and N stocks and available nutrients were not affected by grazing while soil bulk densities (0–30 cm) were higher and P stocks (15–30 cm) were lower under grazing than CK. The slow rate change of soil C and N suggest the rich black grassland soils appear to tolerate intensive grazing.

Festuca campestris alters root morphology and growth in response to simulated grazing and nitrogen form

Summary 1. Large herbivores are known to spatially concentrate and alter the form of nitrogen (N) in grassland systems, which can modify aboveground plant chemical composition and productivity, and result in shifts in grazing pressure in these areas. Root responses to grazing under high N inputs may facilitate these changes, but their responses are less well understood. 2. We examined biomass, root morphology and demography, and nitrogen pool responses of Festuca campestris Rydb. seedlings grown in pots in an environmental chamber and subject to heavy fertilization with isotopically‐labelled N in a NO3‐N or NH4‐N fertilizer treatment, and to no clipping or clipping to 4 cm twice during the experiment. 3. Festuca campestris exhibited re‐growth patterns after defoliation that reflected preferential allocation to aboveground shoots, with percent recovery of shoot biomass twice that of roots. Clipping did not increase the risk of root mortality. Instead, reduced root biomass in clipped plants resulted from slowed elongation and decreased production of new roots. Although roots with smaller diameters and at lower density had a greater risk of root mortality, clipping did not alter the mean root diameter or level of root branching. 4. Under high N fertilization, NH4‐N increased the amount of aboveground biomass, ameliorated the effects of clipping on root production and further reduced the risk of root mortality in clipped plants. N‐form had no effect on root morphology. 5. While total plant N uptake and the percent utilization of fertilizer were lower in clipped plants, total plant nitrogen accumulated per root biomass (g g−1) at harvest was higher in clipped plants. 6. Our findings indicate that where defoliation is coupled with high nitrogen return, Festuca campestris recuperates by increasing nitrogen uptake, shifting production to favour recovery of aboveground biomass, and mitigating carbon losses by decreasing investment in new, actively growing roots. Because application of a more mobile form of nitrogen (NO3‐N) did not alter root morphology, root physiological responses may be most important for re‐growth when nitrogen is not limiting. Root reductions associated with grazing may have a greater impact in locations where grazer‐mediated nitrogen return is spatially decoupled from defoliation.

Seasonal response of herbage production and its nutrient and mineral contents to long-term cattle grazing on a Rough Fescue grassland

This study investigated the effect of long-term cattle grazing on herbage production and its nutrient and mineral concentrations over the grazing season. The grazing experiment was conducted on a Rough Fescue (Festuca campestris Rydb.) grassland established in 1949. The three grazing treatments were moderate grazing (MG), heavy grazing (HG), and a non-grazed exclosure (CK) with corresponding stocking rates of 2.4, 4.8, and 0 animal unit months (AUM) ha−1, respectively. Within each of these three treatments four sampling locations were selected as four replications. Herbage biomass (green standing crop [current years’ production] and litter biomass [previous years’ production]) and its nutrient and mineral concentrations were determined monthly from May to September 2007. The green standing crop increased but litter biomass decreased with grazing and peak green standing crop for MG and HG occurred one month earlier than in the CK. For the green standing crop, total nitrogen (TN) concentration increased with grazing from 28.2gkg−1 in the CK to 39.9gkg−1 in the HG treatment in May while increases (12.4–15.7%) in other months were not significant. Total phosphorus (TP) (16.4%) and δ15N were higher in the HG than in the CK. For the litter, TN and Ca concentrations decreased with grazing, but TP, δ15N, K and Mg concentrations increased. The herbage feed quality also varied over the grazing season with TN, TP, K, and Mg concentrations decreasing over the grazing season while Ca concentration was lowest in spring (3.07gkg−1) and late fall (4.08gkg−1). Grazing appeared to accelerate nutrient cycling and improved herbage quality. These grasslands require disturbance for optimal performance but heavy grazing pressure could severely reduce their health.

Detection of genetic diversity in rough fescue (Festuca campestris Rydb) populations of southern Alberta and British Columbia, Canada, using RAPD markers

Mountain rough fescue (Festuca campestris Rydb.) is a tufted native grass in southern Alberta and British Columbia, Canada, and has attracted interest for use in reclamation. However, its seed is often available from only a few localized sources and may not be adapted for areas removed from the collection site. We conducted a study to determine the genetic variability among rough fescue populations to assess its potential adaptation. Thirty plants were collected from each of six populations and analyzed using Random Amplified Polymorphic DNA (RAPD). One population (Kamloops, BC) was separated by several mountain ranges from the five easterly Alberta populations.The Kamloops population was also separated from the Alberta populations by genetic distance in two clusters. Of the total genetic variation present in the data, 21% was found among populations while the remaining (79%) was found within populations. Nei’s genetic distances among populations were related to their geographical distances. Genetic differences among populations appeared to be caused primarily by differences in gene frequencies rather than rare genes. Also, genetic diversity appeared to increase from west to east suggesting that the more easterly populations had greater adaptation potential. We speculate that the more easterly populations are less likely to share genes since the prevailing winds are from the west. Germplasm from the more easterly populations may be used with suitable precautions within Alberta and possibly around Kamloops. Key words: Genetic distance, geographic distance, reclamation, potential adaptation

Effect of Standing Litter on Rough Fescue Utilization by Cattle

Fescue grasslands are well suited to dormant-season grazing, whereas spring defoliation is detrimental to rough fescue ( Festuca campestris Rydb.). Dormant-season grazing may also condition fescue plants for subsequent selection in spring by removing standing litter (i.e., senesced biomass). This relationship must be understood in order to manage grazing and conserve rough fescue. This study determined the effects of standing litter on plant selection and utilization by cattle in spring. Forty dormant rough fescue plants were conditioned in fall by removing standing litter in a 4 (treatments) × 10 (blocks) randomized complete block design. This design was repeated with the use of 2 separately grazed paddocks. Treatments were a control (no litter removal) and standing litter removed at 14-, 7-, and 2.5-cm stubble height. Nonparametric plant selection data were analyzed with the use of χ 2 methods. Spring biomass utilization was estimated nondestructively through height–weight modeling techniques, and data were analyzed with the use of analysis-of-variance procedures. The stubble height of standing litter affected ( P < 0.05) plant selection by cattle in the first 2 days of the trial when grazing pressure was light. By the end of the 6-d grazing period 96% of fescue plants were selected at least once. Additionally, 18% of plants were regrazed at least once after 3 days, and 48% after 6 days. Thus, the protective barrier effect of standing litter had limited effect on plant selection by cattle except when grazing pressure was light. However, the degree of spring biomass utilization increased with shorter stubble heights. After 6 days of grazing, the current growth of plants with standing litter removed at 2.5 cm was utilized at 64%, and control plants were utilized 9%. Therefore, at high grazing pressure the mass of standing litter influenced the degree of utilization, suggesting litter retention is important in limiting grazing impacts on rough fescue. Los pastizales de “Fescue” están bien adaptados al apacentamiento en la época de dormancia, mientras que la defoliación en primavera es perjudicial para el “Rough fescue” ( Festuca campestris Rydb.). El apacentamiento en durante la dormancia también puede acondicionar las plantas para la selección subsecuente en primavera al remover el mantillo en pie (i.e., la biomasa senescente); esta relación debe ser entendida para manejar el apacentamiento y conservar el “Rough fescue.” Este estudio determinó los efectos del matillo en pie en la selección y utilización de las plantas por el ganado en la primavera. Cuarenta plantas de “Rough fescue” fueron acondicionadas en otoño removiendo el mantillo en pie de ellas y se asignaron a 4 tratamientos en 10 bloques bajo un diseño de bloques completos al azar. Los tratamientos fueron: control (sin remoción del mantillo) y remoción del mantillo en pie a 14, 7 y 2.5 cm de altura del rastrojo remanente, este diseño se repitió usando separadamente dos potreros apacentados. Los datos noparamétricos de la selección de plantas se analizaron con métodos de χ 2 . La utilización de la biomasa en primavera fue estimada por métodos no destructivos mediante técnicas de modelado de altura-peso y los datos fueron analizados usando procedimientos de análisis de varianza. En los primeros 2 días del ensayo, cuando la presión de apacentamiento fue ligera, la altura del rastrojo del mantillo en pie afectó ( P < 0.05) la selección de plantas por el ganado. Al final del periodo de apacentamiento de 6 días, 96% de las plantas de “Rough fescue” fueron seleccionadas al menos una vez. Adicionalmente, 18% de las plantas fueron re- apacentadas al menos una vez después de 3 días y 48% después de 6 días. Así, el efecto de barrera protectora del mantillo en pie fue limitado sobre la selección de las plantas por el ganado, excepto cuando la presión de apacentamiento fue ligera. Sin embargo, el grado de utilización de la biomasa en primavera aumentó en las alturas de rastrojo más cortas. Después de 6 días de apacentamiento, el crecimiento de las plantas con remoción de mantillo en pie a 2.5-cm de altura del rastrojo fue utilizado al 64% mientras que las plantas control se utilizaron 9%. Por lo tanto, con una presión de apacentamiento alta la masa de mantillo en pie influenció el grado de utilización, sugiriendo que la retención de mantillo en pie es importante para limitar los impactos del apacentamiento sobre el “Rough fescue.”.

Long-Term Grazing Effects on Genetic Variability in Mountain Rough Fescue

Festuca campestris Rydb. (mountain rough fescue) is a dominant grass species in the montane grasslands of western Canada. Little is known about the genetic diversity of this plant and the effects of long-term grazing on the genetics of populations. The amplified fragment length polymorphism (AFLP) technique was applied to compare the genetic diversity of fescue plants at adjacent grazed and protected areas for 3 populations spread across a longitudinal range: Stavely in the foothills, Milroy in the Rocky Mountain trench, and Goose Lake on the interior plateau . Five AFLP primer pairs were used to screen the tiller samples of about 39 plants in each grazed (or ungrazed) area, and 139 polymorphic AFLP bands were scored for each individual sample. These scored bands had frequencies ranging from 0.03 to 0.98 with an average of 0.56. About 81% of the total AFLP variation resided within the populations. The Goose Lake population had the lowest level of AFLP variation, but genetically was the most distinct. Four AFLP bands were possibly associated with chromosomal segments significant for grazing resistance. Comparisons of AFLP variation between grazing and nongrazing samples revealed variable and relatively small impacts of the long-term grazing on the genetic diversity of the grazed populations. The AFLP variation of grazed samples was 1.5% lower at Goose Lake, 2.2% higher at Milroy, and not different at Stavely. If developing diverse germplasm for rangeland seedings is desired, one should sample across geographic space rather than combining materials with and without historical grazing pressure . Festuca campestris Rydb. (“Mountain rough fescue”) es una especie de gramínea dominante de los pastizales montañosos del oeste de Canadá. Poco se sabe acerca de la diversidad genética de esta planta y los efectos del apacentamiento a largo plazo sobre la genética de las poblaciones. Se aplicó la técnica de polimorfismo de la longitud de los fragmentos amplificados (AFLP) para comparar la diversidad genética de plantas de “Fescue” de áreas adyacentes apacentadas y sin apacentar (protegidas) para tres poblaciones distribuidas a lo largo de un gradiente longitudinal: Stavely en el pie de la montaña, Milroy en la trinchera de las Montañas Rocallosas y Goose Lake en la meseta interior. Cinco pares de primers AFLP fueron usados para examinar las muestras de hijuelos de aproximadamente 39 plantas de cada área, apacentada y sin apacentar y en cada muestra individual 139 bandas polimórficas AFLP fueron calificadas. Estas bandas calificadas tuvieron frecuencias que variaron de 0.03 a 0.98, con un promedio de 0.56. Aproximadamente 81% de la variación total de AFLP residió dentro de las poblaciones. La población de Goose Lake tuvo el menor nivel de variación de AFLP, pero genéticamente fue la mas distinta. Cuatro bandas AFLP posiblemente estuvieron asociadas con segmentos cromosómicos significativos para la resistencia al apacentamiento. Comparaciones de la variación de AFLP entre muestras apacentadas y no apacentadas revelaron impactos, variables y relativamente pequeños, del apacentamiento de largo plazo en la diversidad genética de las poblaciones apacentadas. La variación de AFLP de las muestras apacentadas fue 1.5% más bajo en Goose Lake, 2.2% más alto en Milroy y si diferencia en Stavely. Si se desea desarrollar germoplasma diverso para siembras de pastizales, uno debe muestrear a través del espacio geográfico en lugar de combinar materiales con y sin historial de presión de apacentamiento.

Effects of heavy grazing pressure on the random amplified polymorphic DNA marker diversity of mountain rough fescue (Festuca campestris Rydb.) in south western Alberta

The Fescue Grassland is found in the western portion of the Northern Great Plains in Canada. Grazing and cultivation threaten this grassland, and a better understanding of its character is needed to preserve its integrity. Mountain rough fescue is highly sensitive to grazing during the growing season, which results in smaller plants and the death of some. The death of plants suggests the potential loss of genetic diversity. Therefore, we compared the genetic diversity of mountain rough fescue plants from sites in south western Alberta (50°12′N, 113°54′W) that had either been heavily grazed by livestock or left ungrazed for 52 yr to determine if grazing pressure had affected their genetic composition. Thirty-four and 43 plants were sampled in the spring of 2001 from very heavily grazed and ungrazed subpopulations, respectively, and their DNA was analyzed using random amplified polymorphic DNA (RAPD). Of the 15 primers used, 12 generated an average of seven polymorphic loci each. Ten loci were present at a frequency of 0.10 or less in the heavily grazed subpopulation and six in the ungrazed subpopulation. RAPD marker diversity between the heavily grazed and ungrazed subpopulations of mountain rough fescue was mainly the result of frequency differences (P &lt; 0.05) produced by 20% of the total markers that were examined, while the subpopulations accounted for only 4.37% of total heterozygosity. Therefore, grazing affected frequency of some markers but did not eliminate genes that may be linked with grazing sensitivity or tolerance. Lack of clear genetic segregation between the subpopulations might be caused by a high gene flow (Nm = 10.92). This mechanism requires further testing in order to prescribe a suitable management response for restoring overgrazed grasslands. Key words: RAPD frequency, F-statistics, genetic identity, genetic distance, gene flow

Non-destructive assessment of cattle forage selection: A test of skim grazing in fescue grassland

This study evaluated a non-destructive scientific method that is non-invasive to the animal, for quantifying foraging selectivity by cattle within heterogeneous pasture swards in order to test the utility of a new grazing system designed to aid conservation of native rough fescue ( Festuca campestris Rydb.) rangeland in western Canada. Skim grazing is a recently developed strategy that involves a light, once-over-spring defoliation, followed by a late to dormant season grazing period. This practice is thought to conserve rough fescue as cattle are assumed to prefer invasive grass species during spring when fescue is sensitive to defoliation. We examined the preferences of cattle for each of four major grass species, two native and two introduced, within rough fescue rangeland, grazing during spring, fall, or spring and fall of 2000 and 2001. We developed height–biomass models for each grass species in each grazing period, determined biomass removal by species, and despite under-estimating actual herbage removal, successfully evaluated cattle preferences. Though the interpretation of established preferences are limited to the conditions of this study, rough fescue together with the introduced species, Kentucky bluegrass ( Poa pratensis L.), were preferred during spring, contrary to our hypothesis. Kentucky bluegrass was also preferred within both fall and fall regrowth pastures. Smooth brome ( Bromus inermis Leyss.) and Parry oat grass ( Danthonia parryii Scribn.) were generally avoided. The failure of cattle to avoid rough fescue during spring indicates skim grazing may negatively impact the conservation of rough fescue grassland. In contrast, fall grazing appears conducive to sustaining fescue grasslands while capitalizing on forage production from invasive species like Kentucky bluegrass.

Long-Term Grazing Effects on Genetic Variability in Mountain Rough Fescue

Festuca campestris Rydb. (mountain rough fescue) is a dominant grass species in the montane grasslands of western Canada. Little is known about the genetic diversity of this plant and the effects of long-term grazing on the genetics of populations. The amplified fragment length polymorphism (AFLP) technique was applied to compare the genetic diversity of fescue plants at adjacent grazed and protected areas for 3 populations spread across a longitudinal range: Stavely in the foothills, Milroy in the Rocky Mountain trench, and Goose Lake on the interior plateau. Five AFLP primer pairs were used to screen the tiller samples of about 39 plants in each grazed (or ungrazed) area, and 139 polymorphic AFLP bands were scored for each individual sample. These scored bands had frequencies ranging from 0.03 to 0.98 with an average of 0.56. About 81% of the total AFLP variation resided within the populations. The Goose Lake population had the lowest level of AFLP variation, but genetically was the most distinct. Four AFLP bands were possibly associated with chromosomal segments significant for grazing resistance. Comparisons of AFLP variation between grazing and nongrazing samples revealed variable and relatively small impacts of the long-term grazing on the genetic diversity of the grazed populations. The AFLP variation of grazed samples was 1.5% lower at Goose Lake, 2.2% higher at Milroy, and not different at Stavely. If developing diverse germplasm for rangeland seedings is desired, one should sample across geographic space rather than combining materials with and without historical grazing pressure.

Defoliation Impacts on Festuca campestris (Rydb.) Plants Exposed to Wildfire

Wildfires commonly occur in the Fescue Prairie of Alberta, but little information exists to provide a basis for making grazing recommendations after burning. A wildfire in April 1999 provided an opportunity to study the effect of season and intensity of post-burn defoliation on foothills rough fescue (F. campestris Rydb.) in southwestern Alberta. A 3 (date of defoliation) x 2 (defoliation intensity) factorial experiment with 10 replicates (plants) was established in both a burned and a non-burned grassland and analyzed as a nested design. Plants were defoliated once during active vegetative growth (17 May), inflorescence development (2 July), or dormancy (30 September), at either 5 or 15-cm clipped stubble heights in the first growing season after fire. Burning increased tiller numbers by 54% compared to non-burned plants but reduced plant ANPP by 51% in the second growing season. While a single defoliation of burned plants, particularly early in the year, had little effect on growth, delaying defoliation into July decreased tillers 1 year later. Increasing defoliation intensity had the greatest impact on non-burned plants, reducing plant height (15%) as well as tiller (21%) and plant (32%) ANPP in the second year. May defoliation reduced etiolated growth 1 year later regardless of burn treatment. A single grazing event after wildfire does not necessarily appear to detrimentally affect rough fescue; however, the low herbage available immediately after fire may not justify the increased risk to the plant with subsequent grazing. DOI:10.2458/azu_jrm_v56i4_bogen

An assessment of variation in foothills rough fescue [Festuca campestris (Rydb.)] in southern Alberta

The genetic diversity of native plants is thought to be an important consideration in the selection of appropriate material for reclamation. Field trials were c onducted in southern Alberta to determine the genetic variability, expressed through phenotypic and performance attributes, of several populations of foothills rough fescue [ Festuca campestris (Rydb.)] found in southern Alberta and south-central British Co lumbia. The objectives of this study were to determine the extent of genetic variability among plants of foothills rough fescue. Sixty-four plants from four populations were sampled in 1992, propagated vegetatively to produce clones for replicated trials a nd planted in four locations in 1993. Eleven plant characteristics, including phenotypic and performance variables, were observed from 1994 to 1997. Since the plants were grown in common environments, variations among them were assumed to be caused by gen etic differences. All variables were affected ( P &lt; 0.05) by collection site and, with a few exceptions, test location, year and their two and three-way interactions. The most important factors specific to our objectives were collection site and its interact ions with test location and year. The rough fescue plants expressed differences ( P &lt; 0.05) among populations for all selected traits but displayed considerable overlap in the range of values for all variables both within and among test sites. Therefore, wh ile the populations may be different, individuals within populations have common attributes that suggest sufficient genetic variability to allow successful establishment over a greater range of environmental variability than present at their origins. Resu lts from a secondary test suggest that selection pressure, induced by grazing, resulted in genotypes that were more winter-hardy. However, this observation needs further validation with a more robust test. Key words:

Defoliation impacts on Festuca campestris (Rydb.) plants exposed to wildfire

Wildfires commonly occur in the Fescue Prairie of Alberta, but little information exists to provide a basis for making grazing recommendations after burning. A wildfire in April 1999 provided an opportunity to study the effect of season and intensity of post-burn defoliation on foothills rough fescue (F. campestris Rydb.) in southwestern Alberta. A 3 (date of defoliation) x 2 (defoliation intensity) factorial experiment with 10 replicates (plants) was established in both a burned and a non-burned grassland and analyzed as a nested design. Plants were defoliated once during active vegetative growth (17 May), inflorescence development (2 July), or dormancy (30 September), at either 5 or 15-cm clipped stubble heights in the first growing season after fire. Burning increased tiller numbers by 54% compared to non-burned plants but reduced plant ANPP by 51% in the second growing season. While a single defoliation of burned plants, particularly early in the year, had little effect on growth, delaying defoliation into July decreased tillers 1 year later. Increasing defoliation intensity had the greatest impact on non-burned plants, reducing plant height (15%) as well as tiller (21%) and plant (32%) ANPP in the second year. May defoliation reduced etiolated growth 1 year later regardless of burn treatment. A single grazing event after wildfire does not necessarily appear to detrimentally affect rough fescue; however, the low herbage available immediately after fire may not justify the increased risk to the plant with subsequent grazing.

Rough fescue (Festuca campestris Rydb.) response to heat injury

Rough fescue (Festuca campestris Rydb.) is an ecologically and economically important native plant species within grasslands of southwest Alberta. This is also a region where wildfires have become prevalent over the last decade. While the risk of long-term damage from fire may be determined by the susceptibility of rough fescue to heat injury, understanding the additive stress imposed by defoliation may assist in the development of grazing strategies facilitating rangeland recovery. Three laboratory studies were conducted to assess rough fescue sensitivity to heat stress, including the added impact of subsequent defoliation. Results indicated that fescue tillers were capable of withstanding temperatures of 60°C, but only for short periods (e.g., 16 s or less). At lower temperatures, a distinct interaction between exposure time and temperature was evident, with shorter times at greater temperatures causing similar reductions in growth as long exposure times at low temperatures. Decreased plant vigour, as evidenced by lower tiller numbers, resulted from defoliation coinciding with active regrowth, reinforcing the notion that rough fescue is sensitive to defoliation following heat stress. The greatest detrimental impact occurred with relatively longer periods of deferment (8 weeks) until defoliation following exposure to heat treatment. These results have implications for the recovery and conservation of burned rough fescue rangeland. Key words: Defoliation, Festuca campestris Rydb., heat stress, mortality, tillers, water bath

A Comparison of Soil Chemical Characteristics in Modified Rangeland Communities

The effects of converting native prairie to simplified agronomic communities on primary production and soil quality are expected to differ over the short-term. A study was initiated at 4 locations: a Mixed Prairie with Stipa comata Trin. &Rupr. dominant in the Brown Soil Zone (1994), a Mixed Prairie with S. comata and S. viridula Trin. dominant in the Dark Brown Soil Zone (1993), and 2 in the Fescue Prairie with Festuca campestris Rydb. dominant in the Black Soil Zone (1993). At each of the 4 sites, 5 treatments representing common production systems were seeded as monocultures [2 grass species, alfalfa (Medicago sativa L. 'Beaver'), and 2 spring wheat (Triticum aestivum L. 'Katepwa) seeded as either continuous or as wheat-fallow], and 1 treatment consisting of abandoned cultivation were compared with a native community in a randomized complete block design with 4 replicates. One site in the Black Soil Zone was an overgrazed prairie (2.4 animal unit month ha-1 since 1949) and a second was mostly ungrazed for the previous 50 years with occasional light fall-grazing. Soils of the modified communities were different (P < 0.05) than of the native community with respect to percent carbon and nitrogen, concentration of monosaccharides, and concentration of most phosphorus constituents. Modifying the community through cultivation and seeding usually caused a reduction in the measured variable except for NaHCO3 inorganic phosphorus that increased. Cultivation rather than the plants of the new community was believed responsible for most of the observed changes in C, N, and various P fractions and the loss of water-stable aggregates remaining on the 2.0 and 1.0 mm sieves. Although the contribution of seeded species on the chemical and physical characteristics would not have been significantly expressed in 2 to 3 years and many more years would be required to reach a steady state, monosaccharide distribution had nevertheless started to shift to one that was plant-affected. DOI:10.2458/azu_jrm_v53i4_dormaar

A comparison of soil chemical characteristics in modified rangeland communities

The effects of converting native prairie to simplified agronomic communities on primary production and soil quality are expected to differ over the short-term. A study was initiated at 4 locations: a Mixed Prairie with Stipa comata Trin. Rupr. dominant in the Brown Soil Zone (1994), a Mixed Prairie with S. comata and S. viridula Trin. dominant in the Dark Brown Soil Zone (1993), and 2 in the Fescue Prairie with Festuca campestris Rydb. dominant in the Black Soil Zone (1993). At each of the 4 sites, 5 treatments representing common production systems were seeded as monocultures [2 grass species, alfalfa (Medicago sativa L. 'Beaver'), and 2 spring wheat (Triticum aestivum L. 'Katepwa) seeded as either continuous or as wheat-fallow], and 1 treatment consisting of abandoned cultivation were compared with a native community in a randomized complete block design with 4 replicates. One site in the Black Soil Zone was an overgrazed prairie (2.4 animal unit month ha-1 since 1949) and a second was mostly ungrazed for the previous 50 years with occasional light fall-grazing. Soils of the modified communities were different (P &lt; 0.05) than of the native community with respect to percent carbon and nitrogen, concentration of monosaccharides, and concentration of most phosphorus constituents. Modifying the community through cultivation and seeding usually caused a reduction in the measured variable except for NaHCO3 inorganic phosphorus that increased. Cultivation rather than the plants of the new community was believed responsible for most of the observed changes in C, N, and various P fractions and the loss of water-stable aggregates remaining on the 2.0 and 1.0 mm sieves. Although the contribution of seeded species on the chemical and physical characteristics would not have been significantly expressed in 2 to 3 years and many more years would be required to reach a steady state, monosaccharide distribution had nevertheless started to shift to one that was plant-affected.