Walter David Willms

Walter David Willms
Agriculture and Agri-Food Canada | AAFC · Lethbridge Research and Development Centre

PhD

About

155
Publications
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Publications

Publications (155)
Article
Climate change may make semiarid grasslands increasingly prone to wildfire. We studied fire seasonality and growing season condition effects on a semiarid grassland in Southern Alberta, Canada. Plots were hand-torched in either fall or spring. Response variables estimated included plant composition and diversity, plant height, aboveground net prima...
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Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) is a common introduced grass in the Canadian prairies, but concerns remain about its possible long-term effects on soil quality, and its influence on soil water repellency (SWR) has not been determined. The long-term (24 yr) effects of crested wheatgrass on soil water repellency (SWR) in compari...
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While northern temperate grasslands are important for supporting beef production, it remains unclear how grassland above- and belowground biomass responds to long-term cattle grazing. Here, we use a comprehensive dataset from 73 grasslands distributed across a broad agro-climatic gradient to quantify grassland shoot, litter, and shallow (top 30 cm)...
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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...
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Cultivating native rangeland can have detrimental effects on soil carbon and nitrogen storage. Understanding how vegetation and soil recover after returning marginal cultivated land to its native state is important since soil plays a key role not only in food production but also in regulating global climate change. Soil samples were taken from two...
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Off-stream waterers (OSWs) located in upland pastures may be effective in reducing livestock impacts on riparian areas and rivers, but little research has been conducted on the impact of OSWs located closer to rivers. We studied cattle behaviour over four years (2012–2015) for a portable OSW at two sites (18–25 m from river) along an unfenced reach...
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A 5 yr (2011–2015) field study was conducted to test the hypothesis that streambank fencing had a significant effect on selected vegetation and soil properties of the Mixed prairie component of a complex corridor pasture. The grazing treatments [ungrazed (UG) – periodic grazing (PG)] inside the corridor pasture were 11 yr (2001–2012) of cattle excl...
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Little is known about the specific role of exotic species on measures of grassland plant diversity, including how this may vary with climatic conditions or large mammal herbivory. This study examined vegetation responses to long-term livestock grazing, including plant richness and diversity, as well as the contribution of exotic species to these me...
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PurposeGrasslands play a crucial role in offsetting greenhouse gas emissions and mitigating climate change. A moderate change in grassland carbon (C) and nitrogen (N) stocks may substantially alter the global C and N cycle and thereby influence climate. But how grassland C and N stocks respond to grazing and slope position remains uncertain. This r...
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Long-term cattle grazing may degrade grassland soils, but how soil CO2, CH4 and N2O fluxes respond to long-term cattle grazing is poorly understood. Therefore, we quantified soil CO2, CH4 and N2O fluxes in response to four levels (none, light, heavy, very heavy) of long-term (>65 yr) cattle grazing on a rough fescue grassland in the foothills of th...
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Grasslands cover more than 40% of the terrestrial surface of Earth and provide a range of ecological goods and services, including serving as one of the largest reservoirs for terrestrial carbon. An understanding of how livestock grazing, influences grassland soil organic carbon (SOC), including its concentration, vertical distribution and associat...
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Unmanaged riparian grazing may negatively impact rivers. The objective was to determine the influence of riparian grazing by cattle on selected channel morphology properties and riparian health of the Lower Little Bow River in southern Alberta. Three study reaches with increasing levels of riparian grazing impact were selected: (1) a fenced reach w...
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Rotational stocking theoretically enables regrazing of regrowth, but regrowth may be limited in xerophytic vegetation. We tested the hypothesis that regrowth would be slow and fixed in Hesperostipa comata (a caespitose, drought-tolerant grass), while growth would be flexible in Pascopyrum smithii (a rhizomatous, less drought-tolerant grass) under i...
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Thirteen-years after cultivating native grassland and establishing continuous wheat (Triticum aestivum L.) and wheat-fallow rotations in southern Alberta, surface soil total N levels were 15% lower, and nitrate (60-90-cm) concentrations were 2.5- and 17-fold greater than native grassland. Wheat-fallow – even without fertilization – markedly enhance...
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Invasion by the rhizomatous grass Kentucky bluegrass (Poa pratensis) is a global phenomenon, including into foothills rough fescue (Festuca campestris) grasslands of southwestern Alberta, Canada. In order to better understand the competitive relationships between these species, we conducted a fallow field study where rough fescue bunchgrass tussock...
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Cattle trails in grazed pastures close to rivers may adversely affect surface water quality of the adjacent river by directing runoff to it. The objective of this 3-yr study (2013-2015) in southern Alberta, Canada, was to determine if cattle trails significantly increased the risk of runoff and contaminants (sediment, nutrients) compared with the a...
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To evaluate mechanisms by which defoliation alters grassland productivity, we examined mixed grass prairie herbage yields under recurring treatments that included hand-clipping of plots over five growing seasons at high intensity and low frequency (HILF), low intensity and high frequency (LIHF), high intensity and high frequency (HIHF), or the end...
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Herbage minerals affect performance of grazing cattle. We investigated the response of herbage P, K, Ca and Mg contents and Ca/P and K/(Ca + Mg) ratios to long-term stocking rate, continuous vs. discontinued grazing practice, and sampling year. Cattle had been stocked at 2·4 and 4·8 animal unit months ha−1 since 1949. Exclosures were installed in A...
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Little is known about how defoliation intensity and frequency alter plant community composition and diversity in northern Great Plains mixedgrass communities. We evaluated defoliation effects in combination with watering on vascular plant composition and diversity in two contrasting ecological sites, a drier upland and more mesic lowland, in the Dr...
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Little research has evaluated naturally vegetated buffers to retain pollutants in soil from concentrated runoff through deep (2–14 m) gullies. Soil enrichment in the flow path of 11 naturally vegetated gullies in southern Alberta, Canada, was used as a long-term signature of filtering during concentrated flow. Soil was sampled at three depth interv...
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Projected global change will increase the level of land-use and environmental stressors such as drought and grazing, particularly in drylands. Still, combined effects of drought and grazing on plant production are poorly understood, thus hampering adequate projections and development of mitigation strategies. We used a large, cross-continental data...
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Semi-nomadic pastoralism was replaced by sedentary pastoralism in Inner Mongolia during the 1960's in response to changes in land use policy and increasing human population. Large increases in numbers of livestock and pastoralist households (11- and 9-fold, respectively) during the past 60 yrs have variously degraded the majority of grasslands in I...
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The influence of grazing protection caused by streambank fencing on soil mesofauna density is unknown. Our objective was to determine if grazing protection (ungrazed vs. grazed), location (upland vs. riparian pasture), and seasonal (spring vs. fall) treatment effects associated with streambank fencing had a significant influence on soil mesofauna d...
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Cattle grazing in riparian pastures adjacent to rivers may increase soil compaction and increase soil nutrients, such as N and P. We conducted a 4-yr study with sampling in 3 yr (2009, 2010, 2012) of riparian zone soils adjacent to fenced and unfenced reaches of the Lower Little Bow River in southern Alberta. We examined the effect of grazing, acce...
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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 geo...
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Proper grazing management practices can generate corresponding compensatory effects on plant community production, which may reduce inter-annual variability of productivity in some grassland ecosystems. However, it remains unclear how grazing influences plant community attributes and the variability of standing crop. We examined the effects of shee...
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Off-stream watering troughs may reduce surface water pollution by shifting nutrient distribution from natural watering sites along the river to around artificial water troughs some distance from the river. The objective of our study was to evaluate the suitability of nine soil properties for assessing the impacts of cattle activity adjacent to eigh...
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This study investigates the applicability of multivariate statistical techniques including cluster analysis (CA), discriminant analysis (DA), and factor analysis (FA) for the assessment of seasonal variations in the surface water quality of tropical pastures. The study was carried out in the TPU catchment, Kuala Lumpur, Malaysia. The dataset consis...
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The purpose of this study was to investigate the response of δN 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 mont...
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We 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...
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Many native grasslands in the Aspen Parkland of western Canada have been converted to seeded forages. We used bait lamina to test the hypothesis that this change has altered soil biological activity. Bait lamina removal varied with both vegetation type and soil depth (p=0.03). Bait removal was 31% in the shallow (0-5 cm) soil profile, and similar b...
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Grazing by large herbivores has been shown to condition vegetation in a manner that improves grassland quality for subsequent herbivory. Fescue grasslands evolved with disturbance from fire and winter grazing by bison but are now grazed primarily by cattle during summer. We examined the effect of long-term summer grazing on the seasonal forage prod...
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The Agriculture and Agri-Food Canada Stavely substation in the native fescue grasslands of south-western Alberta was established in 1949 in response to requests that grassland and range management problems in the foothills area be investigated. Around 42% of the 389 ha site is fenced into 4 pastures where the same stocking rates have been maintaine...
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The goal of beneficial management practices (BMPs) such as off-stream watering without fencing is to direct cattle away from rivers, improve the environmental quality of the riparian zone, and prevent or reduce river pollution. We conducted a four year (2005-2008) study on an unfenced 1.3Â km reach of the Lower Little Bow (LLB) River in southern Al...
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We investigated the effect of increasing soil temperature and nitrogen on greenhouse gas (GHG) emissions [carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)] from a desert steppe soil in Inner Mongolia, China. Two temperature levels (heating versus no heating) and two nitrogen (N) fertilizer application levels (0 and 100 kg N ha−1 year−1)...
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Landspraying while drilling (LWD) is an approved disposal method for water-based drilling mud (WBM) systems in western Canada. The mud is applied either on cultivated land, where it is incorporated by cultivation, or on vegetated land where it is not incorporated. This study examined the effects of summer WBM application (0, 15, 20, 40, and 80 m3 ·...
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Livestock performance is a critical indicator of grassland production systems and is influenced strongly by precipitation and stocking rates. However, these relationships require further investigation in the arid Desert Steppe region of northeastern China. We employed a randomized complete block design with three replications and four grazing treat...
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Question: Litter (dead leaves or stems) affects production by conserving soil moisture. However, that role is not clear for grasslands where most precipitation falls during the growing season when the demand for water is high. Our question was: Does litter affect forage production in such an environment? Location: Typical steppe, Inner Mongolia. Me...
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Canonical analysis was compared with dissimilarity indices for evaluating the food niche of mule deer. Significant differences were found among individual deer primarily in their predilection for shrubs and secondarily in their selection of forbs or grasses. Patterns of selection changed with plant communities, reflecting changing availabilities an...
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Defoliation of dormant native plants often results in reduced plant height and productivity when growth resumes. To identify a possible mechanism for this effect, three experiments were conducted to test the hypothesis that the response is determined by a modified environment at the crown. Rough fescue (Festuca scabrella Torr.) sod was removed from...
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A study was made in the rough fescue grasslands of southwestern Alberta to determine the growth response of rough fescue (Festuca scabrella var. campestris Rydb.) to five cutting frequencies and three cutting heights after 3 years of repeated treatments. The same plants were cut either 1, 2, 4, 8, or 16 times over a 16-week period beginning in mid-...
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In Alberta, the rough fescue complex consists of Festuca altaica Trin., Festuca hallii (Vasey) Piper, and Festuca campestris Rydb. The potential commercial value of these species for grazing, and their ecological significance, necessitates an increased understanding of their environmental adaptation. This study compared the growth response of the t...
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The response of Festuca hallii (Vassey) Piper to time of burning was examined on the Festuca–Stipa grasslands of the Aspen Parklands at the University of Alberta Ranch located 150 km southeast of Edmonton, Alberta. Two defoliation treatments (burning and mowing) were examined on five dates in 1978 (8 April, 27 April, 1 June, 31 July, and 18 October...
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The effects of fall clipping or burning on the subsequent morphology of bluebunch wheatgrass were studied in both the big sagebrush – bluebunch wheatgrass and Douglas fir – bluebunch wheatgrass communities. Observations were made to the 2nd year after treatment. Burning, in the big sagebrush community, resulted in a larger ratio of plant weight to...
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Studies were made in both the Artemisia tridentata and Pseudotsuga menziesii communities to examine some factors affecting available growth in spring. The appearance of tillers was examined in relation to species (Agropyron spicatum. Agropyron cristatum. Poa sandbergii) and temperature. The rate of tiller elongation in Agropyron spicatum was studie...
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Numerous studies have examined the nutritive quality of fodder plants in different seasons but few have related this seasonal response to long-term grazing intensity. Our objective was to examine the effect of long-term grazing on the concentrations of total nitrogen, δ15N, and total phosphorus in selected forage species from the fescue grassland n...
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While plant litter is known to regulate soil moisture, little is known about the extent to which litter impacts moisture over and above the physical environment (i.e., ecosite) throughout the growing season, particularly in cool-temperate grasslands where moisture is considered less limiting for plant growth. In this study, we examined the relative...
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This study investigated how disturbances from cultivation and haying altered the soil organic C (SOC) at two sites: one (Lethbridge) in a Stipa–Agropyron–Bouteloua community (49°7˝ N, 112°57˝ W) and a second (Onefour) in a more xeric Stipa–Bouteloua community (49°3˝ N, 110°27˝ W). Seven disturbance treatments were established on previously uncultiv...
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Off-stream watering troughs may reduce surface water pollution by keeping nutrients away from natural water bodies, but may increase nutrient contaminant of groundwater. The objective of this study was to determine to what extent off-stream watering troughs active for 2 to 7 yr caused enrichment and leaching of soil test P (STP) and KCl-extractable...
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Limited information exists on the effect of streambank fencing on riparian zone pastures. The objective of this study was to test the hypothesis that 4 to 6 yr of streambank fencing would improve the environmental quality of the cattle-excluded pasture compared with the grazed pasture and cause the fenced pasture to act as a buffer or filter strip....
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The goal of beneficial management practices (BMPs) such as streambank fencing is to prevent or reduce water pollution of surface water bodies. We conducted a four year (2004–2007) study on a fenced 800-m reach of the Lower Little Bow (LLB) River in southern Alberta, Canada. Our hypothesis was that riparian health would be improved by streambank fen...
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Soil moisture can limit plant production in cool-temperate grasslands, particularly under recent increases in drought severity and predictions of future climate change. This necessitates research that examines moisture mitigation strategies under the dominant land use of grazing. We examined the effectiveness of plant litter in regulating soil mois...
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Aims Much research has been done on litter in forest ecosystems, but little has been done in grassland ecosystems, although litter plays an important role in grasslands. Our objectives were to determine how litter affects aboveground biomass and productivity of different functional groups and whether litter addition has a positive or negative effec...
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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...
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Relative benefit of introducing forage species to the Northern Great Plains have been examined with contradictory conclusions. In most cases, studies were either confounded by time of establishment or treatments were not randomized and lacked independence. We examined aboveground net primary production (ANPP) in northern mixed prairie using a rando...
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Drilling mud systems are used by the petroleum industry to facilitate and expedite the drilling of oil and natural gas wells.In western Canada, spent water-based muds (WBM) are often applied to cropland and native prairie at low application rates as a disposal option. We speculate that application of drilling waste on native prairie in semiarid cli...
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The effects of grazing on grassland ecosystems must be understood to develop effective soil conservation measures and sustain livestock production. The objective of this research was to characterize the impact of dairy cow grazing intensity on C and N in soil and vegetation on a meadow steppe. The meadow steppe site, located near Hailaer, Inner Mon...
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Grazing intensity and grassland degradation in China has increased with a growing livestock population. The Desert Steppe is vulnerable to the impacts of livestock because of relatively short and sparse ground cover and sandy soil. This study investigates the effects of historic sheep grazing on the vegetation and soil properties of a Desert Steppe...
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Harden, S. 2008. Surface runoff response of native and introduced grasses under simulated rainfall in southern Alberta. Can. J. Soil Sci. 88: 337Á348. Introduced perennial grass-based pastures (e.g., crested wheatgrass, Agropyron cristatum, and Russian wildrye, Elymus junceus) are promoted as desirable alternatives to natural grasslands (StipaÁBout...
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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...
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In spite of overwhelming experimental evidence to the contrary, rotational grazing continues to be promoted and implemented as the only viable grazing strategy. The goals of this synthesis are to 1) reevaluate the complexity, underlying assumptions, and ecological processes of grazed ecosystems, 2) summarize plant and animal production responses to...
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In spite of overwhelming experimental evidence to the contrary, rotational grazing continues to be promoted and implemented as the only viable grazing strategy. The goals of this synthesis are to 1) reevaluate the complexity, underlying assumptions, and ecological processes of grazed ecosystems, 2) summarize plant and animal production responses to...
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Abstract One major challenge in genetic diversity analysis of minor grass species is the lack of informative molecular markers. A set of 210 simple sequence repeat (SSR) markers developed from wheat and barley were evaluated for their transferability to three rough fescue species [Festuca altaica Trinius, F. campestris (Rydb.) and F. hallii (Vassey...
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The Bactrian camel (Camelus bactrianus ferus) is uniquely adapted to the deserts of China and Mongolia. It was domesticated about 3000 years ago but the wild Bactrian camel is endangered with less than 1000 remaining in China. We observed the foraging behaviour of 10 domestic Bactrian camels (Alashan) in a Haloxylon ammodendron C.A. Mey desert of I...
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Snow accumulation is an important process that defines the hydrological characteristics of grasslands and is mediated by vegetation structure. Grazing also affects those processes, but its relationship to snow accumulation is poorly understood. We conducted a study in the rough fescue grasslands in southwestern Alberta (lat 508119300N, long 1138539...
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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 gr...
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Canada, the United States and Mexico all have a Ion history of rangeland monitoring. However none have developed a nationwi ? e database or even a standardized set of protocols. The lack of standardization, inadequately developed relationships between management objectives and monitoring protocols, and an emphasis on data collection rather than ana...
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Snow accumulation is an important process that defines the hydrological characteristics of grasslands and is mediated by vegetation structure. Grazing also affects those processes, but its relationship to snow accumulation is poorly understood. We conducted a study in the rough fescue grasslands in southwestern Alberta (lat 50 degrees11ʹ30 degreesN...
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Seasonal changes in aspen (Populus tremuloides Michx.) resistance to shearing force were described to determine their apparent contribution to seasonal changes in cattle utilization. Shearing resistance of current-year, 1-year-old, and 2-year-old stem-age classes were measured from late spring to early fall. For all stem-age classes, resistance to...