A significant source of sediment in many watersheds is that associated with the layout, construction, and maintenance of roadways. Much work has been done in more mesic forested environments with little or none in semiarid systems. Acc urate estimation of runoff and sediment yield from native surfaced roads located in semiarid mountainous ecosystems is important to both private and public regulatory agencies. The Watershed Erosion Prediction Project (WEPP) model represents the most current erosion prediction technology. WEPP has been applied to the problems of logging road erosion in more mesic forests but has not been tested or evaluated on roadways located in semiarid mountainous ecosystems. Six rainfall simulation experiments were conducted to measure runoff and sediment yield off three separate plots located on Tickville Road, located on Camp W.G. Williams, a National Guard Training Center in Utah . These data were compared with runoff and erosion estimates produced by the WEPP model. WEPP cropland and rangeland erodibility equations were used to predict rill erodibility (Kr), interrill erodibility (Ki), and critical shear (TAUc). These were tested for their effectiveness in predicting road erodibilities in these environments. A sensitivity analysis was performed on those parameters that were suspected of having a substantial impact on model output and accuracy. There was an excellent correlation between predicted and observed total runoff volumes for all simulations (R2= 0.96). The differences were greater than 10% only for plot 2 wet; otherwise, the average difference for all six simulations was 4.9%. When using Kr, K.i , and TAUc as predicted by rangeland methods, predicted sediment yields differed from those measured, on average, by 82%. Predicted sediment yields differed by only 22% compared to calculated sediment yields, when using the cropland erodibility equations to predict Kr, K.i , and TAUc. A sensitivity analysis showed that percent slope, slope length, days since last tillage, and ridge roughness all had a significant impact on WEPP predicted sediment yields. Results show the effectiveness of the WEPP model in predicting runoff and erosion off native surfaced roads in these semiarid mountainous regions.

Symbiotic interactions among various organisms are often necessary for one or both individual's survival. These symbiotic relationships must be considered in restoration projects to allow for the successful establishment of the species. Rhizobia are nitrogen-fixing bacteria found in symbiotic relations with legumes. By utilizing this relationship, restoration practitioners can establish native legume species more successfully while repopulating soil microorganisms into degraded soils. Despite the potential benefits a rhizobium inoculant can have on restoration efforts, minimal research has been done to understand the impacts this treatment has on specific species and the systems they are employed within. Our research goal was to assess the efficacy of applying a commercial rhizobium product (EXCEED ®) and indigenous rhizobium strains on two lupine species (Lupinus argenteus Pursh and Lupinus sericeus Pursh), commonly used for rangeland seedings in the Great Basin region of the western United States. We conducted laboratory and field trials to meet this research goal, with the results of the laboratory experiments shared in chapter 1 and findings from the field reported in chapter 2. In chapter 1, we evaluated in the laboratory whether indigenous rhizobia strains could be isolated, cultured, and applied as a liquid inoculant or a seed coating to induce root nodulation and increase plant growth. The performance of these inoculums was compared against the commercial rhizobium product. Additionally, we tested in a trial if compost could be applied within the seed coating to improve the efficacy of the rhizobium treatment. Our research demonstrated that the commercial inoculum induced root nodulation, and in one of three trials, this treatment improved plant growth. We also found indigenous strains effectively formed nodules on the plant roots when applied through a liquid culture or a seed coating. However, the number of root nodules and the presence of a pink color (indicating nitrogen fixation) were typically higher in the commercial product than in the indigenous strains when applied through a seed coating. These short-term laboratory studies generally provided minimal evidence that rhizobia impacted plant growth. However, data indicated that having compost in the coating alone improved shoot biomass by 33% (P = 0.025). In chapter 2, research assessed the performance of the same rhizobia inoculums tested in the laboratory trials on a mine in northern Utah at two waste-rock sites, one comprised of crushed waste rock and the other made of waste rock amended with topsoil. One year after seeding, we had high plant recruitment at both study sites, and there were more plants, which were more vigorous, in the amended site (P<0.001). These results demonstrate that reclamation efforts on mineland overburden can be improved when topsoil is incorporated into the growing medium. At this stage in the study, there was no difference in plant establishment and vigor between any seed treatments, but future research is planned to assess these metrics in the next growing season. The lack of improvement in plant growth from a rhizobia treatment in some of our laboratory and field trials may be due to the short period of these studies. Nodules that form on mature root systems provide more nitrogen-fixing benefits than those formed on immature roots. Hence, future research should consider conducting trials for more extended periods to understand how the treatments influence the growth of mature plants. Because we found in the laboratory that the rhizobia inoculums were successful in nodulating the test species, we anticipate that future studies will find that these treatments can improve plant performance and subsequently restoration success.

Wetlands are significant contributors to global biodiversity, supporting disproportionately high numbers of species relative to their area. Riparian areas associated with wetlands provide many services that are both ecologically and economically important, such as groundwater recharge, sediment capture and shoreline stabilization, flood mitigation, nutrient processing, increased water quality, carbon sequestration, and essential habitat for wildlife. Agricultural activity has resulted in the drainage or modification of between 40-70% of wetland basins within the Prairie Pothole Region of the northern Great Plains. The impacts of human activity on the remaining wetlands are difficult to estimate and there is no one optimal indicator or assessment method that is applicable to all regions or situations. Locally developed riparian health assessments, designed to evaluate wetland function under different grazing regimes, are cost-effective with the potential for broader use in wetland environmental assessment, monitoring, and management or restoration activities. In this study I investigated the hypothesis that riparian health assessments can distinguish between wetlands in five categories of land use that represent different levels of anthropogenic modification: ungrazed cultivated cropland, ungrazed native grassland, grazed native grassland, ungrazed tame perennial forage, and grazed tame perennial forage. Noting that current riparian health assessment protocols lack a community composition component other than the presence and distribution of invasive and disturbance species, I also sampled plant species frequency at each of my study sites. I found that wetlands in cultivated croplands had significantly lower riparian health scores than wetlands in both tame and native grasslands. Among tame and native sites, grazing status was more important than upland cover type in determining wetland health, with grazed wetlands receiving significantly lower scores than their ungrazed counterparts. Despite their functional similarity to wetlands within native grasslands, species composition of wetlands within ungrazed tame perennial forage more closely resembled that of wetlands in cultivated uplands. Although grazing negatively affected riparian ground cover and soil stability, it significantly reduced both the overall cover and distribution of invasive plant species along wetland reaches. These results suggest that upland revegetation and restoration of function to degraded wetlands is not necessarily followed by re-establishment of original riparian species composition. If biodiversity is a desired outcome of wetland restoration efforts, additional measures must be taken to enable the establishment and persistence of preferred plant species.

In South Africa, the unsustainable use of natural resources by domestic livestock has led to resource depletion and serious land degradation. Rangeland degradation, especially bush encroachment and soil erosion, is particularly acute in the North-West Province, where all districts show signs of desertification and a loss of biodiversity resulting in a deterioration of human and animal health. This has a major impact on livestock productivity and the economic viability of livestock farming with serious consequences for the livelihoods of pastoral communities. It is important to recognise ecological change before irreversible changes occur. The aim of this study, which falls within the Global Environmental Facility Desert Margins Programme (GEF-DMP), was to investigate to what extent vegetation in combination with ant communities can be used as indicators of ecosystem change due to anthropogenic human induced land-use patterns and how can this information be used in land degradation management and biodiversity conservation in the semi-arid western rangelands of Southern Africa. Sites, representing a degradation gradient (relative poor and relative good rangeland condition extremes) within each of three Tribal-, three Commercial- and three Reserve areas, were surveyed. The impacts of these land uses on the herbaceous species composition, woody-, soil- and ant components were evaluated. Both the woody and herbaceous species components reflected the existence of a rangeland condition/degradation gradient across the larger study area. The herbaceous species composition reflected similar degradation tendencies within the Commercial and Reserve land uses, with sites being associated with low rangeland as well as high rangeland condition scores. The tendencies differed between these two land uses based on the woody degradation gradient. The entire Tribal herbaceous- and woody species components showed a transitional shift towards another state, which differed significantly from the Commercial and Reserve land uses. Both the Tribal herbaceous and woody components were associated with low to intermediate rangeland condition ranges, with no significant rangeland condition gradient existing within the Tribal land use. Understanding and quantification of the soil-vegetation dynamics hold important implications for rangeland degradation management. This study provided criteria for selecting the most appropriate measures when incorporating the soil parameters as additive data in the multivariate analyses with the vegetation, ant and nominal environmental data. Different land use practices resulted in different soil patterns, with significant gradients pertaining to the soil stratum and openness/woodiness groups. There was a significant though neglectable difference pertaining to the rangeland condition/degradation gradient based on the soil component. Ants have been extensively used as bio-indicators, also with regard to the monitoring of the environmental effects of rangeland pastoralism. Ant species compositional patterns and functional groups displayed congruent clustering and diversity patterns as those of the vegetation and soil components. In contrast to the vegetation components, ant assemblages did not reflect a degradation gradient, but rather reflected environmental changes (modifications) to the habitat structure and - heterogeneity as a result of different land use disturbances. Both vegetation and ant diversity measures were mainly associated with the Tribal land use. These diversity indices were indicators of habitat complexity, heterogeneity and moderate disturbance, rather than indicators of a rangeland condition/degradation gradient. The diversity patterns are best described by a dichotomy between the humped-shaped productivity/diversity and the habitat complexity/heterogeneity models. Vegetation and ant diversity measures for this study should be considered as environmental indicators of habitat disturbance rather than as biodiversity indicators. It is suggested that vegetation, soil and ant patterns are best described by the state-and-transition model, which encompasses both equilibrium and non-equilibrium systems. The resilient nature of these rangelands, typical of non-equilibrium systems, was reflected by the low to intermediate differences between land uses with regard to the herbaceous, woody, soil and ant components. However, densitydependent coupling of herbivores to key resources resulted in transitional shifts and modification of the vegetation composition and structure within and between land uses, displaying the equilibrium dynamics pertaining to these rangelands. Small disturbances in these rangelands may result in detrimental “snowball” interactive biotic-biotic /abiotic cascades. Spatial heterogeneous patterns within and between land uses as displayed by the vegetation, soil and ant parameters, necessitate that monitoring and management at patch, paddock and landscape scale should be conducted, cautioning against the extrapolation and over simplification of management strategies across all land uses. Because these arid rangelands are linked socio-ecological systems, it is not possible to address biophysical issues associated with land degradation without including the human dimensions. A “Key assessment matrix” is provided for monitoring and management purposes pertaining to land degradation and diversity aspects within and between the different land uses, and can be used by the land user, extension officer and scientist. / Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2007.

In South Africa, the unsustainable use of natural resources by domestic livestock has led to resource depletion and serious land degradation. Rangeland degradation, especially bush encroachment and soil erosion, is particularly acute in the North-West Province, where all districts show signs of desertification and a loss of biodiversity resulting in a deterioration of human and animal health. This has a major impact on livestock productivity and the economic viability of livestock farming with serious consequences for the livelihoods of pastoral communities. It is important to recognise ecological change before irreversible changes occur. The aim of this study, which falls within the Global Environmental Facility Desert Margins Programme (GEF-DMP), was to investigate to what extent vegetation in combination with ant communities can be used as indicators of ecosystem change due to anthropogenic human induced land-use patterns and how can this information be used in land degradation management and biodiversity conservation in the semi-arid western rangelands of Southern Africa. Sites, representing a degradation gradient (relative poor and relative good rangeland condition extremes) within each of three Tribal-, three Commercial- and three Reserve areas, were surveyed. The impacts of these land uses on the herbaceous species composition, woody-, soil- and ant components were evaluated. Both the woody and herbaceous species components reflected the existence of a rangeland condition/degradation gradient across the larger study area. The herbaceous species composition reflected similar degradation tendencies within the Commercial and Reserve land uses, with sites being associated with low rangeland as well as high rangeland condition scores. The tendencies differed between these two land uses based on the woody degradation gradient. The entire Tribal herbaceous- and woody species components showed a transitional shift towards another state, which differed significantly from the Commercial and Reserve land uses. Both the Tribal herbaceous and woody components were associated with low to intermediate rangeland condition ranges, with no significant rangeland condition gradient existing within the Tribal land use. Understanding and quantification of the soil-vegetation dynamics hold important implications for rangeland degradation management. This study provided criteria for selecting the most appropriate measures when incorporating the soil parameters as additive data in the multivariate analyses with the vegetation, ant and nominal environmental data. Different land use practices resulted in different soil patterns, with significant gradients pertaining to the soil stratum and openness/woodiness groups. There was a significant though neglectable difference pertaining to the rangeland condition/degradation gradient based on the soil component. Ants have been extensively used as bio-indicators, also with regard to the monitoring of the environmental effects of rangeland pastoralism. Ant species compositional patterns and functional groups displayed congruent clustering and diversity patterns as those of the vegetation and soil components. In contrast to the vegetation components, ant assemblages did not reflect a degradation gradient, but rather reflected environmental changes (modifications) to the habitat structure and - heterogeneity as a result of different land use disturbances. Both vegetation and ant diversity measures were mainly associated with the Tribal land use. These diversity indices were indicators of habitat complexity, heterogeneity and moderate disturbance, rather than indicators of a rangeland condition/degradation gradient. The diversity patterns are best described by a dichotomy between the humped-shaped productivity/diversity and the habitat complexity/heterogeneity models. Vegetation and ant diversity measures for this study should be considered as environmental indicators of habitat disturbance rather than as biodiversity indicators. It is suggested that vegetation, soil and ant patterns are best described by the state-and-transition model, which encompasses both equilibrium and non-equilibrium systems. The resilient nature of these rangelands, typical of non-equilibrium systems, was reflected by the low to intermediate differences between land uses with regard to the herbaceous, woody, soil and ant components. However, densitydependent coupling of herbivores to key resources resulted in transitional shifts and modification of the vegetation composition and structure within and between land uses, displaying the equilibrium dynamics pertaining to these rangelands. Small disturbances in these rangelands may result in detrimental “snowball” interactive biotic-biotic /abiotic cascades. Spatial heterogeneous patterns within and between land uses as displayed by the vegetation, soil and ant parameters, necessitate that monitoring and management at patch, paddock and landscape scale should be conducted, cautioning against the extrapolation and over simplification of management strategies across all land uses. Because these arid rangelands are linked socio-ecological systems, it is not possible to address biophysical issues associated with land degradation without including the human dimensions. A “Key assessment matrix” is provided for monitoring and management purposes pertaining to land degradation and diversity aspects within and between the different land uses, and can be used by the land user, extension officer and scientist. / Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2007.

The objectives of this study were to determine the effects of two forms of polyacrylamide (PAM) conditioners (Cross-linked and Non-cross-linked PAM) on evaporation, saturated hydraulic conductivity, water retention, crust and crack formation of soils, seed germination, and seedling and tubeling growth. The two PAM conditioners, 0.2% concentration by weight, were mixed with seven soils of different textures (sandy loam, silt, silty clay loam, silt loam, fine sand, medium sand, and coarse sand) to investigate the effects on evaporation, saturated hydraulic conductivity, and water retention. Soil samples of different textures were brought to field capacity and placed in a growth chamber for two weeks to measure evaporation under a controlled environment. A second experiment was carried out in the field to determine the effects of the two PAM conditioners on seedling emergence of crested wheatgrass, Agropyron desertorum, as well as on soil cracking, penetrometer resistance, and soil moisture. The two PAMs were mixed with a silt loam Xerollic Calciorthid at 0.2% concentration by weight. Seedling emergence was monitored directly for two weeks. Soil moisture was measured by TDR. Cracking was described by photographic means. Penetrometer resistance was measured by a hand-held. penetrometer. The third experiment was also carried out in the field, using the same soil texture as in experiment 2, to investigate the effects of the two PAMs on soil moisture at depths between 25 to 45 cm and on sagebrush (Artemisia tridentata) growth. Evaporation was found to be significantly lower in the fine-textured controls than under the two PAM treatments. The sandy loam and sandy soils experienced significantly higher evaporation from the controls. The two PAM conditioners significantly reduced saturated hydraulic conductivity on all soil textures. Water retention increased in the PAM-treated textures at the matric potential range used (0.0, 0.05, 0.1, 1.5 MPa) • The PAM application also did not improve grass seedling emergence or improve soil moisture, and did not have any significant affects on sagebrush growth. Larger cracks were found in the two plots treated with PAM than the controls. Lower penetrometer resistance occurred in the two PAM treatments compared to the untreated control. From this study, it can be concluded that the application of PAM conditioners, at relatively high concentrations used, could be more viable on sandy textures. Other researchers are advised to try lower application rates than used here, particularly with finer textured soils.

Master of Arts / Department of Geography / Douglas G. Goodin / My thesis characterizes the temporal and spatial behavior of ozone and fine particulate matter in the Kansas City metropolitan area. I also investigate the capability of a synoptic weather typing scheme, the Spatial Synoptic Classification, to characterize and explain the behavior of ozone and fine particulate matter in the Kansas City area. Daily maximum ozone concentrations from nine active ozone monitoring stations and daily average particulate concentrations six active PM2.5 monitoring stations were compared to daily SSC weather type records from 2004-2010. Analysis of Variance (ANOVA) tests were conducted on the ozone and PM2.5 data to analyze temporal and spatial behavior. A non-parametric recursive partitioning technique was used to create a conditional inference tree-based regression model to analyze the association between the different SSC weather types and the selected pollutants. The ANOVA results showed significant seasonal trends with both pollutants. In general, ozone concentrations are typically lower in the spring and autumn months and higher during the summer months. PM2.5 concentrations were not as dependent on the season, however, they did tend to be higher in the late summer months and lower in the autumn months. The results also showed significant differences for both pollutants in average concentration depending on location. The ozone concentrations generally tended to be higher in the areas that are located downwind of Kansas City and lowest at the station located in the middle of the urban area. Fine particulates also seemed to be highest in the downwind portion of the urban area and lowest in the region upwind of the city. The conditional inference tree showed that higher concentrations of both pollutants are associated with tropical air masses and lower concentrations are associated with polar air masses.

Thesis (MScConEcol)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Reductionism, an approach to understanding complex systems based on reducing the system to its individual components and the interactions between these components, is the linear and rigid approach to traditional management and research that allows us to understand complicated systems. Yet its application to complex systems has likely added to the degradation of social-ecological systems. In recognition of this, there is currently a shift to holism: the concept that a system is greater than the sum of its components and that the system has emergent properties that are only present through the complex interactions of the whole system. The inclusion of this natural complexity within social-ecological systems is thought to promote resilience – the ability of a system to absorb shock and thus promote sustainability. However, these concepts are largely theoretical and few examples exist that demonstrate ways of transferring them to pragmatic land management. Holistic ManagementTM (HM) could potentially be such a working example. It is a decision-making framework that provides a holistic context for the adaptive management of natural resources. However, limited peer-reviewed research has been applied to this potential to promote sustainability. Thus the current study aimed to address this apparent gap by determining if HM land managers were a distinct group from non-HM (NHM) land managers in regards to their management practices and if HM land managers had a greater adaptive capacity (the management of resilience) than non-HM land managers. The study was conducted in a community of livestock farmers in the arid rangelands of the Karoo, South Africa. Data were mainly gathered through face-to-face interviews with land managers – including 20 self-defined HM land managers and 20 self-defined NHM land managers. To compare the reported management approaches of land managers, two scoring systems were developed. The HM Adoption Index measured the extent to which participants were aligned with key principles and practices of HM (including having a holistic goal, testing decisions, applying the Holistic Planned Grazing, demonstrating continuous learning and innovation). The Adaptive Capacity Index measured the extent to which participants demonstrated key traits of adaptive capacity as identified from the literature. In addition, participants were also asked to describe the strategies they apply to deal with local livestock farming challenges including parasite control, predation management and drought management. A significant difference was found between HM and NHM land managers for both the HM Adoption Index and Adaptive Capacity Index (p<0.01). The majority of HM land managers adopted ―true holistic and ―adaptive management practices (80%) while NHM land managers were mostly ―semi holistic and ―coping (65%). HM land managers also notably tended to report more innovative and environmentally aware methods in dealing with farming challenges and were more likely to be part of study groups which build social capital and promote social learning. Results imply that HM provides a framework that introduces holistic principles to land management, making the holistic context and resilience accessible to individual managers for practical day-to-day decision-making. / AFRIKAANSE OPSOMMING: Reduksie, 'n benadering om komplekse sisteme te verstaan deur om die sisteme te besnoei tot sy individuele komponente en interaksies tussen die komponente, is die liniêre en rigiede benadering tot tradisionele bestuur en navorsing. Dit laat ons toe om komplekse sisteme te verstaan. Tog het die toepassing van reduksie op komplekse sisteme waarskynlik bygedra tot die degradasie van sosiaal-ekologiese sisteme. In herkenning van laasgenoemde is daar tans 'n skuif na holisme: die konsep dat 'n sisteem groter is as die somtotaal van al sy komponente en dat die sisteem voortkomende eienskappe het wat net navorekom deur die komplekse interaksies van die sisteem. Die insluiting van die natuurlike kompleksiteit binne sosiaal-ekologiese sisteme bevorder moontlik weerstandigheid; die vermoë van 'n sisteem om 'n skok te absorbeer en so volhoubaarheid te bevorder. Hierdie konsepte is egter meestal teoreties en min voorbeelde bestaan wat metodes demonstreer om die konsepte oor te dra na pragmatiese grondbestuur. Holistiese BestuurTM (HB) kan moontlik so 'n werkende voorbeeld wees. Dit is 'n raamwerk vir besluitvorming wat 'n holistiese konteks verskaf vir die aanpasbare bestuur van natuurlike hulpbronne. Daar is min eweknie-hersiende navorsing wat HB se potensiaal om volhoubaarheid te bevorder ondersoek. Dus het die huidige studie beoog om die gaping aan te spreek deur te bepaal of HB praktiseerders onderskei kan word van 'n groep van nie-HB (NHB) praktiseerders in terme van bestuurspraktyke en of HB praktiseerders 'n groter aanpasbaarheid (die bestuur van weerstandigheid) toon as NHB praktiseerders. Die studie het plaasgevind in 'n gemeenskap van veeboere in die dorre veld van die Karoo, Suid Afrika. Data was versamel deur aangesig tot aangesig onderhoude met grondbestuurders; 20 self-geïdentifiseerde HB praktiseerders en 20 self-geïdentifiseerde NHB praktiseerders. Twee puntestelsels is ontwikkel om die gerapporteerde benaderings van grondbestuurders te vergelyk. Die HB Toepassing Puntelys het gemeet tot watter mate 'n deelnemer inskakel met die kern beginsels van HB (insluitend om 'n holistiese doelwit te hê, om besluite te toets, om Holistiese Beplande BewydingTM toe te pas en om 'n voortsetting van leer en innovasie te demonstreer). Die Aanpasbaarheid Puntelys het gemeet tot watter mate 'n deelnemer die kern kenmerke van aanpasbaarheid, soos geïdentifiseer in literatuur, demonstreer. Bykomend was deelnemers ook gevra om die strategieë te beskryf wat hulle toepas om die uitdagings van plaaslike veeboerdery tegemoed te kom insluitend die beheer van parasiete, die bestuur van roofdiere en die bestuur tydens droogtes. 'n Betekenisvolle verskil was gevind tussen HB en NHB praktiseerders vir die HB Toepassing Puntelys en die Aanpasbaarheid Puntelys (p<0.01). Die meederheid van HB praktiseerders het ―ware holistiese en ―aanpasbare praktyke toegepas (80%) terwyl NHB praktiseerders se metodes meestal ―semi-holisties en ―korttermyn probleem hantering was (65%). HB praktiseerders het ook 'n waarneembare neiging gehad om innoverende en omgewingsbewuste metodes te rapporteer in verband met veeboerdery uitdagings en was meer waarskynlik deel van 'n studie groep wat sosiale kapitaal gebou en sosiale leer bevorder het. Die resultate het aangedui dat HB 'n raamwerk voorsien wat holistiese beginsels oordra na grondbestuur en so die holistiese konteks en weerstandigheid toeganklik maak vir die individuele bestuurder vir daaglikse praktiese besluitneming en toepassing.

Grasslands are the most threatened terrestrial ecosystem in the world, and as they decline the species that depend on them also decline. Variable stocking rates and resting rangeland could be used by range managers to manipulate plant cover and create wildlife habitat. I used generalized linear mixed-models to evaluate how effects of rest on vegetation and songbirds varied based stocking rates previously applied from 2006-2014 in Grasslands National Park, Canada. My results indicate, in the mixed-grass prairie, succession is retrogressive following rest, and both vegetation and songbirds are resilient to grazing. Recovery of songbirds was linked to the recovery of habitat structure. Songbirds with flexible habitat requirements, such as Savannah and grasshopper sparrows, responded rapidly to livestock exclusion. The retrogressive nature of succession in mixed-grass prairie offers managers an opportunity to take chances when attempting to create wildlife habitat with livestock grazing, as risk of irreversible change is relatively low. / October 2016

Rotational grazing is being promoted by some land managers, government agencies, and conservation groups as superior to season-long grazing for improving pasture and cattle production, and for grassland bird conservation; however, the assumed benefits have not been comprehensively studied. In 2011 and 2012, I examined the effects of twice-over rotational grazing on the nesting success of grassland songbirds in southwestern Manitoba, Canada. I monitored nesting attempts and collected structural vegetation data for five species of obligate grassland bird (n=110) and one shrub-nesting species (n=41). Nesting analyses were conducted using logistic exposure models. Twice-over grazing had a significantly negative effect on the nesting success of the ground nesting species, including Savannah sparrows (Passerculus sandwichensis). Grazing system did not have an effect on vegetation structure. The results are consistent with other rotational grazing studies, and suggest that twice-over rotational grazing does not benefit grassland songbirds in mixed-grass prairie habitats. / October 2016