Exurban development, consisting of low density residential housing in a rural setting, is steadily increasing in North America. This increase may have negative impacts on the habitat for some species, through the introduction of non-native plants and new predators such as house cats. The northern prairie skink (Plestiodon septentrionalis) is listed as Endangered in Canada occurring only in southwestern Manitoba. The objectives of this study included: a) defining prairie skink microhabitat use on private land according to vegetation, temperature and cover availability, b) determining landowner awareness of prairie skinks on their property, and c) determining how landowner stewardship could be used in skink conservation. Mixed methods strategy of inquiry was utilized and data collection procedures included both quantitative habitat surveys and qualitative landowner interviews. I found that prairie skinks were most often found in prairie habitat, and were found most often in areas with a) high percent artificial cover, b) high leaf litter, and c) more pieces of cover per acre. Landowners most often saw skinks near buildings, in flower beds and in debris piles. Landowner attitudes towards skinks were positive,though willingness may not translate into action.

The effects of global climate change on seed germination and plant regeneration have been reported in many species. However, there are no consistent trends in how seed quality and germination are affected by these conditions. Seeds of four native, one invasive, and two pairs of native/invasive species were collected from the USDA-ARS Prairie Heating and CO2 Enrichment Experimental plots in 2007 to 2009, located in the Mixed-grass Prairie near Cheyenne, WY. Field treatments include ambient (385 ppm, c) and elevated (600 ppm, C) CO2 concentrations, control temperature (t) and heating (1.5/3.0°C warmer day/night, T), and deep (ct-d) and shallow (ct-s) irrigation. Seed quality was evaluated and germination tests were conducted under alternating temperatures (10/0, 12.5/2.5, 15/5, 20/10, 25/15, 30/20, 35/25°C). Thermal time requirements (θ50) and base temperatures (Tb) for germination were determined using thermal time models. Elevated CO2 concentrations reduced seed fill and viability, germination and germination rate in Grindelia squarrosa. Heating increased seed viability in Koeleria macrantha from 56% to 79%. Heating, when combined with elevated CO2 concentrations, increased germination while CO2 alone decreased germination by about 14% in Bouteloua gracilis. Heating tended to enhance Tb and to reduce θ50 in Bouteloua gracilis, which may slow the initiation of germination but seeds germinate faster in spring. Elevated CO2 concentrations tended to increase but CT tended to decrease Tb in Centaurea diffusa, but not θ50. Heating tended to increase but all the other treatments tended to reduce Tb in Lanaria dalmatica, leading to a possible earlier start of germination. Irrigation treatments tended to show similar trend of effects on seed quality and germination as that in elevated CO2 concentrations. Species specific changes in seed quality and germination were observed, which may exert substantial cumulative effects on community composition in the long run. Invasive species may be more competitive under future climatic conditions compared with native species. However, the distribution and abundance of some native species, specifically Bouteloua gracilis, may be favored by climate change.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Three different pasture mixtures were established under irrigation at the Elsenburg research farm with the aim of devising nitrogen (N) management strategies for pastures in the Winelands sub-region of South Africa. The pasture mixtures were as follows: i) a mixed grass pasture consisting of perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinaceae) and cocksfoot (Dactylis glomerata); ii) a grass-clover pasture consisting of perennial ryegrass, tall fescue, cocksfoot and red and white clover (Trifolium pratense and Trifolium repens); and iii) a grass-lucerne pasture consisting of perennial ryegrass, tall fescue and lucerne (Medicago sativa). The effect of fertiliser N on selected nutritive characteristics was also evaluated. The grass-legume pastures were subjected to two management strategies: the once-off application of N and the consecutive application of N over the autumn-early spring period. The reaction of the mixed grass pasture to applied N was mostly characterised by an interaction between the season of N application and N application rate. The productivity of the pasture in terms of the primary dry matter production (PDMP) and the total dry matter production (TDMP) was highest in spring and summer with the application of 60 – 80 kg N ha-1, and decreased in autumn and winter. There was a strong response of the winter residual dry matter production (RDMP) to N, which indicated that not all applied N was utilised during the first regrowth cycle, which might present a risk of nitrate being leached below the root zone. The botanical composition of the mixed grass pasture was determined by season of N application, and not N application rate. The tall fescue content was low over all seasons, presumably due to poor establishment and strong competition from accompanying species. In the cooler months perennial ryegrass and tall fescue was the dominant species, while in the warmer months cocksfoot was the main species. Nitrogen application also had a significant effect on the quality of the pasture, most notably the crude protein (CP) content. The response of the CP content was characterised by a strong interaction between season of N application and N application rate. Crude protein levels in excess of 22 % were recorded in autumn and winter with the application of 40 – 80 kg N ha-1. Other characteristics remained within the expected range. The response of the grass-clover and grass-lucerne pastures in terms of productivity and nutritive characteristics were mainly determined by the season of N application, and not N application rate. Productivity tended to be highest in autumn and early spring for both the once-off and the consecutive N application strategies, emphasizing the effect of temperature on pasture growth. The effect of season of N application and the N application rate on the botanical composition of the respective pastures were inconsistent over the two years of the study. The clover content tended to decrease in response to increasing rates of N, while the grass fraction was stimulated. Lucerne productivity decreased from autumn through winter and reached minimum levels in early spring, and was unaffected by fertiliser N rate. The legume component in both the grass-clover and grass-lucerne pastures remained above recommended levels of 20 – 40 % for optimum animal production, even when N was applied consecutively. The nutritive characteristics measured (dry matter (DM) content, CP, in vitro organic matter digestibility (IVOMD)) remained within the expected range, except the total CP content which was very high in the first year (> 30 %), although N application rate did not have a significant effect. Based on these findings, preliminary recommendations for N fertilisation (on low carbon soils) for a mixed grass pasture is 40 kg N ha-1 during autumn and winter and 60 kg N ha-1 in spring and summer. Based on the poor response of the grass-legume pastures to applied N it is doubtful whether fertilisation will lead to an economical advantage, but low rates of approximately 40 kg N ha-1 could be beneficial in a grass-clover pasture during autumn and late winter/early spring based on the relatively strong response of PDMP to N during this period. / AFRIKAANSE OPSOMMING: Drie verskillende weidingsmengsels is onder besproeiing te Elsenburg proefplaas gevestig met die doel om stikstof (N) bestuurstrategieë te ontwikkel vir aangeplante weidings in die Wynland distrik van die Wes-Kaap van Suid Afrika. Die weidingsmengsels was as volg: i) ‘n gemengde gras weiding bestaande uit meerjarige raaigras (Lolium perenne), langswenkgras (Festuca arundinaceae) en kropaargras (Dactylis glomerata), ii) ‘n gras-klawer weiding bestaande uit meerjarige raaigras, kropaargras, langswenkgras, wit - en rooi klawer (Trifolium pratense en Trifolium repens), en iii) ‘n gras-lusern weiding bestaande uit meerjarige raaigras, langswenkgras en lusern (Medicago sativa). Die effek van stikstof bemesting op sekere kwaliteitsaspekte van die onderskeie weidings was ook geëvalueer. Die gras-peulplant weidings was onderworpe aan twee bestuurstrategieë, naamlik die eenmalige toediening van N en die agtereenvolgende toediening van N bemesting tydens die herfs – lente periode. Die reaksie van die gemengde gras weiding op N bemesting was hoofsaaklik gekenmerk deur ‘n interaksie tussen die N bemestingspeil en die seisoen van N toediening. Die produktiwiteit van die weidings i.t.v. die primêre droeëmateriaal produksie (PDMP) en die totale droeëmateriaal produksie (TDMP) was die hoogste in die lente en somer met die toediening van 60 – 80 kg N ha-1 en het in herfs en winter afgeneem. Daar was n sterk respons van die winter residuele droeëmateriaal produksie (RDMP) teenoor N, wat aandui dat nie alle toegediende N tydens die eerste hergroei periode benut was nie en dus ‘n moontlike risiko van loging inhou. Die botaniese samestelling van die gemengde gras weiding was deur die seisoen van N toediening bepaal, en nie die N bemestingspeil nie. Die langswenkgras inhoud was baie laag in alle seisoene, vermoedelik a.g.v. swak vestiging en sterk kompetisie van gepaardgaande spesies in die mengsel. Tydens die koeler seisoene van die jaar was meerjarige raaigras en langswenkgras die dominerende spesies, terwyl kropaargras tydens die warmer maande gedomineer het. Stikstof toediening het ook ‘n betekenisvolle effek op die kwaliteit van die weiding gehad, veral die ru-proteien (RP) inhoud. Die respons van RP was weereens gekenmerk deur ‘n betekenisvolle interaksie tussen die seisoen van N toediening en die N peil. Ru- proteien vlakke hoër as 22% was tydens herfs en winter waargeneem met die toedieningspyle van 40 – 80 kg N ha-1. Ander kwaliteits- eienskappe het binne normale perke gebly. Die respons van die gras-klawer en gras-lusern weidings in terme van produktiwiteit en kwaliteitseienskappe was hoofsaaklik deur die seisoen van N toediening bepaal, en nie deur die N bemestingspeil nie. Die produktiwiteit was die hoogste tydens herfs en vroeë lente vir beide die eenmalige en die herhaalde N toedieningsstrategieë. Hierdie bevindinge beklemtoon die belangrike effek van temperatuur op die groei en produksie van weidingsgewasse. Die effek van seisoen van N toediening en N peil op die botaniese samestelling van die gras-peulgewas weidings was inkonsekwent oor die twee jare van die studie. Die klawer-fraksie was geneig om af te neem soos wat die N peil toegeneem het, terwyl die gras-fraksie toegeneem het. Die lusern-inhoud het van herfs tot lente afgeneem en was ongeaffekteer deur die N peil. Die peulgewas-inhoud van beide weidingsmengsels was deurentyd hoër as die voorgeskrewe minimum vlak van 20 – 40%, selfs met opeenvolgende N-toediening. Die kwaliteitseienskappe gemeet in die studie (droeëmateriaal (DM) inhoud, RP en in vitro organiese materiaal verteerbaarheid (IVOMV)) het binne normale perke gebly, behalwe die totale ru-proteien (TRP) inhoud wat baie hoog was tydens die eerste jaar (>30%), alhoewel dit nie deur die N peil beinvloed was nie. Aan die lig van bogenoemde bevindinge is die voorlopige aanbeveling vir N- bemesting (op lae koolstof gronde) van ‘n gemengde grasweiding 40 kg N ha-1 tydens die herfs en winter en 60 kg N ha-1 tydens lente en somer. Gebasseer op die swak respons van die gras-peulgewas weidings op toegediende N, is dit twyfelagtig of N toediening enige ekonomiese voordeel vir die boer sal inhou. Gebaseer op die relatiewe sterk respons van die gras-klawer PDMP op toegediende N tydens herfs en laat winter/vroeë lente kan dit moontlik voordelig wees om lae N-vlakke van ongeveer 40 kg ha-1 tydens hierdie seisoene toe te dien.

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

A 4-year study was conducted on the Missouri Coteau in the Mixed Grassland Ecoregion of Saskatchewan to determine the effects of mowing to a 7.5 cm stubble height on the growth of <i>Festuca hallii</i> (Vasey) Piper and <i>Stipa curtiseta</i> (A.S. Hitch.) Barkworth. Green standing crop (GSC), dead standing crop (DSC) and above ground net primary production (ANPP) were compared to an unmowed control after a single mowing in April, May, June, July, August, September, October or November on 5 landforms including north aspect-concave-slope, north aspect-convex-slope, south aspect-concave-slope, south aspect-convex-slope and level upland. Mowing reduced GSC, DSC and ANPP with reductions varying among months of mowing and among landforms. Green standing crop, DSC and ANPP of <i>F. hallii</i> were greatest on the north aspects and least on south aspect-convex slope and ranged from 2 to 122 g m-2, 3 to 121 g m-2, and 8 to 122 g m-2, respectively. Mowing reduced GSC of <i>F. hallii</i> for 1 to 11 growing season months and DSC for 1 to >11 growing season months. Mowing in May or November reduced ANPP of <i>F. hallii</i> for 1 growing season, while mowing in other months reduced ANPP for 2 growing seasons. Green standing crop of <i>S. curtiseta</i>, ranging from 3 g m-2 to 55 g m-2, was least on the north aspects and greatest on the south aspect-convex slope and was reduced 1 to 5 growing season months following mowing. Mowing after June reduced DSC of <i>S. curtiseta</i>(5 to 58 g m-2) for 1 to 10 growing season months, and ANPP (6 to 64 g m-2) for 1 growing season. Generally, mowing reduced GSC, DSC and ANPP of <i>F. hallii</i> longer than <i>S. curtiseta</i>. Production of <i>F. hallii</i>- and <i>S. curtiseta</i>-dominated plant communities in the Northern Mixed Prairie will be maintained by providing rest periods between defoliation events based on the number of growing season months for <i>F. hallii</i> to recover production.

A 4-year study was conducted on the Missouri Coteau in the Mixed Grassland Ecoregion of Saskatchewan to determine the effects of mowing to a 7.5 cm stubble height on the growth of <i>Festuca hallii</i> (Vasey) Piper and <i>Stipa curtiseta</i> (A.S. Hitch.) Barkworth. Green standing crop (GSC), dead standing crop (DSC) and above ground net primary production (ANPP) were compared to an unmowed control after a single mowing in April, May, June, July, August, September, October or November on 5 landforms including north aspect-concave-slope, north aspect-convex-slope, south aspect-concave-slope, south aspect-convex-slope and level upland. Mowing reduced GSC, DSC and ANPP with reductions varying among months of mowing and among landforms. Green standing crop, DSC and ANPP of <i>F. hallii</i> were greatest on the north aspects and least on south aspect-convex slope and ranged from 2 to 122 g m-2, 3 to 121 g m-2, and 8 to 122 g m-2, respectively. Mowing reduced GSC of <i>F. hallii</i> for 1 to 11 growing season months and DSC for 1 to >11 growing season months. Mowing in May or November reduced ANPP of <i>F. hallii</i> for 1 growing season, while mowing in other months reduced ANPP for 2 growing seasons. Green standing crop of <i>S. curtiseta</i>, ranging from 3 g m-2 to 55 g m-2, was least on the north aspects and greatest on the south aspect-convex slope and was reduced 1 to 5 growing season months following mowing. Mowing after June reduced DSC of <i>S. curtiseta</i>(5 to 58 g m-2) for 1 to 10 growing season months, and ANPP (6 to 64 g m-2) for 1 growing season. Generally, mowing reduced GSC, DSC and ANPP of <i>F. hallii</i> longer than <i>S. curtiseta</i>. Production of <i>F. hallii</i>- and <i>S. curtiseta</i>-dominated plant communities in the Northern Mixed Prairie will be maintained by providing rest periods between defoliation events based on the number of growing season months for <i>F. hallii</i> to recover production.

Grasslands are characterized by recurring disturbances such as fire and grazing occurring against a background of topoedaphic heterogeneity and climatic variability. The result is a complex, multi-scaled disturbance regime, in which fire and grazing often have interactive roles, yet they have usually been studied independently. Relationships between climate, fire and simulated grazing (=mowing) were explored to determine the roles these disturbances play in shaping patterns and processes in southern mixed-grass prairie. A field experiment investigated the potential effects of these disturbances on above and belowground plant productivity, patch dynamics, and soil respiration over a 2-year period characterized by drought (1998) and normal (1999) rainfall. Spring burning and mowing had interactive effects on aboveground net primary production (ANPP). Consistent with published single factor studies, burning without mowing doubled ANPP, whereas mowing in the absence of burning had neutral effects. However, subsequent mowing on burned plots reduced ANPP gains to levels comparable with all unburned plots. Drought reduced ANPP by 22% relative to a normal rainfall year. In contrast to the traditional model of root response to defoliation, burning and mowing each stimulated root length recruitment measured with minirhizotrons. However, subsequent mowing on burned plots did not produce additional root recruitment. Fire and mowing appear to interact by affecting different components of root recruitment (production and mortality, respectively). Root biomass recovered from ingrowth cores were not correlated with minirhizotron results, and responded only to drought, suggesting that methodological differences have contributed to the varied root responses reported in the literature. Drought suppressed soil respiration, diminished soil moisture, and enhanced soil temperature, whereas fire and/or mowing had little effect. Results suggest that any fire or mowing effects on soil respiration in southern mixed-grass prairie may be highly constrained by moisture limitations during dry periods. In summary, patch level response to fire is a pulse of root recruitment followed by increased ANPP, unless subsequent grazing offsets these gains. Grazing alone produces a pulse of root recruitment, perhaps to replace consumed foliage. This study demonstrates the interactive nature of fire and grazing in grasslands, and the perils of single-factor studies.

No description available.

I examined the effects of nest site vegetation structure and cattle grazing on songbird nesting success in native mixed-grass prairie in Grasslands National Park of Canada and Mankota Community Pastures in southwestern Saskatchewan. This is the first study to compare songbird nesting success in season-long grazed and ungrazed native mixed-grass prairie. Sprague’s pipit, Baird’s sparrow, vesper sparrow, lark bunting, and chestnut-collared longspur all selected for denser vegetation at the nest than was generally available. Sprague’s pipit daily nest survival declined with increased vegetation density and litter depth at the nest site. Vegetative cover did not influence daily nest survival of the other species. Environmental conditions during the study may have resulted in an increased risk of predation for Sprague’s pipits nesting in greater cover. Grazing did not influence daily nest survival of any of the 5 species. Low-moderate intensity cattle grazing appears compatible with management for prairie songbirds in native mixed-grass prairie.