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The amount of semi-natural grasslands has decreased in the agricultural landscape and because of this many grassland species are declining. Semi-natural grasslands are dependent on management, but different studies suggest that different management methods are most favorable to species richness and abundance. The aim of this study was to compare the effects of mowing and grazing on butterfly and bumblebee abundance in Swedish semi-natural grasslands. We used data collected through the Swedish environmental monitoring program NILS. We identified 31 comparable meadows and chose 1-10 pastures in the area surrounding each meadow. For six different species groups we calculated the number of individuals found per 100 m. By standardizing the values of the difference between the means for meadows and pastures we were able to compare the effects of the two methods on abundance in each species group. No species group showed a preference for pastures. A significant preference for meadows was found for two butterfly species groups. The four other groups showed a trend to prefer meadows before pastures. According to our study the recommended management method should be mowing, considering protection of butterflies and bumblebees.

The aim of the study was to integrate economics, forage agronomy and livestock production data to determine the economic costs and benefits of management techniques that can extend the grazing season for beef production in Atlantic Canada. The results of the study show that extending the grazing season is financially and economically beneficial for both an Atlantic beef farmer and the whole Atlantic community. Extending the grazing season could be thus an alternative solution to enhance beef farm viability in Atlantic Canada. It can also contribute to the sustainable development of beef cattle production through its benefits for environmental protection. The results of this study reflect the necessity of supporting and promoting the adoption of extended grazing season practices in Atlantic beef production. This support and this promotion could involve increasing awareness, training on grazing management skills, diffusion at workshops and participatory research.

This study examines changes in lake-water total organic carbon (LW-TOC) and lake sediment geochemistry in two lakes, Stångtjärnen and Holtjärnen in (Dalarna, Sweden), during the Holocene and the role of the historic forest grazing and farming (fäbod-system). The aims of the study were to: 1. Discern the effects of natural processes on the lake’s biogeochemistry in different position in the landscape. 2. Identify the effects and differences in intensity of historic land-use on the lakes. A multi-proxy study was conducted encompassing multi-element (15) geochemistry, biogenic silica, LW-TOC, chlorophyll a and published pollen records. The first lake, Stångtjärnen, is shaped and influenced by surrounding mires, which developed shortly after deglaciation and stabilized the LW-TOC at 19 mg L-1 throughout most of the Holocene, while Holtjärnen, a small upland lake, changed from a productive lake (BSi: 35 %), low humic (LW-TOC: 8 mg L-1) to a less productive (BSi: 4 %) more humic lake (LW-TOC: 12 mg L-1) in 7300 BP. The intensification of agricultural land-use (e.g. hay-making) in Stångtjärnen reduced the concentrations of organic associated elements (Br, Cl) and LW-TOC and increased lithogenic elements (K, Ti), while Holtjärnen showed less anthropogenic influence. The comparison between the two lakes displayed the intensive influence of land-use on the Stångtjärnen catchment, showcased by changes in the sediment geochemistry, vegetation composition and the extent of the forest-grazing system in a landscape perspective. In response to the changes of the Holocene, Stångtjärnen’s mires became the main influence, while Holtjärnen was more sensitive to changes.

Master of Science / Division of Biology / David A. Haukos / Sericea lespedeza (Lespedeza cuneata) is an invasive forb that reduces native grass and forb abundance in tall-grass prairie by up to 92%. Controlling invasions is difficult because traditional land management tools used in the Flint Hills, broad spectrum herbicides, spring prescribed fire, and cattle grazing, are ineffective against sericea. Recent research has demonstrated, however, that mid- and late summer prescribed fire and spring fire with early season grazing by steers followed by late season grazing by sheep are effective at reducing sericea whole plant mass, number of seeds produced, and seed mass. Field results were from two separate experiments conducted in tall-grass prairie study sites in the Flint Hills. On a Geary County, Kansas, study site, the utility of 1) spring fire (control), 2) mid-summer fire, and 3) late summer fire on sericea control were compared. On a Woodson County, Kansas, study site, the utility of 1) spring fire with early season steer grazing followed by rest (control) and 2) spring fire with early season steer grazing and late season sheep grazing on sericea control were compared. At the same study sites, I measured responses by the native wildlife community to use of summer fire and sheep grazing, relative to their controls, to manage sericea lespedeza. Specifically, my objectives were to compare grassland songbird density, grassland songbird nest survival, and grassland butterfly species composition and density among treatments at both study sites. I also related patterns in the vegetation community of each treatment for each study site to respective patterns in grassland bird and butterfly communities. Within study sites, density, nest density, and nest success of grassland bird communities responded similarly to treatments and controls, with the exception that densities of Grasshopper Sparrows (Ammodramus savanarrum) were 3.4- and 2.2-fold greater in mid- and late summer fire plots than spring fire plots, respectively, in the Geary County study site. Species compositions of butterfly communities were similar across treatments within experiments, but grassland specialist species comprised only 8.6 and 1.2% of all butterfly observations in the Geary County and Woodson County experiments, respectively. Grassland specialist butterfly species may benefit from summer fire, as their nectar sources were more abundant in Summer Fire plots than Spring Fire plots. Overall, within each experiment, grassland bird and butterfly communities were similar across treatments, suggesting that treatments did not negatively affect grassland songbird and butterfly communities. I additionally demonstrated that Dickcissel (Spiza americana) nest sites contain a lower proportion of sericea than random points, the first evidence that the invasion is detrimental to grassland songbird species. Lacking control, the continued sericea invasion will out compete cumulatively more forb plants resulting in declining quality of grassland bird nesting habitat on the landscape. Controlling sericea lespedeza invasions will allow native forb species to increase in abundance and improve the condition of grasslands for native wildlife and livestock producers. Therefore, I advocate use of summer fire or spring fire with a combination of cattle and sheep grazing to control sericea lespedeza with the long-term goal of tall-grass prairie restoration.

This study examined the extent to which zooplankton in the James River Estuary (Virginia, USA) exploit the available algal-food resources. Zooplankton abundance, community composition and grazing rates were assessed at three locations which included a site with high algal production (near the VCU Rice Center) and two sites where algal production was lower. Grazing rates were measured by determining the rate of phytoplankton decline (as chlorophyll a) during 48-hour incubation experiments in the presence and absence of zooplankton. Significant differences in zooplankton abundance were observed among the three sites, with the greatest average zooplankton density (434 ± 69 ind/L) occurring at the phytoplankton maxima. There were no significant differences in zooplankton filtration or ingestion rates among the three sites. The amount of chlorophyll a consumed was low at all sites (< 5%), suggesting that only a small proportion of primary production was directly passed to higher trophic levels. Low grazing rates were attributed to poor food quality owing to the presence of non-algal particulate matter and a predominance of cyanobacteria comprising the phytoplankton community. These findings are consistent with prior studies showing that cyanobacteria are a poor quality food source for zooplankton and that non-algal particulates may interfere with grazing rates. Further, this study lends support to the hypothesis that food quality is an important determinant of trophic transfer efficiency in aquatic food webs.

Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Habitat heterogeneity is a key driver of biodiversity in many ecosystems. In native ecosystems, habitat heterogeneity can arise from multiple drivers including nutrients, topoedaphic conditions, and ecological disturbance. Historically, the prairies of North America existed as a heterogeneous mosaic of habitat conditions created by the interaction of fire and grazing by native ungulates. The focus of many grazing systems has been to minimize disturbance caused by grazing by promoting uniform distributions of grazing animals across management units. Patch-burn grazing is an alternative rangeland management practice that has been proposed to restore historical patch dynamics and biodiversity to rangelands by simulating historical disturbance processes. In my dissertation research, I tested the hypothesis that patch- burn grazing restores habitat heterogeneity to rangelands, and that the resulting habitat heterogeneity can promote biodiversity of native wildlife. I focus on responses of small mammals and coyotes to patch-burn grazing to gain a better understanding of wildlife responses to rangeland management, and because grassland mammals are an ecologically important group. My 3.5-year field study of habitat and small mammal responses to rangeland management showed that: 1) patch-burn grazing created greater heterogeneity in vegetative structure and composition of plant functional groups than in positive and negative controls; 2) habitat heterogeneity created by the interaction of fire and grazing increased small mammal richness and diversity compared to a negative control managed for uniform grazing distributions; 3) the interaction of fire and grazing structured small mammal communities in tallgrass prairie; and 4) population dynamic responses of small mammals to fire and grazing disturbance were species- specific. My 3-year study of coyote survival and resource selection revealed that: 1) rangeland management influences resource selection by coyotes in seasons when they depend on small mammal prey, but not during other seasons; and 2) anthropogenic sources of mortality are important for coyotes at a protected area, even in the absence of harvest. My field results show that restoring the drivers of historical patch dynamics to managed rangelands and publicly held grasslands that are not currently grazed could have profound effects on biodiversity conservation in North America, while continuing to provide ecosystem services to society.

Orientador: Ciniro Costa / Resumo: O trabalho objetivou avaliar o desempenho, grau de infecção natural por helmintos gastrintestinais, variáveis hematológicas e análise econômica de borregas com duas estratégias de recria: um em semiconfinamento e outro em confinamento e posteriormente em semiconfinamento com duas taxas de lotação, em área de aveia preta proveniente de sistema integrado de produção agropecuária (SIPA). Foram utilizados 13 borregas da raça Corriedale por tratamento, sendo: T1) Semiconfinamento com menor taxa de lotação por área (686,4kg de PV/ha) durante 70 dias; T2) Semiconfinamento com maior taxa de lotação por área (1113,6kg de PV/ha) durante 70 dias; T3) Confinamento por 28 dias, seguido por semiconfinamento com menor taxa de lotação por área (686,4kg de PV/ha) durante 42 dias; T4) Confinamento por 28 dias, seguido por semiconfinamento com maior taxa de lotação por área (1113,6kg de PV/ha) durante 42 dias. Para as análises foram utilizados os comandos PROC MIXED e PROC GLIMMIX do SAS e as médias ajustadas pelo método dos quadrados mínimos foram usadas nas análises de comparações múltiplas (P ≤ 0,05). Os tratamentos 3 e 4 apresentaram melhor desempenho, maior consumo de matéria seca e menor contagem de ovos por grama de fezes, em relação aos tratamentos 1 e 2. Ao final do experimento, os animais apresentaram percentual médio de Haemonchus (73,1%), seguida por Trichostrongylus (11,4%) e Cooperia (3,9%). As espécies de helmintos gastrintestinais presentes foram: Haemonchus contortus, Trichostr... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Ecological restorations have become increasingly important as humans have made irreversible changes to ecosystems; biogeochemical cycle alterations and land use changes have led to degraded conditions (Vitousek et al. 1997a). While some modifications to the environment are unavoidable, society is beginning to realize that changes are necessary. While some ecosystem functions may be beyond repair (e.g., biodiversity loss and extinction of species), it is important that the problem is faced head on and those functions that are still salvageable be restored. These environmental repairs can be done through ecological restoration. I looked at two different ecosystems, prairie streams and agricultural streams, that have undergone restoration to help functions. Patch-burn grazing (PBG) is increasingly used as a management practice on the few remaining tallgrass prairie parcels in an effort to simulate effects of large ungulate grazers. Yet, little is known about potential impacts and recovery of aquatic habitats from this management approach. My objective was to assess the influence of PBG with cattle on prairie streams and build on previous research at this site. I hypothesized that cattle grazing would negatively impact water quality and reduce stream biotic integrity, but riparian fencing would mitigate these impacts. We also assessed stream recovery for two years following the removal of ungulates from the study sites and hypothesized that biological and chemical effects would reverse. Six headwater streams (two controls, two PBG with 10 m fenced riparian zones, and two PBG with unfenced riparian zones) on Osage Prairie, Missouri, were sampled over seven years (2009-2015) encompassing pre-PBG (2 years), PBG (3 years), and post-PBG (2 years) periods. Macroinvertebrates and water chemistry were sampled monthly. Nitrate (NO3-) concentrations increased in the fenced and unfenced watersheds compared to the control watersheds (p = 0.015 and p < 0.0001, respectively) and between the fenced and unfenced watersheds (p = 0.001) during the PBG period relative to pre-PBG. Total phosphorus (TP) increased in the fenced and unfenced watersheds after grazing began compared to the control (both p < 0.0001) but did not differ between the fenced and unfenced watersheds (p = 0.187). Relative Chironomidae biomass and abundance increased in the unfenced watersheds in response to grazing (p = 0.008 and p < 0.001, respectively). No differences were observed in relative Chironomidae biomass and abundance, NO3-, and TP from pre-PBG to post-PBG indicating the recovery of these metrics. Results suggest that the negative effects of PBG on prairie streams can be somewhat mitigated by riparian fencing. Additionally, these streams are relatively resilient to PBG and recovery can take place during a rest cycle as brief as two years. Approximately one billion dollars is spent annually on restorations of degraded stream reaches in the United States. However, few projects are monitored upon completion, or monitoring focuses on a single parameter. Other than modifications to physical attributes of streams, the influence of restoration projects on ecosystem processes remains largely unknown. We sampled eleven Midwestern streams that had undergone habitat restorations from 3-15 years prior to sampling. Restoration techniques included in-stream habitat enhancements, bank stabilization, and riparian restoration. We predicted that gross primary production (GPP) would be lower in restored streams due to decreased nutrient inputs, and that respiration would be greater due to increased litter inputs from restored riparian areas. We also hypothesized that the restored streams would have greater invertebrate richness, abundance, and biomass, as well as high densities of intolerant taxa such as Ephemeroptera, Plecoptera, and Trichoptera (EPT taxa) due to higher water quality and better habitat. Restored reaches and unrestored upstream reaches were sampled for physical characteristics, water chemistry, benthic algal biomass, whole-stream metabolism, and macroinvertebrate communities. GPP in restored sites was marginally higher than unrestored sites (t5 = 2.53, p = 0.05), despite no differences in PO4-3, NO3-, or NH4+ concentrations. Three restored sites were autotrophic (P/R > 1), while four unrestored sites were heterotrophic. Total macroinvertebrate biomass was marginally higher in the restored sites compared to unrestored sites (t10 = 1.94; p = 0.08). EPT biomass was also marginally higher in restored sites than unrestored sites (t10 = 1.91; p = 0.09) but no difference was observed in EPT abundance. Results suggest that stream habitat restorations enhance some, but not all ecosystem processes and marginally enhance macroinvertebrate communities.

Master of Science / Department of Biology / David C. Hartnett / A key feature of many grass-dominated ecosystems is the formation of grazing lawns, distinct patches characterized by intense grazing by mammalian herbivores and a dense short-statured grass canopy. A central concept of grazing lawns is the positive feedbacks between grazing animals and the grass resource. Intraspecific morphological plant trait changes and differences in plant species composition could both or individually play a role in the differences in characteristics of grazing lawns and neighboring tallgrass swards. I studied grazing lawns in North American tallgrass prairie to: a) test the ‘architectural shift hypothesis’ where continued grazing leads to changes in plant architecture resulting in more efficient foraging for grazers, creating a positive feedback that increases grazing and b) examine soil resource (nutrient and water) availability and grass nutritive quality on and off lawns to test the nutrient- and water-based pathways for grazing lawn maintenance. In a separate study (not reported here), we a) examined plant community structure on and off lawns to determine whether species composition differences account for the distinct grazing lawn characteristics and b) assessed effects of grazing lawn formation on tallgrass prairie plant species diversity. Several differences in morphological traits between dominant grasses on grazing lawns and tallgrass swards support the architectural shift hypothesis. For Sorghastrum nutans, Dichanthelium oligosanthes, and Pascopyrum smithii, leaf-to-stem ratio was twice as high on grazing lawns compared to surrounding matrix tallgrass vegetation and tiller branching was higher and culm internode lengths were shorter on grazing lawns for these species. However, Andropogon gerardii traits did not differ between grazing lawns and tallgrass vegetation. For all four species, above-ground tiller biomass and number of below-ground buds were both higher on grazing lawns. Overall, these morphological responses resulted in a higher grass canopy density (forage biomass per unit canopy volume) on grazing lawns and this increased grass canopy density in turn results in higher grazer foraging efficiency by increasing the amount of forage intake per bite and per unit time. D. oligosanthes, P. smithii, and S. nutans plants on grazing lawns had a significantly lower carbon-to-nitrogen ratio and higher nitrogen content than plants in the matrix tallgrass vegetation, while A. gerardii showed no significant difference in nitrogen content or in carbon-to-nitrogen ratio between grazing lawns and surrounding matrix tallgrass vegetation. With regards to the total grass canopy (all grass species combined), nitrogen content was significantly higher on grazing lawns compared to tallgrass vegetation for all three field seasons, 2016, 2017, and 2018. All measured soil nutrients, ammonium, nitrate, phosphorus, and sodium, were significantly higher on grazing lawns compared to soils of surrounding tallgrass swards, while water content showed no significant difference between grazing lawns and surrounding tallgrass vegetation. The results of this study strongly indicate that developmental and morphological shifts result in increased forage density and increased grazing efficiency on grazing lawns and that the frequent and intense activities of large grazers result in increased plant nitrogen content and lower C:N ratios in grasses on tallgrass prairie grazing lawns. Thus, at least two different mechanisms, plant architectural shifts and the nutrient-based pathway could both contribute to the positive feedbacks that encourage further grazing on lawns and grazing lawn maintenance on tallgrass prairie.