Theses and Dissertations at Montana State University (MSU)
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Item Impacts of a non-native forb, Alyssum desertorum Stapf., and non-target effects of Indaziflam in the sagebrush steppe of Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 2021) Meyer-Morey, Jordan; Chairperson, Graduate Committee: Lisa J. RewNon-native plants can reduce biodiversity and disrupt essential ecosystem services and functions. For most non-native plant species however, quantitative evidence of negative effects is lacking, as are fundamental demographic details; such information can inform whether and at what growth stage to implement control. Control strategies can also negatively impact non-target native plant communities; therefore, evaluating the tradeoffs of management and understanding the actual impacts of the invader is essential. I sought to understand the life history, and evaluate the competitiveness and impacts of the non-native annual forb, Alyssum desertorum Stapf., as well as non-target effects of management, across an elevation gradient in a cool, mountain sagebrush (Artemisia tridentata ssp. vaseyana (Rydb.) Beetle) steppe plant community. Seed viability, fecundity, overwintering success, and likelihood of reaching reproductive maturity of A. desertorum all declined as elevation increased; all life stage transition rates were high, suggesting that targeting seed production or fall germination would be the most effective means for control of this species. Replacement series experiments revealed that A. desertorum is a weak competitor with functionally similar species. Additionally, in the field, the presence of A. desertorum did not affect species richness nor Shannon's diversity aboveground or in the soil seedbank, and functionally similar native annual forbs were not displaced in invaded areas. I evaluated the efficacy and non-target effects of the pre-emergent herbicide, indaziflam, in diverse sagebrush steppe with localized infestations of A. desertorum across an elevational gradient. While indaziflam effectively controlled A. desertorum for two years, the richness and diversity of the surrounding community was reduced. Indaziflam inhibited recruitment of forbs, both in the field and in the seedbank. As indaziflam provides residual control of the soil seedbank for up to three years, my results suggest the future community composition may be altered, particularly native annual forb populations. Considering the weak competitive ability of A. desertorum, the species' minimal impacts to richness and diversity, and the negative effects of indaziflam to annual native forb species, I conclude that the non-target effects of indaziflam would outweigh any benefits to controlling A. desertorum in intact sagebrush steppe.Item Plant diversity of Mediterranean-type ecosystems with an emphasis on cultivated species(Montana State University - Bozeman, College of Agriculture, 2019) Botros, Mina Habib; Chairperson, Graduate Committee: Matthew LavinThe Mediterranean Basin is an important biodiversity hotspot. Unfortunately, only 5% of its original vegetation remains intact because people have managed and transformed the landscape for the past 2000 years. In the last century, humans overused the semi-natural habitats which had a negative impact on the area more than earlier times. This is in addition to the mechanization of agriculture which had a negative impact on the area as well (Puddu, Falcucci, and Maiorano 2011). Mediterranean-type ecosystems (MTEs) are as plant diverse as tropical ecosystems. This biodiversity is larger than expected considering the relatively high latitude and the low productivity of the region. This makes these areas a good case study to examine the processes affecting plant diversity. Five MTEs are described as biodiversity hotspots due to the high numbers of endemic plant species. Scientists are working to decrease the biodiversity loss in the Mediderranean area. Here we will discuss biodiversity, cultivated species, and threats to Mediterranean-type ecosystems. Moreover, we will present the adaptation of these species to biotic and abiotic stresses, in addition to scientists' efforts to develop cultivars well-adapted to these stresses.Item Cultural plant biodiversity in relict wallow-like depressions on the Wind River Indian Reservation, Wyoming, & tribal bison restoration and policy(Montana State University - Bozeman, College of Agriculture, 2016) Baldes, Jason Eric; Chairperson, Graduate Committee: Rick L. LawrenceBison and Native people have co-existed on the North American landscape for millennia. As a keystone species, bison support many other organisms including plants, animals, insects and birds. Their unique dust-bathing behavior create wallow-like depressions (WLDs), altering the landscape at the local level, and are believed to increase water accumulation and support different plant species in the surrounding area. Native Americans traditionally accessed forb plants as foods tools and medicines, which are believed to increase in wallows, and in the wallow like depressions (WLDs) studied in this project. The area chosen for this study is on the Wind River Indian Reservation (WRIR) in Wyoming, home of the Eastern Shoshone and Northern Arapaho Tribes. The northern boundary of the WRIR has been identified as an ideal location for bison restoration. As bison reintroduction might impact plant biodiversity, this study gathered baseline data of cultural plant frequency inside vs. outside 65 WLD locations. Thirty-three plants were associated with WLDs, 11 plants contained sufficient data for comparison, and five plant species had a statistically significant difference in frequency using a paired t-test. Three cultural plants were shown to have greater frequency inside WLDs vs. non-WLDs. This baseline data will potentially be used to monitor changes to the landscape after bison are restored to the WRIR. Multiple tribes are maneuvering the political arena to acquire bison and the process is complex. Federal, tribal, state, and local agencies all vie for a say in management of genetically pure bison of Yellowstone National Park. Tribes are restoring bison and forming coalitions and international treaties to share and restore herds on tribal lands. The Fort Peck Tribes of Montana are re-acquiring land to allocate to their cultural herd of Yellowstone bison and lead the way in becoming a new tribally operated quarantine facility for excess Yellowstone bison. Tribal bison policy and acquisition is an exercise in tribal self-determination and will be a way for tribes to implement programs for cultural and ecological restoration in the coming years.Item Effects of organic and conventional cropping systems on plant diversity and plant soil feedbacks(Montana State University - Bozeman, College of Agriculture, 2015) Johnson, Stephen Patrick; Chairperson, Graduate Committee: Fabian D. Menalled; Zach J. Miller, Erik A. Lehnhoff, Perry R. Miller and Fabian D. Menalled were co-authors of the article, 'Cropping systems modify the impacts of biotic plant-soil feedbacks on wheat (Triticum aestivum L.) growth and competitive ability' submitted to the journal 'Journal of applied ecology' which is contained within this thesis.The reliance on tillage for cover crop termination, weed, and residue management is one of the biggest sustainability challenges facing organic grain farmers. Integrating grazers may be an alternative to tillage for weed management and cover crop termination. We used an on-farm trial to compare tillage-based versus grazed / reduced tillage-based management of organic crops. Our results indicate that using sheep to terminate cover crops andmanage weeds can reduce tillage intensity and provide crop yields weed communities similar to standard, tillage-intensive practices. In addition, growers leasing their land under a grazing lease may be able to increase economic returns. We also implemented a crop rotation study comparing traditional tillage-based organic to reduced-tillage organic with animal-integration, as well as to a no-till conventional system with fertilizer and pesticide inputs. There were no differences in cover crop growth and subsequent winter wheat yielded the same among the three systems. We found little evidence that weed communities differed among the three management systems in the transition to organic period. Generally, shifts in weed communities occurred across all system from one crop to the next, indicating cropping sequence structured weed communities more than divergent tillage and weed management practices Biologically-mediated plant-soil feedbacks (PSFs) are known to alter plant growth, plant-plant interactions, and plant community dynamics in natural systems. Yet, little is known about the magnitude and importance of PSFs in agro-ecosystems. Therefore, we implemented a greenhouse study that investigated the impact of organic and conventional management systems on crop growth and crop-weed interactions as mediated through PSFs. Results indicated that in general, PSFs and plant growth were more positive when soil inocula was collected from organic farms compared to conventional farms, suggesting that cropping systems modify the relative abundance of mutualistic and pathogenic organisms responsible for the observed PSFs. Also, as feedbacks became more positive, crop-weed competition decreased and facilitation increased. Therefore, in annual cropping systems, PSFs can alter plant growth and crop-weed competition.Item Plant functional group diversity as a mechanism for invasion resistance(Montana State University - Bozeman, College of Agriculture, 2002) Pokorny, Monica LynnItem The ecology and integrated management of tall buttercup (Ranunculus acris L.)(Montana State University - Bozeman, College of Agriculture, 2014) Strevey, Hally Kirsten; Chairperson, Graduate Committee: Jane M. MangoldTall buttercup (Ranunculus acris L.) is a perennial invasive forb found in pastures and irrigated meadows. It has been problematic in New Zealand where it excludes important forage species. The impact of tall buttercup is of interest in North America, especially in Montana where it has invaded over 8300 hectares. Minimal published research exists in the region regarding its impacts and methods of control. My research objectives were to 1) determine the associations of tall buttercup with forage, species richness, and plant diversity, 2) test integrated management strategies to control tall buttercup, and 3) assess the importance of soil moisture on seedling emergence and growth. Objective 1 was carried out in flood and sub-irrigated hayfield meadows over two years near Twin Bridges, Montana. Three transects were established along a gradient of increasing tall buttercup cover at two sites. In general, tall buttercup was found to have minimal associations. It was not associated with species richness, and was positively correlated to plant diversity. It was negatively associated with perennial grasses at one site. Objective 2 was conducted in flood and sub-irrigated hayfield meadows over two years near Twin Bridges, Montana. Treatments were applied in a split-plot design with four replications at two sites. Herbicide treatments occurred at the whole-plot level; non-sprayed, aminocyclopyrachlor + chlorsulfuron, aminopyralid and dicamba. Split-plots consisted of mowing and fertilization. All herbicides provided up to two years of tall buttercup control and mowing and fertilization controlled tall buttercup at one site. Forage production increased following aminopyralid and dicamba treatments; however, aminocyclopyrachlor + chlorsulfuron reduced perennial grasses. Objective 3 was explored in the greenhouse testing tall buttercup seedling emergence and growth along a soil moisture gradient. Seeds were planted in one of three different moisture treatments including 25, 50 and 100% field capacity. The 50% and 100% treatments had the highest seedling density, while the 50% treatment had the highest seedling biomass and height. Integrated management should be utilized for tall buttercup control, and altering irrigation practices may provide control by reducing seedling emergence and growth. Future research is warranted to understand tall buttercup invasion potential across habitat types.Item Using ecological theory to guide the implementation of augmentative restoration(Montana State University - Bozeman, College of Agriculture, 2004) Bard, Erin Christina; Co-chairs, Graduate Committee: Roger L. Sheley and Jeff JacobsenInvasive organisms are now considered the second worst threat to native biological biodiversity, behind habitat loss and fragmentation. Successful control of invasive plants can have unexpected impacts on native plants and wildland systems. Therefore, it is important for managers of invasive species to become increasingly concerned with more than target invaders, but also ecological mechanisms and processes like invasion resistance, environmental heterogeneity, and succession that direct plant community dynamics. Augmentative restoration is a management approach that augments existing ecological processes by selectively repairing and replacing those processes that are damaged or missing thereby directing plant communities in a desirable direction. Our overall objective was to test the concept of augmentative restoration. Our overall hypothesis was that successional processes occurring at high levels could be augmented by selectively repairing or replacing successional processes that occur at low levels to increase desired species composition. In a split plot design with 4 replications at 3 sites, 8 factorial treatment combinations from 3 factors (shallow tilling, watering, and seeding) were applied to whole plots, and 2,4-D was applied to sub plots. Cover and density of seeded species, Centaurea maculosa, and Potentilla recta as well as existing native and exotic forbs and grasses were sampled in 2002 and 2003 to produce pretreatment and post-treatment data. ANCOVA was used to analyze cover and density data using pre-treatment data as a baseline covariate. Data indicated that areas with high percent bare ground required seeding and watering to increase seeded species and native forbs, while seeding and tilling increased seeded species and native forbs in areas of high soil moisture. C. maculosa, P. recta, and exotic forbs decreased in response to tilling and 2,4-D. Exotic and native grasses increased in response to tilling and 2,4-D indicating that grasses may have reproduced primarily vegetatively. This data provided evidence that augmentative restoration could provide managers with an ecological framework to develop restoration procedures that address invasion resistance, environmental heterogeneity, and succession in order to enhance native forbs and grasses as well as improve the emergence of seeded species to increase desired plant composition in wildlands damaged by invasive plants.Item The sagebrush steppe of Montana and southeastern Idaho shows evidence of high native plant diversity, stability, and resistance to the detrimental effects of nonnative plant species(Montana State University - Bozeman, College of Agriculture, 2013) Quire, Ryan Lane; Chairperson, Graduate Committee: Matthew LavinThe premise of this study is that plant diversity is a neglected aspect of the North American sagebrush steppe, a once expansive biome that is now highly degraded. What kind of plant diversity is expected in the sagebrush steppe when it is not regularly physically disturbed? What ecological gradients most affect how plant diversity changes over large spatial scales? The answers to these questions could have implications for invasive plant management and the reclamation and restoration of the sagebrush steppe. Methods included sampling four regions of the sagebrush steppe in the northeastern portion of this biome. The Pryor Mountains, the Charles M. Russell National Wildlife Refuge, and the region of the Yellowstone Plateau were sampled in mostly Montana. These high-native-cover sagebrush sites were compared with those sampled in the Upper Snake River Plains region of southeastern Idaho. One hectare transects were established in high-native cover sagebrush steppe. These were paired with transects established in immediately adjacent disturbance-prone settings (e.g., roadsides) where sagebrush steppe vegetation remained intact. Geographically adjacent transects were sampled where they differed in at least one important ecological attribute. Key findings included that mountain big sagebrush steppe is evolutionarily distinct from Wyoming big sagebrush steppe and that the maximum temperature during the warmest month of the year was an important gradient for shaping species and phylogenetic beta diversity. Geographical proximity also had a large influence on the local species composition. The degree of disturbance also had less of an effect perhaps because of the influence of geography. The effects of physical disturbance were still detectable using descriptive approaches that compared infrequent with frequently disturbed transects. Regardless, native species diversity was distinctly diminished by physical disturbance, which is argued to be evidence that the sagebrush steppe is inherently ecologically stable. The implications of this research include the identification of specific taxonomic groups at and above the species level that may serve as benchmarks for sagebrush steppe reclamation or restoration. Long term stable conditions (infrequent disturbance regimes) are very much required for the successful restoration of the sagebrush steppe.