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Author: Lauren Cathleen Connell Publisher: ISBN: 9780438880252 Category : Black-tailed prairie dog Languages : en Pages : 124
Book Description
Globally, vegetation structure and patch variability in grasslands and savannas are strongly driven by natural disturbance regimes. These disturbances influence height and cover of herbaceous and woody plants, and often within a variable spatio-temporally regime that results in a heterogeneous landscape. In North America, semi-arid rangelands include grasslands and sagebrush (Artemisia spp.)-dominated shrublands that evolved with spatially and temporally variable disturbance regimes of wildfire, large ungulate herbivory, and colonial burrowing mammals. Moreover, interactions among multiple disturbances, including wildfire, herbivory by wild and domestic ungulates and colonial burrowing mammals, are driving forces of plant community structure and composition. The effects of these multiple, interactive disturbances are particularly less understood in shrubland-grassland ecotone regions, where divergent climate regimes, disturbance-sensitive vegetation communities, and historic disturbance regimes are juxtaposed and interact to create unique ecosystem responses. My study objectives were thus designed to investigate the effects of multiple, interactive disturbances and their implications for livestock and wildlife management. I addressed these topics in the Thunder Basin National Grassland in northeast Wyoming, U.S.A. In Chapter 1, I investigate the separate and interactive effects of livestock, native ungulates, fire, and small mammals on vegetation structure through a three-tiered, large-scale manipulative experiment. I used nested grazing exclosures to isolate the effects of herbivory from livestock, wild ungulates, or small mammals within areas affected by either historical wildfire, black-tailed prairie dog (Cynomys ludovicianus) colonies, or neither disturbance. I replicated this sampling design four times. I evaluated the interactive effects of herbivory and historical disturbance on vegetation structure by quantifying vegetation height, visual obstruction, shrub density, shrub canopy, and shrub leader growth. The exclusion of wild ungulates and lightly-to-moderately stocked livestock for two years did not affect herbaceous vegetation structure, shrub density, or shrub canopy cover. Maximum vegetation height, visual obstruction, heights of grasses and forbs, and shrub density were all negatively affected by prairie dogs. Both wildfire and black-tailed prairie dogs had lower canopy cover of shrubs and Wyoming big sagebrush, when compared to undisturbed sites. Shrub leaders experienced over 3-times more browsing on prairie dog colonies, when compared to undisturbed areas and the combined presence of livestock and native ungulates on prairie dog colonies caused significantly more leader browsing than in the presence of native ungulates alone. In Chapter 2, I assessed the effects of prairie dog herbivory on forage in a northern mixed-grass prairie. Black-tailed prairie dogs have high dietary overlap with livestock, which can cause forage-centric conflicts between agriculture and conservation. Research suggests prairie dogs can enhance forage quality, but it remains unclear how the strength of trade-offs between quality and quantity varies throughout the growing season, or the degree to which increased forage quality is caused by altered species composition versus altered plant physiology. I collected samples on prairie dog colonies and at sites without prairie dogs during June, July, and August 2016 – 2017 for forage quality, and August 2015 – 2017 for biomass. I collected both composite samples of all herbaceous species and also samples of western wheatgrass ( Pascopyrum smithii [Rydb.] Á. Löve) to isolate mechanisms affecting forage quality. Across years and plant sample types, crude protein, phosphorus, and fat were greater and neutral detergent fiber was lower on prairie dog colonies than at sites without prairie dogs. The effects of prairie dogs on forage quality persisted throughout the season for western wheatgrass samples. Across years, aboveground biomass did not differ significantly between prairie dog colonies and sites without prairie dogs and the effects of prairie dogs on herbaceous biomass were significantly influenced by spring precipitation. My results demonstrate season-long enhanced forage quality on prairie dog colonies due to both compositional and phenological shifts associated with prairie dog herbivory. Across years, enhanced forage quality may help to offset reductions in forage quantity for agricultural producers. In Chapter 3, I evaluated the use of conspecific acoustic signals as a potential management tool for prairie dogs. Black-tailed prairie dogs are a major driver of vegetation structure and heterogeneity in northeastern Wyoming, in addition to being highly influential on forage quality and production. The management of prairie dogs in this region is a great priority by the U.S. Forest Service and private landowners and thus I sought to explore the influence of acoustic signals on prairie dog behavior and its fitness implications. Researchers have demonstrated cues of conspecifics including acoustic signals can be successfully used in the conservation and management of avian species but it has rarely, if ever, been applied to free-roaming small mammals. The black-tailed prairie dog is a colonial, small mammal whose gregarious vocalizations create fitness benefits of group vigilance against predation and increased foraging time.
Author: Lauren Cathleen Connell Publisher: ISBN: 9780438880252 Category : Black-tailed prairie dog Languages : en Pages : 124
Book Description
Globally, vegetation structure and patch variability in grasslands and savannas are strongly driven by natural disturbance regimes. These disturbances influence height and cover of herbaceous and woody plants, and often within a variable spatio-temporally regime that results in a heterogeneous landscape. In North America, semi-arid rangelands include grasslands and sagebrush (Artemisia spp.)-dominated shrublands that evolved with spatially and temporally variable disturbance regimes of wildfire, large ungulate herbivory, and colonial burrowing mammals. Moreover, interactions among multiple disturbances, including wildfire, herbivory by wild and domestic ungulates and colonial burrowing mammals, are driving forces of plant community structure and composition. The effects of these multiple, interactive disturbances are particularly less understood in shrubland-grassland ecotone regions, where divergent climate regimes, disturbance-sensitive vegetation communities, and historic disturbance regimes are juxtaposed and interact to create unique ecosystem responses. My study objectives were thus designed to investigate the effects of multiple, interactive disturbances and their implications for livestock and wildlife management. I addressed these topics in the Thunder Basin National Grassland in northeast Wyoming, U.S.A. In Chapter 1, I investigate the separate and interactive effects of livestock, native ungulates, fire, and small mammals on vegetation structure through a three-tiered, large-scale manipulative experiment. I used nested grazing exclosures to isolate the effects of herbivory from livestock, wild ungulates, or small mammals within areas affected by either historical wildfire, black-tailed prairie dog (Cynomys ludovicianus) colonies, or neither disturbance. I replicated this sampling design four times. I evaluated the interactive effects of herbivory and historical disturbance on vegetation structure by quantifying vegetation height, visual obstruction, shrub density, shrub canopy, and shrub leader growth. The exclusion of wild ungulates and lightly-to-moderately stocked livestock for two years did not affect herbaceous vegetation structure, shrub density, or shrub canopy cover. Maximum vegetation height, visual obstruction, heights of grasses and forbs, and shrub density were all negatively affected by prairie dogs. Both wildfire and black-tailed prairie dogs had lower canopy cover of shrubs and Wyoming big sagebrush, when compared to undisturbed sites. Shrub leaders experienced over 3-times more browsing on prairie dog colonies, when compared to undisturbed areas and the combined presence of livestock and native ungulates on prairie dog colonies caused significantly more leader browsing than in the presence of native ungulates alone. In Chapter 2, I assessed the effects of prairie dog herbivory on forage in a northern mixed-grass prairie. Black-tailed prairie dogs have high dietary overlap with livestock, which can cause forage-centric conflicts between agriculture and conservation. Research suggests prairie dogs can enhance forage quality, but it remains unclear how the strength of trade-offs between quality and quantity varies throughout the growing season, or the degree to which increased forage quality is caused by altered species composition versus altered plant physiology. I collected samples on prairie dog colonies and at sites without prairie dogs during June, July, and August 2016 – 2017 for forage quality, and August 2015 – 2017 for biomass. I collected both composite samples of all herbaceous species and also samples of western wheatgrass ( Pascopyrum smithii [Rydb.] Á. Löve) to isolate mechanisms affecting forage quality. Across years and plant sample types, crude protein, phosphorus, and fat were greater and neutral detergent fiber was lower on prairie dog colonies than at sites without prairie dogs. The effects of prairie dogs on forage quality persisted throughout the season for western wheatgrass samples. Across years, aboveground biomass did not differ significantly between prairie dog colonies and sites without prairie dogs and the effects of prairie dogs on herbaceous biomass were significantly influenced by spring precipitation. My results demonstrate season-long enhanced forage quality on prairie dog colonies due to both compositional and phenological shifts associated with prairie dog herbivory. Across years, enhanced forage quality may help to offset reductions in forage quantity for agricultural producers. In Chapter 3, I evaluated the use of conspecific acoustic signals as a potential management tool for prairie dogs. Black-tailed prairie dogs are a major driver of vegetation structure and heterogeneity in northeastern Wyoming, in addition to being highly influential on forage quality and production. The management of prairie dogs in this region is a great priority by the U.S. Forest Service and private landowners and thus I sought to explore the influence of acoustic signals on prairie dog behavior and its fitness implications. Researchers have demonstrated cues of conspecifics including acoustic signals can be successfully used in the conservation and management of avian species but it has rarely, if ever, been applied to free-roaming small mammals. The black-tailed prairie dog is a colonial, small mammal whose gregarious vocalizations create fitness benefits of group vigilance against predation and increased foraging time.
Author: Fiona Claire Schaus Noonan Publisher: ISBN: Category : Big sagebrush Languages : en Pages : 0
Book Description
"Changes in fire regimes, invasive species dynamics, human land use, and drought conditions have shifted important plant species in the Northern Great Basin (NGB)—including big sagebrush (Artemisia tridentata ssp.), conifers (e.g., Juniperus spp.) and invasive annual grasses (e.g., Bromus tectorum). Characterizing how these overlapping disturbances influence species distributions is critical for land management decision-making. Previous research has explored the individual effects of drought, wildfire, restoration, and invasive species on sagebrush steppe communities, but the specific effects of these disturbances in context with one another remain poorly understood at a landscape scale. To address this gap, I constructed multilevel conditional autoregressive (CAR) species distribution models (SDMs) to map the distributions of big sagebrush, juniper, and cheatgrass on lands managed for grazing in the NGB, both with and without a history of fire. These models illuminate the concurrent influences of species co-occurrences, drought, wildfire characteristics (e.g., fire size, time since fire, and number of fires), and restoration treatments. For all SDMs, results indicate that species co-occurrence exhibits the strongest effect—between 1.23 and 19.2 times greater than the next strongest predictor—on all species’ probability of occurrence, suggesting that vegetation co-occurrence meaningfully influences landscape-scale species distributions. In portions of the NGB both with and without historical fire, number of fires and maximum vapor pressure deficit (VPD) also exert substantial influence on the likelihood of species presence, and results indicate that restoration treatments have broadly met desired outcomes for both sagebrush and juniper Narrowing down to only areas that have previously burned, however, models do not support the efficacy of post-fire restoration. All versions of the SDMs, which rely on Bureau of Land Management-administered grazing allotments as a spatial varying intercept, also explicitly point to the differential influence of long-term management regimes on species distributions. These model predictions capture post-disturbance vegetation outcomes under changing fire, climate, and invasive species regimes and in the context of human decision-making, in turn defining a plausible ecological space as these disturbance and management processes play out into the future."--Boise State University ScholarWorks.
Author: Therese M. Poland Publisher: Springer Nature ISBN: 3030453677 Category : Science Languages : en Pages : 455
Book Description
This open access book describes the serious threat of invasive species to native ecosystems. Invasive species have caused and will continue to cause enormous ecological and economic damage with ever increasing world trade. This multi-disciplinary book, written by over 100 national experts, presents the latest research on a wide range of natural science and social science fields that explore the ecology, impacts, and practical tools for management of invasive species. It covers species of all taxonomic groups from insects and pathogens, to plants, vertebrates, and aquatic organisms that impact a diversity of habitats in forests, rangelands and grasslands of the United States. It is well-illustrated, provides summaries of the most important invasive species and issues impacting all regions of the country, and includes a comprehensive primary reference list for each topic. This scientific synthesis provides the cultural, economic, scientific and social context for addressing environmental challenges posed by invasive species and will be a valuable resource for scholars, policy makers, natural resource managers and practitioners.
Author: Michael D. Reisner Publisher: ISBN: Category : Languages : en Pages : 540
Book Description
Sagebrush steppe ecosystems are one of the most widespread but endangered ecosystems in North America. A diverse array of human-related stressors has gradually compromised these ecosystems' resilience to disturbance and invasion by Bromus tectorum (cheatgrass). The role of the foundational shrub Artemisia as a driver of herbaceous community structure and dynamics during this degradation process is poorly understood. Many of the individual factors driving B. tectorum invasions are well documented. However a predictive understanding of the relative importance of complex, interacting factors in the causal network of simultaneously occurring processes determining invasibility has proven elusive. I examined these issues at the landscape level across 75 sites capturing a range of soil and landscape properties and cattle grazing levels similar to those found across the Great Basin. Cumulative cattle herbivory stress levels were a predominant component of both the overlapping heat and water stress gradients driving the structure of Artemisia interactions with herbaceous species. Consistent with the stress gradient hypothesis, Artemisia facilitation of herbaceous species was most frequent and strongest at the highest stress levels, and competition was most frequent and strongest at the lowest stress levels. The two species with the highest competitive response abilities, Elymus elymoides and Poa secunda, showed the strongest facilitation at the upper limits of their stress tolerances. The structure of Artemisia interactions with the invasive B. tectorum was strikingly different than those with native bunchgrasses. Artemisia interactions with native bunchgrasses shifted from competition to facilitation with increasing heat, water, and herbivory stress, but its interactions remained competitive with B. tectorum along the entire stress gradient. Shifts in the structure of interactions between Artemisia and native bunchgrasses were associated with both an increase and decrease in community compositional and functional stability. I report the first evidence of native species facilitation decreasing community invasibility. Artemisia facilitation increased native bunchgrass composition, which reduced the magnitude of B. tectorum invasion in under-shrub compared to interspace communities. This decreased invasibility did not translate into lower invasibility at the community level because of the limited spatial scale over which such facilitation occurs. Artemisia facilitation increased community compositional and functional stability at intermediate stress levels but decreased community stability at high stress levels. Facilitation became a destabilizing force when native bunchgrass species became "obligate" beneficiaries, i.e. strongly dependent on Artemisia facilitation for their continued persistence in the community. Structural equation modeling assessed the structure of the causal network and relative importance of factors and processes predicted to drive community invasibility. The linchpin of ecosystem invasibility was the size of and connectivity between basal gaps in perennial vegetation, driven by shifts in the structure and spatial aggregation of the native bunchgrass community. Landscape orientation and soil physical properties determined inherent risk to invasion. Resident bunchgrass and biological soil crust communities provided biotic resistance to invasion by reducing the size of and connectivity between basal gaps and thereby limiting available resources and reducing safe sites for B. tectorum establishment. High levels of cattle grazing reduced ecosystem resilience by reducing native bunchgrass and biological soil crust abundance and altering bunchgrass community composition and facilitated B. tectorum invasion. Conserving and restoring resilience and resistance of these imperiled ecosystems will require reducing cumulative stress levels. As global climate change increases heat and water stress, reducing cumulative cattle grazing intensities by altering utilization rates and/or seasons of use may be the only effective means of accomplishing these goals.
Author: Julie Ripplinger Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 48
Book Description
Land-use legacies can affect landscapes for decades to millennia. A long history of shrub management exists in the sagebrush steppe of the Intermountain West where shrub-removal treatments, a type of managed disturbance, have been implemented for over 50 years to reduce sagebrush cover. The assumption behind managed disturbances is that they will increase forage for domestic livestock and improve wildlife habitat. However, the long-term effects of managed disturbance on plant community composition and diversity are not well understood. We investigated the legacy effects of three common types of managed disturbance (chemical, fire, and mechanical treatments) on plant community diversity and composition. We also examined sagebrush steppe resilience to managed disturbance. Based on management assumptions and resilience theory, we expected within-state phase shifts characterized by an initial reduction in biodiversity followed by a return to prior state conditions. We also expected changes in species proportions, characteristic of within-state shifts in state-and-transition models. We also expected an increase in non-native contribution to overall diversity. We found that plant communities experienced a fundamental shift in composition following disturbance, and responded in a flat linear fashion, giving no indication of return to prior community composition or diversity. As expected, we found post-disturbance increases in the number of non-native grass species present. However, native forb species made the largest contribution to altered diversity. Disturbance modified functional group composition, so contrary to our expectations, within-state changes did not occur as a result of disturbance. Our results indicated that sagebrush steppe plant communities are not resilient to chemical, fire, and mechanical treatments, and subsequent to managed disturbance, community composition tips over a threshold into an alternate stable state.
Author: Holly E. Cunningham Publisher: ISBN: 9780438392939 Category : Sagebrush steppe ecology Languages : en Pages : 166
Book Description
Precipitation patterns can provide missing details and information related to historical and present-day vegetation variation within the sagebrush steppe. There is a critical gap in the body of literature involving long-term shifts in plant communities, including the effects precipitation has on secondary plant succession. The environment is competitive between invasive annual grasses and native perennial grasses in sagebrush steppe ecosystems; especially after a fire or other disturbance occurs. This study was conducted on two 16-ha study sites located in southern Idaho that was previously tilled for farming but abandoned in the early 1930s. Species densities data collected in 1933-1947, 1954, 1961, 1992 and 2015 was categorized into plant functional groups for statistical data analysis. Long-term datasets evaluating plant community composition relative to precipitation patterns can increase understanding in how plant communities respond to precipitation influence on the Snake River plain of the sagebrush steppe.
Author: Caley K. Gasch Publisher: ISBN: 9781303631375 Category : Restoration ecology Languages : en Pages : 93
Book Description
The objective of this research was to investigate vegetation and soil property structure in sagebrush steppe ecosystems as they recover from drastic disturbance, particularly in assessing the variability of properties across space. On reclaimed pipelines, I collected vegetation data and analyzed soil for organic carbon, total nitrogen, microbial community structure, moisture, salinity, and alkalinity. Using a Bayesian hierarchical mixed model, I quantified soil properties with posterior predictive distributions to compare reclaimed areas with the reference areas. The variance of most soil properties was affected by disturbance, and not always accompanied by a shift in the mean. Distributions for soil properties in reclaimed areas became more similar to those of undisturbed reference areas as recovery time increased. I then explored the differences in sampling designs, analysis, and inference gained from spatial and non-spatial soil data. I also conducted side-by-side analyses of each data type for a reclaimed area and an undisturbed area. The analysis of random data revealed differences in soil property averages between treatments. These differences were also apparent in the geostatistical analysis, which also provided information about the spatial structure in soil properties at the scale of individual plant effects (10 cm - 10 m). The third project expanded the assessment in both space and time, by including reclaimed pipelines that spanned 55 years, and by sampling at a scale up to 100 meters. I used Bayesian geostatistical models to quantify the correlation structure and to create surface predictions for measured properties. The reclaimed areas maintained uniform grass cover with low diversity and shrub establishment, while the responses of soil properties to disturbance and reclamation were variable. All three modeling approaches indicated that soil properties closely associated with vegetation experienced reduced variability and homogenization across space following disturbance. Soil abiotic properties appeared to be affected by the physical effects of disturbance, but were not associated with homogenization. Development of belowground heterogeneity was possibly delayed by the slow recovery of the plant community, particularly the shrub component. This research illustrates some long lasting ecological consequences of disturbance in sagebrush steppe and emphasizes the need for establishing shrubs in reclaimed sagebrush steppe.
Author: Ryan Lane Quire Publisher: ISBN: Category : Endemic plants Languages : en Pages : 350
Book Description
The 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.
Author: Andrew R. Kleinhesselink Publisher: ISBN: Category : Languages : en Pages :
Book Description
Forecasting the effects of climate change on plant and animal populations is a high priority in ecology. We studied the effects of climate on plant populations through the use of observational and experimental data, as well as analytical models. Our research questions were: (1) Do the effects of interannual climate variation on the population growth rates of widespread species show a coherent pattern across gradients of mean annual climate? (2) How well can population models fit to observational data predict the response of populations to field experiments that manipulate climate? And (3) does niche overlap between competitors predict the magnitude of competition-mediated indirect effects in mechanistic resource competition models? To test the first question, we assessed how interannual variation in climate affected the abundance of big sagebrush (Artemisia tridentata) at 131 monitoring sites across its range. We found that years of above average temperature increased sagebrush abundance at cold sites, but decreased sagebrush abundance at hot sites. This pattern indicates that sagebrush distribution may be limited by hot and cold temperatures at the extremes of its distribution. We addressed iv our second research question by fitting statistical models to over 25 years of observational data on the performance of four dominant plant species in a sagebrush steppe community. We then experimentally manipulated soil moisture in this community and tested how well the statistical models fit to observational data could predict species0́9 responses to the experimental treatments. In two out of four species, we found that including climate effects in our models helped us predict the population-level responses to the experiment. Moreover, effects of historical soil moisture variation on vital rates were generally consistent with the effects of drought and irrigation treatments. Our results provide some evidence that observational data can be used to predict species0́9 responses to climate change in the future. We addressed our third question by simulating environmental change in analytical models of resource competition and quantifying the size of direct and competition-mediated indirect effects that resulted. We showed that the magnitude of indirect effects increased as the niche overlap between competitors increased.
Author: Lauren Cathleen Connell
Author: Lauren Cathleen Connell
Author: Fiona Claire Schaus Noonan
Author: Therese M. Poland
Author: Michael D. Reisner
Author: Julie Ripplinger
Author: Eddie John Van Etten
Author: Holly E. Cunningham
Author: Caley K. Gasch
Author: Ryan Lane Quire
Author: Andrew R. Kleinhesselink