Ecological sites and state-transition models (STMs) have become the preferred means of summarizing plant community dynamics on distinctive types of rangeland. Ecological sites classify rangeland types based on soil-geomorphic and climatic conditions capable of producing a known plant community, while a STM depicts the vegetation dynamics of an ecological site. STMs are usually based on expert opinion rather than site-specific data; however, if they are to gain credibility, STMs must accurately describe the processes that drive plant community dynamics. This study examined three ways of developing process-based STMs using three levels of commonly collected field data. We began by taking field inventories of three ecological sites already mapped in northwestern Utah: Loamy Bottom, Mountain Gravelly Loam, and Upland Loam. The Loamy Bottom site was ideal for developing a data-rich, process-based STM because 1) the site concepts were well-defined, 2) the site was easy to recognize, 3) potential states and transitions had already been hypothesized, and 4) the site was easily accessible. The Loamy Bottom study was designed to link plant community structural indicators to measurable indicators of ecological process. Principal components analysis and cluster analysis were used to classify 14 study plots into four distinct states. Simple linear regression showed relationships between perennial grass cover, perennial canopy gaps, and soil organic carbon. Analysis of variance (ANOVA) linked four general vegetation classes to soil stability measurements. The resulting STM describes the structure and function of four alternative states. The other two STMs, developed for the Mountain Gravelly Loam and Upland Loam ecological sites, used less-intensive data collection methods. Rangeland health assessments, used for the Upland Loam STM, are useful for refining initial ecological site and STM concepts, documenting states, hypothesizing transitions, and locating study locations for future research. Quantitative production and cover estimates, used for the Mountain Gravelly Loam STM, are useful for describing the structure of states, but structural indicators must be coupled with process measurements, as with the Loamy Bottom STM to understand the drivers of state change. A coordinated data collection effort is needed to produce STMs that accurately depict the plant community dynamics of ecological sites.

Wildlife managers have fed elk in North America for nearly 100 years. Giving winter feed to elk can compensate for a shortage of natural winter range and may boost elk populations while also helping prevent commingling with livestock and depredation of winter feed intended for livestock. In contrast to these benefits of supplemental feeding, there are economic and environmental costs associated with feeding, and elk herds that winter on feeding grounds have a higher risk of contracting and transmitting disease. Brucellosis is of primary concern now, and Chronic Wasting Disease may be in the future. Many see the discontinuation of winter-feeding programs as a necessary step for decreasing the risk of disease spread due to high animal densities associated with feeding during winter. My research evaluated the use of behavioral training to reduce reliance on supplemental winter feeding of elk, while minimizing population reductions and human-wildlife conflicts. My study was conducted at Deseret Land & Livestock (DLL) in Rich County, UT, where managers at DLL have over 20 years of data on elk feeding during winters of varying intensities. I tested the effectiveness of range improvements, strategic cattle grazing, dispersed supplemental feeding, hunting, and herding to distribute and hold elk in desired areas during winter. I compared elk numbers on the feed ground during this study with historic data on DLL, and also contrasted elk responses with other comparable feed sites in Wyoming that served as controls. In 2 mild winters we completely eliminated elk feeding without incident and were able to reduce the quantity and duration of feeding during 1 severe winter. Since the conclusion of my study, DLL has further reduced quantity and duration of feeding during severe winters, and has completely eliminated feeding in light winters. Based on a Before After Control Impact (BACI) analysis, the reduction in the proportion of the elk population fed at the study site was significantly less than the proportion of the elk populations fed at the control sites in Wyoming (P = 0.057). Based on these results, I anticipate wildlife managers can decrease dependence on costly supplemental winter feeding and reduce the risks of disease while keeping human-wildlife conflicts at a minimum. This research illustrates an adaptive method that can enable wildlife managers to keep elk populations in northern Utah at or near their current size, while constraining disease outbreak and transmission risks within "acceptable" levels.

The Puerto Rican coqui frog, Eleutherodactylus coqui, was introduced to Hawaii in the late 1980s via the commercial horticulture trade. Previous research has shown that coquis can change invertebrate communities, but these studies were conducted at small scales using controlled, manipulative experiments. The objective of this research was to determine whether coqui invasions change invertebrate communities at the landscape scale across the island of Hawaii. At each invasion front, we measured environmental variability on either side of the front and removed sites that were too variable across the front to ensure that the impacts we measured were the result of the invasion. After doing this, there remained 15 sites for which we compared invertebrate communities in 30 m x 30 m plots situated on either side of coqui invasion fronts. In each plot, we collected invertebrate samples from three invertebrate communities, the leaf litter, foliage, and flying invertebrate communities. Multivariate analyses show that coqui frogs change leaf litter communities, by reducing microbivore and herbivore abundances. Coqui also change flying community composition, but have no measurable effect on foliage communities. Across sites, we found that coquis reduced the number of leaf litter invertebrates by 27%, and specifically abundant Acari by 36%. We also found that coquis increased the abundance of flying Diptera by 19% across sites. We suggest that the leaf litter community is altered through direct coqui predation and that Diptera increase because of increased frog carcasses and excrement in invaded plots. Results support previous studies conducted in more controlled settings, but add to our understanding of the invasion by demonstrating that coqui effects on invertebrate communities are measurable at the landscape scale.

This study tested the performance of classification, regression, and ordination techniques to evaluate the spatiotemporal dynamics of threats to big sagebrush ecological sites. The research was focused on invasion by annual exotic grasses and encroachment by woodlands. We sought to identify those areas that have had a persistent coverage of cheatgrass (Bromus tectorum) in big sagebrush ecological sites. We took advantage of the contrast in greenness between multi-temporal (within one year) remotely sensed vegetation indices captured in the spring and summer to find a distinct phenological signature that allowed mapping cheatgrass. We utilized support vector machines (SVM) to classify three temporal scenarios for which field data sets were available. SVM performed very well with accuracies of 70% (producer's) and 95% (user's) for the class of interest (presence of cheatgrass). This was the focus of chapter 2. In chapter 3 we report the development of vegetation continuous fields (VCF) for three years of interest 1996, 2001, and 2007 in order to detect active woodland encroachment. We prepared VCF for shrubs, trees, herbaceous vegetation, and bare ground using a suite of remotely sensed spectral reflectance, vegetation indices, and transformations. We compared the performance of multivariate regression trees (MRT) and random forests (RF) to develop the VCF multi-temporal series. RF outperformed MRT in both accuracy and ability to appropriately map the continuum of percent cover across large landscapes. We estimate that 17,570 hectares of big sagebrush lands showed encroachment by woodlands. Our goal in chapter 4 was to develop a similarity index for large rangeland landscapes. Trend assessments field sites and a long-term annual series (1984 - 2008) of remotely sensed imagery were used in conjunction with multidimensional scaling (MDS) to measure ecological distance to undesired states such as invasion by exotic annuals and encroachment by woodlands. In this chapter our units of analysis were soil-mapping units, which were predominantly composed of one ecological site (>60%). Our MDS results show that different ecological sites can be identified in the reduced MDS statistical space. The observed transitions and trajectories of mountain, Wyoming, and basin big sagebrush sites correlated well with the ecological expectation in semiarid lands. We anticipate that managers can use our protocols to update ecological site descriptions and state and transition models from a remotely sensed perspective.