Landscape and Habitat Attributes Influencing Beaver Distribution

Removal of beaver across the North America landscape from the 1600s through the 1800s has played a major influence on the alteration of stream and riparian resources. Degradation of riparian habitats has negatively impacted many wildlife and fish species, including species listed under the Endangered Species Act. The ability of beavers to modify stream ecosystems offers a unique opportunity to restore these habitats. Many private and government agencies are working towards using beaver as a restoration tool, not only for better functioning ecosystems but also to benefit humans. Taking the big picture look, beaver and their ability to modify the environment are viewed by describing the ecological benefits and impacts to stream ecosystems and influences on fish habitat and populations; analyzing landscape and habitat attributes influencing beaver distribution using data from a large scale stream and riparian monitoring program (Pacfish/Infish Biological Opinion Effectiveness Monitoring (PIBO EM); the human dimension aspects and how beaver can be used to benefit humans in a sustainability framework; the economic incentives of using beaver for stream restoration; and, policies, laws, and administrative considerations associated with beaver. PIBO EM Preliminary data from PIBO EM suggests that as beaver populations make a comeback they will occupy a diverse range of habitats. The data demonstrates that beaver occupy a wide range of landscape characteristics and site habitats, but particular attributes are more important than others in determining where beaver are present. The overlap of so many landscape, site, and vegetation attributes between sites with and without beaver activity and given the vast majority of PIBO EM sites are currently without beaver, indicates that many areas may already be suitable for beaver occupation, providing optimism for beaver restoration opportunities. Many groups and organizations are spending money, effort, and time into developing habitat criteria and habitat suitability indexes for beaver reintroductions. Collaborative efforts with PIBO EM would offer data and information from a large geographical area, saving valuable resources to be used for more effective beaver management. Although beaver populations have been affected by removal from trapping and loss of habitat through urbanization, as beaver populations increase they will occupy much of their former range, restoring degraded habitats for the betterment of both mankind and fish and wildlife

Two Papers on Puerto Rico's Debt Crisis

My dissertation utilizes the natural experiment of Puerto Rico's debt crisis in order to investigate the economic effects of (sub)sovereign default risk and the pricing of security contract provisions. The first chapter uses the interesting case of Puerto Rico to address the questions: do investors price contract provisions and the related law? Does the pricing of contract provisions vary with credit risk? Puerto Rico provides an interesting case allowing the study of three different types of contract provisions in the presence of high and increasing credit risk; a strong legal system; and rich data to select well matched control groups. I find that investors indeed price contract provisions specifying governing law, securing debt with specific revenues, and including collective action clauses. I also find that investors especially price these contract provisions when credit risk is highest. The second chapter uses Puerto Rico's unique characteristics as a U.S. territory to examine the real effects of (sub) sovereign default risk. In the post-2012 period of increased default probabilities, Puerto Rico spirals into a significant decline and the co-integrating relationship with real activity on the US mainland breaks down. Cross-industry variation in default risk exposure identifies significantly higher employment growth declines in external finance and government demand dependent industries. Using government bond yields and stock returns we confirm that news of increased default risk raises the cost of capital for the Puerto Rican government and for publicly traded Puerto Rican firms.Doctor of Philosoph

Winterfat seed viability and dormant season livestock grazing

Krascheninnikovia lanata (winterfat) is a valuable forage species with an average of 10% crude protein during winter when there are few nutritious options for livestock and wildlife. However, excessive grazing throughout the west has negatively impacted survival of winterfat stands. We hypothesized that four years rest from dormant season livestock grazing, along with rest from antelope and rabbit browse, would result in greater seed viability and aboveground biomass relative to grazed plots. In locations across the Catlow Valley, Oregon with winterfat communities, two 40 x 40 m plots, a control and an exclosure, were established at each of 15 locations divided among three pastures: north, middle and south. The control plot could be grazed by livestock and wildlife in all seasons (although cattle were only in the study area during the dormant season). The second plot at each location was a large animal exclosure that prevented grazing by cattle and antelope. At four locations a cattle/antelope/rabbit exclosure was also installed. This total of 34 plots was used to test the effects of location and type of use on winterfat seed viability and aboveground plant biomass. Four years rest from dormant season grazing did not affect the viability of winterfat seed or the levels of aboveground winterfat biomass; however, location across the study area did affect the levels of winterfat aboveground biomass. There was significant variation in the data attributable to unknown factors but represented by the influence that pasture location had on seed state (viable, dead and empty) and winterfat plant biomass. In the most productive locations, increases in winterfat aboveground biomass were correlated with increases in seed viability and decreases in density of winterfat m² while increases in winterfat seed viability were correlated with decreases in the percentage of empty seed. In the locations with the highest levels of dead seed, increases in dead seed were correlated with increases in winterfat density m² and decreases in empty winterfat seed. Plants in the cattle/antelope/rabbit exclosures had the highest winterfat density, the lowest plant biomass, lower levels of empty seed and the highest level of dead seed, the reverse of the most viable plots in the study area. From observation, these plants have a greater amount of woody base growth from prior years and appear more decadent. Further research is needed to see if winterfat seed viability and biomass production is associated with some level of browse. Nuttall's saltbush is the dominant shrub on the site, and its increase is correlated with increases in winterfat aboveground biomass and decreases in the level of dead winterfat seed. These results suggest that resources which vary by pasture location such as precipitation, soil nutrients, texture, or moisture holding capacity determined levels of winterfat aboveground plant biomass, winterfat seed state, and the density of Nuttall's saltbush and that on high resource sites, winterfat allocates resources to existing plants in rather than creating the new individuals The lack of response to four years rest from dormant season grazing, the low levels of viable seed, the low density of winterfat, and the encroachment of Nuttall's saltbush all suggest reduced vigor of winterfat in this study area. One possible explanation is that, since recovery toward a later successional stage would be expected with reduced grazing pressure (Dyksterhuis 1949), these arid lands are significantly degraded by stress or disturbance (Westoby et al. 1989; Laycock 1991) and that recovery is no longer possible without significant intervention. This suggests that the study area has crossed an ecological threshold. An alternate possibility is that since recruitment of winterfat is episodic and driven by precipitation events, climatic fluctuations may have prevented the sequence of good precipitation years needed for stand maintaining winterfat recruitment (Pechanec 1964). Further study is needed to evaluate these possibilities

Connecting wind-driven upwelling and offshore stratification to nearshore internal bores and oxygen variability

This study utilizes field observations in southern Monterey Bay, CA, to examine how regional-scale upwelling and changing offshore (shelf) conditions influence nearshore internal bores. We show that the low-frequency wind forcing (e.g., upwelling/relaxation time scales) modifies the offshore stratification and thermocline depth. This in turn alters the strength and structure of observed internal bores in the near-shore. An internal bore strength index is defined using the high-pass filtered potential energy density anomaly in the nearshore. During weak upwelling favorable conditions and wind relaxations, the offshore thermocline deepens. In this case, both the amplitude of the offshore internal tide and the strength of the nearshore internal bores increase. In contrast, during strong upwelling conditions, the offshore thermocline shoals toward the surface, resulting in a decrease in the offshore internal tide amplitude. As a result, cold water accumulates in the nearshore (nearshore pooling), and the internal bore strength index decreases. Empirical orthogonal functions are utilized to support the claim that the bore events contribute to the majority of the variance in cross-shelf exchange and transport in the nearshore. Observed individual bores can drive shock-like drops in dissolved oxygen (DO) with rapid onset times, while extended upwelling periods with reduced bore activity produce longer duration, low DO events

Work, love, and death thought accessibility: a terror management investigation

Terror management theory suggests that following culturally derived scripts for valued behaviour protects people from death concerns, and conversely, not meeting standards for cultural value can weaken this protection, heightening mortality concerns. Using this conceptual framework we examine (1) how considerations of loss of employment, a source of cultural value for many, relates to the accessibility of death-related cognition, and (2) the moderating role of job market health and (3) involvement in close relationships. Study 1 found that writing about being unemployed (vs. a control topic) led to greater mortality-related cognition. Study 2 found that considering unemployment heightened death-cognition, but only when participants were led to perceive the job market as unhealthy. Finally, Study 3 found that considering unemployment led to greater death-cognition, but not for those involved in a close relationship. Findings offer insight into a previously overlooked consequence of unemployment, and factors that may serve a protective function