Supplemental Material: Quaternary basaltic volcanic fields of the American Southwest

<div>Listing of published age dates and total Quaternary volcano counts in the southwest USA. <br></div>

Supplemental Material: Quaternary basaltic volcanic fields of the American Southwest

<div>Listing of published age dates and total Quaternary volcano counts in the southwest USA. <br></div>

Supplemental Material: Quaternary basaltic volcanic fields of the American Southwest

<div>Listing of published age dates and total Quaternary volcano counts in the southwest USA. <br></div>

The Combined Effects of Multiple Invasive Species on the Persistence of Experimental Populations of Imperiled Pahrump Poolfish

Many ecosystems have been invaded by more than one non-native species, but research evaluating the combined effects of multiple invasive species has been limited. In the southwest USA, many aquatic systems have been invaded by multiple species such as non-native crayfish and non-native fishes. We used experimental mesocosms to test individual and combined effects of invasive Red Swamp Crayfish, Procambarus clarkii , and Western Mosquitofish, Gambusia affinis , on endangered Pahrump Poolfish, Empetrichthys latos. We found that crayfish alone reduced adult poolfish survival, however crayfish did not limit production of poolfish juveniles. By contrast, mosquitofish had no effect on survival of poolfish adults, but significantly reduced recruitment of juveniles. When both crayfish and mosquitofish were present, both adult survival and juvenile production were significantly decreased. These findings were consistent with the recent decline of a wild poolfish population from over 10,000 fish to less than 1,000 poolfish following the establishment of crayfish and mosquitofish. This study demonstrates that conservation management of the Pahrump Poolfish must have active management and removal of invasive species, otherwise extirpation and eventually extinction will likely occur and provides an example for the compounding effects of multiple invasive species for other study systems.

Monitoring Tamarix Changes Using WorldView-2 Satellite Imagery in Grand Canyon National Park, Arizona

Remote sensing methods are commonly used to monitor the invasive riparian shrub tamarisk (Tamarix spp.) and its response to the northern tamarisk beetle (D. carinulata), a specialized herbivore introduced as a biocontrol agent to control tamarisk in the Southwest USA in 2001. We use a Spectral Angle Mapper (SAM) supervised classification method with WorldView-2 (2 m spatial resolution) multispectral images from May and August of 2019 to map healthy tamarisk, canopy dieback, and defoliated tamarisk over a 48 km segment of the Colorado River in the topographically complex Grand Canyon National Park, where coarse-resolution satellite images are of limited use. The classifications in May and August produced overall accuracies of 80.0% and 83.1%, respectively. Seasonal change detection between May and August 2019 indicated that 47.5% of the healthy tamarisk detected in May 2019 had been defoliated by August 2019 within the WorldView-2 image extent. When compared to a previously published tamarisk map from 2009, derived from multispectral aerial imagery, we found that 29.5% of healthy tamarisk canopy declined between 2009 and 2019. This implies that tamarisk beetle impacts are continuing to accumulate even though land managers have noted the presence of the beetles in this reach of the river for 7 years since 2012.

Preliminary Assessment of Carbon and Nitrogen Sequestration Potential of Wildfire-Derived Sediments Stored by Erosion Control Structures in Forest Ecosystems, Southwest USA

The role of pyrogenic carbon (PyC) in the global carbon cycle is still incompletely characterized. Much work has been done to characterize PyC on landforms and in soils where it originates or in “terminal” reservoirs such as marine sediments. Less is known about intermediate reservoirs such as streams and rivers, and few studies have characterized hillslope and in-stream erosion control structures (ECS) designed to capture soils and sediments destabilized by wildfire. In this preliminary study, organic carbon (OC), total nitrogen (N), and stable isotope parameters, δ13C and δ15N, were compared to assess opportunities for carbon and nitrogen sequestration in postwildfire sediments (fluvents) deposited upgradient of ECS in ephemeral- and intermittent-stream channels. The variability of OC, N, δ13C, and δ15N were analyzed in conjunction with fire history, age of captured sediments, topographic position, and land cover. Comparison of samples in 2 watersheds indicates higher OC and N in ECS with more recently captured sediments located downstream of areas with higher burn severity. This is likely a consequence of (1) higher burn severity causing greater runoff, erosion, and transport of OC (organic matter) to ECS and (2) greater cumulative loss of OC and N in older sediments stored behind older ECS. In addition, C/N, δ13C, and δ15N results suggest that organic matter in sediments stored at older ECS are enriched in microbially processed biomass relative to those at newer ECS. We conservatively estimated the potential mean annual capture of OC by ECS, using values from the watershed with lower levels of OC, to be 3 to 4 metric tons, with a total potential storage of 293 to 368 metric tons in a watershed of 7.7 km2 and total area of 2000 ECS estimated at 2.6 ha (203-255 metric tons/ha). We extrapolated the OC results to the regional level (southwest USA) to estimate the potential for carbon sequestration using these practices. We estimated a potential of 0.01 Pg, which is significant in terms of ecosystem services and regional efforts to promote carbon storage.

A study of millennials' preferred work-related attributes and retention

PurposeThe purpose of this study is to examine the differences in preferred work-related attributes across generational cohorts. Specific focus is given to investigating whether millennials have different preferences than previous generations.Design/methodology/approachThis study uses cross-sectional survey data of 300 employees of a large firm in the southwest USA. Conjoint analysis is used to collect employee responses that are then subjected to analysis of variance (ANOVA).FindingsThe results of this study demonstrate that employees from different generations have significantly different preferences on four work-related attributes: job security, potential for advancement, work/life balance and company leadership.Research limitations/implicationsThis study extends the generational cohort theory by employing psychological contract theory to discover and explain significant differences in preferences for varying work-related attributes for different generations. Like much cross-sectional research, these findings have to be validated and generalized.Practical implicationsFirms can use the results of this study to help understand how different generations value different work-related attributes, thus helping improve employee satisfaction and retention.Originality/valueThe originality of this research lies in its very unique approach, conjoint analysis, to be one of the first studies to test empirically the preferences for work-related attributes across generational cohorts. It lays the foundation for future research to expand upon while also giving practicing managers a useful tool to understand the needs of their employees.