The Relative Importance of Patch Area and Perimeter–Area Ratio to Grassland Breeding Birds

Habitat fragmentation has been implicated as a major cause of population decline in grassland birds. We tested the hypothesis that a combination of area and shape determines the use of grassland patches by breeding birds. We compared both species richness and individual species presence in 45 wet meadow grasslands in the floodplain of the central Platte River, Nebraska. Bird data were collected through the use of belt transects and supplemented by walking and listening outside transects. Our data supported our primary hypothesis that perimeter–area ratio, which reflects both the area and shape of a patch, is the strongest predictor of both individual species presence and overall species richness. The probability of occurrence for all six common species (Grasshopper Sparrows, Bobolinks, Upland Sandpipers, Western Meadowlarks, Dickcissels, and Red-winged Blackbirds) was significantly inversely correlated with perimeter–area ratio. The probability of occurrence of Grasshopper Sparrows, Bobolinks, Upland Sandpipers, and Western Meadowlarks was also correlated with area. We conclude that species richness is maximized when patches are large (\u3e50 ha) and shaped so that they provide abundant interior areas, free from the impacts of edges

The Relative Importance of Patch Area and Perimeter–Area Ratio to Grassland Breeding Birds

Habitat fragmentation has been implicated as a major cause of population decline in grassland birds. We tested the hypothesis that a combination of area and shape determines the use of grassland patches by breeding birds. We compared both species richness and individual species presence in 45 wet meadow grasslands in the floodplain of the central Platte River, Nebraska. Bird data were collected through the use of belt transects and supplemented by walking and listening outside transects. Our data supported our primary hypothesis that perimeter–area ratio, which reflects both the area and shape of a patch, is the strongest predictor of both individual species presence and overall species richness. The probability of occurrence for all six common species (Grasshopper Sparrows, Bobolinks, Upland Sandpipers, Western Meadowlarks, Dickcissels, and Red-winged Blackbirds) was significantly inversely correlated with perimeter–area ratio. The probability of occurrence of Grasshopper Sparrows, Bobolinks, Upland Sandpipers, and Western Meadowlarks was also correlated with area. We conclude that species richness is maximized when patches are large (\u3e50 ha) and shaped so that they provide abundant interior areas, free from the impacts of edges

The Electrical Structure of Thunderstorms

The time histories of thunderstorm charge distribution during three storms occurring during the summer of 1940 in the vicinity of the Albuquerque Airport were investigated by the use of eight synchronized recording electrometers arranged in a particular pattern over a field 1.6 kilometers above sea level

Influence of Richness and Seeding Density on Invasion Resistance in Experimental Tallgrass Prairie Restorations

In recent years, agricultural producers and non-governmental organizations and agencies have restored thousands of hectares of cropland to grassland in the Great Plains of the United States. However, little is known about the relationships between richness and seeding density in these restorations and resistance to invasive plant species. We assessed the effects of richness and seeding density on resistance to invasive and other unseeded plant species in experimental tallgrass prairie plots in central Nebraska. In 2006, twenty-four 55 m × 55 m plots were planted with six replicates in each of four treatments: high richness (97 species typically planted by The Nature Conservancy), at low and high seeding densities, and low richness (15 species representing a typical Conservation Reserve Program mix, CP25), at low and high seeding densities. There was a significant negative relationship between richness and basal cover of unseeded perennial forbs/legumes and unseeded perennial/annual grasses, abundance of bull thistle (Cirsium vulgare), and the number of inflorescences removed from smooth brome (Bromus inermis) transplants. Invasion resistance may have been higher in the high richness treatments because of the characteristics of the dominant species in these plots or because of greater interspecific competition for limiting resources among forbs/legumes with neighboring plants belonging to the same functional group. Seeding density was not important in affecting invasion resistance, except in the cover of unseeded grasses. Increasing seed mix richness may be more effective than increasing the seeding density for decreasing invasion by unseeded perennial species, bull thistle, and smooth brome

Responses of predatory invertebrates to seeding density and plantspecies richness in experimental tallgrass prairie restorations

In recent decades, agricultural producers and non-governmental organizations have restored thousandsof hectares of former cropland in the central United States with native grasses and forbs. However,the ability of these grassland restorations to attract predatory invertebrates has not been well docu-mented, even though predators provide an important ecosystem service to agricultural producers bynaturally regulating herbivores. This study assessed the effects of plant richness and seeding density onthe richness and abundance of surface-dwelling (ants, ground beetles, and spiders) and aboveground(ladybird beetles) predatory invertebrates. In the spring of 2006, twenty-four 55 m × 55 m-plots wereplanted to six replicates in each of four treatments: high richness (97 species typically planted by TheNature Conservancy), at low and high seeding densities, and low richness (15 species representing a typ-ical Natural Resources Conservation Service Conservation Reserve Program mix, CP25), at low and highseeding densities. Ants, ground beetles, and spiders were sampled using pitfall traps and ladybird beetleswere sampled using sweep netting in 2007–2009. The abundance of ants, ground beetles, and spidersshowed no response to seed mix richness or seeding density but there was a significant positive effect ofrichness on ladybird beetle abundance. Seeding density had a significant positive effect on ground beetleand spider species richness and Shannon–Weaver diversity. These results may be related to differencesin the plant species composition and relative amount of grass basal cover among the treatments ratherthan richness

Gamification in Defense Acquisition Training and Education

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumLeveraging research conducted as part of an Acquisition Research Program sponsored thesis, this paper expands upon an essay written by our research team (submitted to USNI), in which we argue that gamified learning (building games to promote learning of traditional material) presents a unique opportunity for enhancing education and training within the defense workforce. We provide an in-depth explanation of what gamification is and why it might be particularly useful for enhancing learning in non-traditional defense contexts, using defense acquisition as a test case. We present initial evidence from our empirical research to highlight the opportunities and challenges for advancing military education into the present age through gamified learning methods. Finally, we outline future directions for research in gamification for defense applications, bringing attention to the need for collaboration across the defense-focused entities exploring the potential for gaming in future defense education and training.Approved for public release; distribution is unlimited

Assessing Responses of \u3ci\u3eBetula papyrifera\u3c/i\u3e to Climate Variability in a Remnant Population along the Niobrara River Valley in Nebraska U.S. through Dendroecological and Remote Sensing Techniques

Remnant populations of Betula papyrifera have persisted in the Great Plains after the Wisconsin Glaciation along the Niobrara River Valley, Nebraska. Population health has declined in recent years, and has been hypothesized to be due to climate change. We used dendrochronological techniques to assess the response of B. papyrifera to microclimate (1950-2014), and satellite imagery [Landsat 5 TM (1985-2011) and MODIS (2000-2014)] derived NDVI as a proxy for population health. Growing-season streamflow and precipitation were positively correlated with raw and standardized tree-ring widths and basal area increment increase. Increasing winter and spring temperatures were unfavorable for tree growth while increasing summer temperatures were favorable in the absence of drought. The strongest predictor for standardized tree-rings was the Palmer Drought Severity Index, suggesting that B. papyrifera is highly responsive to a combination of temperature and water availability. The NDVI from vegetation community was positively correlated with standardized tree-ring growth, indicating the potential of these techniques to be used as a proxy for ex-situ monitoring of B. papyrifera. These results aid in forecasting the dynamics of the species in the face of climate variability and change in both remnant populations and across its current distribution in northern latitudes of North America