Browsing by Author "Johnson, Andrew"
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- Effects of environmental conditions on reproductive effort and nest success of Arctic-breeding shorebirdsWeiser, Emily L.; Brown, Stephen C.; Lanctot, Richard B.; Gates, H. River; Abraham, Kenneth F.; Bentzen, Rebecca L.; Bety, Joel; Boldenow, Megan L.; Brook, Rodney W.; Donnelly, Tyrone F.; English, Willow B.; Flemming, Scott A.; Franks, Samantha E.; Gilchrist, H. Grant; Giroux, Marie-Andree; Johnson, Andrew; Kendall, Steven J.; Kennedy, Lisa V.; Koloski, Laura; Kwon, Eunbi; Lamarre, Jean-Francois; Lank, David B.; Latty, Christopher J.; Lecomte, Nicolas; Liebezeit, Joseph R.; McKinnon, Laura; Nol, Erica; Perz, Johanna; Rausch, Jennie; Robards, Martin; Saalfeld, Sarah T.; Senner, Nathan R.; Smith, Paul A.; Soloviev, Mikhail; Solovyeva, Diana; Ward, David H.; Woodard, Paul F.; Sandercock, Brett K. (2018-07)The Arctic is experiencing rapidly warming conditions, increasing predator abundance, and diminishing population cycles of keystone species such as lemmings. However, it is still not known how many Arctic animals will respond to a changing climate with altered trophic interactions. We studied clutch size, incubation duration and nest survival of 17 taxa of Arctic-breeding shorebirds at 16 field sites over 7years. We predicted that physiological benefits of higher temperatures and earlier snowmelt would increase reproductive effort and nest survival, and we expected increasing predator abundance and decreasing abundance of alternative prey (arvicoline rodents) to have a negative effect on reproduction. Although we observed wide ranges of conditions during our study, we found no effects of covariates on reproductive traits in 12 of 17 taxa. In the remaining taxa, most relationships agreed with our predictions. Earlier snowmelt increased the probability of laying a full clutch from 0.61 to 0.91 for Western Sandpipers, and shortened incubation by 1.42days for arcticola Dunlin and 0.77days for Red Phalaropes. Higher temperatures increased the probability of a full clutch from 0.60 to 0.93 for Western Sandpipers and from 0.76 to 0.97 for Red-necked Phalaropes, and increased daily nest survival rates from 0.9634 to 0.9890 for Semipalmated Sandpipers and 0.9546 to 0.9880 for Western Sandpipers. Higher abundance of predators (foxes) reduced daily nest survival rates only in Western Sandpipers (0.9821-0.9031). In contrast to our predictions, the probability of a full clutch was lowest (0.83) for Semipalmated Sandpipers at moderate abundance of alternative prey, rather than low abundance (0.90). Our findings suggest that in the short-term, climate warming may have neutral or positive effects on the nesting cycle of most Arctic-breeding shorebirds.
- Forest composition, fuel loading, and soil chemistry resulting from 50 years of forest management and natural disturbance in two southeastern Coastal Plain watersheds, USACoates, T. Adam; Johnson, Andrew; Aust, W. Michael; Hagan, Donald L.; Chow, Alex T.; Trettin, Carl C. (2020-10-01)Globally, prescribed fire, harvesting, and understory mastication, alone and in combination, are common forest management practices. Timber commodities, wildlife habitat, wildfire fuel reduction, soil conservation, and water quality are frequently targeted and assessed as these practices are utilized. In the 1960s, a study of paired, first-order watersheds was established in coastal South Carolina, USA, to evaluate the long-term impacts of forest management (i.e. prescribed fire, thinning, mastication of understory vegetation) on water quantity and quality. Following Hurricane Hugo in 1989, this included salvage logging on one watershed, but not the other. In 2015, these watersheds were comprehensively evaluated to determine differences in forest species composition, fuels, and soil chemistry. Softwood basal area was greater in the managed watershed than in the unmanaged watershed and hardwood basal area was greater in the unmanaged watershed than in the managed watershed. Total fuel mass did not differ between the two watersheds, but 1-hr and 1000-hr rotten fuel mass were greater on the unmanaged watershed. Ten-hr fuel mass was greater on the managed watershed. Calcium, nitrogen, magnesium, phosphorus, potassium, and pH differed between the litter (Oi horizon) and duff (Oe + Oa horizons) of both watersheds, but carbon only differed in the duff. Mineral soil (Ultisols, 0-10 and 10-20 cm depths) calcium and phosphorus differed between the watersheds, but pH and the other chemicals did not. Collectively, these results indicated that: (1) forest management and natural disturbance on these watersheds altered long-term forest structure; (2) different species compositions and the inclusion or exclusion of salvage logging after Hurricane Hugo produced different fuel compositions that may potentially impact potential wildfire hazard and fire behavior; (3) organisms as a primary soil-forming factor were impacted by long-term management, therefore, some soil chemical properties were affected. Collectively, these analyses highlighted the broad, long-term impacts to ecosystem properties and processes that might directly and indirectly result from active forest management and natural disturbance and the scale of site-specific assessment that might be considered when landowner objectives are targeted in forest management plans and practices.
- Mineral Soil Chemical Properties as Influenced by Long-Term Use of Prescribed Fire with Differing Frequencies in a Southeastern Coastal Plain Pine ForestCoates, T. Adam; Hagan, Donald L.; Aust, W. Michael; Johnson, Andrew; Keen, John Caleb; Chow, Alex T.; Dozier, James H. (MDPI, 2018-11-27)Recent studies suggest increased fire frequency may impair soil chemistry, but few studies have examined long-term effects of repeated, frequent prescribed fires on forest soil properties in the southeastern Coastal Plain, USA. In this study, forest soil chemistry at the 0–10 and 10–20 cm mineral soil depths of sandy surface horizons (Entisols and Spodosols) were compared among units burned 0, 4, 6, and 8 times between 2004 and 2015 and 0 and 20 times between 1978 and 2015 in a longleaf (Pinus palustris Mill.)–loblolly (Pinus taeda L.) pine savanna at the Tom Yawkey Wildlife Center (Georgetown, SC, USA). At the 0–10 cm soil depth, soil pH (p = 0.00), sulfur (p = 0.01), calcium (p = 0.01), iron (p < 0.01), manganese (p < 0.01), and aluminum (p = 0.02) treatment means differed (2004–2015). Calcium and manganese displayed positive, significant relationships and sulfur displayed a negative, significant relationship with increasing fire frequency (p < 0.05). However, correlation of these relationships was low (r2 ≤ 0.23). Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the mean of the unburned compartment, sulfur (p = 0.01) and iron (p < 0.01) were less in soils from the burned compartments. At the 10–20 cm soil depth, soil pH (p = 0.01), manganese (p = 0.04), phosphorus (p = 0.01), potassium (p = 0.02), and iron (p < 0.01) treatment means differed (2004–2015). Potassium displayed a negative, significant relationship and soil pH displayed a positive, significant relationship with increasing fire frequency (p < 0.05). Correlation of these relationships was low (r2 ≤ 0.16), however. Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the unburned compartment, potassium (p = 0.00) and iron (p < 0.01) were less in soils from burned compartments. These results are inconsistent with studies suggesting that forest soil chemistry is substantially altered by increased fire frequency and support other studies from this region that have documented minimal or temporary soil chemical changes associated with frequent prescribed fires.
- Traces of Time through Space: Advantages of Creating Complex Canvases in Collaborative MeetingsKirshenbaum, Nurit; Davidson, Kylie; Harden, Jesse; North, Christopher L.; Kobayashi, Dylan; Theriot, Ryan; Tabalba, Roderick; Rogers, Michael; Belcaid, Mahdi; Burks, Andrew; Bharadwaj, Krishna; Renambot, Luc; Johnson, Andrew; Long, Lance; Leigh, Jason (ACM, 2021-11-05)Technology have long been a partner of workplace meeting facilitation. The recent outbreak of COVID-19 and the cautionary measures to reduce its spread have made it more prevalent than ever before in the form of online-meetings. In this paper, we recount our experiences during weekly meetings in three modalities: using SAGE2 - a collaborative sharing software designed for large displays - for co-located meetings, using a conventional projector for co-located meetings, and using the Zoom video-conferencing tool for distributed meetings. We view these meetings through the lens of effective meeting attributes and share ethnographic observations and attitudinal survey conducted in our research lab. We discuss patterns of content sharing, either sequential, parallel, or semi-parallel, and the potential advantages of creating complex canvases of content. We see how the SAGE2 tool affords parallel content sharing to create complex canvases, which represent queues of ideas and contributions (past, present, and future) using the space on a large display to suggest the progression of time through the meeting.
- Viral Politics: Jacques Derrida's reading of Auto-immunity and Carl SchmittJohnson, Andrew (2010-05-01)Since Jacques Derrida’s 1989 essay “Force of Law: the Mystical Foundations of Authority,” Carl Schmitt has been a perennial subject of Derrida’s political critique. I will argue that Derrida’s concept of auto-immunity is uniquely applicable to Derrida’s interpretation of Schmitt’s political philosophy. Therefore, my argument will consist of two interrelated but equally divergent parts; the digressive structure will attempt to mimic Derrida’s complex style of weaving opposed concepts into a coherent whole. First, I will demonstrate the many forms of Derrida’s concept of auto-immunity. Second, I will exhibit how this schema uniquely applies to Derrida’s criticisms of Schmitt and the contemporary state of politics.