College of Arts & Sciences
Recent Submissions
-
Veech, Joseph A.; Crist, Thomas O.; Summerville, Keith S. (Ecological Society of America, 2003)[more][less]
Abstract: Abstract. The aggregation model of species coexistence predicts that insect species diversity within a community is maintained by intraspecific aggregation among resource patches. An untested corollary of this prediction is that diversity within resource patches should decrease with increasing intraspecific aggregation. The recently derived species–aggregation relationship provides a general formulation of this prediction: as intraspecific aggregation increases within a geographic area, the species richness within samples of the area decreases. We tested this prediction by compiling and analyzing 76 data sets of arthropod species distribution and abundance. For each data set, we determined the mean amount of intra- and interspecific aggregation and three types of within-sample or local species diversity: species richness, evenness, and dominance. Using regression, we found a negative relationship between intraspecific aggregation and all three types of local diversity. Intraspecific aggregation explained a significant percentage of the variation in species diversity, typically between 20% and 60%. By comparison, interspecific aggregation usually explained <1% of the variation in species diversity. Our study provides empirical support for the species–aggregation relationship as a general macroecological pattern that emerges from intraspecific aggregation. Description: Keith S. Summerville ia a professor of Environmental Science in the Department of Environmental Science and Policy at Drake University. He can be contacted at keith.summerville@drake.edu URI: http://hdl.handle.net/2092/494 Files in this item: 1
summervilleecology8412.pdf (101.0Kb) -
Summerville, Keith S.; Crist, Thomas O. (Ecological Society of America, 2002)[more][less]
Abstract: Abstract. Two pressing questions for forestry and conservation biology are whether periodic logging in forest ecosystems significantly changes biodiversity and whether the changes can be mitigated through appropriate harvest methods. Such questions of timber resource management, however, are rarely applied to nonpest insect species, particularly in temperate forest systems. We studied the effects of timber harvest on species richness, abundance, and community composition of forest Lepidoptera (moths). Moths were sampled in 16 forest stands occurring in two watersheds (managed and wilderness) in southeastern Ohio during summer 2000. Stands were chosen from one of four management categories: clear-cut, selectively logged, unlogged, and wilderness. Specifically, we tested the following predictions: (1) shifts in moth community composition would be affected by postharvest changes in stand structure and floristic composition, (2) variation in species richness would be determined by the magnitude of the logging disturbance, and (3) unlogged stands within managed landscapes would contain different species assemblages compared to wilderness stands. Canonical correspondence analysis (CCA) revealed significant compositional differences among moth communities sampled from forest stands differing in harvest regime. Variation among moth communities was mainly attributable to postharvest changes in stand floristic composition rather than stand structure. Postdisturbance shifts in moth community composition were related to the magnitude of displacement of a given forest stand to earlier successional stages. We also found that both species richness of the overall moth community and several feeding guilds were significantly lower in clear-cut stands, but species richness did not differ between selectively logged and unlogged stands. Thus, selective logging appears to be a better strategy for timber harvest when concern is for maintaining species richness of Lepidoptera within stands. Finally, although no differences were detected in overall species richness or abundance of moths sampled from stands in managed or wilderness watersheds, the CCA suggested that the surrounding landscape influenced the variation in community composition within and among forest stands. Therefore, we suggest that the long-term maintenance of lepidopteran species diversity and community composition within temperate deciduous forests managed for timber may ultimately depend on successful regeneration of harvested stands to precut floristic composition as well as the preservation of larger areas of unlogged forests. Description: Keith S. Summerville is a professor of Environmental Science in the Department of Environmental Science and Policy. He can be contacted at keith.summerville@drake.edu URI: http://hdl.handle.net/2092/492 Files in this item: 1
summervilleecoapp123effects.pdf (232.0Kb) -
Wacha, Richard S.; Ulrick, Kelly (Mason City, Iowa : North Iowa Area Community College, 2001)[more][less]
Abstract: An online guide to wildflowers of the Saylorville Lake Recreation Area, Des Moines River Basin, Polk Co., Iowa, is maintained as a public information project in cooperation with the U.S. Army Corps of Engineers. Each wildflower is represented by a digital image and scientific description. Digitally created diagrams of leaf and flower structure are also included. Issues associated with maintenance of the online guide are discussed. These include: (a) collection of data and online delivery methods, (b) features of a traditional guide compared to those of an electronic guide delivered online, (c) an electronic guide as a database, (d) incorporatig online data in CD-ROM and PDF formats, and (e) publishing online data through the peer review process. Description: Richard S. Wacha is Professor of Biology in the Department of Biology at Drake University. He can be contacted at richard.wacha@drake.edu URI: http://hdl.handle.net/2092/491 Files in this item: 1
wachawildflowers.pdf (912.3Kb) -
Summerville, Keith S.; Conoan, Christopher J.; Steichen, Renae M. (Ecological Society of America, 2006)[more][less]
Abstract: Restoration ecologists are increasingly turning to the development of trait-filter models, which predict how evolved traits limit species membership within assemblages depending on existing abiotic or biotic constraints, as a tool to explain how species move from a regional species pool into a restored community. Two often untested assumptions of these models, however, are that species traits can reliably predict species' broadscale distribution and that the effects of traits on community membership do not vary between restored and remnant habitats. The goals of this study were to determine whether combinations of ecological traits predispose moth species toward recolonization of restored prairies and to assess the degree to which restored prairies contain moth assemblages comparable with prairie remnants. In 2004, we collected 259 moth species from 13 tallgrass prairie remnants and restorations in central Iowa. Principal components analysis (PCA) was used to identify significant combinations of ecological traits that were shared by groups of moth species. Logistic regression was then employed to test for significant effects of the trait combinations on the frequency of prairie sites occupied by moth species. PCA partitioned moth traits into four axes that explained a total of 81.6% of the variance. Logistic regression detected significant effects for all four PCA axes on the fraction of sites occupied by moths. Species frequently filtered from the regional species pool into prairies were those that had long flight periods and were multivoltine, displayed a feeding preference for legumes but not other forb families, and were regionally abundant but relatively small in body size. Ordination revealed significant differences in moth communities among prairies, suggesting that species traits and habitat characteristics likely interact to create observed patterns of species recolonization of restorations. Thus, the optimal approach to restoring the lepidopteran fauna of tallgrass prairies may involve locating prairie plantings adjacent to habitat remnants.© 2006 by the Ecological Society of America. Description: Keith S. Summerville is a professor of Environmental Science in the Department of Environmental Science and Policy at Drake University. He can be contacted at keith.summerville@drake.edu URI: http://hdl.handle.net/2092/415 Files in this item: 1
summervilleecoapp163.pdf (152.0Kb) -
Rieck, Michael Q.; Dhar, Subhankar (Springer-Verlag, 2005)[more][less]
Abstract: For a connected graph, representing a sensor network, distributed algorithms for the Set Covering Problem can be employed to construct reasonably small subsets of the nodes, called k-SPR sets. Such a set can serve as a virtual backbone to facilitate shortest path routing, as introduced in [4] and [14]. When employed in a hierarchical fashion, together with a hybrid (partly proactive, partly reactive) strategy, the κ-SPR set methods become highly scalable, resulting in guaranteed minimal path routing, with comparatively little overhead. © Springer-Verlag Berlin Heidelberg 2005. Description: Michael Q. Rieck is Associate Professor of Computer Science in the Department of Math and Computer Science at Drake University. He can be contacted at michael.rieck@drake.edu URI: http://hdl.handle.net/2092/409 Files in this item: 1
rieck1.pdf (164.1Kb)