After large-scale disturbances such as fire, seeding can be necessary to reestablish a plant community and prevent soil erosion. While native plants are ideal for providing ecosystem services and supporting wildlife, currently seeded natives often fail to establish in disturbed landscapes. Further, reseeding with native plants is often hindered by...
Climate change, whether referring to historic ice ages or contemporary shifts in global climate patterns, has been linked to wide-ranging and regionally variable changes in biotic communities.
Understanding the factors that drive the maintenance of polymorphisms in plant populations has long been of interest to evolutionary biology. Variation in floral traits has often been attributed to selection by pollinators, but recent evidence suggests that other biotic and abiotic agents may also contribute to floral trait differentiation. In...
The tallgrass prairie once dominated much of the mid-western United States. Today, this highly productive system has been severely reduced, contributing to an array of environmental problems. The recent renaissance in natural area restoration and stewardship of the tallgrass prairie in the Chicago Wilderness region (Illinois, USA), especially in the...
The prairie grasses Andropogon gerardii and Sorghastrum nutans have seeds with awns that twist in response to changes in humidity. The humidity-sensitive, or hygroscopic, part of the awn twists, moving the bent, passive portion in an arc. This trait has been demonstrated to improve seedling recruitment in other grass species...
Restoration managers may select seed from a variety sources for their restoration projects. If the purchased seed is not of the local ecotype, land managers run the risk of poor establishment in the short-term and outcrossing between local and non-local ecotypes, genetic swamping, and the loss of local genetic diversity...
Due to concerns about population declines and habitat destruction, secretive marsh birds (SMBs) are of high conservation concern at state, regional, and national levels. Gaps in research on SMB habitat pose barriers to conservation and wetland restoration efforts.
Fire is an agent of ecosystem change that has played a critical role in shaping the tallgrass prairie ecosystem. Periodic prescribed fire maintains the prairie by removing woody and invasive plant species, and stimulating growth of native herbaceous species. Fire’s beneficial effect on the tallgrass prairie aboveground community, in terms...
Once widespread throughout southern Wisconsin, Quercus savannas are now one of the most endangered communities due to fire suppression and increasing landscape fragmentation. These plant communities are also highly susceptible to invasions by nonnative, exotic species. Understanding the mechanisms of exotic species invasion has been the focus of numerous studies....
Hybridization is an important evolutionary pathway to genetic diversity, fitness, and ultimately to the emergence of new species. In contrast, hybridization between a native and an introduced species can lead to a loss of locally adapted gene complexes and ultimately to the extinction of the native. In the last decade,...
Underutilized crops have the potential to economically benefit developing countries and to improve global food security. Breadfruit (Artocarpus altilis, Moraceae) is one such crop that can provide essential nutrients and requires relatively low-energy input to maintain compared to major crops. Humans have selected for many cultivars of breadfruit since its...
With increasing urbanization and creation of novel habitat types, green roofs can provide usable habitat for many species. To date, most research on green roofs has focused on minimizing the environmental impacts of buildings but little is known about the ecological services they provide. Previous research has shown that although...
The underutilized tropical fruit tree, “cempedak” (Artocarpus integer (Thunb.) Merr. , Moraceae), is a major crop in Malaysia but the distribution of genetic diversity in the crop and its putative wild progenitor, “bangkong” (Artocarpus integer var. silvestris Corner), have not been studied. To investigate the diversity and origins of cempedak,...
The introduction of non-native pests in general, and invasive plants in particular, has been receiving increasing interest by scientists, environmental groups, and to a certain extent the general public. Deleterious effects from the release of such alien species include threats to the environment, national economies, and even human health. The...
Plant-aphid systems provide a valuable opportunity for studying the ecological consequences of land use change for interacting species. The North American tallgrass prairie has undergone severe reduction and fragmentation due to agricultural development. The prairie perennial Echinacea angustifolia, a model system for studying population-level effects of habitat fragmentation, hosts a...
Current ecological restoration efforts seek to restore a target community, maximize biodiversity or provide habitat for rare species. In practice, restoration ecology is often initiated and sustained without knowledge or reverence to the belowground ecosystem processes, though these processes often subtend the long-term sustainability of aboveground and belowground ecological communities.
The environmental and plant physiological correlates of plant growth and reproductive effort in the locally threatened orchid, Cypripedium candidum Muhl. ex Willd were examined in the context of a conceptual model of demographic and reproductive trade-offs, focusing on three Illinois populations. This study addresses the current status and long-term trends...
Nitrogen (N) deposition can alter belowground microbial communities, especially ectomycorrhizal (ECM) fungi, resulting in a reduced ability of associated trees to access organic nutrients. This study tested whether N addition decreases ECM species richness and shifts ECM species composition across spatial scales in a subtropical slash pine (Pinus elliottii) plantation...
Identifying factors that shape the spatial distribution of genetic variation within and among natural populations is crucial to understanding many population> and landscape>level processes. In this study, I characterize the strength and extent of spatial genetic structure in Oenothera harringtonii (Onagraceae), an insect>pollinated, gravity>dispersed herb endemic to the grasslands of...
Habitat fragmentation can alter the conditions of natural plant populations, introducing novel selective pressures. The ability of a population to respond to environmental change can be inferred by assessing the population’s genetic diversity and the heritability of traits thought to be under selection.
Two experiments were conducted to assess the germination, growth, and survival of Cirsium pitcheri Torr. ex Eaton T & G in the Chicagoland region. The first experiment involved growing seeds from various native populations to determine tolerance for the current Chicagoland climate. The second experiment tested three of the populations...
Pollination is a reproductive necessity in the majority of the world’s flowering plants. Pollen limitation threatens plant reproduction, particularly in self-incompatible species. Although assessing pollen limitation usually requires pollen supplementation experiments, alternative methods support the findings of traditional pollen supplementation experiments.
Pollination is a reproductive necessity in the majority of the world’s flowering plants. Pollen limitation threatens plant reproduction, particularly in self-incompatible species. Although assessing pollen limitation usually requires pollen supplementation experiments, alternative methods support the findings of traditional pollen supplementation experiments.
Past efforts to reintroduce the native legume species Desmodium glutinosum and Lespedeza violacea into restored woodlands have not produced self-sustaining populations. Proposed factors preventing reintroduction include herbivory, persistent environmental effects of invasive shrubs, poor performance of commercial Rhizobium inoculants, and competitive displacement associated with elevated nitrogen availability. To address these...
Contemporary Ethiopian is, without question, facing enormous challenges. At the core of these challenges lay a state-building process major constituencies and elite groups were either alienated from, forced to acquiesce to, or coopted into. Unable to derive political legitimacy from democratic participation, successive governments largely relied on coercion and neopatrimonialism,...
The textbook proceeds with an introduction to theory and concept building, moves to an explanation of causal inference (how do we 'know' whether something is causal?), and then provides a quick introduction to data and hypothesis testing. Following that, each chapter is devoted to a particular research method used within...
This book discusses how cities that have developed through the successive stages of capitalism should transform themselves when adapting to the conditions of the contemporary global age. Since modern times, the capitalist economy has largely defined society, politics, and environment—this has casued the collapse of communities, the crisis of democracy,...
This introductory chemistry textbook was compiled by Shelby Hatch at Northwestern University and is adapted from the following sources:
"Introductory Chemistry" by David W. Ball, The Saylor Foundation, Cleveland State University, is licensed
under CC BY-NC-SA 4.0 and is available at https://open.umn.edu/opentextbooks/textbooks/introductory-chemistry ; "Chemistry of Cooking" by Sorangel Rodriguez-Velazquez, American...
This report shows that compensation plans have not met the needs of victims of nuclear disasters for three primary reasons: compensation plans have been devised by unelected officials and without full public knowledge or participation, governments have often capped the liability of the owners of nuclear facilities, which distorts cost-benefit...
Trees in urban areas offer ecosystem services like carbon sequestration, storm water attenuation, reduction of energy used in buildings and wildlife habitat. Cities invest substantial funds and resources to maintain a healthy urban forest, and much research has been done to improve its resiliency and sustainability. Studies have been done...
This report shows the results of acoustic emission (AE) monitoring, and provides additional information on the nature of the ultrasonic indications in the north east trunnion shaft.
A remote global monitoring system is being operated on a 65 year old lift bridge in Sturgeon Bay Wisconsin. The system uses both strain gages and clinometers to continuously monitor the "health" of the fracture critical components of the bridge. Ruggedized miniaturized data loggers are locally mounted on the structure...
This paper describes application of AE monitoring techniques to localize the sources of large noises in civil structures. These noises occur during operation of moveable portions of a structure in such things as lift bridges and moveable sports stadium roofs. The use of straightforward AE monitoring techniques can provide clear...
Acoustic emission (AE) testing was used to identify the source of audible “bangs” generated during opening and closing of a large, double-leaf rolling-lift bascule bridge. The data were analyzed using a combination of well-established AE
techniques, including first hit analysis (FHA), planar location analysis, and linear location analysis. The FHA...
Scour is by far the primary cause of bridge failures in the United States. Scour and other hydraulic effects are particularly threatening because the deterioration is often invisible, hidden beneath turbid water. Many scour monitoring methods attempt to measure the development of scour pockets themselves. However, this is difficult due...
Acoustic emission (AE) testing was deployed on details of two large steel Interstate Highway bridges: one cantilever through-truss and one trapezoidal box girder bridge. Quantitative measurements of activity levels at known and suspected crack locations were made by monitoring AE under normal service loads (e.g., live traffic and wind). AE...
Slides for a workshop for Northwestern University on sharing and preserving research findings using the library's resources. This workshop was delivered at Computational Research Day 2017.