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Beth A. Middleton

Publications and source records attributed to Beth A. Middleton.

86 records · Page 5Linked to original sources
USGS2006

Fire management in fens and wet grasslands grazed by cattle

Managers grapple with the problem of shrub invasion in fens and wet grasslands, and the invasion of shrubs is a particular problem in newly acquired natural areas that were once grazed by cattle. The specific management for any particular fen or wet grassland depends greatly on its previous land-use history. Managers should have a clear understanding of the grazing and drainage history of newly acquired fens and wet grasslands so that well-informed management decisions can be made.

Open-File Report↗
USGS2006

Baldcypress swamp management and climate change

In the future, climates may become warmer and drier in the southeastern United States; as a result, the range of baldcypress (Taxodium distichum) swamps may shrink. Managers of baldcypress swamps at the southern edge of the range may face special challenges in attempting to preserve these swamp habitats in the future if climates become warmer and drier.

Open-File Report↗
USGS2006

Impoundment and baldcypress swamp management

Baldcypress swamps (Taxodium distichum) are impounded for many reasons, but this practice results in the demise of the swamp. The permanent impoundment of baldcypress swamps first lowers primary production and eventually results in death of the trees.

Open-File Report↗
USGS2005

Species frequency dynamics in an old-field succession: Effects of disturbance, fertilization and scale

Question: Can patterns of species frequency in an old-field be explained within the context of a metapopulation model? Are the patterns observed related to time, spatial scale, disturbance, and nutrient availability? Location: Upland and lowland old-fields in Illinois, USA. Method: Species richness was recorded annually for seven years following plowing of an upland and lowland old-field subject to crossed fertilizer and disturbance treatments (mowing and rototilling). Species occupancy distributions were assessed with respect to the numbers of core and satellite species. Results: In both fields, species richness became higher in disturbed plots than in undisturbed plots over time, and decreased in fertilized plots irrespective of time. A bimodal pattern of species richness consistent with the Core-satellite species (CSS) hypothesis occurred in the initial seed bank and through the course of early succession. The identity of native and exotic core species (those present in > 90% of blocks) changed with time. Some core species from the seed bank became core species in the vegetation, albeit after several years. At the scale of individual plots, a bimodal fit consistent with the CSS hypothesis applied only in year 1 and rarely thereafter. Conclusions: The CSS hypothesis provides a metapopulation perspective for understanding patterns of species richness but requires the assessment of spatial and temporal scaling effects. Regional processes (e.g. propagule availability) at the largest scale have the greatest impact influencing community structure during early secondary succession. Local processes (e.g., disturbance and soil nutrients) are more important at smaller scales and place constraints on species establishment and community structure of both native and exotic species. Under the highest intensity of disturbance, exotic species may be able to use resources unavailable to, or unused by, native species.

Journal of Vegetation Science↗
USGS2004

Biodiversity and ecosystem functioning: Synthesis and perspectives

Does diversity matter in restored communities? This edited book explores the diversity–function debate, which has raged in ecology during the past several decades. The diversity–function question is relevant in restoration, but the question has not yet received a straightforward hearing in the field of restoration science. None of the authors of this book explicitly relate their ideas to restoration, but the book can educate restorationists about the most recent developments in the diversity–function debate. It is also an excellent book for students to learn about the recent developments and historical background of the diversity–function debate and can be used for graduate-level seminars in restoration or plant ecology.

Restoration Ecology↗
USGS2004

Characterization of the habitat of Lythrum salicaria L. in floodplain forests in western Turkey—Effects on stem height and seed production

Lythrum salicaria (purple loosestrife) is an invasive wetland perennial in North America native to Eurasia. Because light environment may limit the species’ distribution, information on the relationship of forest canopy coverage to relative height and seed set in its native environment could give insight into its control in North America. This study examined the effect of various light environments related to forest canopy structure on seed set and stem height in L. salicaria in three biogeographical regions of Turkey spanning latitudes from 36 to 39° N. In Turkey, Lythrum salicaria grows in discrete patches in the canopy gaps of riverine forests, which often are dominated by Populus alba . The mean number of seeds per individual and stem height increased with decreasing canopy coverage (10437±284 to 20652±664 seeds individual −1 and 116±2 to 173±2 cm, respectively). A number of insect seed herbivores were noted on these Turkish populations, most notably a seed predator ( Nanophyes marmoratus ), which destroyed all seeds in infested capsules. Our study suggested that the light characteristics associated with canopy gaps influenced the seed set and height of L. salicaria . Other factors likely played a role, such as insect herbivores, soil fertility, and competition with other species, which may also be affected by the light levels provided at various levels of canopy coverage.

Wetlands↗
USGS2004

Latitudinal variation in carbon storage can help predict changes in swamps affected by global warming

Plants may offer our best hope of removing greenhouse gases (gases that contribute to global warming) emitted to the atmosphere from the burning of fossil fuels. At the same time, global warming could change environments so that natural plant communities will either need to shift into cooler climate zones, or become extirpated (Prasad and Iverson, 1999; Crumpacker and others, 2001; Davis and Shaw, 2001). It is impossible to know the future, but studies combining field observation of production and modeling can help us make predictions about what may happen to these wetland communities in the future. Widespread wetland types such as baldcypress (Taxodium distichum) swamps in the southeastern portion of the United States could be especially good at carbon sequestration (amount of CO2 stored by forests) from the atmosphere. They have high levels of production and sometimes store undecomposed dead plant material in wet conditions with low oxygen, thus keeping gases stored that would otherwise be released into the atmosphere (fig. 1). To study the ability of baldcypress swamps to store carbon, our project has taken two approaches. The first analysis looked at published data to develop an idea (hypothesis) of how production levels change across a temperature gradient in the baldcypress region (published data study). The second study tested this idea by comparing production levels across a latitudinal range by using swamps in similar field conditions (ongoing carbon storage study). These studies will help us make predictions about the future ability of baldcypress swamps to store carbon in soil and plant biomass, as well as the ability of these forests to shift northward with global warming.

Fact Sheet↗
USGS2004

Purple loosestrife volunteers

Purple loosestrife (Lythrum salicaria) is a perennial plant native to Eurasia where it grows along streams, rivers, and wet seepage areas (fig. 1). Seeds were inadvertently brought to North American territories in the ballast water of ships. Purple loosestrife was also intentionally planted throughout North America for its ornamental flowers but has since escaped cultivation to spread to wetlands. Some purple loosestrife plants release millions of seeds during the summer season, and these seeds readily disperse to new wetlands via water, animals, and even on people’s shoes. In addition, both its roots and stem fragments can sprout and begin new plants. When purple loosestrife invades a wetland, the species sometimes becomes more dominant than the original native wetland species, such as cattails and sedges. While many people think that purple loosestrife reduces the value of wetlands for wildlife, these claims are disputed. Most people agree, however, that purple loosestrife grows more prolifically in North America than elsewhere, probably because the species has left its native enemies behind in Eurasia and Australia. Although we do not understand how well the species grows in various climates, there is some thought that purple loosetrife may never fully invade the southern United States. Studies looking at the species’ response to temperature and analyses of its growth patterns across latitudes can help us determine its future threat to uninvaded portions of the United States. This is where volunteers come in. Volunteers in North America, Eurasia, and Australia are helping assess purple loosestrife growth in their regions (fig. 2). The program is part of Dr. Beth Middleton’s project to compare the role of purple loosestrife in its native and invasive habitats. Anyone can participate, and volunteers currently include high school and college students, retirees, professionals from all disciplines, agency personnel, and university faculty. Volunteers collect data by marking off a sampling area, recording the number and height of purple loosestrife, and observing the sunlight and water conditions at each location. Data collection only occurs once in each wetland and takes less than 30 minutes (see form below). The results of the study will help efforts to control and predict the future spread of this species.

Fact Sheet↗
USGS2004

Natural restoration basics for wetlands

Around the world, dams, diversions, and drainage systems reengineer rivers for navigation, farming, and urban development, and this has caused vast changes in the environmental conditions of the flood plains adjacent to these rivers (Middleton, 2002). Even though “flood pulses,” the periodic overflow of these rivers, were once the most important hydrological factor regulating all functions of the flood plain (Junk and others, 1986), now they have been reduced or eliminated along many of the world’s waterways (Sparks and others, 1998). These changes in river channels have created a hydrologic setting on flood plains that has not been conducive to restoration and nature conservation (Middleton, 2002). Consequently, USGS scientists are studying the long-term effects of hydrologic changes on flood plains, such as how the restoration of baldcypress (Taxodium distichum) swamps has been hindered because seeds cannot disperse or germinate without the seasonally driven high and low water levels associated with the flood pulse.

Fact Sheet↗
USGS2004

Seedling growth of Wisconsin fast plants (Brassica rapa) in field environments

In this 3-week laboratory, students investigate the effects of an abiotic or biotic ecological factor on the growth or reproduction of rapid-cycling brassica ( Brassica rapa L. : Wisconsin Fast Plants) seedlings in the field. Measurable treatments include light, wind, herbivory, chemical or organic fertilizer, insecticides, and growth regulators (i.e., gibberellic acid spray, auxin paste). Students learn how to develop an hypothesis and apply the scientific method in a field setting. Students work in pairs and set up their experiments using previously prepared Wisconsin Fast Plant seedlings. One week later students harvest their plants during a return field trip after which they collect their data, write individual scientific reports, and present their findings in-class. This experiment is unique because Wisconsin Fast Plants are used in a field experiment instead of the usual laboratory setting.

Teaching Issues and Experiments in Ecology (TIEE)↗
USGS2003

Soil seed banks and the potential restoration of forested wetlands after farming

1 Changes in farming practice provide an opportunity to restore once extensive forested wetlands on agricultural land. In some parts of the world, however, it has proved difficult to restore the full complement of plant species through natural regeneration. Similarly, the restoration of forested wetlands by replanting has often resulted in ecosystems of low diversity. Better methods of restoring these important ecosystems are now required and baldcypress swamps provide an opportunity to investigate alternative approaches to the restoration of forested wetlands. This study examined the composition of seed banks of farmed fields to determine their value in restoring swamps in the south-eastern United States. 2 A seed bank assay of soils from baldcypress swamps was conducted to determine the extent to which seeds are maintained during farming for various lengths of time. Soils from swamps that were farmed for 0–50 years were collected near the northern boundary of the Mississippi Alluvial Valley along the Cache River, Illinois. Soils were placed in a glasshouse setting in flooded and freely drained conditions, and the numbers and species of seeds germinating were recorded. 3 Woody species including trees, shrubs, and vines were poorly represented in seed banks of both farmed and intact sites (51 and 9 sites, respectively). Missing dominants in the seed banks included tree species with short-lived seeds such as Taxodium distichum and Nyssa aquatica . Cephalanthus occidentalis constituted the most abundantly dispersed seed of all woody species. 4 Herbaceous species were well represented in the seed banks of both farmed and intact swamps (species richness of 207 vs. 173 species, respectively) suggesting that herbaceous species may live longer than woody species in seed banks. Few of the herbaceous species decreased in seed density in seed banks with time under cultivation, although seed density was lower at sites that had not been farmed. Species that relied on vegetative organs for dispersal were absent in the seed banks of farmed sites including Heteranthera dubia , Hottonia inflata , Lemna minor , Lemna trisulca and Wolffia columbiana . These species may require active reintroduction during restoration. 5 Synthesis and applications. Both restoration ecologists and managers of nature conservation areas need to be cognisant of seed bank and dispersal characteristics of species to effectively restore and manage forested wetlands. In the case of baldcypress swamps, critical components of the vegetation are not maintained in seed banks, which may make these floodplain wetlands difficult to restore via natural recolonization. Ultimately, the successful restoration of abandoned farm fields to forested wetlands may depend on the re-engineering of flood pulsing across landscapes to reconnect dispersal pathways.

Illinois↗
USGS1999

Wetland restoration, flood pulsing, and disturbance dynamics

While it is generally accepted that flood pulsing and disturbance dynamics are critical to wetland viability, there is as yet no consensus among those responsible for wetland restoration about how best to plan for those phenomena or even whether it is really necessary to do so at all. In this groundbreaking book, Dr. Beth Middleton draws upon the latest research from around the world to build a strong case for making flood pulsing and disturbance dynamics integral to the wetland restoration planning process. While the initial chapters of the book are devoted to laying the conceptual foundations, most of the coverage is concerned with demonstrating the practical implications for wetland restoration and management of the latest ecological theory and research. It includes a fascinating case history section in which Dr. Middleton explores the restoration models used in five major North American, European, Australian, African, and Asian wetland projects, and analyzes their relative success from the perspective of flood pulsing and disturbance dynamics planning. Wetland Restoration also features a wealth of practical information useful to all those involved in wetland restoration and management, including: * A compendium of water level tolerances, seed germination, seedling recruitment, adult survival rates, and other key traits of wetland plant species * A bibliography of 1,200 articles and monographs covering all aspects of wetland restoration * A comprehensive directory of wetland restoration ftp sites worldwide * An extensive glossary of essential terms

Book↗