8 research outputs found
Discoloration of Polyvinyl Chloride (PVC) Tape as a Proxy for Water-Table Depth in Peatlands: Validation and Assessment of Seasonal Variability
No full textAuthor Wilcox employed by:
US Geological Survey – Great Lakes Science Center, 1451 Green Road, Ann Arbor, MI 48105, USASummary
1. Discoloration of polyvinyl chloride (PVC) tape has been used in peatland ecological and hydrological studies as an inexpensive way to monitor changes in water-table depth and reducing conditions.
2. We investigated the relationship between depth of PVC tape discoloration and measured water-table depth at monthly time steps during the growing season within nine kettle peatlands of northern Wisconsin. Our specific objectives were to: (1) determine if PVC discoloration is an accurate method of inferring water-table depth in Sphagnum -dominated kettle peatlands of the region; (2) assess seasonal variability in the accuracy of the method; and (3) determine if systematic differences in accuracy occurred among microhabitats, PVC tape colour and peatlands.
3. Our results indicated that PVC tape discoloration can be used to describe gradients of water-table depth in kettle peatlands. However, accuracy differed among the peatlands studied, and was systematically biased in early spring and late summer/autumn. Regardless of the month when the tape was installed, the highest elevations of PVC tape discoloration showed the strongest correlation with midsummer (around July) water-table depth and average water-table depth during the growing season.
4. The PVC tape discoloration method should be used cautiously when precise estimates are needed of seasonal changes in the water-table.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
Lake Michigan Wetlands: Classification, Concerns, and Management Opportunities
No full textAuthor Wilcox was a government employee when he wrote this article.The wetlands that border Lake Michigan are an extremely important component of the lake ecosystem. Wetlands are considered to be among the most productive and ecologically diverse habitats on earth, with attributes of both upland and aquatic ecosystems. Although wetlands comprise only a small fraction of the total area of Lake Michigan, they provide habitat for thousands of species of plants and animals and perform environmental functions that affect the whole lake (Wilcox, 1995; Environment Canada, 2002). However, unlike open waters of the lake that have been studied for nearly a century, wetlands have been studied for only a few decades. The numerous forms of degradation and assault on wetland resources have been documented, but few are understood thoroughly. Management of wetlands and the problems they face has thus not progressed quickly, and debates still occur regarding descriptions of wetlands. In this paper, I will review the status of wetland classifications used for Lake Michigan and the other Great Lakes, as well as the major management concerns and opportunities presented by Lake Michigan wetlands.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
Optically Stimulated Luminescence Dating of Late Holocene Raised Strandplain Sequences Adjacent to Lakes Michigan and Superior, Upper Peninsula, Michigan, USA
No full textAuthor Wilcox was a government employee at the time of the article.This study evaluates the accuracy of optically stimulated luminescence to date well-preserved strandline sequences at Manistique/ Thompson bay (Lake Michigan), and Tahquamenon and Grand Traverse Bays (Lake Superior) that span the past ~4500 yr. The single aliquot regeneration (SAR) method is applied to produce absolute ages for littoral and eolian sediments. SAR ages are compared against AMS and conventional 14C ages on swale organics. Modern littoral and eolian sediments yield SAR ages b100 yr indicating near, if not complete, solar resetting of luminescence prior to deposition. Beach ridges that yield SAR ages b2000 yr show general agreement with corresponding 14C ages on swale organics. Significant variability in 14C ages N2000 cal yr B.P. complicates comparison to SAR ages at all sites. However, a SAR age of 4280 F 390 yr (UIC913) on ridge77 at Tahquamenon Bay is consistent with regional regression from the high lake level of the Nipissing II phase ca. 4500 cal yr B.P. SAR ages indicate a decrease in ridge formation rate after ~1500 yr ago, likely reflecting separation of Lake Superior from lakes Huron and Michigan. This study shows that SAR is a credible alternative to 14C methods for dating littoral and eolian landforms in Great Lakes and other coastal strandplains where 14C methods prove problematic. D 2004 University of Washington. All rights reserved.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
A Paleoecological Test of a Classical Hydrosere in the Lake Michigan Dunes
No full textAuthor Wilcox was employed by National Park Service, Indiana Dunes National Lakeshore, Porter, Indiana 46304 USA.Aquatic vegetation varies along a chronosequence of dune ponds at Miller Woods, Indiana Dunes National Lakeshore. Submersed and floating-leaved macrophytes dominate the vegetation of the youngest ponds. Older ponds contain mixed assemblages of submersed, floating-leaved, and emergent plant taxa. The oldest ponds are dominated by emergent plants, especially Typha angustifolia. We conducted paleoecological studies at one of the oldest ponds to test the hypothesis that the modern vegetational array along the pond chronosequence represents a hydrarch successional sequence. Macrofossil stratigraphy of the 3000-yr-old pond indicates no significant changes in pond vegetation following early colonization until < 150 BP. Pond vegetation before 150 BP consisted of a diverse assemblage of submersed, floating-leaved, and emergent macrophyte taxa. Pollen and macrofossil data indicate a major, rapid vegetational change at < 150 BP, evidently in response to local human disturbance. Pollen data reveal that the extensive Typha stands in the older ponds have developed recently, following postsettlement disturbance. Modern vegetational differences along the chronosequence reflect differential effects of disturbance rather than autogenic hydrarch succession. This study illustrates a major pitfall in inferring successional trends from spatial sequences of vegetation.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
Implications of Hydrologic Variability on the Succession of Plants in Great Lakes wetlands
No full textAuthor Wilcox worked for the government agency:
U.S. Geological Survey–Great Lakes Science Center, 1451 Green Road, Ann Arbor, Michigan, USA 48105;Primary succession of plant communities directed toward a climax is not a typical occurrence in wetlands because these ecological systems are inherently dependent on hydrology, and temporal hydrologic variability often causes reversals or setbacks in succession. Wetlands of the Great Lakes provide good examples for demonstrating the implications of hydrology in driving successional processes and for illustrating potential misinterpretations of apparent successional sequences. Most Great Lakes coastal wetlands follow cyclic patterns in which emergent communities are reduced in area or eliminated by high lake levels and then regenerated from the seed bank during low lake levels. Thus, succession never proceeds for long. Wetlands also develop in ridge and swale terrains in many large embayments of the Great Lakes. These formations contain sequences of wetlands of similar origin but different age that can be several thousand years old, with older wetlands always further from the lake. Analyses of plant communities across a sequence of wetlands at the south end of Lake Michigan showed an apparent successional pattern from submersed to floating to emergent plants as water depth decreased with wetland age. However, paleoecological analyses showed that the observed vegetation changes were driven largely by disturbances associated with increased human settlement in the area. Climateinduced hydrologic changes were also shown to have greater effects on plant-community change than autogenic processes. Other terms, such as zonation, maturation, fluctuations, continuum concept, functional guilds, centrifugal organization, pulse stability, and hump-back models provide additional means of describing organization and changes in vegetation; some of them overlap with succession in describing vegetation processes in Great Lakes wetlands, but each must be used in the proper context with regard to short- and long-term hydrologic variability.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
Education and Training of Future Wetland Scientists and Managers
No full textAuthor Wilcox was employed by:
U.S. Geological Survey–Great Lakes Science CenterWetland science emerged as a distinct discipline in the 1980s. In response, courses addressing various aspects of wetland science and management were developed by universities, government agencies, and private firms. Professional certification of wetland scientists began in the mid-1990s to provide confirmation of the quality of education and experience of persons involved in regulatory, management, restoration/construction, and research involving wetland resources. The education requirements for certification and the need for persons with specific wetland training to fill an increasing number of wetland-related positions identified a critical need to develop curriculum guidelines for an undergraduate wetland science and management major for potential accreditation by the Society of Wetland Scientists. That proposed major contains options directed toward either wetland science or management. Both options include required basic courses to meet the general education requirements of many universities, required upper-level specialized courses that address critical aspects of physical and biological sciences applicable to wetlands, and a minimum of four additional upper-level specialized courses that can be used to tailor a degree to students’ interests. The program would be administered by an independent review board that would develop guidelines and evaluate university applications for accreditation. Students that complete the required coursework will fulfill the education requirements for professional wetland scientist certification and possess qualifications that make them attractive candidates for graduate school or entry level positions in wetland science or management. Universities that offer this degree program could gain an advantage in recruiting highly qualified students with an interest in natural resources. Alternative means of educating established wetland scientists are likewise important, especially to provide specialized knowledge and experience or updates related to new management discoveries, policies, and regulations.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
Predicting Wetland Plant Community Responses to Proposed Water-level-regulation Plans for Lake Ontario: GIS-based Modeling
No full textAuthor Wilcox was a government employee when he wrote this article.Integrated, GIS-based, wetland predictive models were constructed to assist in predicting the responses of wetland plant communities to proposed new water-level regulation plans for Lake Ontario. The modeling exercise consisted of four major components: 1) building individual site wetland geometric models; 2) constructing generalized wetland geometric models representing specific types of wetlands (rectangle model for drowned river mouth wetlands, half ring model for open embayment wetlands, half ellipse model for protected embayment wetlands, and ellipse model for barrier beach wetlands); 3) assigning wetland plant profiles to the generalized wetland geometric models that identify associations between past flooding / dewatering events and the regulated water-level changes of a proposed water-level-regulation plan; and 4) predicting relevant proportions of wetland plant communities and the time durations during which they would be affected under proposed regulation plans. Based on this conceptual foundation, the predictive models were constructed using bathymetric and topographic wetland models and technical procedures operating on the platform of ArcGIS. An example of the model processes and outputs for the drowned river mouth wetland model using a test regulation plan illustrates the four components and, when compared against other test regulation plans, provided results that met ecological expectations. The model results were also compared to independent data collected by photointerpretation. Although data collections were not directly comparable, the predicted extent of meadow marsh in years in which photographs were taken was significantly correlated with extent of mapped meadow marsh in all but barrier beach wetlands. The predictive model for wetland plant communities provided valuable input into International Joint Commission deliberations on new regulation plans and was also incorporated into faunal predictive models used for that purpose.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
Reconstructing Paleo Lake Levels from Relict Shorelines along the Upper Great Lakes
No full textAuthor Wilcox was employed by: U.S. Geological Survey, Great Lakes Science Center, 1451 Green Road, Ann Arbor, MI 48105Shorelines of the upper Great Lakes include many embayments that contain strandplains of beach ridges. These former shoreline positions of the lakes can be used to determine changes in the elevation of the lakes through time, and they also provide information on the warping of the ground surface that is occurring in the Great Lakes after the weight of glacial ice was removed. Relative lake-level hydrographs can be created by coring the beach ridges to determine the elevation of basal foreshore (swash zone) deposits in each ridge and by obtaining radiocarbon dates of basal wetland sediments between ridges to generate an age model for the ridges. Because the relative-level hydrographs are the combination of lake-level change and vertical ground movement (isostatic rebound), the rebound must be removed to produce a graph that shows only the physical limits and timing of past lake-level fluctuations referenced to a common outlet. More than 500 vibracores of beach-ridge sediments were collected at five sites along Lake Michigan and four sites along Lake Superior. The cores showed a sequence of dune deposits overlying foreshore deposits that, in turn, overlie upper shoreface deposits. The base of the foreshore deposits is coarser and more poorly sorted than an overlying and underlying sediment and represents the plunge-point sediments at the base of the swash zone. The plunge-point deposits are a close approximation of the elevation of the lake when the beach ridge formed. More than 150 radiocarbon ages of basal wetland sediments were collected to produce age models for the sites. Currently, age models exist for all Lake Michigan sites and one Lake Superior site. By combining the elevation data with the age models, six relative lake-level hydrographs were created for the upper Great Lakes. An iterative approach was used to remove rebound from the five Lake Michigan relative hydrographs and merge the graphs into a single hydrograph. The resultant hydrograph shows long-term patterns of lake-level change for lakes Michigan and Huron and is referenced to the Port Huron outlet. When the age models are completed for the Lake Superior sites, a hydrograph will be created for the entire lake.SUNY BrockportEnvironmental Science and Ecology Faculty Publication
