Environmental Science & Ecology.
The 2.1 hectare lake at the University of Michigan-Dearborn has existed since 1915. Visual observations indicate that six species of turtles indigenous to Michigan live in the lake. In order of abundance the six species of turtles are Painted Turtle (Chrysemys picta marginate), Snapping Turtle (Chelydra serpentine), Blandings Turtle (Emydoidea blandingii), Red-eared Slider (Trachemys scripta elegans), Map Turtle (Graptemys geographica), and Stinkpot Turtle (Stemotherus odoratus). Using dip nets, hoop nets, and basking traps, mark and recapture data have been collected during 1996, 1998, 1999, and 2000. The estimated population size of each species has varied over the years. The current populations estimates are as follows: Painted Turtle, 78, Snapping Turtle, 25, Blandings Turtle, 11, Red-eared Slider, fewer than 7, Map Turtle, 1, and Stinkpot Turtle 0. Based on size and age ranges, the Painted Turtles, Snapping Turtles, Blandings Turtles, and Red-eared Slider are reproducing in this habitat.
A Watershed Level Sample Design Used to Assess Habitat Suitability for Juvenile Salmonid Production. Bradley E. Thompson, Daniel B. Hayes, and David A. Thomas, Department of Fisheries and Wildlife, Michigan State University, 13 Natural Resources Building, East Lansing, MI 48824
One goal of fisheries research is to quantitatively link measurable stream habitat attributes to fish production. Two questions inherent to this type of research are (1) at what spatial scale is fish habitat quantitatively linked to fish production, and therefore (2) at what spatial scale should the researcher define and measure habitat attributes? The spatial breadth of habitat variables currently used in lotic fish research span a broad range of spatial scale. For example, data collection may focus on the small scale of average substrate size in an individual riffle to a broader scales of the percent of pool habitats in a stream reach, up to a large scale of basin relief for an entire watershed. For some species or communities, scientists may need to collect data at several spatial scales, often balancing sample size requirements with limited time and resources. In this paper we describe and illustrate a field sampling design that helps improve the utility of habitat attribute data collected at spatial sca les ranging from the microhabitat to the watershed level. We then illustrate how we used habitat attribute data collected according to this sample design to generate a habitat supply simulation model for steelhead smolt production in a cold-water watershed located in Michigan's northern Lower Peninsula.
Use of Mapping to Study the Microdistribution of Freshwater Mussels (Bivalvia: Unionidae) in the Raisin River, Michigan. M. T. Shackelford, W. O'Brien, and W. P. Kovalak, Department of Natural Sciences, University of Michigan--Dearborn, Dearborn, MI 48128-1491
Mapping of mussel densities (no./[m.sup.2]) was used to identify factor(s) regulating the microdistribution of freshwater mussels (Bivalvia: Unionidae) in a 200-meter-long reach of the headwaters of the Raisin River, Jackson County, MI. For pigtoe mussels (Fusconaia flava), the most common species (mean density 9.0/[m.sup.2]) in this reach, highest densities occurred where the thalweg intersected the shoreline: areas of locally greater erosion rates. Lowest densities occurred in areas that were permanently or seasonally silty. These observations suggest that siltation, even in relatively small quantities associated with seasonal low-flows, is the primary factor regulating the microdistribution of pigtoes. Pigtoe abundance was independent of other factors often thought to regulate mussel microdistribution (e.g., current speed, water depth, and distance from shore). Pigtoe abundance was only weakly related to sediment particle size. Mean density was greater in coarse sand-fine gravel sediments, but the differe nce was not statistically significant. Other species that occurred at much lower densities exhibited a high degree of spatial overlap with pigtoes. This suggested that siltation was also the primary factor limiting microdistribution of less common species.
The Influence of an Invasive Macrophyte (Myriophyllum spicatum L.) on Zooplankton Community Structure. K. L. Rogers and P. A. Soranno, Department of Fisheries and Wildlife, Michigan State University; email@example.com
In many lakes, aquatic plant beds are the main structural component of the littoral (nearshore) zone. By increasing spatial heterogeneity, plant beds can offer colonizable habitat as well as refuge from predation for aquatic organisms, especially zooplankton. However, foraging efficiency is higher in open water than within macrophytes. Often, exotic plants that invade and dominate a lake significantly alter macrophyte communities, which has great potential to alter littoral zone community structure. However, little research has examined the impact that macrophyte communities have on zooplankton communities. Zooplankton are vital food for young fish and may play a key role in preventing nuisance algae blooms. Because of their significance, understanding the impact of exotic plants on zooplankton is pertinent to understanding the overall impact of macrophytes on aquatic systems. We examined what impact varying levels of the exotic plant Eurasian watermilfoil (Myriohphyllum spicatum L., EWM) have on pelagic (offshore) and littoral zooplankton community structure. Specifically, do differences in the plant community influence mean size, standing biomass, and abundance of zooplankton? Can differences in the plant community affect patterns of these community characterist ics in both the pelagic to littoral zones? We sampled zooplankton (Cladocera, Copepoda, and Rotifera) from six mesotrophic lakes in southern Michigan and examined mean size, biomass, and abundance.
A Study of the Process and Perceptions of Changing Agricultural Practices in Ambalavero, Madagascar. Stacy Turschak, Department of Environmental Studies, Alma College, 518 West Center Street, Alma, MI 48801; 517/466-8074
Currently Landscape Development Interventions (LDI), a USAID program, is working in Madagascar to protect the environment by providing agricultural alternatives to tavy, slash-and-burn agriculture. Ideally LDI offers associations of farmers, who make a commitment not to practice tavy, training on how to make their agricultural practices more sustainable and more profitable. The problems and benefits of working with LDI in the village of Ambalavero are explored. The village is located in the Beforona commune--the area in Madagascar where human pressure on the environment as a result of tavy is the greatest. In Ambalavero, the farmer's association, SANTARA, is just beginning to incorporate LDI's ideas and ideals. This study examines the history of LDI's involvement in the community, how agricultural practices have changed, and how community dynamics affect participation in LDI's program. For example, a deeply embedded belief in the importance of tavy, fear of foreigners, and poverty are particularly important o bstacles to participation in SANTARA. At the same time the prospect of economic gain rather than environmental protection was generally the motivating factor for participation. Overall cultural, economic, and geographic factors all have important impacts on the people's involvement in SANTARA.
The Problems and Possibilities of Incorporating Environmental Education in the Developing World. Stacy Turschak, Department of Environmental Studies, Alma College, 518 W Center Street, Alma, MI 48801; 517/466-8074
Since 1975 when the Belgrade Charter established the first international environmental education (EE) precedent, EE has been a key issue in the global environmental movement. Current trends in EE programs throughout the developing world are examined and evaluated based on the ideal that successful EE programs should promote action not just provide knowledge. Currently there are three main types of EE: formal, nonformal, and informal. Each type of EE has problems and benefits. Evaluation of EE programs is often problematic, but generally they must incorporate the political, social, cultural, and economic constraints placed on the people involved. This is especially important in developing countries where high population growth, low literacy rates, lack of female empowerment, low school attendance, and poverty are everyday themes. In these countries, EE programs that focus on practical environmental problems like fuelwood shortages and water contamination are much more likely to be successful. However practical ity does not guarantee success. Each program is extremely sensitive to the donor's situation and the local situation. This study examines numerous environmental education programs. General suggestions on how to improve program success are provided.
Effects of a Hardwood Understory on Carbon Turnover and Storage in Red Pine Stands. Brenda Tinsley and Kim McCracken, Department of Biology, Grand Valley State University, Allendale, MI 49401
Carbon cycling in forest ecosystems is a key component of the global carbon cycle. Rising levels of [CO.sub.2] in the atmosphere have made carbon storage in forest ecosystems of particular interest. The purpose of this study was to examine the influence of a hardwood understory on carbon cycling and storage in red pine stands. Study plots were composed of a monoculture red pine (MP) stand and a red pine stand with a hardwood understory (HU). In the fall of 2000, litterfall, above-ground biomass, above-ground net primary production, soil respiration, and soil organic carbon content in the two stands were calculated. Soil characteristics, temperature, and moisture were also examined to explain differences between sites. Preliminary results show that during September and October the HU site had higher litterfall carbon input (69.8 g C [m.sup.-2]) and greater carbon storage in above-ground biomass (12.7 kg C [m.sup.-2]). The MP site had lower litterfall carbon input (52.5 g C [m.sup.-2]) and less carbon storage i n above-ground biomass (9.9 kg C [m.sup.-2]). Carbon loss rates from soil respiration were similar with the HU site losing slightly more (77.4mg C [m.sup.-2][h.sup.-1]) than the PM site (72.6mg C [m.sup.-2] [h.sup.-1]). The hardwood understory in the pine stand appears to increase inputs of litterfall carbon, possibly due to higher biomass, without greatly adding to carbon release through soil respiration.
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|Article Type:||Critical Essay|
|Date:||Mar 22, 2001|
|Next Article:||French & Italian Language & Literature.|