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Botany & plant ecology.

Investigating the Environmental and Physiological Causes of Abiotic Leaf Scorch in Quercus rubra. Philip S. Kurzeja, Department of Plant Biology, Michigan State University

Leaf scorch is a common symptom of declining trees in the urban landscape, including Northern red oaks, Quercus rubra. We are investigating the physiological factors that may cause leaf scorch. Established trees with a known history of leaf scorch are systematically evaluated at eight sites, each exhibiting scorched and non-scorched oaks of the same age, planting history, and soil structure. Depth of root flare, girdling root severity, soil compaction (resistance and bulk density), and soil profile are measured to document site problems in the replicated plots. Photosynthetic efficiency, leaf xylem pressure, leaf water conductance, leaf transpiration and plant tissue nutrition are measured to examine differences in physiological performance between scorched and non-scorched oaks on the same site and among sites. Scorched trees exhibited greater planting depth than non-scorched trees, and lower levels of manganese, photosynthesis efficiency, xylem pressure, conductance, and transpiration.

Ray Tissue Response to Urban Wind Environment. David Rayman and Frank Telewski, Plant Biology Department, Michigan State University

Exposure to wind is a mechanical stress that has been known to alter tree development at the tissue level. Cross sections were obtained from Gledistia tricanthos and Tilia americana that experienced mechanical wind stress primarily from just two directions, which resulted in elliptical stems. The purpose of this study is to determine if axes that experience different wind stress due to wind vectors altered by buildings result in developmental changes that affect ray structure. Tree cores from the long and short axes were obtained of different growth rings then cross sectioned by microtome. Tangential sections were then stained and ray length, width and area were measured using image analysis software. Preliminary results indicate that in Tilia rays on the axis that experienced the most mechanical wind stress were shorter and thicker. Shorter and thicker ray cells may provide trees with increased resistance to mechanical bending and thicker ray cells may provide trees with increased resistance to mechanical bending and thus protect against stem damage.

Variant Nuclear Size and Condition Occur in Progeny of Phytophthora infestans, as Determined by Flow Cytometry Analysis. Prissana Wiriyajitsonboom, Department of Plant Pathology, Michigan State University

Phytophthora infestans is a fungus-like Oomycete which causes the disease on potato known as late blight or potato blight. Mating type A1 isolates caused the Irish potato famine in 1845 and subsequent disease, until relatively recently. Late blight is again causing serious epidemics worldwide since the second mating type (A2) migrated from Mexico to other areas of the world in the 1980s. Mating of A1 and A2 types would be expected to lead to new races and virulence phenotypes in progeny. However, populations in the northern temperate zone have continued to reproduce only asexually. Our use of laser flow cytometry has for the first time yielded convincing evidence that different isolates from Michigan usually contain nuclei of different sizes, different DNA content in picograms/nucleus. Additionally, flow cytometry has revealed that some isolates contain two to three nuclear populations of different sized nuclei in a single thallus. Our research has focused on documenting the nuclear condition of diverse parents and then examining the nuclear size and nuclear condition of rare viable progeny. Crosses between a parent containing two nuclear populations and a parent containing one population were generated in the laboratory for three different pairs of parents. The crosses yielded progeny of unique nuclear size and condition. The studies have contributed to understanding sexual reproduction in nature and problems during meiotic conjugation and division which may be involved in the persistence of the clonally reproducing population in Michigan.

Investigation of the Roles of Spittlebugs, Cankers, Stem Density and Ground Water in Branch Dieback and Mortality in Regenerating White Pine. Rachel Griesmer, Department of Plant Biology, Michigan State University

Regeneration of white pine is managed with crowded planting to discourage White pine weevil (WPW) attack and to obtain straight stems following WPW destruction of terminal leaders. Branch dieback and limited mortality were observed in these stands in the Au Sable and Manistee river corridors from 2006-2009. This threatens regeneration in one of the only areas in Michigan with virgin white pine forests. Disease symptoms, previously unrecorded in Michigan, included tip dieback and ultimately branch death due to canker girdling with occasional tree mortality from running cankers. Our preliminary investigations indicated that the disease might be a decline syndrome of complex biotic and abiotic origin. We developed the hypothesis that two predisposing factors, high stem density and lower ground water, were increasing susceptibility to an inciting factor--a spittlebug epidemic. The inciting factor was causing a further progression in stress which was allowing a contributing factor--a fungal canker pathogen, to assert itself. To examine our hypothesis, replicated plots were established in Crawford County, Michigan where branch samples from both healthy and infected trees were collected. Fungi were isolated from cankers and identified via microscopy and DNA sequence of ribosomal DNA regions. Initial observations and identification of Pine spittlebug (Aphrophora parallela) in the field were followed by quantification of feeding scars to assess their impact. Additionally, field estimates of stem density (basal area) were conducted for healthy and infected sites. Further investigation of climate data, particularly ground water levels, and trials of co-inoculation with spittlebug and pathogenic fungi are discussed. We integrate the biotic and abiotic factors into diagnosis of the decline and offer new guidelines for managing stem density in regenerating white pine in Crawford County.

Local Adaptation of Silver Maple Populations to Water Availability. (Poster) Nicholas Bennett, Michelle Claus, Andrew Furton, Lacey Higgins, Kaitlin McKinnon, Courtney McNaughton, Carly Steffi, and John M. Landosky, Western Michigan University, Department of Environmental Studies

Understanding the degree to which trees are adapted to their local environmental conditions can help predict how rapid environmental change may affect tree species and the communities they support. We considered whether silver maple Acer saccharin= populations are adapted to their local water conditions. We used two common gardens in Southwest Michigan including source populations from throughout the United States and selected source populations to create a spectrum of source water availability. We measured A. saccharinum growth and survivorship. Both common gardens are located in wet environments; one of the common gardens experiences periodic flood stress. We therefore expected A. saccharinum growth and survivorship to be positively correlated with mean annual precipitation in both common gardens. We found some support for our hypothesis. We found a positive relationship between source population precipitation and growth in the non-flood stressed common garden, perhaps suggesting that A. saccharinum populations are locally adapted to take advantage of high water availability but not flood stress. Though we had little power to detect a relationship between source population precipitation and survivorship, we found weak evidence for a positive relationship. Together these data suggest that A. saccharinum currently contains the genetic variation required for rapid evolutionary change.

Variations in Pathogenic Resistance to Fungal Cankers in Silver Maple Acer saccharinum. (Poster) Kellee Campbell, Mike Coryell, Sara Eggleston, Remy Long, Kristiena Sartorelli, Andrew Weissenborn, and John M. Landosky, Western Michigan University, Environmental Studies Program

Many trees are affected by fungal pathogens. Trees, especially Acer spp., will induce a canker, a localized area of dead bark with a callused ridge, which can isolate the infection and prevent the fungus from spreading. The induction of canker, and its effectiveness at preventing fungal infection, may be affected by environmental conditions. We measured the incidence and effectiveness of canker, primarily caused by Necteria fungi, in two silver maple Acer saccharinum common gardens in Southwest Michigan. Half of one common garden was planted in a frost pocket and the other common garden was planted on a graded flood plain, causing different levels of stress within and perhaps between common gardens. We originally expected that stress would increase canker number and size and ultimately decrease growth and increase mortality. Contrary to our original hypothesis, canker area was greater in non-stressed trees, especially for trees under frost stress. In the graded flood-plain, the mortality rate of the tree was significantly higher, and in more heavily stressed trees, there was no difference in mortality for the trees within the frost-pocket. Stressed trees may be less able to isolate fungal infection with canker, causing less canker but more morality under stress.

The Effect of Climate on Growth and Survivorship of Silver Maple Acer saccharinum. (Poster) Jonathan Grippi, Nola Wiersma, Spencer Welling, Rachel Smith, Paula Fader, Brian Weir, Lisa Alton, John M. Landosky, Western Michigan Univ., Environmental Studies Program

Populations often adapt to their local environments, but which adaptations are most important? We utilized two silver maple Acer saccharinum common gardens located in Southwest Michigan containing genotypes from source populations distributed across the United States. We selected three source populations to match aspects of the Southwest Michigan environment, temperature (Nebraska), precipitation (Kansas), and biome (Minnesota). We observed tree growth (DBH) and survivorship. While source population did affect growth and survivorship, suggesting that A. saccharinum populations were genetically distinct for evolutionarily important traits, there was no consistent pattern between common gardens and source populations. We therefore did not detect any strong evidence for any single similarity to the Southwest Michigan environment to be more important than another. Future work considering replicated source populations for each environmental variable may yield more conclusive results.

An Evaluation of Four Plant Species for Use in Sand Mine Revegetation. Thomas J. Schmidt and Todd A. Aschenbach, Grand Valley State University, Department of Biology

Sand mining results in environmental degradation. In this greenhouse experiment, we evaluated the growth from seed of four plant species: Indian grass (Sorghastrum nurans), little blue stem (Schizachyrium scoparium), lupine (Lupinus perennis), and Illinois ticktrefoil (Desmodium illinoense) for their potential use in sand mine revegetation. We evaluated the growth of each species grown with or without peat (P) and fertilizer (F): +P/+F, +P/-F, -P/+F, -P/-F. Five seeds per species were planted in 100 [cm.sup.2] pots; each treatment was replicated 10 times. Across all species, germination was significantly higher with peat (mean = 25% with peat vs. 18% without). Lupine and Illinois ticktrefoil exhibited greater germination when grown with peat. Lupine exhibited the greatest root (mean = 0.007 g), shoot (mean = 0.023 g) and total biomass (mean = 0.031 g). Across all species, root, shoot, and total biomass were significantly greater when grown with peat and fertilizer combined. Root, shoot, and total biomass of lupine were significantly greater when grown with peat. Total biomass of Illinois ticktrefoil was significantly greater with peat and fertilizer, and total biomass of Indian grass was greatest with fertilizer. Results can be used to determine appropriate species and soil amendment combinations for sand mine revegetation.

Land Management Implications of Carbon Assimilation Rate Differences among Plant Communities--Measurement Process. Susan Boersma, Andrew Wiersma and David Dornbos, Calvin College, Department of Biology

Roughly half of the carbon dioxide assimilated by photosynthesis is sequestered in wood or soils as organic carbon. Plants harvest [CO.sub.2] from the atmosphere, countering combustion emissions. The project objectives were to determine plant communities at Pierce Cedar Creek Institute (PCCI) and to quantify [CO.sub.2] assimilated by each community. Species composition was determined at six GPS coordinates per community. By measuring 13 plant species we accounted for 70% of PCCI's land. Using GIS, we determined each plant communities land area. When coupled with leaf area indices of each plant community, hourly light intensity during the growing season, and light transmission rates through canopy layers, the canopy-level [CO.sub.2] assimilation rate for each plant community is calculated from species-specific light use efficiency curves. We found that [CO.sub.2] contribution of plant communities varied with community [CO.sub.2] assimilation rate and community location. Restored prairie, mixed swamp, and early succession forest were significant carbon assimilators, but for different reasons. Prairies encompass a small area but exhibit high assimilation rates. Mixed swamp and early succession forest exhibit modest assimilation rates but encompass large areas. Between April 15 and August 9, 2009, 132 MT of [CO.sub.2] was assimilated at PCCI representing an asset in its carbon budget.

The Importance of Wild Rice Camps for the Continued Research and Harvesting of Wild Rice in Lower Michigan. Scott Herron, Josh Byers, Brenna Chencinski, Andrea Lodholtz, Lauren Mitten, Nicole Patrosso, Michael Reynolds, and Sarah Thompson, Ferris State University, Department of Biology

The lower peninsula of Michigan is at the southern terminus of the range of northern wild rice, Zizania palustris L. Wild rice camps play an important role in the restoration and development of sustainable ricing communities in Lower Michigan. Wild rice camps use the experiential learning model to train students and participants in the production of tools and techniques used in wild rice processing and harvesting. These rice camps educate future generations and provide the rice used for reseeding by ecologists. Results from the 2008 (Lac Vieux Desert, Michigan), and 2009 (Mecosta, Michigan) rice camps show the effectiveness of this model towards the restoration of local seed sources. Scott Herron and undergraduate researchers at the Ferris State University's Wild Rice and Ethnobiology Lab have used these camps to gather wild rice seed used in research, including water chemistry analysis, seed viability and germination, fungal smut pathogen lifecycles, and restoration potential of local seed sources.

Gender Bending in the Fern Osmunda cinnamomea: A Tale of Two Pheromones? Stephanie Hollingsworth, Eric Andres, and Gary Greer, Grand Valley State University, Biology Department

We conducted three studies using nutrient-enriched agar to investigate pheromonal control of gender expression in gametophytes of the fern Osmunda cinnamomea. The first study was a time series of isolates to determine the default sequence of gender expression. Two pathways were observed: (i) a predominant (95%) asexual to male to hermaphrodite gender sequence and (ii) asexual to female sequence (5%). In both pathways, gametangia were produced only after formation of an apical notch. The second study was a time series of multispore populations, wherein gametophytes possessed either a male to hermaphrodite (48%) or directly female (46%) pattern of gender expression. The increase in frequency of females in the multispore populations relative to the isolates reveals the presence of a feminizing pheromone, the first reported in ferns. The third study used gibberellin (0[micro]M, 100[micro]M & 1mM) as an assay for a gender influencing pheromone. At eight weeks, the control (0[micro]M) was 42% female and 58% hermaphrodite. In contrast, the frequency of males increased with GA concentration (14% and 88% respectively) while that of females and hermaphrodites declined to zero. Thus, exogenous GA induces or prolongs maleness and the identity of the feminizing pheromone remains unknown.

Primary Succession at Vermilion Beach, Michigan May Challenge Piping Plover Habitat. Thaddeus Lewandowski and Gregory Zimmerman, Lake Superior State University, Department of Biology

Vermilion beach is located in Michigan's Upper Peninsula on the south shore of Lake Superior, approximately eight miles west of Whitefish Point. Vegetation is found in bands roughly parallel to the Lakeshore at this high energy, dune-swale beach site. Beach grass, wormwood and beach pea occur in dry areas, willow and alder in poorly drained areas, and sedges and rushes in wet areas as is typical in other south shore Lake Superior beaches. Patches of moss, sundew and cranberry which occur less frequently in the region achieve high local densities at Vermilion. Increased extent of the later successional woody vegetation may be undesirable for piping plover, Charadrius melodus, which prefer open beaches with sparse vegetation. To assess possible succession toward more woody vegetation, these vegetation zones were described and documented on the beach in October of 2009 and compared to historic information of dominant plant communities collected in July 1998. While the total vegetated area of the beach has increased, the data suggests that Vermilion is not necessarily following a successional pathway to wider zones of woody vegetation. The results are encouraging since Vermilion has traditionally supported breeding pairs of Great Lakes endangered Piping plover. Frequent natural or anthropogenic disturbance may not be necessary to slow, halt or reverse the succession sequence to preserve the landscape of Vermilion beach as suitable nesting habitat for Piping plover.

Ailanthus altissima's Impact on Abundance of Transcripts Linked to Nodule Formation in Trifolium pratense. Jesse Lincoln and Gary K. Greer, Grand Valley State University, Biology Dept.; Margaret A. Dietrich, Grand Valley State University, Cell and Molecular Biology Dept.

Legumes, including Trifolium pratense (Fabaceae), participate in a symbiotic relationship with Rhizobia, resulting in the formation of root nodules within which atmospheric nitrogen is fixed. Our previous study demonstrated increased nodulation in Trifolium exposed to root leachates from the Asiatic invasive tree Ailanthus altissima (Simaroubaceae). Increased nitrogen fixation by legumes likely benefits neighboring Ailanthus and potentially contributes to its invasiveness. Here we report transcript abundance for Trifolium genes encoding the enzymes chalcone synthase and chalcone isomerase in response to Ailanthus leachates. These enzymes are involved in flavonoid production to solicit Rhizobia for nodulation. In light of our previous experiment, we predict that the transcript abundance of the enzymes will increase in Trifolium as a result of exposure to Ailanthus leachates. We grew three groups of Trifolium hydroponically: one control group received deionized water, another received Ailanthus leachates filtered through activated carbon, and the treatment group received unfiltered leachates. Root tissues were harvested from each group of Trifolium, RNA converted to cDNA, and transcript abundance is currently being analyzed using qPCR.

Effects of Long Term Warming on Vegetation in Northern Alaska. Jeremy May and Robert Hollister, Grand Valley State University

Warming in the Arctic and its effects on plant communities has been documented in recent years. This study investigates the effects long term warming on four plant communities in northern Alaska. Vegetation surveys were done using a point frame method on two communities in Atqasuk, Alaska and two communities in Barrow, Alaska. Warming was shown to decrease species diversity, and species evenness. There were also changes in plant community structure with a decrease in small stature plants and an overall increase in taller plants, such as graminoids and shrubs, resulting in an overall increase in canopy height. The changes in vegetation structure have the potential to lead to shifts in plant community function and may ultimately result in changing the habitat quality, energy balance, and carbon exchange.

Detection and Attribution of Long-Term Changes in Vegetation Phenology and Growth in Northern Alaska. Rob Slider and Bob Hollister, Grand Valley State University, Department of Biology

Climate Change is expected to greatly affect Arctic Ecosystems. Impacts on Arctic vegetation are of particular interest due to the role of plants in trophic interactions, energy balance, and carbon budgets. Studying plant phenology and growth may improve predictions of the effects of Climate Change on Arctic ecosystems. This study examined long-term phenological and growth responses of Arctic plants in northern Alaska to natural temperature variation and experimental warming. Regression analyses revealed that flower burst has been occurring earlier ([R.sup.2] =-0.03, p = 0.01) and graminoid inflorescence and leaf lengths have tended to increase over the past decade at these study sites ([R.sup.2] = 0.03, p = 0.07, and [R.sup.2] = 0.05, p = 0.26, respectively). Inflorescence and leaf length responses showed strong correlations with Thawing Degree Days from Snowmelt--a synthetic measure of experienced temperature ([R.sup.2] = 0.78, p < 0.001, and [R.sup.2] = 0.45, p < 0.001, respectively). Meta analyses of warming effect on plant traits indicated that experimental warming consistently resulted in earlier flowering and increased inflorescence and leaf lengths of graminoids. These findings suggest the phenology and growth of plants at these sites are changing over time and that responses are due to warming.

Woody Invasive Plants as Potential Sources of Cellulosic Ethanol. Jennie Heidmann and David Dornbos, Calvin College, Department of Biology

Cellulosic ethanol is receiving attention as a biofuel that is renewable, reduces the carbon footprint, and does not necessarily jeopardize food stocks. It is derived from the breakdown of cellulose and hemicelluloses from plant cell walls into simple sugars which are then fermented into ethanol. Switchgrass, a C4 plant that grows exceptionally well in the warm, dry climate of the plains, has been the focus of much cellulosic ethanol research because it grows rapidly there. In Michigan's cooler, wetter climate, however, we hypothesize that C3 plants such as the invasive shrubs autumn olive and buckthorn may represent higher potential for cellulosic ethanol in Michigan than switchgrass. Two studies were used to determine the suitability of these invasive shrubs. The practicality of growing and harvesting these plants was looked at in a re-growth study in which all of the plants grew back equally well. The chemical composition of each plant was also determined by initial ethanol extraction followed by acid hydrolysis and derivitization and identification of sugars by gas chromatography. The extractives in each plant decreased with age while lignin concentration increased. The highest concentration of sugar was glucose followed by xylose. Three year old Autumn Olive had the lowest extractives concentration and the highest glucose. A further biomass accumulation study will help to identify whether invasive shrubs are good potential cellulosic ethanol sources.

Warming the Tundra: Changes in Cover of Species Groups. Jennifer A. Liebig, Jeremy L. May, Robert T. Slider and Robert D. Hollister, Grand Valley State University, Biology Dept.

Tundra plants have responded to experimental warming by increasing in cover. This study seeks to identify different types of species with similar responses to warming. Data was collected using a point-frame method at two dry heath sites and two wet meadow sites in Barrow and Atqasuk, Alaska. Abundance of vascular plant species was analyzed using a variety of classification schemes from Eric Hulten, Thorvald Sorensen and other sources. In several cases, the species classification scheme was an effective predictor of species response to warming. For example, Sorensen's floral wintering stage groups show that species at stage 5 and at stage 7 increased in cover most dramatically at the two wet sites and the two dry sites, respectively. Groups defined by Hulten's maps of distribution showed that species from northern groups increased in cover at the two wet sites, though the response at dry sites was varied. For each site, the changes in cover observed in the warmed plots reveals the changes the community will see as a result of warming.

Insect Herbivores Affect Mycorrhizal Interactions in Asclepias syriaca. Rachel Vannette and Mark Hunter, University of Michigan, Department of Ecology and Evolutionary Biology

Plants and insect herbivores are some of the most abundant organisms on the planet, and insect herbivory can affect the allocation of plant resources within the plant. One sink for such resources are mycorrhizal fungi. Over 80% of all land plants associate with mutualistic fungi within their roots, which demand carbon nutrition in return for mineral nutrients and water. Changes in plant allocation patterns may change the abundance and species of mycorrhizal fungi that associate with these plants, however, little is known about the effects of different herbivore species on mycorrhizal associations. The abundance and species of mycorrhizal fungi that associate with plant hosts can differentially affect the performance and phenotype of individual plants. Additionally, changes in mycorrhizal associations can also determine the dynamics of ecological communities (competition, succession etc.). As a result, understanding the effects of ubiquitous insect herbivores on mutualistic fungal associations is important in most ecological communities.

We examined the changes in abundance and community diversity of fungal symbionts that associate with A. syriaca in the presence and absence of insect herbivory. We found substantial changes in mycorrhizal colonization following herbivory by caterpillars, but not aphid herbivores. We conclude that insect herbivory can significantly alter mycorrhizal interactions and the mechanisms and outcomes of this effect should be further explored.

Site Preparation and Hand Pulling Effects on Spotted Knapweed Control and Native Plant Establishment in the Bass River Recreation Area, Ottawa County, Michigan. Corey K. Kapolka and Neil W. MacDonald, Grand Valley State University, Department of Biology

Establishment of native plant communities on sites infested by spotted knapweed (Centaurea maculosa Lam.) requires the application of effective control measures. The objective of our study was to examine the first-year effects of mowing and herbicide site preparation treatments combined with hand pulling on spotted knapweed control and native plant establishment on this knapweed-infested site in western Michigan. Initial mowing and herbicide treatments were applied to forty-eight plots in the summer of 2008, and we seeded these plots with a mixture of native grasses and forbs in the spring of 2009. We hand pulled bolted knapweed from selected plots in mid July, 2009, and determined residual knapweed densities and native plant occurrence on all plots in late July, 2009. All site preparation treatments began to reduce the knapweed soil seedbank, while both glyphosate and clopyralid herbicides substantially reduced mature spotted knapweed densities. Hand pulling effectively reduced seed-producing knapweed densities to less than 0.5[m.sup.-2] on both mowed and glyphosate-treated plots; hand pulling was unnecessary on clopyralid plots because mature knapweed were totally absent in 2009. Planted native warm-season grasses were present on all treatment combinations, but full development of a diverse native plant community is expected to take several years.

Land Management Implications of Carbon Assimilation Rate Differences among Plant Communities (II). (Poster) Andrew Wiersma, Susan Boersma, and David Dornbos, Calvin College, Department of Biology

Plants can be viewed as tools to harvest [CO.sub.2] from the atmosphere, countering emissions and enhancing soil quality. Our objective was to evaluate the potential of various plant communities to assimilate [CO.sub.2], potentially reducing the carbon footprint of Pierce Cedar Creek Institute (PCCI). Apparent photosynthesis rates were determined for 13 plant species at 9 light levels allowing the determination of light use efficiency relationships for these species. These species comprised the majority of the leaf area in each plant community type. The process of scaling up from leaf level photosynthesis to the landscape involved integrating hourly light levels during the growing season, species composition of the plant communities at PCCI, and the area of each plant community using leaf area index as a way to model canopy density. Significant differences existed among the thirteen plant species evaluated and the communities that they comprise. Restored prairie and brushy fields were significant contributors to fixed carbon because of fast [CO.sub.2] uptake rates. Old woodlands were less productive than young. Restoration practices to optimize carbon assimilation rates, while protecting biodiversity and aesthetic attractiveness, could include selective harvest of wood products from old woodlands and conversion of shrubby fields to native tall grass prairie.
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Publication:Michigan Academician
Geographic Code:1U9AK
Date:Sep 22, 2012
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