Thesis (Ph. D.)--Syracuse University, 2009. / "Publication number: AAT 3385847."

<p> Tallgrass prairie is one of the most endangered ecosystem types in North America, as over 99% of historic tallgrass prairie has been lost, even though it is one of the younger ecosystem types. The main factors behind the dramatic loss of tallgrass prairie include conversion to agriculture or development and a suppression of the natural fire regime in these grassland areas. Any natural prairies left are often too small and isolated to serve as viable habitat for grassland-dependent species, making the efforts at restoring these areas critical. Prairie restoration is crucial to grassland-dependent species because it increases the area of suitable habitat. Once a prairie restoration has taken place, it must be managed and evaluated to keep succession at bay and to help ensure that all restoration objectives have been met. Illinois has less than 1% of natural tallgrass prairie remaining, causing the grassland bird communities of the state to experience severe population declines within their ranges. Grassland bird species are important pollinators and dispersers of plants, and are under significant decline, which make them important priorities for conservation efforts. Birds in general are good ecological indicators of restoration success as they can be seen and heard easily, they have specific habitat requirements, and they are often the first animals to reach a restoration effort. Illinois has seen several prairie restoration attempts take place within the last 40 years, but very few studies have been conducted to assess the relative success or failure of these restoration efforts. The objectives of this study are to (1) examine temporal trends in the avian community composition, richness, and diversity among prairie restorations at The Nature Institute, (2) to test whether these trends are heading in the direction of the old growth reference prairie, and (3) to investigate which habitat attributes are the best predictors of the presence and abundance of prairie bird species. I hypothesize that (1) the restorations are on track to attain the bird community composition and diversity of an old growth prairie; (2) changes in vegetation structure over time during restoration provide suitable habitat for particular species of prairie birds. Five 20 m radius sampling plots were established in each of the study sites and utilized for both avian and vegetation sampling. Avian sampling took part in two periods, one spanning the entire avian breeding season from late May into early August, and the other corresponded with avian migration and lasted from September into late October. Plots were divided into regular distance intervals (0-5 m, 6-10 m, 11-15 m, 16-20 m) and all birds within as well as those flying over and outside of the plot were recorded. Vegetation characteristics (e.g., litter depth, forb coverage, and vegetation height) were measured along a 40 m transect within each study plot. Species richness, Antilog Shannon&rsquo;s and Simpson&rsquo;s diversity indices, and density (birds per hectare) for each plot was calculated. Non-metric multidimensional scaling ordination was utilized to visualize patterns within the avian community data and to assess whether or not the restorations were on track to achieve the avian community structure of the old-growth reference prairie. Diversity indices were highest in the youngest restorations before dropping off at the oldest restoration and the reference prairie. Indicator species analysis showed that the northern cardinal, willow flycatcher, indigo bunting, and the ruby-throated hummingbird were indicative of restored prairies less than seven years old, whereas species like the chipping sparrow, common yellowthroat, and the red-winged blackbird signaled older prairie restorations (15-29 years). Field sparrows were found to be indicator species of the old-growth reference prairie used in this study. Non-metric multidimensional scaling showed that each study prairie was different from one another based on their avian communities and that the restorations are not on track to achieve the avian community structure found in the reference prairie. The results of this research will provide valuable information to prairie managers across the region. Results from this study show that small isolated prairie restorations, although good for community outreach and public education on the topic, will not meet objectives related to stopping prairie bird declines in a region. Large and well-connected prairie restorations are ideal for grassland-dependent species when planning out future restoration efforts.</p><p>

<p> Overall, the results of this study show that there are evident trends among the three ecoregions and delta of the White River. The forest stands of the Pine Ridge/Pierre Shale Ecoregion are the oldest along the river, as evidenced by aerial mapping going back into the 1930s and by the larger average trunk diameters of the trees. Historic aerial photographs for this ecoregion shows a relative static system from the 1930s-2010, with little destruction of existing or creation of new forests within the floodplain. Along with the older age of the forests, the stands in this ecoregion have the lowest floral diversity. The Pine Ridge/Pierre Shale forests are also unique along the river in that they are largely dominated by Acer negundo (box elder), a late-successional species that is largely absent from the forests of the other ecoregions. As the river continues downstream and enters the Badlands Ecoregion it gains size and volume, while its riparian forests decrease in patch size and tree density. Although the forests become smaller, the variety of communities and diversity of species increase. Unlike the Pine Ridge/Pierre Shale Ecoregion, the Badlands&rsquo; land cover was dynamic from the 1930s-2010, with increases in forest and declines in river channel area (-29%). Farther downstream and with a larger river channel, the River Breaks has even larger and more diverse riparian forests and the highest plant species richness and diversity among the ecoregions. The rate of land cover change was the greatest in the River Breaks, as the larger river has greater power for eroding existing communities and depositing sediment for recruitment. The area of riparian woody vegetation increased sharply from the 1930s-2010 (58%), while the area of channel declined (-20%). This ecoregion had the most perennial streamflow, with fewer zero flow days than in the upstream ecoregions. The Delta is unique as the only portion of the river where flows are affected by the Fort Randall Dam on the Missouri River. The impact of the reservoir on the area is evident, as it has the largest proportional area of forest along the river, as well as having the flora with the highest wetland affinity.</p>

<p> Mead&rsquo;s Milkweed (<i>Asclepias meadii</i>) is a federally threatened plant of tallgrass prairies in North America. Studies aimed at understanding the biology and ecology of this rare milkweed usually focus on healthy or restored populations in the tallgrass prairies of Kansas, Iowa, and Illinois. Thus, this study was designed to provide details about unique, understudied habitats surrounding isolated populations in the Missouri Ozarks. </p><p> The igneous glades of the St. Francois Mountains are small grasslands with shallow soils and harbor some of the healthiest populations of <i> A. meadii</i>. Three soil samples were collected at each site and used to describe the physical and chemical characteristics by pedon. Plant cover was sampled on multiple occasions throughout the growing season using thirty-five 1 m² quadrats at both sites. Cover data was analyzed using Shannon&rsquo;s Diversity and Evenness indices. The results of this study show that these communities are fairly diverse, grass-dominated areas on strongly acidic, nutrient poor soils. They also provide a dynamic, rather than static, view of the plant community. Diversity and evenness are consistent throughout the growing season, as is the cover of most dominant families and grass species. The cover from other species depended on the time of year. In general, overall diversity and evenness fluctuate little during the growing season. </p><p> Concerns for <i>A. meadii</i> are often centered on inbreeding and outbreeding depressions, therefore restoration efforts will depend heavily on the success of introduced individuals to augment genetically depauperate populations and reintroductions. Determining the basic characteristics of communities (plant composition plus soil parameters) associated with <i> A. meadii</i>, as was done here, can help guide restoration efforts by matching characteristics between source and target populations.</p>

<p> Although herbaceous communities are important components of floodplain ecosystems, the factors constraining their restoration and post-restoration dynamics are poorly understood. Over the decade following restoration of a 3.2 km reach of the Merced River and floodplain in California, we tracked herbaceous community composition to distinguish floodplain habitats and utilized perturbations from revegetation treatments and post-restoration flooding to generate community assembly rule hypotheses regarding treatment effectiveness and persistence, with a particular interest in native perennials capable of suppressing non-natives over time if undisturbed. Revegetation treatments comprised combinations of sowing a sterile cover crop, sowing native species, and inoculating mycorrhizae. Most surveyed floodplain areas comprised a low terrace characterized by exceptionally droughty soils, relatively deep groundwater, and occasional flooding lasting into summer. Few species could tolerate both flood and drought to this extent, and the flood year community was generally distinct from that in non-flood years. Both communities were dominated by ruderals capable of avoiding stress and re-establishing following disturbance, including many non-native annual grassland species. Only <i>Artemisia douglasiana</i> responded to the treatments, as most seeded native species failed to establish, including those native perennial grasses expected to suppress non-native annuals, while other seeded native species either established adequately from natural dispersal or failed to persist through moderate flooding. Neither the cover crop nor mycorrhizal inoculation had any meaningful effect. Restoration efforts in naturally ruderal-dominated habitats may be better spent allowing natural regeneration, addressing particularly noxious invasives, and identifying or constructing habitats supporting long-lived native perennials. </p><p> Although originally developed for population sizes and population growth rates, modern capture-recapture models can estimate demographic rates in complex situations: multistate models for multiple study sites and stage-structured populations, superpopulation entry probability models for recruitment, and multievent models when state assessments are uncertain. However, combinations of these complications, such as recruitment studies with uncertain state assessments, are common, yet no single model has explicitly incorporated all of these elements. Ultimately, these models estimate the same fundamental population process with the same general approach, and we combine them in a generalized hidden process model based upon a simple discrete state and transition population model with Poisson recruitment that can estimate how recruitment and survivorship rates vary with respect to measured covariates from uncertain state assessments for a stage-structured population at multiple sites. Although closely related to the motivating models, the generalized model relaxes the Markov assumption. While we provide the distributions necessary to implement Bayesian data augmentation methods, we also provide an efficient analytical likelihood with a compact parameter space that is applicable in the absence of density-dependent mortality. As a demonstration, we estimate the influence of several covariates on recruitment and survivorship rates from uncertain observations of <i>Salix gooddingii </i> seedlings at different locations along a riparian gradient, and we use simulations to examine variation in the precision of estimated parameters. </p><p> In Mediterranean climates, cottonwoods and willows often exhibit high germination and seedling mortality rates, with recruitment occurring primarily in the occasional year when favorable spring floods improve survivorship. However, along the Robinson Reach of the Merced River, both germination and mortality rates appeared to be atypically low. To understand why these rates were so low along this recently restored flow-regulated, gravel-bedded stream, we surveyed <i>Populus fremontii, Salix exigua,</i> and <i> Salix gooddingii,</i> estimated germination and survivorship rates, and examined their correlations with factors expected to constrain recruitment, namely seed release, seed arrival, moist germination beds, light levels, groundwater depth, groundwater recession rates, and shear stress. Germination/initial establishment rates were low due in part to low seed arrival rates. Only <i> Salix gooddingii</i> was abundant enough to model in detail, and while moist germination surfaces increased germination/initial establishment, rates were low overall. Survivorship rates for <i>Salix gooddingii</i> seedlings and for small individuals were not correlated with any examined covariates. Seedlings tolerated moderate competition, and the absence of major scouring, even during 6 year flows, enabled survival at sites with sufficiently shallow groundwater that seedlings were unaffected by groundwater recession rates.</p>

<p> Increased nutrient availability has been widely linked to the success of invasive plants, however a general mechanism explaining these observations is lacking. Stoichiometric homeostasis (<i>H</i>), which is the regulation of internal nutrient concentrations, has been used to explain changes in plant community diversity under alterations in nutrient availability. One hypothesis holds that plants with high regulation (larger <i>H</i>) decrease in abundance in nutrient enriched conditions but are stable in nutrient deficient and drought conditions, likely due to extensive root systems. Additionally, plants with low regulation (lower <i>H</i>) increase in abundance under nutrient enriched conditions but are sensitive to drought conditions. I tested the hypotheses that <i>H</i> would be higher in native grasses than in invasive grasses, that <i>H</i> would be modulated by environmental conditions, and that differences in <i>H</i> would be associated with differences in growth and biomass allocation. I calculated <i> H</i> and measured plant growth and growth traits in two native (<i> Pascopyrum smithii</i> and <i>Elymus canadensis</i>) and two invasive (<i>Bromus inermis</i> and <i>Agropyron cristatum </i>) grasses grown in two experiments. Both experiments contained a range of N:P fertilizer supply concentrations and the first experiment contained a two-level drought treatment while the second experiment contained a two-level mycorrhizal inoculation treatment. </p><p> In the first experiment, I found support for the hypothesis that <i> H</i> is higher in native than invasive plants, that environmental conditions (i.e. water availability) affect the value of <i>H</i>, and that differences in <i>H</i> were associated with differences in growth. In the second experiment, there was no successful mycorrhizal inoculation, resulting in no differences in <i>H</i> between mycorrhizal treatment groups. There were significant differences in total growth between the second experiment native and invasive grasses, despite there being no significant differences in <i>H</i>. Differences in <i>H</i> values between control-treated grasses in the two experiments may be due to differences in greenhouse temperature and light conditions. These results show first, significant differences exist in <i>H</i> between invasive and native grasses, with invasive grasses expressing lower values of <i> H</i>, second, environmental conditions effect the expression of <i> H</i>, and third, that differences in the expression of <i>H</i> are matched by differences in growth.</p><p>

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2009. / Title from PDF t.p. (viewed on Feb. 5, 2010). Source: Dissertation Abstracts International, Volume: 70-04, Section: B, page: 2009. Adviser: Loren H. Rieseberg.

Thesis (PH. D.)--University of Michigan, 1943. / "Reprinted from Ecological monographs, 15 ... January, 1945." "Literature cited": p. 106-108.

<p>Numerical clustering encompasses a group of exploratory multivariate statistical methods devoted to finding groups in data based on either responses of individual variables or dissimilarity measures calculated from the variables. Despite their popularity, there have been few controlled comparisons of methods using data of known clustering structure and which compare more than a few methods. This study utilizes simulated plant community data to assess what data properties affect the performance of numerical clustering methods used in vegetation classification, including properties that can be controlled during data collection and measured before statistical analysis. This was done by with simulation experiments varying properties of species assemblages themselves ? ?-diversity, ?-diversity, and the level and type of noise in the data ? or the clustering structure of sampling units (SUs) in environmental space ? number of SUs per group, equality of number of SUs or cluster dispersion among groups, the proximity of adjacent clusters, and the number of clusters. Cluster recovery was measured using the Adjusted Rand Index (ARI) ? a chance-corrected measure of the proportion of elements classified similarly in two clustering results. ARI is an approximation of the proportion of sites correctly classified, so scores near 1.0 indicate accurate cluster recovery, while scores near 0.0 indicate poor cluster recovery. Methods are robust if they have a mean ARI score near 1.0 despite variation in data properties. Methods tested include flexible beta clustering, TWINSPAN, average, complete, and single linkage, K-means, Partitioning Around Medoids, ISOPAM, OPTPART, OPTSIL, Noise Clustering, model-based EM clustering (Mclust), Fuzzy Analysis (FANNY), and Information Analysis. Where applicable, methods were tested using four combinations of standardization and dissimilarity, yielding 59 unique combinations of method, standardization, and dissimilarity. Across all experiments, a couple of general trends emerge. No methods are robust when either ?-diversity or ?-diversity are very low. When ?-diversity is lowered by including a second set of generalist species along with a set of specialists, mean ARI scores are considerably higher than when decreasing ?-diversity by increasing the range of all species in the data set. Most methods are less robust when implemented with Euclidean distances, except for Ward?s method, PAM, FANNY, and Information Analysis (which only uses the information statistic calculated from presence data as a dissimilarity measure). Nonhierarchical methods fail when the number of SUs is highly unequal between clusters, except for OPTSIL initiated form Flexible Beta clustering results. Hierarchical methods are more sensitive to intermediate and outlier sites, though Ward?s method, Flexible Beta, Information Analysis, and TWINSPAN all perform better than UPGMA, complete linkage, and single linkage. Sources of random error are unimportant individually, but may be more important when paired with other factors. The optimal choice of clustering method is a product of trade-offs between near optimal performance in most experiments and robustness where other methods fail. For this reason, I recommend using Flexible Beta clustering with possible refinement by OPTSIL as a standard clustering method for vegetation classification. Flexible Beta clustering achieved mean ARI scores that are among the highest in all experiments, while remaining robust to factors that nonhierarchical methods (equality of number of SUs) and other hierarchical methods (intermediate/outlier SUs) are not robust to. OPTSIL did not always drastically improve Flexible Beta results, but it also never made them worse. Nevertheless, in models with low ?-diversity and when adjacent clusters are close together, OPTSIL does improve Flexible Beta Results.

Tropospheric ozone is considered the most damaging gaseous air pollutant worldwide to which plants are exposed. Tissue injuries, reductions in plant growth and productivity, and changes in crop quality are some of the effects of ozone on plants. Ozone causes more damage to vegetation than all other air pollutants combined. The economic impacts of ozone on crop growth and productivity continue to be significant. Over the past several decades, researchers have focused on quantifying ozone-related damage on plants and establishing methods to explain plants' reaction to ozone. Increasingly, however, it has been shown that plant species react to ozone in many different ways: some are excessively susceptible and their development suffers or is severely reduced; others adapt themselves to new environmental conditions and become more tolerant. In some cases, certain cultivars even show resistance. The studies presented here focus on the impacts of ozone injury on the development of plants with varying degrees of sensitivity to ozone exposure and how growth rate and morphological characteristics affect plant responses to ozone at various concentrations. The degree of plant sensitivity to ozone was determined by comparative field studies, or by using open top field chambers where plants were exposed to ozone at various concentrations. In addition to crop yield evaluations from plants with differences in response to ozone, stomatal conductance was measured as a method of determining potential physiological changes. Stomatal density and aperture size were also assessed. The present studies assess the relationship between morphological characteristics of ozone-sensitive and ozone-tolerant genotypes of bush bean (Phaseolus vulgaris L.) and ozone exposure under different environmental conditions. The results support the expectation that genotypes within same species may show differences in response to ozone. Morphological characteristics, especially that of leaves, seem to influence individual plant responses to various atmospheric treatments.