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Thesis (Ph. D.)--Columbia University, 1936. / Vita. Includes bibliographical references (p. 42).

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). Two folded sheets in pocket. Includes bibliographical references (leaves 145-161). Also available via the World Wide Web.

Thesis (Ph. D.)--Columbia University, 1936. / Vita. Bibliography: p. 42.

In rivers and streams, fine sediment pollution is one of the most commonly attributed causes of ecological degradation. As fine sediment is also an important natural component of these ecosystems, and is variable both temporally and spatially, setting environmental targets and using conventional monitoring to determine where fine sediment is causing ecological degradation, is a complex challenge. An alternative approach is the use of biomonitoring tools, which utilise biota to gauge and track changes in the environment. This thesis examines the current state of sedimentbiomonitoring, considers the numerous theoretical and methodological decisions made during tool development, and applies a best practice approach to the development and testing of a sediment-specific tool. An existing biological index, which utilises knowledge of biological and ecological traits, is used as a basis for this development, following an evaluation of its performance over 835 minimally impacted temperate river and stream sites. The index is further developed using empirical data to assign indicator weights to individual taxa. The resulting index, the Empirically-weighted Proportion of Sediment-sensitive Invertebrates (E-PSI) index had moderate to strong correlations with fine sediment in independent test datasets of minimally (n = 84) (family-level: rs = -0.72; mixed-level: rs = -0.70; p < 0.01) and agriculturally impacted sites (n = 754) (family-level: rs = -0.68, p < 0.01). The E-PSI index has retained a biological basis, is easily integrated into regulatory agency protocols, and can be applied retrospectively to historic datasets. Despite the improved performance, a high amount of variation was observed between E-PSI and fine sediment cover. This is likely the result of the presence of multiple pressures, uncertainties concerning sediment-biota interactions, and the relatively low precision of sediment quantification techniques. Due to the prevalence of freshwater non-native invasive species, the effects of North American signal crayfish (Pacifastacus leniusculus) invasions on sediment- biomonitoring and fine sediment are also investigated. Additionally, given the subjective nature and lack of representativeness of many existing sediment quantification techniques, a novel, more objective, verifiable, and non-destructive method is developed and presented as “proof of concept”. This thesis contributes significantly to the literature concerning biomonitoring tool development and testing, and has resulted in a sediment-specific index that has a stronger correlation with its specific pressure, than the average biomonitoring tool used throughout Europe. The E-PSI index can be used alongside a suite of other biomonitoring tools, to identify the most likely causes of ecological degradation, and inform more targeted monitoring.

Perennial frost mounds developed across northern Europe following retreat of the late Quaternary ice sheets (c. 23–19). Their relict forms comprise depressions with surrounding ramparts (periglacial ramparted depressions - PRDs). Although PRD surface geometry is well-documented, their origin is less well-understood. There is little agreement on: i) definitive identification of PRDs, ii) PRD formation processes, and iii) the relationship between different frost-mound types (i.e. pingo, palsa and lithalsa). For the first time, this research characterises the internal structure of a relict lithalsa in the Ardennes (Belgium-German border), at macro- (e.g. coring, logging) and micro-scales (thin sections) and contextualises this with observations on the hydrological, lithological and topographic setting. Micromorphology enables the study of sedimentary environments and processes of formation. This investigation identifies diagnostic suites of microstructures indicative of frost action, landform development and environmental setting. The results are then applied to suspected PRDs in Norfolk (Walton Common) and Wales (the Cledlyn Valley), for which a likely frost-mound origin is confirmed. This approach: i) identifies the internal structure of PRDs, ii) considers the potential for change in deformation with depth and lateral extent within the rampart, and iii) considers the differences and similarities in micro-textures and structures in a variety of grain sizes across the sites where PRDs occur. Key microstructures identified, indicative of cryogenic origins, include: i) a vertical to subvertical microfabric (e.g. frost-jacked grains), ii) platy-prismatic, sub-angular aggregates, iii) planar deformation (e.g. fragmented domains, frost-cracked grains), and iv) evidence of pore-water movement on thawing of ice and associated grain translocation (e.g. silt and clay cappings). Microstructures attributed to PRD development include: i) a sub-vertical microfabric of similarly inclined elongate grains, associated with tilted strata, ii) microstructures linked to mass-wasting during frost-mound growth or rampart formation (e.g. grain concentrations, grain coatings of silt and clay, curvilinear grain arrangements, skelsepic plasmic fabric), iii) planar structures (e.g. grain lineations, linear concentrations of grains and fragmented domains and fractured grains, that may reflect shear strain during rampart-formation processes), and vi) multiple domains, interpreted as re-homogenisation of sediment caused by frost-mound heave, and subsequent rampart-formation processes. Consequently, this research identifies and characterises PRDs, which: i. provides a better understanding of the genesis of PRDs, for the classification of different types of ice-cored hills, ii. informs palaeoenvironmental reconstruction, since ice-cored hills are diagnostic of former permafrost (frozen ground conditions), iii. informs civil engineering projects where sediments are disturbed by PRD development (e.g. heave and subsidence).

<p> Biological soil crusts are communities of bacteria, microfungi, algae, lichens, and/or bryophytes that colonize the surfaces of soils where other vegetation is sparse. Soil crust communities are best known from the world&rsquo;s arid and semiarid regions, including North America&rsquo;s hot and cool deserts, where they aid in soil stabilization and aggregation, reduce erosion, and contribute to nutrient inputs in the soil. Although a significant body of work has emerged on soil crust function in arid and semiarid environments, there is still much to be learned about their geographical distributions within and across different vegetation communities. Sagebrush shrublands and pinyon-juniper woodlands are common communities in the central Great Basin, but this region is under-studied with respect to biological crust composition and distribution. I collected data on soil pH and the cover of plant functional groups and biological soil crusts in sagebrush and pinyon-juniper zones in the Wassuk Range of western Nevada. Regression models revealed that in the shrublands, soil crusts associate negatively to rock cover and positively to moderately dense shrub canopy. In the woodlands, ground-cover of rocks and woody litter have a negative association with soil crusts. Sagebrush and pinyon-juniper communities are facing many stressors and undergoing changes in structure. My results offer a possible starting point for assessing how the biological crusts in these habitats might respond to these changes based on their current distributional controls. Future research should further explore the response of biological crusts to trajectories of change in the central Great Basin ecoregion.</p>

<p> Integrating animal movement information with the spatial analysis of landscape structure is critical for restoring biological communities in spatially-structured landscapes. This integration can be accomplished by focusing on functional connectivity&mdash;a landscape&rsquo;s potential for the movement of organisms among resource patches&mdash;in relation to the spatial and structural connectivity of landscape elements. I carried out three investigations in order to examine how landscape structure interacts with the ecological factors associated with animal movement processes, and thereby produce actionable outcomes for the restoration of wildlife populations. This work combined population- and individual-level data of dispersing wildlife to better resolve the influence of spatial structure on functional connectivity. First, I used a meta-analysis to quantify the relationship between structural and functional connectivity for a broad scope of animal species. Second, I assessed the influence of landscape position and habitat density on colonization, movement, and population dynamics of wood frogs <i>(Lithobates sylvatica)</i> within a network of restored vernal pools. Third, I experimentally evaluated dispersal and habitat selection of green frogs <i>(Lithobates clamitans)</i> within this vernal pool system.</p><p> The meta-analysis demonstrated that universal scaling relationships of species and the landscapes they are moving through interact as key drivers mediating the level of functional connectivity afforded to wildlife by structural connectivity. Mark-recapture data revealed rapid colonization of the restored vernal pool network by wood frogs, with subsequently moderate levels of frog movement among neighboring pools. Local pool density interacted with the colonization process and terrestrial habitat availability to limit wood frog productivity within a pool cluster. Experimental dispersal data for green frogs artificially translocated within the pool network showed key differences between movement in familiar and novel environments. Differing movement behaviors and habitat selection patterns indicated that a habitat patch for this species is on the scale of a pool cluster rather than an individual pool. Together, the observed spatial dynamics of these vernal pool amphibians contribute a framework for improving amphibian dispersal modeling, potential responses to rapid environmental changes, and predicting colonization and subsequent population dynamics in restored systems. The results of this dissertation improve our understanding of how spatial structure interacts with organism-specific factors to produce observed patterns of functional connectivity.</p>

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