A foundation of ecology rediscovered: 100 years of succession on the William S. Cooper plots in Glacier Bay, Alaska

Understanding plant community succession is one of the original pursuits of ecology, forming some of the earliest theoretical frameworks in the field. Much of this was built on the long-term research of William S. Cooper, who established a permanent plot network in Glacier Bay, Alaska, in 1916. This study now represents the longest-running primary succession plot network in the world. Permanent plots are useful for their ability to follow mechanistic change through time without assumptions inherent in space-for-time (chronosequence) designs. After 100-yr, these plots show surprising variety in species composition, soil characteristics (carbon, nitrogen, depth), and percent cover, attributable to variation in initial vegetation establishment first noted by Cooper in the 1916–1923 time period, partially driven by dispersal limitations. There has been almost a complete community composition replacement over the century and general species richness increase, but the effective number of species has declined significantly due to dominance of Salix species which established 100-yr prior (the only remaining species from the original cohort). Where Salix dominates, there is no establishment of “later” successional species like Picea. Plots nearer the entrance to Glacier Bay, and thus closer to potential seed sources after the most recent glaciation, have had consistently higher species richness for 100 yr. Age of plots is the best predictor of soil N content and C:N ratio, though plots still dominated by Salix had lower overall N; soil accumulation was more associated with dominant species. This highlights the importance of contingency and dispersal in community development. The 100-yr record of these plots, including species composition, spatial relationships, cover, and observed interactions between species provides a powerful view of long-term primary succession.Ye

From genes to landscapes: the distribution of western conifers

2013 Summer.Includes bibliographical references.Managing and conserving forest ecosystems under a rapidly changing climate will require an understanding of the drivers of species distributions across a gradient of temporal and spatial scales. My dissertation research evaluated the relationship between distributional patterns of tree species and the processes driving these patterns from local to continental scales. I addressed three questions: 1) Which local abiotic and biotic processes are most important in determining the distribution of tree species along a hydrologic gradient in southeast Alaska? 2) How is genetic variation partitioned across the range of Pinus contorta, and is this variation explained by geographic or landscape variables? 3) How will Pinus contorta respond to predicted climate change? At the local scale, I assessed the role of abiotic and biotic constraints in limiting three tree species (Pinus contorta, Picea sitchensis, and Tsuga heterophylla) along a hydrologic gradient in southeast Alaska. I used a Bayesian hierarchical model to identify the strongest predictors of species' occurrence and biomass. Model predictions identified abiotic variables, including soil nitrogen, pH, and depth to water, as the primary factors limiting species' success in anaerobic wetland ecosystems. Competition was identified as the limiting factor in aerobic forest ecosystems. At the continental scale, I quantified the impact of historic evolutionary processes in shaping patterns of genetic diversity across the range of Pinus contorta, a widespread and morphologically variable species. I estimated gene flow and assessed the effect of the landscape on population structure. Gene flow is high across the range of the species, and patterns of variation are most strongly influenced by landscape barriers to gene flow and the environmental variation associated with its heterogeneous range. This suggests that, despite widespread gene flow, subspecies are adapted to local conditions. I then used correlative and mechanistic species distribution models to evaluate potential, future habitat suitability at the species and subspecies levels of Pinus contorta. Model results predict that P. contorta will maintain a large portion of its current habitat, but two of the more geographically constrained subspecies will lose a significant portion of suitable habitat. My work provides an understanding of the ecological and evolutionary processes shaping tree species distributions across a gradient of temporal and spatial scales, from historic to current timeframes and local to range-wide extents. Results from my research show that different processes determine patterns of distribution across this gradient of scales. Linking these patterns and processes will be essential for forest management and conservation in light of a rapidly changing climate

Residues from cyclododecane consolidation following desalination

This paper is published in the book ‘Subliming Surfaces: Volatile Binding Media in Heritage Conservation’, ed. Christina Rozeik (University of Cambridge Museums, 2018), pp. 101-107.1500 Central and South American archaeological ceramics in the Field Museum of Natural History, Chicago, required desalination treatment. Cyclododecane (CDD) was investigated as a temporary consolidant for extremely friable ceramics during desalination, leading to an investigation of post-sublimation residue. Watch glasses, new unglazed terracotta saucers, and thick potsherds from the archaeological collection were treated and desalinated. No residues were detected after sublimation on watch glasses, the saucers, and archaeological potsherds that did not undergo desalination. Residues were found on all archaeological potsherds that were desalinated. Microscopical study and infrared spectroscopy (ATR-FTIR) indicated the residue to be primarily of biological origin. Its presence could result from the growth within the CDD of bacteria, mould and yeast present in the archaeological ceramic. There was no evidence of CDD remaining in the residue. Residues on desalinated potsherds consolidated with molten CDD were thin, lightly cohesive sheets. The residue could be lifted off with electrostatically charged nylon brush or polyester film. Residues formed in the CDD applied as a solution were less cohesive and could only be removed by brushing. In most cases, some ceramic particles were lost. It was concluded that temporary consolidation with CDD was not useful in desalination treatments

Estimating frontal and parietal involvement in cognitive estimation: a study of focal neurodegenerative diseases

We often estimate an unknown value based on available relevant information, a process known as cognitive estimation. In this study, we assess the cognitive and neuroanatomic basis for quantitative estimation by examining deficits in patients with focal neurodegenerative disease in frontal and parietal cortex. Executive function and number knowledge are key components in cognitive estimation. Prefrontal cortex has been implicated in multilevel reasoning and planning processes, and parietal cortex has been associated with number knowledge required for such estimations. We administered the Biber Cognitive Estimation Test (BCET) to assess cognitive estimation in 22 patients with prefrontal disease due to behavioral variant frontotemporal dementia (bvFTD), to 17 patients with parietal disease due to corticobasal syndrome (CBS) or posterior cortical atrophy (PCA) and 11 patients with mild cognitive impairment (MCI). Both bvFTD and CBS/PCA patients had significantly more difficulty with cognitive estimation than controls. MCI were not impaired on BCET relative to controls. Regression analyses related BCET performance to gray matter atrophy in right lateral prefrontal and orbital frontal cortices in bvFTD, and to atrophy in right inferior parietal cortex, right insula and fusiform cortices in CBS/PCA. These results are consistent with the hypothesis that a frontal-parietal network plays a crucial role in cognitive estimation

Cognitive estimation:Performance of patients with focal frontal and posterior lesions

The Cognitive Estimation Test (CET) is a widely used test to investigate estimation abilities requiring complex processes such as reasoning, the development and application of appropriate strategies, response plausibility checking as well as general knowledge and numeracy (e.g., Shallice and Evans, 1978; MacPherson et al., 2014). Thus far, it remains unknown whether the CET is both sensitive and specific to frontal lobe dysfunction. Neuroimaging techniques may not represent a useful methodology for answering this question since the complex processes involved are likely to be associated with a large network of brain regions, some of which are not functionally necessary to successfully carry out the CET. Instead, neuropsychological studies may represent a more promising investigation tool for identifying the brain areas necessary for CET performance. We recently developed two new versions of the CET (CET-A and CET-B; MacPherson et al., 2014). We investigated the overall performance and conducted an error analysis on CET-A in patients with focal, unilateral, frontal (n= 38) or posterior (n= 22) lesions and healthy controls (n=39). We found that frontal patients' performance was impaired compared to healthy controls on CET demonstrating that our CET-A is affected by frontal lobe damage. We also found that frontal patients generated significantly poorer estimates than posterior patients on CET-A. This could not be explained by impairments in fluid intelligence. The error analyses suggested that for CET-A, extreme and very extreme responses are impaired following frontal lobe damage. However, only very extreme responses are significantly more impaired following frontal lobe than posterior damage and so represent a measure restricted to frontal "executive" impairment, in addition to overall CET performance

Climate-Mediated Changes to Linked Terrestrial and Marine Ecosystems across the Northeast Pacific Coastal Temperate Rainforest Margin

Coastal margins are important areas of materials flux that link terrestrial and marine ecosystems. Consequently, climate-mediated changes to coastal terrestrial ecosystems and hydrologic regimes have high potential to influence nearshore ocean chemistry and food web dynamics. Research from tightly coupled, high-flux coastal ecosystems can advance understanding of terrestrial–marine links and climate sensitivities more generally. In the present article, we use the northeast Pacific coastal temperate rainforest as a model system to evaluate such links. We focus on key above- and belowground production and hydrological transport processes that control the land-to-ocean flow of materials and their influence on nearshore marine ecosystems. We evaluate how these connections may be altered by global climate change and we identify knowledge gaps in our understanding of the source, transport, and fate of terrestrial materials along this coastal margin. Finally, we propose five priority research themes in this region that are relevant for understanding coastal ecosystem links more broadly.Ye

Electromagnetic field representation in inhomogeneous anisotropic media

Some of the basic developments in the theory of electromagnetic field representation in terms of Hertz vectors are reviewed. A solution for the field in an inhomogeneous anisotropic medium is given in terms of the two Hertz vectors. Conditions for presentation of the field in terms of uncoupled transverse electric and transverse magnetic modes, in a general orthogonal coordinate system, are derived when the permeability and permittivity tensors have only diagonal components. These conditions are compared with some known special cases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47031/1/339_2004_Article_BF00883972.pd

Carbon Storage in Old-Growth Western Larch (Larix occidentalis) Forests of Western Montana

Over the last 30 years, the structural development of western old-growth ecosystems has been of great interest in ecological research. As the loss of historical forested acreage in western Montana became more widely recognized, the preservation of frequent-fire old-growth stands became a focus of forest management. And, although old-growth studies are commonly found in the literature, few studies focus on long-term carbon (C) storage associated with interior old-growth. This limited understanding of the C storage capacity and patterns in old-growth forests of western Montana leaves little ability to evaluate the role of old-growth forests in ecosystem level C storage capacity. Further, there is a disconnect between old-growth definitions and old-growth management. Forest Service definitions for interior old-growth ecosystems inadequately describe the structure, composition, and function of these ecosystems, and definitions applied from the Pacific Northwest do not capture the unique qualities of old-growth of the Northern Rockies. In this thesis, I first present a review of existing literature on definitions and characteristics of old-growth ecosystems of the Pacific Northwest and contrast these with old-growth forests of the Northern Rockies. In the second chapter, I present studies undertaken to generate empiric data on C storage in old-growth forests of this region. Specifically, studies were conducted to compare ecosystem C of old-growth western larch (Larix occidentalis) stands to that of paired 30-40 year old second growth stands in western Montana. Old-growth forests were found to store nearly three times more C than second growth forests, with most of the difference coming from C stored in the overstory. Finally, the third chapter describes a web-based plant guide that simplifies the challenge of plant identification by eliminating the use of technical vocabulary, focusing instead on visually recognizable plant characters and providing students with a more user-friendly means of identifying specimens and obtaining species-specific information