A dendroclimatological study of long-term growth patterns of yellow-cedar trees in Southeast Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2006Yellow-cedar is a very long-lived, commercially important tree species found along the coasts of Southeast Alaska and also in small populations in Prince William Sound. However, this is the first study of the tree's annual ring growth patterns in the region. Tree cores were collected from over 400 trees across a large latitudinal gradient and cross-dated using standard dendrochronological techniques. Radial tree-ring growth was measured and compared to reconstructed weather station data to gain a better understanding of the climatic conditions favoring yellow-cedar growth. We found consistent, significant positive correlations between ring widths and mean monthly temperatures in August, previous January, and previous December, and negative relationships with May and December precipitation. Climate indices we created using these variables explain approximately 25% of growth variability in five distinct yellow-cedar populations. Long-term growth patterns in tree populations going back three centuries were similar across all sites, specifically the sustained below mean growth during the 1800s. Yellow-cedar at the northern limits of its distribution shows a common growth signal which may indicate the influence of larger pressure anomalies, such as EI Nino-Southern Oscillation (ENSO), on the climate factors affecting the trees

Photographic Guide to Pinyon and Juniper Tree Maturity Classes

Two series of color photographs illustrate the variation in growth habitat of five maturity classes of pinyon pine (Pinus edulis Engelm.) and Utah juniper trees (Juniperus osteosperma (Torr.) Little) froma variety of sites across Northern Arizona. Information provided with each photograph includes a cross-dated age and measures of height, crown radius, and multiple diameters. Three site quality levels alow the user to calibrate the guide to their site and account for miscrosite variation. A pictorial summary of bark characteristics is presented for both species. This photographic guide provides an efficient way to estimate the age of pinyon pine and juniper trees in the field for ecological restoration, as well as general research ecology, in pinyon-juniper ecosystems throughout Northern Arizona and nearly regions

Greater Sage-Grouse (Centrocercus urophasianus) Demographic Rates and Predator Communities in a Degraded Landscape in Modoc County, California

The greater sage-grouse (Centrocercus urophasianus: hereafter; sage-grouse) population in Modoc County California is geographically isolated and has been subsidized by translocation to prevent inbreeding depression since 2005. Despite significant efforts to increase the population through translocations and habitat improvement by cutting encroaching western juniper (Juniperus occidentalis), only a single lek remains (from 56 in the 1940s). Since 2017, several large wildfires have occurred on the area that led to an increase in invasive grasses and a decrease in sagebrush (Artemisia sp.) cover that has further degraded important nesting and brooding habitat. In addition to supporting the last known sage-grouse lek, Clear Lake Reservoir is a major stopover point and nesting site for migratory waterfowl and wading birds. This abundance of prey species also attracts a diverse and abundant generalist predator community. I estimated survival for adult females, nests, and chicks and assessed habitat and biotic characteristics that may influence these survival rates to identify factors that may be limiting population growth. I also estimated coyote (Canis latrans) probability of use and avian predator densities to evaluate the predation risk to females, nests and chicks on this study area. I monitored 37 females marked with GPS PTTS, 39 nests, and 8 broods during 3 years (2019-2021). I measured vegetation characteristics for nests at the microsite and landscape scale to evaluate effects on daily nest survival (DNS). I used 70 camera traps to take over 4.9 million photos that I used to estimate coyote probability of use within each season during 2020 and 2021. During these two years I also conducted avian point-count surveys every two weeks at each camera trap location to estimate raven (Corvus corax), and raptor (i.e., hawk (Buteo sp.), harrier (Circus hudsonius), and eagle (Aquila chrysaetos and Haliaeetus leucocephalus)) densities using a distance sampling approach. Nest success across a 29-day incubation period, the maximum number of incubation days at my field site, was 29% (95% CI: 17.1 to 44.8). Chick survival across a 54 day period was 22% (95% CI: 0.9 to 72.3), and female adult survival across a 12 month period was 29% (95% CI: 17.8 to 43.7). At the microhabitat scale, shrub and medusahead cover were the two most supported covariates associated with DNS. Daily nest survival increased as shrub cover increased (β= 3.3; 95% 0.89 to 5.8) but decreased as medusahead cover increased (β= -2.8; 95% CI -5.0 to -0.56). At the landscape scale the log-linear structure of annual grass cover at 400m around the nest had the strongest effect on DNS which increased with increasing grass cover to ~35%, where DNS then stabilized (β = 3.0; 95% CI 0.28 to 5.8). Shrub cover at the landscape scale around nests was 12 % lower than what has been recommended for California and Nevada on the landscape scale, and the amount of annual grasses was 10 % higher than other study sites affected by large wildfires in Oregon, California, and Nevada. My estimated vital rates were 45-55% lower than range-wide estimates. During the course of the sage-grouse breeding season, coyotes used approximately 96 % (95% CI: 0.80 to 0.99) of the camera trap locations and coyote detection probabilities were highest during early brood-rearing for sage-grouse. Raven (Corvus corax) and raptor densities were 0.29 ravens/km2 (95% CI = 0.19 to 0.44) and 0.22 raptors/km2 (95% CI = 0.16 to 0.31), respectively. The overlap of brood-rearing with peak coyote activity could explain decreased brood survival within the first two weeks post-hatch, and why adult predation was the primary cause of brood loss. Ravens and hawks also far outnumber sage-grouse, and the presence of nesting resident predators may be detrimental to this small population of nesting sage-grouse than what might be expected given the estimated density of avian predators. My results suggested recent habitat changes associated with wildfire and the resulting increased distribution of invasive grasses on the study area may have had a detrimental effect on this population across all life stages. The densities and occurrence of predators combined with the reduced availability of vegetation cover used for concealment, and increased perching and nesting structures for avian predators through juniper encroachment, may have increased the risk of sage-grouse females, nests, and chicks to predation

Observations of the habitats and biodiversity of the submarine canyons at Sodwana Bay

The discovery of coelacanths, Latimeria chalumnae, in Jesser Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000 triggered renewed interest in the deep subtidal habitats associated with submarine canyons. Information stemming from three recreational Trimix diving expeditions in Wright and Jesser canyons between April 1998 and June 2001 revealed distinct and diverse invertebrate and fish communities in the canyons of the Greater St Lucia Wetland Park (GSLWP). In total, 69 invertebrate taxa were collected from Wright Canyon, including at least 15 new records for South Africa plus 11 potential new species and 16 range or depth extensions. Divers documented the first five coelacanth specimens and obtained information on fish distribution and abundance. Five different habitat types were recognized supporting distinct biological communities; the sandy plains outside of the canyons, scattered rock outcrops within the sandy plains, the canyon margin, canyon walls and caves and overhangs. The canyon margin is the richest habitat and supports dense communities of invertebrate suspension feeders, as well as a diverse and abundant fish fauna. Dominant canyon invertebrates included sponges, black corals, gorgonians, alcyonarian soft corals and stylasterine lace corals. These invertebrates support a diverse epifauna including basket- and brittlestars, winged oysters and other molluscs. The canyons within the GSLWP protect large populations of commercially important linefish species including the sparids, Chrysoblephus puniceus, C. anglicus, Polysteganus praeorbitalis and P. caeruleopunctatus, as well as several species of serranids and lutjanids. Additional biological sampling and standardized quantitative sampling within the canyons and deep reefs is required to develop a better understanding of their biological communities and the factors that shape them

Patient-reported outcomes of periacetabular osteotomy from the prospective ANCHOR cohort study

BACKGROUND: Current literature describing the periacetabular osteotomy (PAO) is mostly limited to retrospective case series. Larger, prospective cohort studies are needed to provide better clinical evidence regarding this procedure. The goals of the current study were to (1) report minimum 2-year patient-reported outcomes (pain, hip function, activity, overall health, and quality of life), (2) investigate preoperative clinical and disease characteristics as predictors of clinical outcomes, and (3) report the rate of early failures and reoperations in patients undergoing contemporary PAO surgery. METHODS: A large, prospective, multicenter cohort of PAO procedures was established, and outcomes at a minimum of 2 years were analyzed. A total of 391 hips were included for analysis (79% of the patients were female, and the average patient age was 25.4 years). Patient-reported outcomes, conversion to total hip replacement, reoperations, and major complications were documented. Variables with a p value of ≤0.10 in the univariate linear regressions were included in the multivariate linear regression. The backward stepwise selection method was used to determine the final risk factors of clinical outcomes. RESULTS: Clinical outcome analysis demonstrated major clinically important improvements in pain, function, quality of life, overall health, and activity level. Increasing age and a body mass index status of overweight or obese were predictive of improved results for certain outcome metrics. Male sex and mild acetabular dysplasia were predictive of lesser improvements in certain outcome measures. Three (0.8%) of the hips underwent early conversion to total hip arthroplasty, 12 (3%) required reoperation, and 26 (7%) experienced a major complication. CONCLUSIONS: This large, prospective cohort study demonstrated the clinical success of contemporary PAO surgery for the treatment of symptomatic acetabular dysplasia. Patient and disease characteristics demonstrated predictive value that should be considered in surgical decision-making. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence

Sex differences in clinical outcomes following surgical treatment of femoroacetabular impingement

BACKGROUND: Sex-based differences in clinical outcomes following surgical treatment of femoroacetabular impingement remain largely uncharacterized; this prospective, multicenter study evaluated these differences both directly and adjusted for covariates. METHODS: Hips undergoing surgical treatment of symptomatic femoroacetabular impingement were prospectively enrolled in a multicenter cohort. Patient demographics, radiographic parameters, intraoperatively assessed disease severity, and history of surgical procedures, as well as patient-reported outcome measures, were collected preoperatively and at a mean follow-up of 4.3 years. A total of 621 (81.6%) of 761 enrolled hips met the minimum 1 year of follow-up and were included in the analysis; 56.7% of analyzed hips were female. Univariate and multivariable statistics were utilized to assess the direct and adjusted differences in outcomes, respectively. RESULTS: Male hips had greater body mass index and larger α angles. Female hips had significantly lower preoperative and postoperative scores across most patient-reported outcome measures, but also had greater improvement from preoperatively to postoperatively. The preoperative differences between sexes exceeded the threshold for the minimal clinically important difference of the modified Harris hip score (mHHS) and all Hip disability and Osteoarthritis Outcome Score (HOOS) domains except quality of life. Preoperative sex differences in mHHS, all HOOS domains, and Short Form-12 Health Survey physical function component score were greater than the postoperative differences. A greater proportion of female hips achieved the minimal clinically important difference for the mHHS, but male hips were more likely to meet the patient acceptable symptom state for this outcome. After adjusting for relevant covariates with use of multiple regression analysis, sex was not identified as an independent predictor of any outcome. Preoperative patient-reported outcome scores were a strong and highly significant predictor of all outcomes. CONCLUSIONS: Significant differences in clinical outcomes were observed between sexes in a large cohort of hips undergoing surgical treatment of femoroacetabular impingement. Despite female hips exhibiting lower baseline scores, sex was not an independent predictor of outcome or reoperation. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence

Prioritising surveillance for alien organisms transported as stowaways on ships travelling to South Africa

The global shipping network facilitates the transportation and introduction of marine and terrestrial organisms to regions where they are not native, and some of these organisms become invasive. South Africa was used as a case study to evaluate the potential for shipping to contribute to the introduction and establishment of marine and terrestrial alien species (i.e. establishment debt) and to assess how this varies across shipping routes and seasons. As a proxy for the number of species introduced (i.e. 'colonisation pressure') shipping movement data were used to determine, for each season, the number of ships that visited South African ports from foreign ports and the number of days travelled between ports. Seasonal marine and terrestrial environmental similarity between South African and foreign ports was then used to estimate the likelihood that introduced species would establish. These data were used to determine the seasonal relative contribution of shipping routes to South Africa's marine and terrestrial establishment debt. Additionally, distribution data were used to identify marine and terrestrial species that are known to be invasive elsewhere and which might be introduced to each South African port through shipping routes that have a high relative contribution to establishment debt. Shipping routes from Asian ports, especially Singapore, have a particularly high relative contribution to South Africa's establishment debt, while among South African ports, Durban has the highest risk of being invaded. There was seasonal variation in the shipping routes that have a high relative contribution to the establishment debt of the South African ports. The presented method provides a simple way to prioritise surveillance effort and our results indicate that, for South Africa, port-specific prevention strategies should be developed, a large portion of the available resources should be allocated to Durban, and seasonal variations and their consequences for prevention strategies should be explored further. (Résumé d'auteur