Long-Term Landscape Changes in a Subalpine Spruce-Fir forest in Central Utah, USA

Background: In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species throughout the region. This study uses retrospective vegetation and fire history data to reconstruct the drivers of past disturbance and environmental change. Understanding the relationship among climate, antecedent disturbances, and the legacy effects of settlement-era logging can help identify the patterns and processes that create landscapes susceptible to bark beetle epidemics. Methods: Our analysis uses data from lake sediment cores, stand inventories, and historical records. Sediment cores were dated with radiometric techniques (14C and210Pb/137Cs) and subsampled for pollen and charcoal to maximize the temporal resolution during the historical period (1800 CE to present) and to provide environmental baseline data (last 10,500 years). Pollen data for spruce were calibrated to carbon biomass (C t/ha) using standard allometric equations and a transfer function. Charcoal samples were analyzed with statistical models to facilitate peak detection and determine fire recurrence intervals. Results: The Wasatch Plateau has been dominated by Engelmann spruce forests for the last ~10,500 years, with subalpine fir becoming more prominent since 6000 years ago. This landscape has experienced a dynamic fire regime, where burning events are more frequent and of higher magnitude during the last 3000 years. Two important disturbances have impacted Engelmann spruce in the historical period: 1) high-grade logging during the late 19th century; and (2) a high severity spruce beetle outbreak in the late 20th century that killed \u3e90 % of mature spruce (\u3e10 cm dbh). Conclusions: Our study shows that spruce-dominated forests in this region are resilient to a range of climate and disturbance regimes. Several lines of evidence suggest that 19th century logging promoted a legacy of simplified stand structure and composition such that, when climate became favorable for accelerated beetle population growth, the result was a landscape-scale spruce beetle outbreak. The lasting impacts of settlement-era landscape history from the Wasatch Plateau, UT may be relevant for other areas of western North America and Europe where sufficient host carrying capacity is important in managing for resistance and resilience to outbreaks

Use of ERTS-1 data to access and monitor change in the west side of the San Joaquin Valley and central coastal zone of California

There are no author-identified significant results in this report

Positive youth development in swimming: clarification and consensus of key psychosocial assets

The purpose of this study was to gain a more cohesive understanding of the assets considered necessary to develop in young swimmers to ensure both individual and sport specific development. This two stage study involved (a) a content analysis of key papers to develop a list of both psychosocial skills for performance enhancement and assets associated with positive youth development, and (b) in-depth interviews involving ten expert swim coaches, practitioners and youth sport scholars. Five higher order categories containing seventeen individual assets emerged. These results are discussed in relation to both existing models of positive youth development and implications for coaches, practitioners and parents when considering the psychosocial development of young British swimmers

Waveguide-integrated silicon T centres

The performance of modular, networked quantum technologies will be strongly dependent upon the quality of their quantum light-matter interconnects. Solid-state colour centres, and in particular T centres in silicon, offer competitive technological and commercial advantages as the basis for quantum networking technologies and distributed quantum computing. These newly rediscovered silicon defects offer direct telecommunications-band photonic emission, long-lived electron and nuclear spin qubits, and proven native integration into industry-standard, CMOS-compatible, silicon-on-insulator (SOI) photonic chips at scale. Here we demonstrate further levels of integration by characterizing T centre spin ensembles in single-mode waveguides in SOI. In addition to measuring long spin T_1 times, we report on the integrated centres' optical properties. We find that the narrow homogeneous linewidth of these waveguide-integrated emitters is already sufficiently low to predict the future success of remote spin-entangling protocols with only modest cavity Purcell enhancements. We show that further improvements may still be possible by measuring nearly lifetime-limited homogeneous linewidths in isotopically pure bulk crystals. In each case the measured linewidths are more than an order of magnitude lower than previously reported and further support the view that high-performance, large-scale distributed quantum technologies based upon T centres in silicon may be attainable in the near term

Adaptive capacity in social–ecological systems: a framework for addressing bark beetle disturbances in natural resource management

The ability of natural resource agencies to act before, during, and after outbreaks of conifer bark beetles (Coleoptera: Curculionidae) is important to ensure the continued provision of ecosystem services. Adaptive capacity refers to the capability of an agent or system to adapt to change, regardless of whether it is examined as an independent social or ecological entity, or as a coupled social–ecological system. Understanding the components of a disturbance and the associated effects to ecosystem services, social systems, and natural resource management increases the ability to adapt to change and ensure continued resilience. This paper presents a definition and conceptual framework of adaptive capacity relevant to bark beetle disturbances that was developed through an interdisciplinary workshop held in 2016. The intent is to assist natural resource managers and policy-makers in identifying important adaptation characteristics to effectively address bark beetle disturbances. The current state of knowledge regarding institutional, social, and environmental factors that influence adaptive capacity are identified. The mountain pine beetle (Dendroctonus ponderosae) in the western USA is used as a specific example to discuss several factors that influence adaptive capacity for increasing resilience. We hope that our proposed framework serves as a model for future collaborations among both social and physical scientists and land managers to better address landscape-level disturbances that are being exacerbated by climate change