Front Range Region Of Colorado Research Articles

Forest restoration treatments indirectly diversify pollination networks via floral- and temperature-mediated effects.

In North American conifer forests, a variety of federally initiated thinning programs are implemented to restore pre-European settlement forest structures, but these changes may impact ecosystem function via impacts on sensitive biotic communities. Across the wildland-urban interface of the Front Range region of Colorado, agencies associated with the Collaborative Forest Landscape Restoration Program (CFLRP) have implemented thinning treatments across thousands of hectares of ponderosa pine forest; here we leverage these treatments as an experimental framework to examine thinning effects on a pollinator community. We measured variation in forest structure and sampled bee community assemblages using multiple methods (trapping and netting) to compare bee biodiversity and patterns of floral visitation by bees (bee-flower networks) between mechanically thinned stands that were 3-10 years after treatment and nonthinned stands. Three key findings emerged: (1) Native bee abundance, richness, and diversity were 120%, 53%, and 37% greater, respectively, in thinned stands. In addition, nestedness, richness, and abundance of bee-flower interactions were all substantially higher in thinned stands, and there was increased functional redundancy in bee assemblages after thinning. (2) Structural equation modeling indicated that variation in temperature and floral abundance were mediated by canopy openness and correlated with bee richness and abundance, thereby indirectly driving variation in bee-flower interactions. (3) Four floral species (Penstemon virens, Cerastium arvense, Erysimum capitatum, and Geranium caespitosum) were identified as key connectors in bee-flower interaction networks, though these were not necessarily the most abundant flowering plants. Our analyses indicate that native bee α-diversity and bee-flower interactions positively responded to thinning treatments, and these effects were indirectly driven by canopy removal. We conclude that CFLRP treatments have conservation value for native bee communities. Further monitoring is warranted to evaluate the longevity of these effects.

The COVID-19-wildfire smoke paradox: Reduced risk of all-cause mortality due to wildfire smoke in Colorado during the first year of the COVID-19 pandemic

BackgroundIn 2020, the American West faced two competing challenges: the COVID-19 pandemic and the worst wildfire season on record. Several studies have investigated the impact of wildfire smoke (WFS) on COVID-19 morbidity and mortality, but little is known about how these two public health challenges impact mortality risk for other causes. ObjectivesUsing a time-series design, we evaluated how daily risk of mortality due to WFS exposure differed for periods before and during the COVID-19 pandemic. MethodsOur study included daily data for 11 counties in the Front Range region of Colorado (2010–2020). We assessed WFS exposure using data from the National Oceanic and Atmospheric Administration and used mortality counts from the Colorado Department of Public Health and Environment. We estimated the interaction between WFS and the pandemic (an indicator variable) on mortality risk using generalized additive models adjusted for year, day of week, fine particulate matter, ozone, temperature, and a smoothed term for day of year. ResultsWFS impacted the study area on 10% of county-days. We observed a positive association between the presence of WFS and all-cause mortality risk (incidence rate ratio (IRR) = 1.03, 95%CI: 1.01–1.04 for same-day exposures) during the period before the pandemic; however, WFS exposure during the pandemic resulted in decreased risk of all-cause mortality (IRR = 0.90, 95%CI: 0.87–0.93 for same-day exposures). DiscussionWe hypothesize that mitigation efforts during the first year of the pandemic, e.g., mask mandates, along with high ambient WFS levels encouraged health behaviors that reduced exposure to WFS and reduced risk of all-cause mortality. Our results suggest a need to examine how associations between WFS and mortality are impacted by pandemic-related factors and that there may be lessons from the pandemic that could be translated into health-protective policies during future wildfire events.

Excess mortality in the Colorado Front Range during the COVID-19 pandemic and a concurrent intense wildfire season

BACKGROUND AND AIM: COVID-19 has had a substantial public health impact in the United States. In the western US, the pandemic has coincided with some of the worst wildfires in history. The current analysis aimed to estimate excess mortality in the Front Range region of Colorado during the convergent disasters of the COVID-19 pandemic and an intense wildfire season. METHODS: We obtained weekly death counts from 2010-2020 for the study area from the state's vital statistics program. We modeled all-cause mortality and deaths due to cardiovascular, respiratory or kidney disease, cancer, diabetes, deaths of despair (suicide and overdose), and other causes. To estimate excess deaths, we fit quasipoisson generalized additive models for each cause with a smoothing term for week to account for temporal trends using data from January 2010 through the first week in March (prior to the first case of COVID-19 in the state). We then predicted expected deaths from the second week in March through December 2020. We defined excess deaths as the difference between the observed count and the upper limit of the 95% prediction interval for each week. RESULTS:In 2020, we estimated 3740 excess deaths, which exceeded the observed number of COVID-19 deaths (n = 3159). Most excess deaths occurred at the beginning of the pandemic (March-April) and from October through December. When examining specific causes, the timing of excess deaths varied. Excess cardiovascular disease deaths (n = 257) occurred throughout the pandemic. Excess deaths of despair (n = 103) peaked in July and August. CONCLUSIONS:Our results suggest there may be important environmental factors contributing to excess deaths during the pandemic. We hypothesize that some excess deaths may be attributable to pandemic lockdown policies or exposure to high temperatures or wildfire smoke. Future work will further examine the confluence of heat, wildfires, and COVID-19 on mortality risk in Colorado. KEYWORDS: COVID-19, wildfires, socioeconomic factors, mortality

Health and Environmental Justice Implications of Retiring Two Coal-Fired Power Plants in the Southern Front Range Region of Colorado.

Despite improvements in air quality over the past 50 years, ambient air pollution remains an important public health issue in the United States. In particular, emissions from coal‐fired power plants still have a substantial impact on both nearby and regional populations. Of particular concern is the potential for this impact to fall disproportionately on low‐income communities and communities of color. We conducted a quantitative health impact assessment to estimate the health benefits of the proposed decommissioning of two coal‐fired electricity generating stations in the Southern Front Range region of Colorado. We estimated changes in exposures to fine particulate matter and ozone using the Community Multiscale Air Quality model and predicted avoided health impacts and related economic values. We also quantitatively assessed the distribution of these benefits by population‐level socioeconomic status. Across the study area, decommissioning the power plants would result in 2 (95% CI: 1–3) avoided premature deaths each year due to reduced PM2.5 exposures and greater reductions in hospitalizations and other morbidities. Health benefits resulting from the modeled shutdowns were greatest in areas with lower educational attainment and other economic indicators. Our results suggest that decommissioning these power plants and replacing them with zero‐emissions sources could have broad public health benefits for residents of Colorado, with larger benefits for those that are socially disadvantaged. Our results also suggested that researchers and decision makers need to consider the unique demographics of their study areas to ensure that important opportunities to reduce health disparities associated with point‐source pollution.

Precipitable water characteristics during the 2013 Colorado flood using ground-based GPS measurements

Abstract. During 9–16 September 2013, the Front Range region of Colorado experienced heavy rainfall that resulted in severe flooding. Precipitation totals for the event exceeded 450 mm, damages to public and private properties were estimated to be over USD 2 billion, and nine lives were lost. This study analyzes the characteristics of precipitable water (PW) surrounding the event using 10 years of high-resolution GPS PW data in Boulder, Colorado, which was located within the region of maximum rainfall. PW in Boulder is dominated by seasonal variability with an average summertime maximum of 36 mm. In 2013, the seasonal PW maximum extended into early September and the September monthly mean PW exceeded the 99th percentile of climatology with a value 25 % higher than the 40-year climatology. Prior to the flood, around 18:00 UTC on 8 September, PW rapidly increased from 22 to 32 mm and remained around 30 mm for the entire event as a result of the nearly saturated atmosphere. The frequency distribution of September PW for Boulder is typically normal, but in 2013 the distribution was bimodal due to a combination of above-average PW values from 1 to 15 September and much drier conditions from 16 to 30 September. The above-normal, near-saturation PW values during the flood were the result of large-scale moisture transport into Colorado from the Tropical Eastern Pacific and the Gulf of Mexico. This moisture transport was the product of a stagnating cutoff low over the southwestern United States working in conjunction with an anticyclone located over the southeastern United States. A blocking ridge located over the Canadian Rocky Mountains kept both of the synoptic features in place over the course of several days, which helped to provide continuous moisture to the storm, thus enhancing the accumulated precipitation totals.

Estimates of Extreme Precipitation Frequency Derived from Spatially Dense Rain Gauge Observations: A Case Study of Two Urban Areas in the Colorado Front Range Region

Precipitation design values, which describe precipitation extremes expected within a specified time period, provide critical guidance for public policy and the design of hydrologic infrastructure. Unfortunately, conventional design value calculations are limited by a major assumption: They treat precipitation as a point-based phenomenon, measured at spatially isolated gauges. We argue that because precipitation occurs over areas, design value calculations should be based on an areal conception of precipitation. Using spatially dense Community Collaborative Rain, Hail and Snow (CoCoRaHS) Network data in two Colorado cities (Fort Collins and Boulder), we develop a “hyperlocal” design value calculation in which nearby observations within a representative precipitation region (RPR) “compete” to capture a single twenty-four-hour maximum. We find that design values for shorter return periods (one to fifty years) derived from just ten years of hyperlocal data, which we express as probabilistic distributions rather than single values, typically exceed those calculated using single-point records of 100 years or more. Hyperlocal design values for longer return periods (more than fifty years) are generally smaller than those calculated from the single-point data due to the temporally limited CoCoRaHS record. We also find that the dependence of design values on RPR size contrasts between Fort Collins and Boulder, as design values grow markedly larger as the RPR size increases in Fort Collins but not in Boulder. We attribute this behavior to the Boulder Global Historical Climatology Network station's location in a topographically favored area for precipitation and propose that future studies evaluate the hyperlocal design value method in a variety of geographic settings.

A decadal satellite analysis of the origins and impacts of smoke in Colorado

Abstract. We analyze the record of aerosol optical depth (AOD) measured by the MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite in combination with surface PM2.5 to investigate the impact of fires on aerosol loading and air quality over Colorado from 2000 to 2012, and to evaluate the contribution of local versus transported smoke. Fire smoke contributed significantly to the AOD levels observed over Colorado. During the worst fire seasons of 2002 and 2012, average MODIS AOD over the Colorado Front Range corridor were 20–50% larger than the other 11 yr studied. Surface PM2.5 was also unusually elevated during fire events and concentrations were in many occasions above the daily National Ambient Air Quality Standard (35 μg m−3) and even reached locally unhealthy levels (> 100 μg m−3) over populated areas during the 2012 High Park fire and the 2002 Hayman fire. Over the 13 yr examined, long-range transport of smoke from northwestern US and even California (> 1500 km distance) occurred often and affected AOD and surface PM2.5. During most of the transport events, MODIS AOD and surface PM2.5 were reasonable correlated (r2 = 0.2–0.9), indicating that smoke subsided into the Colorado boundary layer and reached surface levels. However, that is not always the case since at least one event of AOD enhancement was disconnected from the surface (r2<0.01 and low PM2.5 levels). Observed plume heights from the Multi-angle Imaging SpectroRadiometer (MISR) satellite instrument and vertical aerosol profiles measured by the space-based Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) showed a complex vertical distribution of smoke emitted by the High Park fire in 2012. Smoke was detected from a range of 1.5 to 7.5 km altitude at the fire origin and from ground levels to 12.3 km altitude far away from the source. The variability of smoke altitude as well as the local meteorology were key in determining the aerosol loading and air quality over the Colorado Front Range region. Our results underline the importance of accurate characterization of the vertical distribution of smoke for estimating the air quality degradation associated with fire activity and its link to human health.

Urbanization and wetland communities: applying metacommunity theory to understand the local and landscape effects

SummaryUrbanization is a growing threat to ecological communities and has become a leading cause of population extirpations in a wide range of taxa. Because the effects of urbanization are often multifaceted, identifying the pathways through which changes in communities occur has remained a persistent challenge.We draw upon metacommunity theory to evaluate competing explanations for the effects of urbanization, focusing on the relative importance of processes at local (e.g. abiotic and biotic characteristics) and regional (e.g. habitat connectivity and dispersal) scales. Over 4 years, we sampled 201 wetlands in theFrontRange region ofColorado, which is one of the most rapidly developing areas in theUSA.Wetlands embedded within urban areas exhibited significantly lower taxonomic richness and diversity compared to those in agricultural or grassland areas. Relative to grassland wetlands, urban wetlands supported a 60% lower richness of amphibians and aquatic reptiles and a 33% lower richness of aquatic insects, molluscs and crayfish. These patterns were associated with changes in biotic factors (introduced fishes and bullfrogs), abiotic factors (nutrients, conductivity and vegetation) and landscape characteristics (road density and surrounding wetland area).The use of an information‐theoretic approach and structural equation modelling suggested that the effects of urbanization on richness were mainly driven by changes in road density. Analyses of community composition indicated that discrete communities formed along the urban systems gradient, such that actively dispersing predators associated more negatively with urban system relative to herbivores with passive dispersal.Synthesis and applications. These results highlight the importance of considering both local and regional factors in addressing conservation‐related challenges and underscore the benefits of linking conceptual work on metacommunity theory with applied efforts to mitigate the effects of urbanization.

A Method for Monitoring Movements of Small Fishes in Urban Streams

AbstractThe Front Range region of Colorado is an ecological transition zone between the Rocky Mountains and the western Great Plains. Changes to streams resulting from urban and agricultural land uses have contributed to the decline of many plains and transition zone fishes. The fragmentation of stream systems by dams, weirs, and diversions is among the most detrimental of these changes. These structures can inhibit fish spawning migrations, the search for sporadic resources, and recolonization of empty habitats. To assess the magnitude of the problem, there is a distinct need to determine whether existing instream structures are barriers to migration. A relatively simple method of doing so involves giving fish a unique mark and tracking their movements in the vicinity of a suspected barrier. We individually marked fish (15 species; 2,724 individuals) with visual implant elastomer (VIE) marks and tracked their movements across a grade control structure in Spring Creek in Fort Collins, Colorado. Results from a multistratum mark–recapture analysis showed that the grade control structure in Spring Creek prevented upstream movement by most fish. The approach we used identifies problematic instream structures that impede movements and present a potential stressor to fish assemblages in urban streams. The use of individual VIE marks is one of the few methods that can provide accurate information on the movements of small‐bodied fishes in streams, but the commonly encountered design issues associated with this type of study must be considered.

Spatiotemporal Distribution of Black Bear‐Human Conflicts in Colorado, USA

Abstract: Management and conservation of large carnivores increasingly includes conflicts with humans. Consequently, a greater understanding of spatiotemporal trends of conflicts is needed to efficiently allocate resources and apply targeted management. Therefore, we examined spatial and temporal distribution of American black bear (Ursus americanus; hereafter, bear)‐human conflicts in Colorado, USA, related to 3 conflict types (agriculture operations, human development, and road kills). We used the Getis‐Ord Gi* spatial clustering statistic to describe location and assess magnitude of bear‐human conflicts in Colorado during 1986–2003 and investigated temporal trends of bear‐human conflicts by type. Bear‐human conflicts showed distinct spatial clustering by type, and areas of high clustering overlapped conflict types. Clustering for agriculture operations conflicts had the largest overall Gi* value and overlapped counties with high sheep production. Both human development and road‐kill conflict clusters were high in areas of high‐quality oak (Quercus spp.)—shrub habitat in the central and southern portions of Colorado's Front Range region and near the city of Durango in southwestern Colorado. Bear‐human conflicts varied by year and type but overall increased during the 18 years. Summed across years, most conflicts were related to agriculture (32%), followed by road kills (27%) and human development (24%). The greatest proportion of agriculture operations‐related conflicts (76%), human development‐related conflicts (36%), and road kills (47%) occurred in 1988, 1999, and 2003, respectively. Considering that bear‐human conflicts in Colorado increased over time and will likely continue to increase, we suggest wildlife managers improve data collection by obtaining detailed location data, categorizing conflict types uniformly, and applying conflict regulations consistently to strengthen inference of similar analyses. We also suggest that managers target efforts to mitigate damage by focusing on areas with high clustering of conflicts.