Long-term tropical cyclones activity shapes forest structure and reduces tree species diversity of U.S. temperate forests

Increasing tropical cyclone (TC) pressure on temperate forests is inevitable under the recent global increase of the intensity and poleward migration of TCs. However, the long-term effects of TCs on large-scale structure and diversity of temperate forests remain unclear. Here, we aim to ascertain the legacy of TCs on forest structure and tree species richness by using structural equation models that consider several environmental gradients and use an extensive dataset containing >140,000 plots with >3 million trees from natural temperate forests across eastern United States impacted by TCs. We found that high TC activity (a combination of TC frequency and intensity) leads to a decrease in maximum tree sizes (height and diameter), an increase in tree density and basal area, and a decline in the number of tree species and recruits. We identified TC activity as the strongest predictor of forest structure and species richness in xeric (dry) forests, while it had a weaker impact on hydric (wet) forests. We highlight the sensitivity of forest structure and tree species richness to impacts of likely further increase of TC activity in interaction with climate extremes, especially drought. Our results show that increased TC activity leads to the homogenization of forest structure and reduced tree species richness in U.S. temperate forests. These findings suggest that further declines in tree species richness may be expected because of the projected increase of future levels of TC activity.

Snowpacks decrease and streamflows shift across the eastern US as winters warm

Climate change is increasing winter temperatures across the planet, altering snowmelt hydrology. This study addresses a gap in snow research in non-alpine areas by examining changes to snow and winter and spring streamflow across most of the eastern US using daily observations from weather stations and stream gages from water years 1960-2019. These daily data were aggregated across drainage basins and classified winters with similar temperatures; differences between winters and both seasonal and annual trends were statistically quantified. Winters were classified as "warm" or "cool" in each drainage basin relative to the 60-year mean; analysis of the data indicates that warm winters occur more frequently in recent decades from an average of 0.39 to 3.96 warm winters/decade from the 1960's to the 2010's respectively. Those classifications were then used to examine changes in snowpack over the same period, which shows that warmer winters have on average 50.1 cm less annual snowfall, a reduced maximum snowpack depth by 14.4 cm, and 34 more bare ground days. These changes correlate with shifts to higher winter streamflows as well as peak basin yields that are 0.02 cm lower and occur three days earlier in warm winters. In addition to altered soil moisture and stream ecosystem dynamics, these snow and streamflow changes may have negative infrastructure and economic implications including impacts to winter tourism and agriculture.

What Happened to Paul? Manifestation of Abnormal Pain Response for Individuals With Autism Spectrum Disorder

During the progression of a pilot nutrition intervention designed to teach cooking skills to young adults with autism spectrum disorder (ASD), one participant-Paul-fell in the parking lot. Prior to the accident, Paul had been making significant gains in the program and had communicated in a number of ways his enthusiasm. After his accident, which resulted in broken and dislocated bones in his ankle, his demeanor was dramatically altered, program gains were lost, and staff noted the appearance of many new challenging behaviors. This article analyzes Paul's behavior in reference to the pain response in autism. For some time, it was believed that many individuals with ASD did not experience pain based on anecdotal reports of how individuals responded to injury with seeming indifference. This view has given way of late to a more nuanced understanding of how atypical sensory processing and stimulus over-selectivity spill over into pain pathways and pain amplification mechanisms. The consequence is not a reduction in pain sensation, but a different expression of pain, determined by that individual's particular communicative, cognitive, or physiological challenges. From this perspective, many of the disruptive and harmful behaviors that emerged after Paul's accident can be seen as a delayed response to the incident. This article concludes by arguing that professionals across all domains of health care need to begin to see behavior as communicative for those with ASD. This is particularly true of changes in behavior, which can be significant indicators of health care problems rather than something to be dismissed as another manifestation of the condition.

Contributions of regional air pollutant emissions to ozone and fine particulate matter-related mortalities in eastern U.S. urban areas

Ground-level ozone and fine particulate matter (PM2.5) are associated with adverse human health effects such as lung structure dysfunction, inflammation and infection, asthma, and premature deaths. This study estimated contributions of emissions of anthropogenic nitrogen oxides (NOx), volatile organic compounds (VOCs) and sulfur dioxides (SO2) from four regions to summertime (i.e., June, July, and August) ozone and PM2.5-related mortalities in seven major Metropolitan Statistical Areas (MSAs with more than 4 million people) in the eastern United States (U.S.). A photochemical transport model, Community Multi-scale Air Quality (CMAQ) with sensitivity analyses, was applied to quantify the contribution of the regional anthropogenic emissions to ambient ozone and PM2.5 concentrations in the seven MSAs. The results of the sensitivity analysis, along with estimates of concentration-response from published epidemiologic studies, were used to estimate excess deaths associated with changes in ambient daily 8-h average ozone and daily PM2.5 concentrations during the summer of 2007. The results show that secondary PM2.5 (i.e., PM2.5 formed in the atmosphere) had larger effects on mortality (95% confidence interval (C.I.) ranged from 700 to 3854) than ambient ozone did (95% C.I. was 470-1353) in the seven MSAs. Emissions of anthropogenic NOx, VOCs and SO2 from the northeastern U.S. could cause up to about 2500 ozone and PM2.5-related deaths in the urban areas examined in this study. The results also show that the contributions of emissions from electrical generating units (EGUs) and anthropogenic non-EGU sources to ozone-related mortality in the MSAs were similar. However, emissions from EGUs had a more significant impact on PM2.5-related deaths than anthropogenic emissions from non-EGUs sources did. Anthropogenic NOx and VOCs emissions from the regions where the MSAs are located had the most significant contributions to ozone-related mortalities in the eastern U.S. urban areas. On the other hand, PM2.5-related mortalities in the MSAs were more likely to be affected by precursors transported from other regions.

Evaluation of a seven-year air quality simulation using the Weather Research and Forecasting (WRF)/Community Multiscale Air Quality (CMAQ) models in the eastern United States

The performance of the Weather Research and Forecasting (WRF)/Community Multi-scale Air Quality (CMAQ) system in the eastern United States is analyzed based on results from a seven-year modeling study with a 4-km spatial resolution. For 2-m temperature, the monthly averaged mean bias (MB) and gross error (GE) values are generally within the recommended performance criteria, although temperature is over-predicted with MB values up to 2K. Water vapor at 2-m is well-predicted but significant biases (>2 g kg(-1)) were observed in wintertime. Predictions for wind speed are satisfactory but biased towards over-prediction with 0<MB<0.5 m s(-1) and root mean square error (RMSE) around 1.5 to 2 m s(-1). Wind direction, predicted without observation nudging, is not well-reproduced with GE values as large as 50° in summertime. Performance in other months is better with RMSE around 20-30° and MB within ± 10°. O3 performance meets the EPA criteria of mean normalized bias (MNB) within ± 0.15 and accuracy of unpaired peak (AUP) within 0.2. Normalized gross error (NGE) is mostly below 0.25, lower than the criteria of 0.35. Performance of PM10 is satisfactory with mean fractional bias (MFB) within ± 0.6, but a large under-prediction in springtime was frequently observed. Performance of PM2.5 and its components is mostly within performance goals except for organic carbon (OC), which is universally under-predicted with MFB values as large as -0.8. The predicted frequency distribution of PM2.5 generally agrees with observations although the predictions are slightly biased towards more frequent high concentrations in most areas. Elemental carbon (EC), nitrate and sulfate concentrations are also well reproduced. The other unresolved PM2.5 components (OTHER) are significantly overestimated by more than a factor of two. No conclusive explanations can be made regarding the possible cause of this universal overestimation, which warrants a follow-up study to better understand this problem.