From the Cover: Rocky Mountain subalpine forests now burning more than any time in recent millennia

The 2020 fire season punctuated a decades-long trend of increased fire activity across the western United States, nearly doubling the total area burned in the central Rocky Mountains since 1984. Understanding the causes and implications of such extreme fire seasons, particularly in subalpine forests that have historically burned infrequently, requires a long-term perspective not afforded by observational records. We place 21st century fire activity in subalpine forests in the context of climate and fire history spanning the past 2,000 y using a unique network of 20 paleofire records. Largely because of extensive burning in 2020, the 21st century fire rotation period is now 117 y, reflecting nearly double the average rate of burning over the past 2,000 y. More strikingly, contemporary rates of burning are now 22% higher than the maximum rate reconstructed over the past two millennia, during the early Medieval Climate Anomaly (MCA) (770 to 870 Common Era), when Northern Hemisphere temperatures were ∼0.3 °C above the 20th century average. The 2020 fire season thus exemplifies how extreme events are demarcating newly emerging fire regimes as climate warms. With 21st century temperatures now surpassing those during the MCA, fire activity in Rocky Mountain subalpine forests is exceeding the range of variability that shaped these ecosystems for millennia.

The 2020 fire season punctuated a trend of increasing wildfire activity throughout the 21st century across the western United States (“the West”). This trend is well-linked to increasingly fire-conducive climate conditions (1) and anthropogenic climate change (2), and it is coming with devastating human impacts (3).Across different ecosystems and regions of the West, the causes of increasing fire activity vary (4–6), and thus so too do potential management and policy solutions (7, 8). Over a century of policies have limited Indigenous fire stewardship and emphasized fire suppression, leading to significant fire deficits in low- and mid-elevation forests that historically burned frequently in low-intensity surface fires (9, 10). This differs from high-elevation subalpine forests, where fire history records show that large, stand-replacing fires typically burned once every one to several centuries over recent millennia (11–17). Continued 21st century warming in these high-elevation forests is predicted to increase fire activity beyond the historical range of variability (18, 19). Detecting if and when such changes emerge, however, and understanding the magnitude of ongoing change requires placing contemporary burning in the context of the past.Here, we use a unique network of paleofire records spanning the past 2,000 y to test the hypothesis that 21st century climate change has led to unprecedented fire activity in Rocky Mountain subalpine forests. These high-elevation forests are useful sentinels of climate change impacts because their typically cool, moist climate limits frequent fire, and they have historically experienced less land-use change and fire suppression than lower-elevation forests. To place late 20th and 21st century wildfire activity in a millennial-scale context, we draw on existing tree-ring and lake sediment records of fire history from subalpine forests in a ∼30,000 km² region in the central Rocky Mountains of Colorado and Wyoming (Fig. 1A), similar in size to the Greater Yellowstone Ecosystem.Open in a separate windowFig. 1.Wildfire and climate in the central Rocky Mountains. (A) Central Rocky Mountains (“Ecoregion”) and focal study area, with fire perimeters from 1984 to 2019 (thin, light red lines) and 2020 (thick, dark red lines; see also SI Appendix, Fig. S3). The 20 lakes with published paleofire records are shown with white circles; lakes recording fire events during the early MCA, c. 770 to 870 CE, are shown in red. The general locations of published tree-ring–based stand-age and fire-scar records used to reconstruct fire extent are shown with black plus symbols; the geographic extent represented by each study exceeds the extent of the symbols. (B) Ecoregion-wide area burned for fire perimeters displayed in A and average May to September VPD. Percentages above red bars are the proportion of total area burned (from 1984 to 2020) contributed by the given year.     

Modeling the effect of facial topographies upon the visual field of humans and primates

Purpose:  To establish a virtual device that can predict the effect of facial features on the visual field of humans and primates.
Methods:  Virtual masks were obtained from human subjects, and macaque, chimpanzee and baboon taxidermic specimens, and aligned with upright head orientation at the center of a virtual perimeter-like dome (radius = 50 m) developed with Cinema 4D. Virtual searchlights positioned at the masks' pupils were then allowed to 'paint' facial elements obstructing their path, and demarcate the unobstructed rays at the perimetric surface and on a virtual ground floor related to eye level. Searchlight positions along the human mask's pupillary axis were identified by maximum congruence to Goldmann visual field limits.
Results:  The human contours largely concur with large-stimulus isopters displaying the limiting role of the nasal ridge, and the relatively extended ventral and temporal limits. In contrast, the facial design of chimpanzees and baboons obstructs significant portions of the ventral foreground (>2 m cf < 0.5 m in human), while there appear to be larger binocular overlaps (125° in chimp cf 90° in human).
Conclusions:  The model provides information on anatomical constraints for monocular and binocular visual field extensions including projection of the ventral field on a virtual floor.     

云南省横断山区柏氏禽刺螨种群生态学研究

目的了解云南省横断山区柏氏禽刺螨的地域及生境分布、优势宿主及其种群空间分布格局等。方法选取云南省5个地理小区中的28个县（市）进行现场调查，每个小区按室内和室外两种生境诱捕小兽并采集体表革螨，70％乙醇固定，Hoyer液封片后于光学显微镜下鉴定种类。用负二项分布吲直、聚块性指标m^＊／m、Taylor幂法则和Iwao模型法综合分析柏氏禽刺螨的空间格局。结果在捕获的11560只小兽（隶属于3目4科8属15种）体表共采集到柏氏禽刺螨3339只，28个县（市）中有21个县（市）采集到该螨，主要分布于西南区（占90％以上），室内（2914只，占87．27％）明显高于室外（425只，占12．73％）。在15种宿主中，90％的柏氏禽刺螨寄生于褐家鼠和黄胸鼠体表，为该螨的优势宿主。经聚集强度指标测定和回归分析均判定该螨为聚集分布。结论柏氏禽刺螨是云南省境内的广布种，主要寄生于褐家鼠和黄胸鼠等家鼠体表，其在主要宿主动物之间的分布呈聚集分布格局。     

Evidence that chytrids dominate fungal communities in high-elevation soils

Periglacial soils are one of the least studied ecosystems on Earth, yet they are widespread and are increasing in area due to retreat of glaciers worldwide. Soils in these environments are cold and during the brief summer are exposed to high levels of UV radiation and dramatic fluctuations in moisture and temperature. Recent research suggests that these environments harbor immense microbial diversity. Here we use sequencing of environmental DNA, culturing of isolates, and analysis of environmental variables to show that members of the Chytridiomycota (chytrids) dominate fungal biodiversity and perhaps decomposition processes in plant-free, high-elevation soils from the highest mountain ranges on Earth. The zoosporic reproduction of chytrids requires free water, yet we found that chytrids constituted over 70% of the ribosomal gene sequences of clone libraries from barren soils of the Himalayas and Rockies; by contrast, they are rare in other soil environments. Very few chytrids have been cultured, although we were successful at culturing chytrids from high-elevation sites throughout the world. In a more focused study of our sites in Colorado, we show that carbon sources that support chytrid growth (eolian deposited pollen and microbial phototrophs) are abundant and that soils are saturated with water for several months under the snow, thus creating ideal conditions for the development of a chytrid-dominated ecosystem. Our work broadens the known biodiversity of the Chytridomycota, and describes previously unsuspected links between aquatic and terrestrial ecosystems in alpine regions.     

烧伤创面细菌生态和抗生素治疗

The main factors influencing the bacterial ecology on burn wound are the selection of antibacterial agents and systemic antibiotic. Some antibacterial agents more active against P. aeruginosa were developed in 1960s,and the detection rate of P. aeruginosa on burn wound has been declined, and the detection rate of Enter obacter iaceae species and Acineto bacter SPP. has been raised since then. In 1990s,the third generation Cephalospor in was widely used in burn unit and the detection rate of staphylococcuse aureus showed an increased trend. Especially, the positive rate of MRSA was increased significantly. Under the selection pressure of antibacterial agent, the resistant strains are rapidly increased and the antibiotics against opportunistic pathogen on burn wound should be selected continuously. Finally, the bacterial ecology pattern on burn wound is changing incessantly. The result is that the prevalence of infection of muhi-drug resistance strains and opportunistic pathogen appears on burn wound. In order to optimize the antibiotic therapy, the bacterial ecology pattern on burn wound has to be investigated, and the dominant pathogen including invasive and currently prevailing strains in the burn unit also should always be surveyed. In addition, we also should know the mechanisms of bacterial resistance. The .regular surveillance of antibiotic resistance in the clinical isolates is the most important and valuable for understanding the trend of bacterial resistance. The antibiotic therapy should be decided according to the result of susceptibility tests.     

Great ranging associated with greater reproductive investment in mammals

Most animals must travel to find food, incurring an unavoidable energy and time cost. Economic theory predicts, and experimental work confirms, that within species, increasing the distance traveled each day to find food has negative fitness consequences, decreasing the amount of energy invested in maintenance, repair, and reproduction. Here, we show that this relationship between daily distance traveled and reproductive success is fundamentally different between species and over evolutionary time in many lineages. Phylogenetically controlled analyses of 161 eutherian mammals indicate that, after controlling for body mass, evolutionary increases in the daily distance traveled are associated with corresponding increases in both total fertility (number of offspring per lifetime) and total offspring mass (grams of offspring per lifetime). This suggests that over evolutionary time, increasing travel distance is often part of a strategy for procuring more food energy and not necessarily a response to decreased food availability. These results have important implications for ecological comparisons among species, including assessments of habitat quality based on locomotor behavior.     

Predormancy omnivory in European cave bears evidenced by a dental microwear analysis of Ursus spelaeus from Goyet,Belgium

Previous morphological and isotopic studies indicate that Late Pleistocene cave bear (Ursus spelaeus) diet ranged from mostly vegetarian to omnivory or even carnivory. However, such analyses do not provide information on seasonal diets, and only provide an average record of diet. A dental microwear analysis of 43 young and adult individuals demonstrate that, during the predormancy period, cave bears from Goyet (Late Pleistocene, Belgium) were not strictly herbivorous, but had a mixed diet composed of hard items (e.g., possibly bone), invertebrates (e.g., insects), meat (ungulates, small vertebrates), and/or plant matter (hard mast, seeds, herbaceous vegetations, and fruits). Therefore, our results indicate that cave bears at Goyet were generalist omnivores during the predormancy period, which is consistent with current data on the dietary ecology of extant bears during this season. These data also raise questions about the ecological role and causes of the extinction of cave bears.     

Dousing our inflammatory environment(s): is personal carbon trading an option for reducing obesity – and climate change?

Obesity and climate change are two problems currently challenging humanity. Although apparently unrelated, an epidemiological approach to both shows a similar environmental aetiology, based in modern human lifestyles and their driving economic forces. One way of analysing this is through inflammation (defined as ‘. . . a disturbance of function following insult or injury’) of both the internal (biological) and external (ecological) environments. Chronic, low‐grade, systemic inflammation has recently been shown to accompany obesity, as well as a range of biological pathologies associated with obesity (diabetes, heart disease, some cancers, etc.). This is influenced by the body's inability to soak up excess glucose as a result of insulin resistance. In a broader sense, inflammation is a metaphor for ecological ‘pathologies’, manifest particularly in unnatural disturbances like climate change, ocean acidity, rising temperatures and species extinction, associated with the inability of the world's environmental ‘sinks’ to soak up carbon dioxide (‘carbon resistance’?). The use of such a metaphorical analysis opens the possibilities for dealing with two interdisciplinary problems simultaneously. Strategies for managing climate change, including personal carbon trading, could provide a ‘stealth intervention’ for reducing population levels of obesity by increasing personal energy expenditure and decreasing energy‐dense food intake, as well as reducing the carbon emissions causing climate change.     

Seasonal variation in prevalence of antibody to hantaviruses in rodents from southern Argentina

We conducted a small mammal trapping study to investigate temporal variation in prevalence of infection in hantavirus reservoir populations in the Patagonian Andes mountain range, Rio Negro province, Argentina. Rodent blood samples collected in natural and periurban habitats and at the home of an hantavirus pulmonary syndrome (HPS) case patient were analysed by enzyme-linked immunosorbent assay. Organ tissue samples were tested by polymerase chain reaction (PCR) and nucleotide sequence analysis. Eight species of 1032 rodents were captured in 15 551 trap nights, giving an overall trap success of 6.6%. Hantavirus antibody was detected in 30 of 555 Oligoryzomys longicaudatus (reservoir of Andes virus), three of 411 Abrothrix longipilis, and one of 10 Loxodontomys micropus. Antibody prevalences in O. longicaudatus were 13.7% in spring 1996, 59.3% in summer 1996, 2.1% in autumn 1997, 12.4% in winter 1997 and 3.1% in spring 1997. A much higher antibody prevalence (33%) was found during trapping around the residence of an HPS case patient. Higher prevalences were found in older male O. longicaudatus. There was no apparent correlation of antibody prevalence with rodent population density, or of rodent population density or antibody prevalence with numbers of human cases. For an HPS case that occurred in our study area in 1997, we identified the probable rodent reservoir and likely site of exposure by matching the genetic sequences of virus obtained from a rodent and the HPS case patient.