Mechanisms of Anaerobic Soil Disinfestation: Volatile Fatty Acids Reduce Viability of Athelia (Sclerotium) rolfsii Sclerotia in Acidic Soil Conditions and Have Limited Effects on Endemic Trichoderma spp.

Volatile fatty acids (VFAs), such as acetic and n-butyric acid, released during anaerobic decomposition of organic soil amendments during anaerobic soil disinfestation (ASD) likely play a role in soilborne plant pathogen inoculum suppression. However, research is limited on the direct effects of soil VFA exposure on fungal plant pathogen inoculum, effects on pathogen antagonists such as Trichoderma spp., and the role of soil microbial VFA metabolism on reducing exposure effects. The present study addresses these limitations through a series of studies evaluating the effects of VFA (acetic or n-butyric acid), VFA concentration (4, 8, or 16 mmol/kg soil), soil sterilization by autoclaving, and soil amendment on the viability of Athelia rolfsii (Sclerotium rolfsii) sclerotia post VFA exposure, and soil populations of Trichoderma spp. HCl and water-only controls were included. After 4-days exposure in an acidic, anaerobic environment, sclerotial viability, and colonization by culturable fungi or bacteria were assessed with standard procedures. Greenhouse experiments were similarly conducted to evaluate endemic soil populations of Trichoderma spp. following soil exposure to VFAs and Trichoderma spp. populations assessed with standard soil dilution plating onto semi-selective medium. Sclerotial germination was generally reduced by soil exposure to acetic (35.1% germination) or n-butyric (21.9% germination) acids compared to water (74.3% germination) and HCl (62.7% germination). Germination was reduced as VFA concentration increased from 4 to 8 and 16 mmol/kg (39.5, 29.1, and 16.9%, respectively). In amended soils, there was no difference in sclerotial germination compared to non-amended soils, but in the greenhouse experiment there was a Trichoderma spp. population increase of over 300% in amended soil [3.4 × 106 colony forming units (CFU)/g soil] compared to the non-amended soil (9.6 × 105 CFU/g soil). Soil autoclaving had no effect on sclerotial germination at low VFA concentrations, but sclerotial germination was reduced at higher VFA concentrations compared to non-autoclaved soil. Our results suggest that VFAs contribute to sclerotial mortality in strongly acidic soil environments, and mortality is influenced by VFA components and environment. Antifungal activity is less for acetic acid than for n-butyric, and less in non-sterile soil environments more typical of field conditions than in sterile laboratory conditions.

Relationship between meteoric ¹⁰Be and NO₃⁻ concentrations in soils along Shackleton Glacier, Antarctica

Outlet glaciers that flow through the Transantarctic Mountains (TAM) experienced changes in ice thickness greater than other coastal regions of Antarctica during glacial maxima. As a result, ice-free areas that are currently exposed may have been covered by ice at various points during the Cenozoic, complicating our understanding of ecological succession in TAM soils. Our knowledge of glacial extent on small spatial scales is limited for the TAM, and studies of soil exposure duration and disturbance, in particular, are rare. We collected surface soil samples and, in some places, depth profiles every 5 cm to refusal (up to 30 cm) from 11 ice-free areas along Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet. We explored the relationship between meteoric 10Be and NO3- in these soils as a tool for understanding landscape disturbance and wetting history and as exposure proxies. Concentrations of meteoric 10Be spanned more than an order of magnitude across the region (2.9×108 to 73×108 atoms g−1) and are among the highest measured in polar regions. The concentrations of NO3- were similarly variable and ranged from ∼1 µg g−1 to 15 mg g−1. In examining differences and similarities in the concentrations of 10Be and NO3- with depth, we suggest that much of the southern portion of the Shackleton Glacier region has likely developed under a hyper-arid climate regime with minimal disturbance. Finally, we inferred exposure time using 10Be concentrations. This analysis indicates that the soils we analyzed likely range from recent exposure (following the Last Glacial Maximum) to possibly >6 Myr. We suggest that further testing and interrogation of meteoric 10Be and NO3- concentrations and relationships in soils can provide important information regarding landscape development, soil evolution processes, and inferred exposure durations of surfaces in the TAM.

Using Mobile Phone Data to Understand the Demographic Characteristics and Behavioral Patterns of Park Visitors in a Megacity, Beijing, China

BackgroundUrban parks are important places that allow urban residents to experience nature but are also associated with the risk of exposure to contaminated soil. Local researches on demographic characteristics and population behavior patterns are the basis of soil exposure assessment. The objectives were to determine park visitors’ demographic characteristics and behavioral patterns. MethodsA total of 86 urban parks in Beijing were selected, and mobile phone data were used to quantify the park visits, identify the demographic characteristics of the visitors, and determine the visitors’ stay times. A Kruskal-Wallis test and kernel density estimation were used for difference analysis and to describe the spatial aggregation of visitors, respectively. A random forest model was used to analyze the factors influencing the visitors’ stay times.ResultsVisitor numbers at comprehensive parks and theme parks decreased significantly in winter, whereas seasonal variations in visitor numbers at community parks and country parks were small. Almost half of the visitors to Beijing’s urban parks were foreign visitors, who, unlike local visitors, preferred to visit parks located in the city’s center. Parks were mostly used by males and visitors aged 31–45. Most visitors stayed in the park for 1–2 h, and the distance from a given visitor’s home to the park was the most important factor affecting stay time, contributing 80.65% of the difference in stay time.ConclusionsThis study provides a quantitative analysis of the patterns relating to urban park use by different groups of people. Changes in behavior patterns of different groups of people should be considered when assessing soil exposure.

Regeneration Dynamics on Treefall Mounds and Pits for 10 Years after a Windfall in a Natural Mixed Forest

The treefall mounds and pits resulting from uprooting caused by strong winds is an indispensable microtopography for the regeneration of many tree species through improved light conditions and mineral soil exposure. These microtopographies are expected to become more important because global warming is predicted to increase windstorm frequency. This study aimed to clarify the characteristics of mounds and pits that contribute to the early establishment of major tree species in a natural mixed forest of northern Japan. The 39 tip-up mounds caused simultaneously by a strong typhoon in September 2004 were selected. In 2006, light intensity and soil moisture contents were measured in each mound and pit. Seedlings of all tree species were counted, and in 2014, the height of saplings was measured. The initial seedling density, regardless of tree species, was significantly higher in the pits than on the mound, but the density at the 10-th growing season decreased significantly in the pits and was comparable between the two locations. Intense light conditions favor regeneration of Betula sp. (Betula platyphylla and B. ermanii). In contrast, for Abies sachalinensis and Picea glehnii, the light intensity had a negative effect, so it was concluded that regeneration of conifers would be limited under the condition where strong winds form large gaps.

Quantitative Classification of Desertification Severity for Degraded Aquifer Based on Remotely Sensed Drought Assessment

Natural and anthropogenic causes jointly lead to land degradation and eventually to desertification, which occurs in arid, semiarid, and dry subhumid areas. Furthermore, extended drought periods may cause soil exposure and erosion, land degradation and, finally, desertification. Several climatic, geological, hydrological, physiographic, biological, as well as human factors contribute to desertification. This paper presents a methodological procedure for the quantitative classification of desertification severity over a watershed with degraded groundwater resources. It starts with drought assessment using Standardized Precipitation Index (SPI), based on gridded satellite-based precipitation data (taken from the CHIRPS database), then erosion potential is assessed through modeling. The groundwater levels are estimated with the use of a simulation model and the groundwater quality components of desertification, based on scattered data, are interpolated with the use of geostatistical tools. Finally, the combination of the desertification severity components leads to the final mapping of desertification severity classification.

Testing different remote sensing compositing periods for SOC content extraction in areas across Germany

<p>High spatial and temporal soil information is crucial to analyze soil developments and for monitoring long term changes to avoid soil degradation. A sufficient soil organic carbon (SOC) content is one of the key soil properties to achieve sustainable high productivity of soils, soil health and increased agroecosystem resiliency. For the usage of remote sensing approaches, naturally exposed soils in Germany occur rarely. Mainly agricultural regions can provide areas of exposed soils for short periods of time during a year. The Soil Composite Mapping Processor (SCMaP) is a fully automated approach to make use of per-pixel based bare-soil compositing to overcome the issue of limited soil exposure based on multispectral Landsat (TM 4, ETM 5, ETM+ 7 and OLI 8) imagery for individually determined time periods between 1984 and 2019.</p><p>Due to the high spatial and temporal resolution the SCMaP soil reflectance composites contain a considerable potential to derive detailed soil parameters as the SOC contents of exposed soils to add information to existing soil maps on field scale for areawide applications. Besides the soil reflectance composites several field soil samples provided by different federal authorities build the data base for the SOC modeling. Machine learning (ML) algorithms incl. Partial Least Squares and Random Forest regression with various inputs and set-ups are used and applied for several test areas in Germany. Furthermore, the capabilities of different compositing lengths (5-, 10- and 30-years) to derive spatial SOC contents are tested. The results and the validation of the different ML approaches and compositing lengths will be shown, providing insight into the benefits of this approach.</p>

Prosthetic finger joint infection due to Aspergillus terreus

Fungal periprosthetic joint infections (PJI) are rare but associated with significant mortality. We report a case of a finger PJI secondary to Aspergillus terreus in an immunocompetent patient with soil exposure, successfully treated with surgical debridement and voriconazole. Identification of A. terreus is important because of intrinsic amphotericin B resistance.

Direct and indirect effects of land-use intensity on plant communities across elevation in semi-natural grasslands

Grassland biodiversity is vulnerable to land use change. How to best manage semi-natural grasslands for maintaining biodiversity is still unclear in many cases because land-use processes may depend on environmental conditions and the indirect effects of land-use on biodiversity mediated by altered abiotic and biotic factors are rarely considered. Here we evaluate the relative importance of the direct and indirect effects of grazing intensity on plant communities along an elevational gradient on a large topographic scale in the Eastern Carpathians in Ukraine. We sampled for two years 31 semi-natural grasslands exposed to cattle grazing. Within each grassland site we measured plant community properties such as the number of species, functional groups, and the proportion of species undesirable for grazing. In addition, we recorded cattle density (as a proxy for grazing intensity), soil properties (bare soil exposure, soil organic carbon, and soil pH) and densities of soil decomposers (earthworms and soil microorganisms). We used structural equation modelling to explore the direct and indirect effects of grazing intensity on plant communities along the elevation gradient. We found that cattle density decreased plant species and functional diversity but increased the proportion of undesirable species. Some of these effects were directly linked to grazing intensity (i.e., species richness), while others (i.e., functional diversity and proportion of undesirable species) were mediated via bare soil exposure. Although grazing intensity decreased with elevation, the effects of grazing on the plant community did not change along the elevation gradient. Generally, elevation had a strong positive direct effect on plant species richness as well as a negative indirect effect, mediated via altered soil acidity and decreased decomposer density. Our results indicate that plant diversity and composition are controlled by the complex interplay among grazing intensity and changing environmental conditions along an elevation gradient. Furthermore, we found lower soil pH, organic carbon and decomposer density with elevation, indicating that the effects of grazing on soil and related ecosystem functions and services in semi-natural grasslands may be more pronounced with elevation. This demonstrates that we need to account for environmental gradients when attempting to generalize effects of land-use intensity on biodiversity.

Increased Risk of Legionella Pneumonia as Community-acquired Pneumonia after Heavy Rainfall in 2018 in West Japan

Background: Japan experienced a heavy rainfall event from June 28 to July 8, 2018, and many casualties were caused by both heavy rainfall and flooding. Few studies have investigated patients’ characteristics and causative pathogens of community-acquired pneumonia before and after heavy rainfall events. The aim of the present study was to evaluate the causative pathogens and clinical characteristics of hospitalised patients with community-acquired pneumonia before and after the heavy rainfall event using prospective cohort data.Methods: The study was divided into two periods: July to November 2013-2017 (pre heavy rainfall) and July to November 2018 (post heavy rainfall). The patients’ clinical characteristic and causative pathogens before and after the heavy rainfall were investigated. Regarding the causative pathogens, precipitation and seasonal patterns were adjusted.Results: There were no significant differences in the number and clinical characteristics of patients pre and post heavy rainfall. However, the frequency of Legionella pneumonia was significantly higher after than before the heavy rainfall event (8.9% vs 3.0%, P = 0.02) and remained significant after adjusting for precipitation and season. Three of 7 Legionella pneumonia patients engaged in reconstruction work and 2 Legionella pneumonia patients had soil exposure.Conclusions: An increased risk of Legionella pneumonia after not only rainfall and serious flooding, but also following recovery work or soil exposure should be considered. Trial registration: A prospective epidemiological study for patients with pneumonia in a single center in Japan, UMIN000004353. Registered 7 October 2010, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000005195