Stratigraphic Studies of the Winter Snow Layer, Mount Logan, St. Elias Range

A traverse of King Trench, which rises from Upper Ogilvie Glacier (2300 m) to King Col (4500 m) a distance of 16 km, Yukon Territory, was made for US Army CRREL, June 1965, to see if techniques of stratiographic analysis of snow and firn could be successfully applied to studies of the alpine climate, as they have been on the Greenland ice sheet, Data on near-surface snow accumulation, temperature and density from eight pits along the traverse provide a climatological model which relates the variations in snow properties to localized topographic obstruction or enhancement of katabatic air drainage. Limited conclusions suggest directions for future study rather than for application to other large ranges or even other parts of St.Elias Range: topography may be the most important control in determining the areal distribution of near-surface climatic elements in mountains; extrapolation of climatological parameters to mountain slopes from nearby valley stations or free-air soundings is not a valid approach: analysis of pertinent stratiographic parameters of the alpine snow pack may be a useful approach to study of local mountain climates.Études stratigraphiques de la couche de neige hivernale, Mont Logan, chaîne de Saint-Élie. Les auteurs présentent les résultats d'une étude par cheminement des propriétés de la neige infra-superficielle, dans la zone de la King Trench, sur le mont Logan, chaîne de Saint-Élie. En supposant que ces propriétés de la neige sont liées aux processus thermodynamiques agissant pendant la période de déposition, les auteurs proposent un modèle climatologique de la King Trench qui relie les variations observées dans les propriétés de la neige le long du cheminement à une augmentation ou une rétention topographique localisée de l'écoulement catabatique de l'air. Les auteurs supposent qu'au voisinage de la surface des pentes couvertes de neige, le climat peut généralement être partiellement déduit de l'interaction entre la topographie locale et l'écoulement catabatique de l'air

That Indian rag : two step intermezzo

https://digitalcommons.library.umaine.edu/mmb-vp/2580/thumbnail.jp

IBMR Updating to IBMR 2008

The last version of Indus Basin Model Revised (IBMR) is based on data from 2000 (primarily the Agricultural Statistics of Pakistan and water-related data from the Water and Power Development Authority [WAPDA]) and earlier farm surveys (for example, 1976 XAES Survey of Irrigation Agriculture and the Farm Re-Survey in 1988 as part of the Water Sector Investment Planning Study [WSIPS])

The Current Water and Agriculture Context, Challenges, and Policies

Surveys the current policy environment for addressing water and agricultural issues in a changing climate, which is shaped by economic development plans at the national and provincial levels, sector plans for water and agriculture (from long-term, multi-decade plans to medium-term, annual plans), and recent cross-cutting policy documents on climate change. Key challenges include (1) limited water storage, (2) problematic trends in surface water and groundwater use, (3) inflexible and uncertain water allocation institutions, and (4) low water-use efficiencies and productivity. Water and agricultural policy challenges arise as provincial development plans continue to focus on the role of infrastructure in water and food security. Recent policy documents highlight the increasing importance of improving irrigation efficiency, improvement of yields, and the socioeconomic distribution of development opportunities and benefits—including food security—but planning documents and budgets do not always comprehensively address the linkages between water management and productivity of the agriculture sector

The Way Forward

Draws together findings from the chain of analyses on Pakistan's Indus Basin, distinguishing between the relative significance of different scenarios, impacts, and adaptations, and highlighting recommendations for research, planning, and policies that can help expand the range of options for Indus Basin management. Key findings include: (1)The 1991 Provincial Water Allocation Accord (DIVACRD) remains a critical hydrologic constraint; (2) Future climate risks will likely impact the macro-economy and households; (3) Non-farm household incomes will suffer more due to increased crop prices; (4) An increase in basin-wide storage will increase the hydropower generation and minimize the impacts of extreme events; (5) Different adaptation investments show potential to minimize the impacts of future climate risks and meet food security objectives; (6) Climate change will likely impact future food availability nationwide; and (7) Groundwater depletion in the fresh water area and basin-wide salinity issues will grow worse with no policy intervention

Sensitivity and Scenario Results

Presents the results of various scenarios using models used to study water, climate, agriculture and the economy in Pakistan's Indus Basin, and discusses the policy and investment implications. The water allocations per the 1991 Provincial Accord and within provinces remain the most critical constraint. Relaxing the Accord constraint, and allowing optimal economic allocation between and within provinces, would enhance the ability to manage extreme events by more reliably meeting system-wide demands. A plausible range of climate changes within the next 80 years could see gross domestic product (GDP), Ag-GDP, and household income decrease by 1.1, 5.1, and 2.0 percent, respectively, on an annual basis. Improvements to system-wide efficiency, construction of new storage, and investments in agriculture technologies to increase crop yield could increase production, but without specific interventions, environmental considerations, such as flow to the sea, changes in depth to groundwater, and the overall salinity situation, are projected to worsen

The interplay of fungal and bacterial microbiomes on rainforest frogs following a disease outbreak

Emerging infectious diseases are a serious threat to wildlife populations, and there is growing evidence that host microbiomes play important roles in infection dynamics, possibly even mitigating diseases. Nevertheless, most research on this topic has focused only on bacterial microbiomes, while fungal microbiomes have been largely neglected. To help fill this gap in our knowledge, we examined both the bacterial and fungal microbiomes of four sympatric Australian frog species, which had different population-level responses to the emergence of chytridiomycosis, a widespread disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). We sequenced 16,884 fungal amplicon sequence variants (ASVs) and 41,774 bacterial ASVs. Bacterial communities had higher richness and were less variable within frog species than were fungal communities. Nevertheless, both communities were correlated for both ASV richness and beta diversity (i.e., frogs with similar bacterial richness and community composition tended to also have similar fungal richness and community composition). This suggests that either one microbial community was having a large impact on the other or that they were both being driven by similar environmental factors. For both microbial taxa, we found little evidence of associations between Bd (prevalence or intensity) and either individuals' ASVs or beta diversity. However, there was mixed evidence of associations between richness (both bacterial and fungal) and Bd, with high richness potentially providing a protective effect. Surprisingly, the relative abundance of bacteria that have previously been shown to inhibit Bd was also positively associated with Bd infection intensity, suggesting that a high relative abundance of those bacteria provides poor protection against infection

microDecon: a highly accurate read‐subtraction tool for the post‐sequencing removal of contamination in metabarcoding studies

Contamination is a ubiquitous problem in microbiome research and can skew results, especially when small amounts of target DNA are available. Nevertheless, no clear solution has emerged for removing microbial contamination. To address this problem, we developed the R package microDecon (https://github.com/donaldtmcknight/microDecon), which uses the proportions of contaminant operational taxonomic units (OTUs) or amplicon sequence variants (ASVs) in blank samples to systematically identify and remove contaminant reads from metabarcoding data sets. We rigorously tested microDecon using a series of computer simulations and a sequencing experiment. We also compared it to the common practice of simply removing all contaminant OTUs/ASVs and other methods for removing contamination. Both the computer simulations and our sequencing data confirmed the utility of microDecon. In our largest simulation (100,000 samples), using microDecon improved the results in 98.1% of samples. Additionally, in the sequencing data and in simulations involving groups, it enabled accurate clustering of groups as well as the detection of previously obscured patterns. It also produced more accurate results than the existing methods for identifying and removing contamination. These results demonstrate that microDecon effectively removes contamination across a broad range of situations. It should, therefore, be widely applicable to microbiome studies, as well as to metabarcoding studies in general

Infection dynamics, dispersal, and adaptation: understanding the lack of recovery in a remnant frog population following a disease outbreak

Emerging infectious diseases can cause dramatic declines in wildlife populations. Sometimes, these declines are followed by recovery, but many populations do not recover. Studying differential recovery patterns may yield important information for managing disease-afflicted populations and facilitating population recoveries. In the late 1980s, a chytridiomycosis outbreak caused multiple frog species in Australia's Wet Tropics to decline. Populations of some species (e.g., Litoria nannotis) subsequently recovered, while others (e.g., Litoria dayi) did not. We examined the population genetics and current infection status of L. dayi, to test several hypotheses regarding the failure of its populations to recover: (1) a lack of individual dispersal abilities has prevented recolonization of previously occupied locations, (2) a loss of genetic variation has resulted in limited adaptive potential, and (3) L. dayi is currently adapting to chytridiomycosis. We found moderate-to-high levels of gene flow and diversity (Fst range: <0.01-0.15; minor allele frequency (MAF): 0.192-0.245), which were similar to previously published levels for recovered L. nannotis populations. This suggests that dispersal ability and genetic diversity do not limit the ability of L. dayi to recolonize upland sites. Further, infection intensity and prevalence increased with elevation, suggesting that chytridiomycosis is still limiting the elevational range of L. dayi. Outlier tests comparing infected and uninfected individuals consistently identified 18 markers as putatively under selection, and several of those markers matched genes that were previously implicated in infection. This suggests that L. dayi has genetic variation for genes that affect infection dynamics and may be undergoing adaptation

Response of a structure to an explosive-generated ground shock

Measurements were made of ground accelerations and the resulting building accelerations at a point very near a large quarry blast. It is shown that, in the case of simple buildings, the building acceleration may be calculated with satisfactory accuracy from a knowledge of the ground acceleration. The response of the test building to the ground acceleration of a typical strong-motion earthquake was computed, and it was found that the resulting accelerations were in excess of those usually provided for in earthquake-resistant design. It is concluded that the satisfactory performance of well-designed structures during strong earthquakes may have two explanations: first, that vibration energy is dissipated by stresses in excess of the elastic limit, with the result that hidden damage may occur; and second, that ordinary buildings may have sources of strength which are not taken into account in their design