Effect of biodegradable poly-3-hydroxybutyrate amendment on the soil biochemical properties and fertility under varying sand loads

Background: Poly-3-hydroxybutyrate (P3HB) is a bacterial intracellular carbon and energy storage polymer, used as a thermoplastic polyester in a wide array of industrial and agricultural applications. However, how the soil microbiome and fertility are altered by exogenously applied P3HB has been relatively unexplored. This study aimed to assess the effects of P3HB addition to nutrient restricted soil: its biological properties and lettuce (Lactuca sativa L. var. capitata L.) biomass production. The experiment was designed to evaluate impacts of spatial arrangement of the relatively organic-rich (soil organic matter, P3HB particles) versus poor fractions of the matrix with confounding factors such as variable microbial biomass, inherent nutrient/energy status, different water relations (due to variable hydrophysical properties of soil augmented by sand at different ratios). Results: The results revealed that P3HB in soils induced inconsistent to contradictory changes in the microbial abundance as well as in most enzymatic activities. The differences were conditioned by the sand content both under P3HB presence or absence. On the other hand, dehydrogenase, urease activities, basal and substrate-induced soil respirations were mostly enhanced by P3HB addition, directly with increasing sand content (several respiration types). Nevertheless, P3HB significantly inhibited lettuce biomass production. Conclusions: P3HB introduction to soil boosts the microbial activity owing to the preferential utilization of P3HB as C source, which depletes soil N and strongly inhibits the plant growth. Enhanced microbial activity in P3HB-amended soils with high sand content (60-80%) suggested that in nutrient-impoverished soil P3HB can temporarily replace SOM as a C source for microbial communities due to the shift of their structure to preferentially P3HB-degrading microbiome

Human activities and biodiversity opportunities in pre-industrial cultural landscapes: relevance to conservation

1. Conservation practices in Europe frequently attempt to perpetuate or mimic the ‘traditional’ forms of management of semi-natural habitats, but with a limited understanding of what these entailed. 2. We review the emerging understanding of ecological processes, structures and management interventions that enhance biodiversity (wildlife) at diverse scales. These are then examined in the context of pre-industrial (c. 1200-1750) land management systems in lowland England, in order to identify historic practices which are likely to have provided important wildlife resources, but which are relatively neglected in current conservation management. 3. Principles enhancing alpha and beta diversity and the conservation status of threatened species, include: structural complexity and heterogeneity at nested spatial scales; physical disturbance and exposure of mineral substrate; nutrient removal; lengthened successional rotations; and spatial variation in grazing regimes. 4. The available evidence suggests that pre-industrial management was generally characterised by: intense resource exploitation and significant levels of biomass harvest; complex nested structural heterogeneity both between and within landscape elements; overlaying of multiple land-uses; and spatial and temporal variability in management, rendering the concept of long-lived ‘traditional’ practice problematic. Grazing patterns are poorly understood but intensive grazing was probably the norm in most contexts, potentially resulting in simplified sward structures and suppressed ecotonal vegetation. 5. In much of the pre-industrial period, early-successional and disturbed microhabitats were widespread but ungrazed or lightly grazed herb-rich vegetation may have been limited, the converse of current conservation management. The key change since then has been homogenisation at multiple scales, coupled with reduction of specific niches and conditions. 6. Synthesis and applications: In adopting perceived ‘traditional’ management practices, modern conservation rarely achieves the range and complexity of conditions that were present in the past. A better understanding of past practices allows more favourable management of those surviving semi-natural habitats where historic assemblages persist – with greater emphasis on physical disturbance and variability in prescriptions both temporally and spatially. When creating or restoring habitats, after interruption of management sufficiently long for dependent assemblages to be lost, better appreciation of historic management encourages novel forms of intervention to enhance biodiversity, with emphasis on complex structural and spatial heterogeneity at nested scales, biomass removal and nutrient reduction. These two distinct but overlapping approaches are complementary to the use of large herbivores to create and maintain dynamic ecotonal mosaics in the manner advocated by some proponents of ‘rewilding’

GPAW: open Python package for electronic-structure calculations

We review the GPAW open-source Python package for electronic structure calculations. GPAW is based on the projector-augmented wave method and can solve the self-consistent density functional theory (DFT) equations using three different wave-function representations, namely real-space grids, plane waves, and numerical atomic orbitals. The three representations are complementary and mutually independent and can be connected by transformations via the real-space grid. This multi-basis feature renders GPAW highly versatile and unique among similar codes. By virtue of its modular structure, the GPAW code constitutes an ideal platform for implementation of new features and methodologies. Moreover, it is well integrated with the Atomic Simulation Environment (ASE) providing a flexible and dynamic user interface. In addition to ground-state DFT calculations, GPAW supports many-body GW band structures, optical excitations from the Bethe-Salpeter Equation (BSE), variational calculations of excited states in molecules and solids via direct optimization, and real-time propagation of the Kohn-Sham equations within time-dependent DFT. A range of more advanced methods to describe magnetic excitations and non-collinear magnetism in solids are also now available. In addition, GPAW can calculate non-linear optical tensors of solids, charged crystal point defects, and much more. Recently, support of GPU acceleration has been achieved with minor modifications of the GPAW code thanks to the CuPy library. We end the review with an outlook describing some future plans for GPAW

Vyhodnocení plodnosti raka signálního včetně post-ovulačního stavu vaječníků

The theoretical part of diploma thesis is aimed at breeding, growth and molting events in crayfish. Thesis is also aimed at life cycle and reproduction of three indigenous crayfish species (Astacus astacus, Austropotamobius torrentium, Pontastacus leptodactylus) and two introduced crayfish species (Faxonius limosus, Pacifastacus leniusculus). The results show apparent linear dependence between female size (POCL), abdomen surface (1M: y = -1061,2 + 65,4*x; r2 = 0,9829; p10-5; 2M: y = -1160,4 + 68,7*x; r2 = 0,8732; p < 10-5) and fertility (1M: y = -194,4 + 12,8*x; r2 = 0,4104 p = 0,0042; y = -330.9 + 15,9*x; r2 = 0.4372; p < 10-4) in once (1M) and twice (2M) molted females. As the length of carapax increase, the area of the abdomen increase and fertility increase in both groups of females. Furthermore, the differences in fertility, carapax length, abdomen surface, and weights in once and twice molted females of signal crayfish. In group of once molted females fertility (t-test, t = -3.12, p = 0.003), carapax length (t-test, t = -3.17, p = 0.003) = -3.24; p = 0.002) and the weight (t-test, t = -3.35; p = 0.002) was higher than in twice molted group of female. Consequentially evaluation of egg size of females. The size of the eggs did not differ between groups of females (1M and 2M) (t-test, t = -0.975, p = 0.335). The mean egg size for both groups of females was 2.71 ? 0.18 mm. Evaluation of post-ovulation conditions of the ovary, including visible signs of females that resorbed unovulated oocytes. Evaluating how much unovulated oocytes were found in the ovaries. Only in 46.4% of the total number of females were ovaries completely empty. In once and twice molted females were found in average 2.2 ? 3.8 and 1.9 ? 2.6. unovulated oocytes, respectively. In once molted, three females didn't lay eggs, two females lost the clutch of eggs. In twice molted females, six females did not lay the eggs and four females lost the clutch

Embryonic and postembryonic development of marbled crayfish in different temperatures

The aim of this bachelor thesis was to characterise the life cycle by parthenogenetic reproduction of marbled crayfishProcambarus fallax f. virginalis and to focus on the effects of its life cycle at different temperatures. The theoretical part of this thesis is focused on the reproductive biology of crayfish, with emphasis on embryonic and postembryonic development of marbled crayfish. It also acquaints us with the reproduction of indigenous crayfish and introduced crayfish species occurring in the territory of the Czech Republic. The practical part acquaints us with the conditions that need to be adhered during the experiment, changes in embryo development and assessing embryo development at different temperatures. Our experiment confirmed that the postembryonic stages of marbled crayfish were able to survive at low temperature (10 °C). Individuals were able to undergo the first postembryonic stadium at the lower temperature, but they developed slowly. Individuals develop without problems at 15 °C. The duration of postembryonic development was a little bit longer than in warmer temperature. There were expectations that the highest survival rate would be at higher temperatures, but our experiment showed that our predictions were false. Temperature of 20 °C was shown as the lowest survival rate, but we suspect that this poor result wasn't caused by the effect of water temperature, but rather by other physical-chemical water parameters which were not controlled. The highest survival rate of embryos in our experiment was at 15 °C. This thesis deals with the prediction of survival rates of marbled crayfish in the Czech Republic as written in the scientific literature and the obtained results refer to the ability in hatched individuals of marbled crayfish to tolerate the natural conditions of low temperatures in the Czech Republic