Технологічне забезпечення виробничої потужності марганцевих кар’єрів при змінному попиті на рудну сировину

Запропонована технологічна схема, в якій розкривні уступи перерозподіляються по висоті у межах певної потужності розкриву при заданій продуктивності кар’єру, а верхній та нижче розташований уступи об’єднані та відробляються транспортно-відвальним способом, для чого у внутрішньому відвалі створюється додаткова приймальна ємність. Набула подальшого розвитку методика розрахунку виробничої потужності кар’єру. Удосконалено метод вибору комплексів технологічного устаткування для слабкостійких обводнених порід, де враховується коефіцієнт запасу стійкості укосів внутрішнього відвалу.The technological flow chart in which stripping bench are redistributed on a height within the limits of certain power of overburden at the set productivity of quarry is offered. It is proposed to merge overhead and below located benches and work out them by transport-dump method, for what an additional receiving capacity is created in an internal dump. The computational procedure of quarry production capacity is obtained the further development. The method of choice of complexes of technological equipment for weak-steady and watered rocks is improved. The coefficient of slope stability margin of internal dump is considered in this method

Greksza Veronika - Mohay Ágoston: Bevezetés az Európai Unió jogába

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Speeding up the snail’s pace : bird-mediated dispersal of aquatic organisms

Contains fulltext : 93702.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 27 juni 2012Promotores : Groenendael, J.M. van, Klaassen, M. Co-promotor : Velde, G. van der175 p

Regurgitation by waterfowl: An overlooked mechanism for long-distance dispersal of wetland plant seeds

Abstract Birds commonly regurgitate indigested particles after foraging. Many frugivorous birds regurgitate seeds ingested with the flesh of fruits, which importantly contributes to plant dispersal in terrestrial ecosystems. In freshwater ecosystems, waterbirds are known to defecate viable seeds in their faeces, but little is known about regurgitation as a potential additional seed dispersal mechanism. We experimentally fed eight mallards (Anas platyrhynchos) with a high and low volume of seeds of ten wetland plant species, and monitored regurgitation and defecation of intact seeds over 24 h. Regurgitation occurred at least once in all individual mallards and was induced by two different mechanisms: i) feeding of high food volumes was significantly associated with regurgitation of all seed species from the crop after retention times of 1-3 h, and ii) large indigestible seeds were expelled from the gizzard 11 or more hours after feeding. Seed regurgitation was much less plant species-specific than survival of seeds passing digestion, which suggests it is a particularly suitable dispersal mechanism for plant species unable to disperse by endozoochory (such as plant species with large, soft-bodied seeds). Observations of regurgitation by wild waterbirds are needed to improve our knowledge on this additional role of waterbirds in ecosystem functioning

Prerequisites for flying snails: external transport potential of aquatic snails by waterbirds

The widespread distributions of aquatic species often contrast with their limited ability to disperse by their own propulsion among wetlands isolated by land. Studies of the potential role of water birds as dispersal vectors have been focused mainly on internal transport (endozoochory). However, many anecdotal observations that small species adhere to flying birds also exist (ectozoochory). We addressed the hypothesis that ectozoochory may contribute to the widespread distributions of aquatic snails (Gastropoda) in several experiments. We tested the likelihood that snails would attach to mallards (Anas platyrhynchos) leaving macrophyte vegetation with high densities of 3 snail species. All species tested (Gyraulus albus, Anisus vortex, and Radix balthica) readily attached to the mallards’ bodies. The rate of attachment was proportional to snail density, and the birds’ feathers contained most snails. However, Oof the snails detached when mallards subsequently walked for 3 m. Snails of 12 species attached within minutes to any surroundings available when floating in the water, a result indicating that active crawling onto birds may facilitate dispersal. Snails we attached deliberately to duck bills with mud could remain attached for up to 8 h. We measured desiccation tolerance of 13 common aquatic snail species. Almost all snail species survived 48 h of desiccation at 10 to 20uC. The ability to retain water did not differ between species with an operculum and species that form a mucus layer (epiphragm) in their shell openings. Our experiments indicate that aquatic snails possess a range of prerequisites for successful bird-mediated dispersal, but the capacity of snails (and other propagules) to remain attached during flight and successfully colonize new habitats upon arrival must still be assessed.

Prior knowledge about spatial pattern affects patch assessment rather than movement between patches in tactile-feeding Mallard

1. Heterogeneity in food abundance allows a forager to concentrate foraging effort in patches that are rich in food. This might be problematic when food is cryptic, as the content of patches is unknown prior to foraging. In such case knowledge about the spatial pattern in the distribution of food might be beneficial as this enables a forager to estimate the content of surrounding patches. A forager can benefit from this pre-harvest information about the food distribution by regulating time in patches and/or movement between patches. 2. We conducted an experiment with mallard Anas platyrhynchos foraging in environments with random, regular, and clumped spatial configurations of full and empty patches. An assessment model was used to predict the time in patches for different spatial distributions, in which a mallard is predicted to remain in a patch until its potential intake rate drops to the average intake rate that can be achieved in the environment. A movement model was used to predict lengths of interpatch movements for 3. Consistent with predictions, in the clumped distribution mallard spent less time in an empty patch when the previously visited neighbouring patch had been empty than when it had been full. This effect was not observed for the random distribution. This shows that mallard use pre-harvest information on spatial pattern to improve patch assessment. Patch assessment could not be evaluated for the regular distribution. 4. Movements that started in an empty patch were longer than movements that started in a full patch. Contrary to model predictions this effect was observed for all spatial distributions, rather than for the clumped distribution only. In this experiment mallard did not regulate movement in relation to pattern. 5. An explanation for the result that pre-harvest information on spatial pattern affected patch assessment rather than movement is that mallard move to the nearest patch where the expected intake rate is higher than the critical value, rather than to the patch where the highest intake rate is expected.

Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities

Summary 1.Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination, and how these interactions determine plant community assembly. We hypothesize that a drawdown water regime enhances seed establishment compared to a year-round stable water level, that this increases species richness and diversity, and that this is modulated by species traits and shore morphology. 2.Germination of 20 wetland plant species with different dispersal capacities (floating capacity expressed as seed floatation half-time) and soil moisture preferences for germination (Ellenberg F) was tested on artificial shores in 24 outdoor ponds in two complementary experiments over 8 weeks. The ‘dispersal experiment’ tested the effect of water regime on recruitment of hydrochorously dispersing seeds. The ‘seed bank experiment’ tested the effect of water regime on germination from a sown seed bank, on steep and gradual shores. 3.In the dispersal experiment, the drawdown regime increased recruitment and species richness. Longer floating species colonized a larger shoreline section. Soil moisture preference for germination did not determine colonization patterns. 4.In the seed bank experiment, the drawdown regime increased the number of seedlings on gradual sloping shores, but not on steep shores. The number of germinating seedlings corresponded to the area subjected to the drawdown regime in both shore types. Species richness was not affected by water regime or shore morphology, and species traits did not determine shoreline colonization. Most seeds germinated in moist soil conditions for all species. 5.Synthesis. A spring drawdown instead of stable water regime stimulates establishment of hydrochorously dispersing seeds in temperate wetlands, leading to higher species richness and diversity. Germination from the seed bank is more affected by water regime and shore surface than by the tested species traits. Species traits, water levels and shore morphology together determine wetland plant community assembly, with dispersal as the main driver of seedling community diversity. Water-level regulations and shore morphology can be used to influence plant communities in wetland restoration.