Application of ventsim to low pressure gas drainage and high pressure nitrogen reticulation systems

This paper outlines a methodology employed to apply Ventsim ventilation modelling software to gas drainage and nitrogen injection systems. Use of the software to account for compressible flow, specified gas compositions and the resistance of conduits of various dimensions makes it suitable for both ventilation circuits and gas reticulation systems. Unlike mine ventilation circuits, in gas drainage systems it is necessary to specify flow rates arising from gas pre drainage holes as these are dependent on gas reservoir properties. This requires a mass flow balance to be obtained between underground gas drainage holes and that reporting to surface pump(s). In nitrogen injection systems it is convenient to create an interface between the gas drainage reticulation system and the mine workings which in turn is connected to the ventilation system. However, it is also possible to keep the two systems separate for simplicity and tuning. The results of applying these strategies to an operating gas pre drainage system are described. These provide the “as built” pipe friction factors obtained by matching the model results to observed differential pressures. The Pike River re-entry nitrogen injection system has also been modelled. This uses the same principles as the negative pressure gas drainage models but with high positive pressures of up to 1,000 kPa (10bar)

Comparison of Northern Bobwhite Chick Fecal and Crop Analyses

Impacts of modem agriculture on gamebird brood ecology have been studied in a number of species. One common factor cited has been the decline in available invertebrate food available to foraging chicks. In the United Kingdom, assessment of chick diet has been accomplished mainly through fecal analysis of wild chicks, whereas in North America crop analysis of human-imprinted chicks has become a commonly applied technique. We compared results of both techniques on groups of human-imprinted northern bobwhite (Colinus virginianus) chicks to determine if these different techniques provide similar results. Chicks were allowed to forage in groups of 6-8 in cotton fields with various cover crops. We euthanized half the chicks for crop analysis and isolated the other half of the chicks for 12 hours to collect feces. We found a positive relationship between total number of invertebrates/chick in crops and feces (P = 0.01, R2 = 0.51). However, among important chick-food Orders the relationship varied greatly: Coleoptera (P = 0.10, R2 = 0.34), Homoptera (P \u3c 0.001, R2 = 0.41), and Hymenoptera (P = 0.81, R2 = 0.05). Our results suggest that there is a positive relationship between the 2 techniques, but that composition of the diet relative to what foods might be available in a particular site could be biased. We suggest more detailed research on technique development and standardization of techniques for assessing this important component of bobwhite life history

Linking agri-environment scheme habitat area, predation and the abundance of chick invertebrate prey to the nesting success of a declining farmland bird

1. Across Europe, farmland bird populations have continued to decline since the 1970s owing to the intensification of farming practices. Studies of such declines have tended to focus specifically on either the impacts of habitats (nesting and foraging), nest predators or prey availability on bird demographics. The study presented here provides new insights into the relative effects of each of these factors on Yellowhammer nest survival. The Yellowhammer was selected for this study as it is a UK red-listed bird species whose population is in decline across much of Europe.2. We use a long-term dataset of 147 nests, monitored between 1995 and 2007, to provide an insight into how Yellowhammer nest survival is influenced by nesting habitat (nest concealment and nest height), foraging habitats (habitat coverage within 100 m of nests), the removal of nest predators (Magpie Pica pica abundance as an inverse measure of avian predator removal through gamekeeping) and food availability (measured with a D-vac invertebrate suction sampler). 3. Our results indicated that Yellowhammer hatching success was negatively related to the coverage of spring agri-environment scheme habitats, a group which represents invertebrate-rich agri-environment habitats, but hatching success increased with nest height. Fledging success was positively related to the coverage of the seed-rich habitat Wild Bird Seed mixture. The farm-level abundance of Yellowhammer chick-food invertebrates declined over the study period. 4. Synthesis and application. Our results highlight the importance of simultaneously considering multiple agents that shape avian breeding success, i.e. their ability to produce offspring, to inform conservation management. Our key finding for land managers relates to the positive relationship between the proportion seed rich foraging habitat within the Yellowhammer’s average foraging range and Yellowhammer fledging success, which shows that a habitat intended primarily to provide winter food resources is also important to breeding birds. Chick food abundance in this habitat was, however, similar to broadleaf and cereal crops. We recommend that this habitat should be provided near to potential Yellowhammer nesting sites and adjacent to invertebrate-rich agri-environment scheme habitats such as beetle banks and conservation headlands to further boost invertebrate resources for a declining farmland bird

Daily energy expenditure in the face of predation : hedgehog energetics in rural landscapes

This research was funded by a grant from the People's Trust for Endangered Species and the British Hedgehog Preservation Society.Peer reviewedPublisher PD

Anthropogenically-mediated density dependence in a declining farmland bird

Land management intrinsically influences the distribution of animals and can consequently alter the potential for density-dependent processes to act within populations. For declining species, high densities of breeding territories are typically considered to represent productive populations. However, as density-dependent effects of food limitation or predator pressure may occur (especially when species are dependent upon separate nesting and foraging habitats), high territory density may limit per-capita productivity. Here, we use a declining but widespread European farmland bird, the yellowhammer Emberiza citrinella L., as a model system to test whether higher territory densities result in lower fledging success, parental provisioning rates or nestling growth rates compared to lower densities. Organic landscapes held higher territory densities, but nests on organic farms fledged fewer nestlings, translating to a 5 times higher rate of population shrinkage on organic farms compared to conventional. In addition, when parental provisioning behaviour was not restricted by predation risk (i.e. at times of low corvid activity), nestling provisioning rates were higher at lower territory densities, resulting in a much greater increase in nestling mass in low density areas, suggesting that food limitation occurred at high densities. These findings in turn suggest an ecological trap, whereby preferred nesting habitat does not provide sufficient food for rearing nestlings at high population density, creating a population sink. Habitat management for farmland birds should focus not simply on creating a high nesting density, but also on ensuring heterogeneous habitats to provide food resources in close proximity to nesting birds, even if this occurs through potentially restricting overall nest density but increasing population-level breeding success

Scientific Opinion addressing the state of the science on risk assessment of plant protection products for in-soil organisms

Following a request from EFSA, the Panel on Plant Protection Products and their Residues developed an opinion on the science behind the risk assessment of plant protection products for in-soil organisms. The current risk assessment scheme is reviewed, taking into account new regulatory frameworks and scientific developments. Proposals are made for specific protection goals for in-soil organisms being key drivers for relevant ecosystem services in agricultural landscapes such as nutrient cycling, soil structure, pest control and biodiversity. Considering the time-scales and biological processes related to the dispersal of the majority of in-soil organisms compared to terrestrial non-target arthropods living above soil, the Panel proposes that in-soil environmental risk assessments are made at in- and off-field scale considering field boundary levels. A new testing strategy which takes into account the relevant exposure routes for in-soil organisms and the potential direct and indirect effects is proposed. In order to address species recovery and long-term impacts of PPPs, the use of population models is also proposed