An ‘Advanced Production System’ (APS) dramatically changed soil properties such as pH (P<0.001; panel A) compared to properties in conventional citriculture (CC). Responses by soil organisms to these ...changes included higher infestation rates by the bacterium Paenibacillus sp. on the entomopathogenic nematode Steinernema diaprepesi (P=0.05; panel B), which may have contributed to reduced numbers of infective juveniles (IJs) of native nematodes in APS plots (P=0.01; panel C). Display omitted
•‘Advanced’ system (ACP) modifies soil properties and citrus trees mature earlier.•Native entomopathogenic nematode (EPN) numbers were reduced by ACP.•Higher Paenibacillus sp. infestation rate on S. diaprepesi in APS.•Nematophagous fungal responses to EPNs depended on EPN species.•APS has the potential to exacerbate herbivory by subterranean pests.
Since its first detection in 2005, the bacterial disease huanglongbing (HLB or citrus greening) has emerged as a critical threat to the citrus industry in Florida. An “Advanced Production System” (APS) could mitigate the impact of HLB by bringing citrus trees into production more quickly and economically than conventional citriculture methods. However, unlike conventional practices, APS fertigates plants daily, thereby changing the soil properties in ways that might impact soil biota. We tested the hypothesis that changes to soil properties caused by APS would affect the abundance of native entomopathogenic nematodes (EPNs) and/or the survival of augmented EPNs. The densities of organisms at different trophic levels were measured by real-time qPCR in three experiments conducted in an ongoing field experiment. Target organisms included 6 entompathogenic nematodes, 5 nematophagous fungi (NF) and a phoretic bacterium, Paenibacillus sp. Soil properties, free-living nematodes and citrus fibrous roots were also measured. Compared to soil under conventional citriculture (CC), APS increased soil pH and Mg content, while reducing the electrical conductivity, and content of K, Mn and Fe. The naturally occurring EPN Steinernema diaprepesi was 5times less abundant in APS plots where these nematodes were more heavily encumbered by the phoretic bacterium Paenibacillus sp., which limits the foraging success of EPNs. In general, when EPNs were augmented in either treatment, fewer Steinernema riobrave than Heterorhabditis indica were recovered and recovery of both species declined rapidly over time. As seen with native S. diaprepesi, fewer augmented S. riobrave were recovered from APS plots in two of the three experiments, whereas the management system did not affect the recovery of H. indica. More of some endoparasitic and trapping NF were recovered from soil augmented with S. riobrave than with H. indica. However, variation in the responses of NF to the management systems suggests that these NF species were not primarily responsible for the steinernematid responses to APS. Although APS has the potential to reduce EPN populations and exacerbate herbivory by subterranean pests such as the root weevil Diaprepes abbreviatus, additional study of the physical causes of this effect may reveal ways to avoid the problem.
Ensemble forecasts aim at framing the uncertainties of the potential future development of the hydro-meteorological situation. A probabilistic evaluation can be used to communicate forecast ...uncertainty to decision makers. Here an operational system for ensemble based flood forecasting is presented, which combines forecasts from the European COSMO-LEPS, SRNWP-PEPS and COSMO-DE prediction systems. A multi-model lagged average super-ensemble is generated by recombining members from different runs of these meteorological forecast systems. A subset of the super-ensemble is selected based on a priori model weights, which are obtained from ensemble calibration. Flood forecasts are simulated by the conceptual rainfall-runoff-model ArcEGMO. Parameter uncertainty of the model is represented by a parameter ensemble, which is a priori generated from a comprehensive uncertainty analysis during model calibration. The use of a computationally efficient hydrological model within a flood management system allows us to compute the hydro-meteorological model chain for all members of the sub-ensemble. The model chain is not re-computed before new ensemble forecasts are available, but the probabilistic assessment of the output is updated when new information from deterministic short range forecasts or from assimilation of measured data becomes available. For hydraulic modelling, with the desired result of a probabilistic inundation map with high spatial resolution, a replacement model can help to overcome computational limitations. A prototype of the developed framework has been applied for a case study in the Mulde river basin. However these techniques, in particular the probabilistic assessment and the derivation of decision rules are still in their infancy. Further research is necessary and promising.
Co-occurrence matrix-based textural features were analyzed and three algorithms were developed to identify bare spots, wild blueberry plants, and weeds with the aim of applying agrochemicals to wild ...blueberry cropping fields in a spot-specific manner. Images were acquired using four cameras and a ruggedized laptop with custom-written programs coded in Microsoft Visual® C++. Textural features were extracted from the images using MATLAB® and analyzed with SAS® . Forty-four textural features were extracted from co-occurrence matrices of NTSC luminance (L), hue, saturation, and intensity (HSI) images. Multiple discriminant analysis using all 44 features (DF_ALL model) showed 98.1% of overall classification accuracy and 83 ms of processing time of an image with C++ calculation. Based on the results of multiple discriminant analysis and two-step linear discrimination plotting, the DF_HSI(SD), DF_SI(SD) , and HSI(LD) algorithms are preferred algorithms with overall accuracy of 94.9%, 92.7%, and 91.4%, and processing time of 55, 27, and 29 ms, respectively. Any of three reduced textural feature algorithms can be employed for spot-specific application of agrochemicals in wild blueberry cropping fields. The choice of one algorithm over another will depend on whether processing speed or accuracy is more important for the end-user's application.
As a result of the severe floods in Europe at the turn of the millennium, the ongoing shift from safety oriented flood control towards flood risk management was accelerated. With regard to technical ...flood control measures it became evident that the effectiveness of flood control measures depends on many different factors, which cannot be considered with single events used as design floods for planning. The multivariate characteristics of the hydrological loads have to be considered to evaluate complex flood control measures. The effectiveness of spatially distributed flood control systems differs for varying flood events. Event-based characteristics such as the spatial distribution of precipitation, the shape and volume of the resulting flood waves or the interactions of flood waves with the technical elements, e.g. reservoirs and flood polders, result in varying efficiency of these systems. Considering these aspects a flood control system should be evaluated with a broad range of hydrological loads to get a realistic assessment of its performance under different conditions. The consideration of this variety in flood control planning design was one particular aim of this study. Hydrological loads were described by multiple criteria. A statistical characterization of these criteria is difficult, since the data base is often not sufficient to analyze the variety of possible events. Hydrological simulations were used to solve this problem. Here a deterministic-stochastic flood generator was developed and applied to produce a large quantity of flood events which can be used as scenarios of possible hydrological loads. However, these simulations imply many uncertainties. The results will be biased by the basic assumptions of the modeling tools. In flood control planning probabilities are applied to characterize uncertainties. The probabilities of the simulated flood scenarios differ from probabilities which would be derived from long time series. With regard to these known unknowns the bias of the simulations was considered by imprecise probabilities. Probabilities, derived from measured flood data were combined with probabilities which were estimated from long simulated series. To consider imprecise probabilities, fuzzy sets were used to distinguish the results between more or less possible design floods. The need for such a differentiated view on the performance of flood protection systems is demonstrated by a case study.
We have analysed the microseismic activity within the Rwenzori Mountains area in the western branch of the East African Rift. Seismogram recordings from a temporary array of up to 27 stations reveal ...approximately 800 events per month with local magnitudes ranging from -0.5 to 5.1. The earthquake distribution is highly heterogeneous. The majority of located events lie within faults zones to the east and west of the Rwenzoris with the highest seismic activity observed in the northeastern area, where the mountains are in contact with the rift shoulders. The hypocentral depth distribution exhibits a pronounced peak of seismic energy release at 15 km depth. The maximum extent of seismicity ranges from 20 to 32 km and correlates well with Moho depths that were derived from teleseismic receiver functions. We observe two general features: (i) beneath the rift shoulders, seismicity extends from the surface down to ca. 30 km depth; (ii) beneath the rift valley, seismicity is confined to depths greater than 10 km. From the observations there is no indication for a crustal root beneath the Rwenzori Mountains. The magnitude frequency distribution reveals a b-value of 1.1, which is consistent with the hypothesis that part of the seismicity is caused by magmatic processes within the crust. Fault plane solutions of 304 events were derived from P-polarities and SV/P amplitude ratios. More than 70 % of the source mechanisms exhibit pure or predominantly normal faulting. T-axis trends are highly uniform and oriented WNW-ESE, which is perpendicular to the rift axis and in good agreement with kinematic rift models. At the northernmost part of the region we observe a rotation of the T-axis trends to NEN-SWS, which may be indicative of a local perturbation of the regional stress field.
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