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Hummocky soil landscapes are characterized by 3D spatial patterns of soil types that result from erosion-affected pedogenesis. Due to tillage and water erosion, truncated profiles have been formed at steep and mid slopes and colluvial soils at hollows, while intact profiles remained at plateau positions. Pedogenetic variations in soil horizons lead to spatial differences in the soil water balance at hillslope positions. Here, possible interactions between erosion affected soil properties, the water balances, and the crop growth and feedback effects of erosion on the leaching rates were assumed. The hypothesis was tested by water balance simulations comparing uniform with hillslope position-specific crop and root growths for soils at plateau, flat mid slope, steep slope, and hollow using the Hydrus-1D program. The boundary condition data were monitored at the CarboZALF-D experimental field site, which was cropped with perennial lucerne (Medicago sativa L.) in 2013 and 2014. Crop and root growth at the four hillslope positions was assumed proportional to observed leaf area index (LAI). Fluxes of dissolved organic and inorganic carbon (DOC, DIC) were obtained from simulated water fluxes and measured DOC and DIC concentrations. For the colluvic soil at hollow, the crop growth was initially highest and later limited by an increasing water table; here the predominately upward flow led to a net input in DIC and DOC. For the truncated soils at steep slopes, simulations support the hypothesis that reduced crop growth caused an increase in percolation and DIC leaching from the subsoil horizons, which in turn led to accelerated soil development and more soil variations along eroding hillslopes in arable soil landscapes. (C) 2015 Elsevier B.V. All rights reserved.
Preface to BPM 2014
(2016)
Bank voles can harbour Puumala virus (PUUV) and vole populations usually peak in years after beech mast. A beech mast occurred in 2014 and a predictive model indicates high vole abundance in 2015. This pattern is similar to the years 2009/2011 when beech mast occurred, bank voles multiplied and human PUUV infections increased a year later. Given similar environmental conditions in 2014/2015, increased risk of human PUUV infections in 2015 is likely. Risk management measures are recommended.
QuestionHow important is the effect of micro-relief and vegetation type on the characteristics of vascular plants and bryophytes in low-centred polygons? LocationSiberian Arctic, Russia. MethodsEight low-centred polygons in northern Siberia were surveyed for vegetation along transects running from the rim to the pond via the rim-pond transition of each polygon and across a vegetation type gradient from open forest to tundra. ResultsThe cover of vascular plants and bryophytes displays no significant differences between the rim and rim-pond transition but is significantly lower in the pond section of the polygons. Alpha-diversity of vascular plants decreases strongly from rim to pond, whereas bryophyte diversity in pond plots is significantly distinct from the rim and the rim-pond transition. There is no clear trend in cover for either plant group along the vegetation type transect and only a weak trend in -diversity. However, both gradients are reflected in the compositional turnover. The applied indicator species analysis identified taxa characteristic of certain environmental conditions. Among others, we found vascular plants primarily characteristic of the rim and bryophyte taxa characteristic of each micro-relief level and vegetation type. ConclusionsThe observed gradual pattern in -diversity and composition of polygonal vegetation suggests that micro-relief is the main driver of changes in the vegetation composition, while vegetation type and the related forest cover change are of subordinate importance for polygonal vegetation patterns along the Siberian tree line.
QuestionThe empirical evidence of root herbivory effects on plant community composition and co-existence is contradictory. This originates from difficulties connected to below-ground research and confinement of experimental studies to a small range of environmental conditions. Here we suggest coupling experimental data with an individual-based model to overcome the limitations inherent in either approach. To demonstrate this, we investigated the consequences of root herbivory, as experimentally observed on individual plants, on plant competition and co-existence in a population and community context under different root herbivory intensities (RHI), fluctuating and constant root herbivore activity and grazing along a resource gradient. LocationBerlin, Germany, glasshouse; Potsdam, Germany, high performance cluster computer. MethodsThe well-established community model IBC-Grass was adapted to allow for a flexible species parameterization and to include annual species. Experimentally observed root herbivory effects on performance of eight common grassland plant species were incorporated into the model by altering plant growth rates. We then determined root herbivore effects on plant populations, competitive hierarchy and consequences for co-existence and community diversity. ResultsRoot herbivory reduced individual biomass, but temporal fluctuation allowed for compensation of herbivore effects. Reducing resource availability strongly shifted competitive hierarchies, with, however, more similar hierarchies along the gradient under root herbivory, pointing to reduced ecological species differences. Consequently, negative effects on co-existence and diversity prevailed, with the exception of a few positive effects on co-existence of selected species pairs. Temporal fluctuation alleviated but did not remove negative root herbivore effects, despite of the stronger influence of intra- compared to interspecific competition. Grazing in general augmented co-existence. Most interestingly, grazing interacted with RHI and resource availability by promoting positive effects of root herbivory. ConclusionsThrough integrating experimental data on the scale of individual plants with a simulation model we verified that root herbivory could affect plant competition with consequences for species co-existence. Our approach demonstrates the benefit that accrues when empirical and modelling approaches are brought more closely together, and that gathering data on distinct processes and under specific conditions, combined with appropriate models, can be used to answer challenging research questions in a more general way.
Aim We aimed to identify patient characteristics and comorbidities that correlate with the initial exercise capacity of cardiac rehabilitation (CR) patients and to study the significance of patient characteristics, comorbidities and training methods for training achievements and final fitness of CR patients. Methods We studied 557 consecutive patients (51.76.9 years; 87.9% men) admitted to a three-week in-patient CR. Cardiopulmonary exercise testing (CPX) was performed at discharge. Exercise capacity (watts) at entry, gain in training volume and final physical fitness (assessed by peak O-2 utilization (VO2peak) were analysed using analysis of covariance (ANCOVA) models. Results Mean training intensity was 90.7 +/- 9.7% of maximum heart rate (81% continuous/19% interval training, 64% additional strength training). A total of 12.2 +/- 2.6 bicycle exercise training sessions were performed. Increase of training volume by an average of more than 100% was achieved (difference end/beginning of CR: 784 +/- 623 wattsxmin). In the multivariate model the gain in training volume was significantly associated with smoking, age and exercise capacity at entry of CR. The physical fitness level achieved at discharge from CR as assessed by VO2peak was mainly dependent on age, but also on various factors related to training, namely exercise capacity at entry, increase of training volume and training method. Conclusion CR patients were trained in line with current guidelines with moderate-to-high intensity and reached a considerable increase of their training volume. The physical fitness level achieved at discharge from CR depended on various factors associated with training, which supports the recommendation that CR should be offered to all cardiac patients.
Return to work (RTW) is a pivotal goal of cardiac rehabilitation (CR) in patients after acute cardiac event. We aimed to evaluate cardiopulmonary exercise testing (CPX) parameters as predictors for RTW at discharge after CR. We analyzed data from a registry of 489 working-age patients (51.5 +/- A 6.9 years, 87.9 % men) who had undergone inpatient CR predominantly after percutaneous coronary intervention (PCI 62.6 %), coronary artery bypass graft (CABG 17.2 %), or heart valve replacement (9.0 %). Sociodemographic and clinical parameters, noninvasive cardiac diagnostic (2D echo, exercise ECG, 6MWT) and psychodiagnostic screening data, as well as CPX findings, were merged with RTW data from the German statutory pension insurance program and analyzed for prognostic ability. During a mean follow-up of 26.5 +/- A 11.9 months, 373 (76.3 %) patients returned to work, 116 (23.7 %) did not, and 60 (12.3 %) retired. After adjustment for covariates, elective CABG (HR 0.68, 95 % CI 0.47-0.98; p = 0.036) and work intensity (per level HR 0.83, 95 % CI 0.73-0.93; p = 0.002) were negatively associated with the probability of RTW. Exercise capacity in CPX (in Watts) and the VE/VCO2-slope had independent prognostic significance for RTW. A higher work load increased (HR 1.17, 95 % CI 1.02-1.35; p = 0.028) the probability of RTW, while a higher VE/VCO2 slope decreased (HR 0.85, 95 % CI 0.76-0.96; p = 0.009) it. CPX also had prognostic value for retirement: the likelihood of retirement decreased with increasing exercise capacity (HR 0.50, 95 % CI 0.30-0.82; p = 0.006).
The high rate GPS velocity determination technology which is based on the broadcast ephemeris and epoch differenced model can retrieve displacement of ground motion with the precision of a few centimetres to decimetres in real time. Moreover, the precision of the recovered displacement can be improved if the un-modelled errors such as broadcast ephemeris residuals, atmospheric residuals, multipath effects and high frequency noise are tackled more accurately. In this paper, we propose a method to improve the precision of the recovered displacement by appropriately making use of reference station corrections. For the reference stations, the coordinates are highly constrained to extract the error corrections that are to be broadcast via a communication link to the rover. After correcting the rover’s observations, some errors such as ephemeris residuals and atmospheric residuals are effectively eliminated or at least reduced. This improves the accuracy of the observations and thus enhances the reliability of the velocity estimation. The displacement can be recovered by integrating the estimated velocity after de-trending using a linear trend that is caused by the un-corrected residuals. The series of validation results in the experiment have shown that the displacement of the simulated motion can be real time recovered with a precision of 1–2 cm, and is thus applicable for real time monitoring of the ground motion.
Towards the assimilation of tree-ring-width records using ensemble Kalman filtering techniques
(2016)
This paper investigates the applicability of the Vaganov–Shashkin–Lite (VSL) forward model for tree-ring-width chronologies as observation operator within a proxy data assimilation (DA) setting. Based on the principle of limiting factors, VSL combines temperature and moisture time series in a nonlinear fashion to obtain simulated TRW chronologies. When used as observation operator, this modelling approach implies three compounding, challenging features: (1) time averaging, (2) “switching recording” of 2 variables and (3) bounded response windows leading to “thresholded response”. We generate pseudo-TRW observations from a chaotic 2-scale dynamical system, used as a cartoon of the atmosphere-land system, and attempt to assimilate them via ensemble Kalman filtering techniques. Results within our simplified setting reveal that VSL’s nonlinearities may lead to considerable loss of assimilation skill, as compared to the utilization of a time-averaged (TA) linear observation operator. In order to understand this undesired effect, we embed VSL’s formulation into the framework of fuzzy logic (FL) theory, which thereby exposes multiple representations of the principle of limiting factors. DA experiments employing three alternative growth rate functions disclose a strong link between the lack of smoothness of the growth rate function and the loss of optimality in the estimate of the TA state. Accordingly, VSL’s performance as observation operator can be enhanced by resorting to smoother FL representations of the principle of limiting factors. This finding fosters new interpretations of tree-ring-growth limitation processes.