Land Cover and Land Use Change-Driven Dynamics of Soil Organic Carbon in North-East Slovakian Croplands and Grasslands Between 1970 and 2013

Soil organic carbon (SOC) in agricultural land forms part of the global terrestrial carbon cycle and it affects atmospheric carbon dioxide balance. SOC is sensitive to local agricultural management practices that sum up into regional SOC storage dynamics. Understanding regional carbon emission and sequestration trends is, therefore, important in formulating and implementing climate change adaptation and mitigation policies. In this study, the estimation of SOC stock and regional storage dynamics in the Ondavská Vrchovina region (North-Eastern Slovakia) cropland and grassland topsoil between 1970 and 2013 was performed with the RothC model and gridded spatial data on weather, initial SOC stock and historical land cover and land use changes. Initial SOC stock in the 0.3-m topsoil layer was estimated at 38.4 t ha−1 in 1970. The 2013 simulated value was 49.2 t ha−1, and the 1993–2013 simulated SOC stock values were within the measured data range. The total SOC storage in the study area, cropland and grassland areas, was 4.21 Mt in 1970 and 5.16 Mt in 2013, and this 0.95 Mt net SOC gain was attributed to interconversions of cropland and grassland areas between 1970 and 2013, which caused different organic carbon inputs to the soil during the simulation period with a strong effect on SOC stock temporal dynamics

Similarity between interval-valued fuzzy sets taking into account the width of the intervals and admissible orders

In this work we study a new class of similarity measures between interval-valued fuzzy sets. The novelty of our approach lays, firstly, on the fact that we develop all the notions with respect to total orders of intervals; and secondly, on that we consider the width of intervals so that the uncertainty of the output is strongly related to the uncertainty of the input. For constructing the new interval-valued similarity, interval valued aggregation functions and interval-valued restricted equivalence functions which take into account the width of the intervals are needed, so we firstly study these functions, both in line with the two above stated features. Finally, we provide an illustrative example which makes use of an interval-valued similarity measure in stereo image matching and we show that the results obtained with the proposed interval-valued similarity measures improve numerically (according to the most widely used measures in the literature) the results obtained with interval valued similarity measures which do not consider the width of the intervals

New implications for Tunguska explosion based on magnetic, dendrological, and lacustrine records

Introduction: Evenkia is a district in Krasnoyarsk Krai, Russia, characteristic of preserved areas of East Siberian continental taiga. In 1908, this region experienced catastrophe (Tunguska event = TE). Over 2,000 km2 of boreal forest were felled and burned [1,2]. The exact cause of this event is not known but this event has often been associated with either an asteroid or comet encounter [3,4,5]. Material and Methods: We collected tree samples that survived the explosion within the tree collapse area. Most of the tree is Siberian larix. Samples were analyzed for elemental composition (XRF and similar). We collected sediment from three lakes, Zapoviednoe, Cheko, and Gin. Lake Zapoviednoe and Cheko varved sediment came from similar depth of about 35-40 m with conical bottom bachymetry. Lake Gin was shallow (50-60 cm) and had no varves. Chronology of the sediment was already established in Cheko lake using 210Pb, 137Cs, and 226Ra radioactive isotopes analysis [6]. An increase in 137Cs corresponded to 1961 [6]. We ran similar analysis for the two new lakes, Gin and Zapoviednoe and established the sediment chronology. Zapoviednoe lake sediment was exposed to 0-50 keV X-Ray Fluorescence and major element data, including magnetic susceptibility, were obtained across the TE containing sediment. We plotted aeromagnetic data from the world magnetic map flown at ~4 km [7,8] over the tree fall area. Magnetic paleointensity was obtained from the samples collected from Mount Stoikovich and Farrington near epicentre. Results: Tree samples provided an evidence that the ovepressure wave compressed the floem fluid rich in Ca, Sr, Mn into the xylem at the time of TE. This compression had strong anisotropy with maximum compression directed towards the epicenter. We detected that after TE, during the past 40 years the Larix trees in Tunguska have anomalous increase in Hg concentration. Lake sediment revealed 2-4 mm thick clay layer deposited at the time of TE. The layer has anomalous decrease in Fe, while magnetic susceptibility increased. In addition the TE layer has significant increase in Pa, Mo, Th, Cd, Nb, Y, Cu, Cr, Sr, Ti, and V. Aeromagnetic data showed negative magnetic anomaly covering the toppled forest area around the epicenter. Samples from Mount Farrington indicated magnetic paleofields exceeding 1 mT. Four samples from Mount Stoikovitch detected paleofields consistent with geomagnetic field intensity while two samples indicated magnetic paleofield exceeding 0.1 mT. Discussion and Conclusion: TE was shown to leave a biochemical signature in the wood of Larix Sibirica sensitive to explosion direction. TE area was subjected to large energy pulse that may have compromised the permafrost in the area. This was indicated here by an excess of Hg detected in the last 40 years of tree ring material. Tunguska layer in the Zapoviednoe lake is of very fine nature, resembling the clay. While the content of Fe dropped from 160 ppm to 19 ppm the magnetic susceptibility increased two fold. This is an evidence of quick and intense burst of energy, melting vapourizing the dust, causing agglutination of the dust material. This resulted in a ubiquitous presence of nanophase iron with large magnetic susceptibility that became part of molten dust particulates and deposited in the lake sediment. Anomalous elemental increase in lake suggested possible allochtonous material. Paleomagnetic data revealed presence of plasma during the TE near rock surfaces.Web of Science5

Performance of 13 crop simulation models and their ensemble for simulating four field crops in Central Europe

The main aim of the current study was to present the abilities of widely used crop models to simulate four different field crops (winter wheat, spring barley, silage maize and winter oilseed rape). The 13 models were tested under Central European conditions represented by three locations in the Czech Republic, selected using temperature and precipitation gradients for the target crops in this region. Based on observed crop phenology and yield from 1991 to 2010, performances of individual models and their ensemble were analyzed. Modelling of anthesis and maturity was generally best simulated by the ensemble median (EnsMED) compared to the ensemble mean and individual models. The yield was better simulated by the best models than estimated by an ensemble. Higher accuracy was achieved for spring crops, with the best results for silage maize, while the lowest accuracy was for winter oilseed rape according to the index of agreement (IA). Based on EnsMED, the root mean square errors (RMSEs) for yield was 1365 kg/ha for winter wheat, 1105 kg/ha for spring barley, 1861 kg/ha for silage maize and 969 kg/ha for winter oilseed rape. The AQUACROP and EPIC models performed best in terms of spread around the line of best fit (RMSE, IA). In some cases, the individual models failed. For crop rotation simulations, only models with reasonable accuracy (i.e. without failures) across all included crops within the target environment should be selected. Application crop models ensemble is one way to increase the accuracy of predictions, but lower variability of ensemble outputs was confirmed