Local‐ and regional‐scale biomorphodynamics due to tree uprooting in semi‐natural and managed montane forests of the Sudetes Mountains,Central Europe

In this work, direct and indirect geomorphic consequences of wind‐related tree uprooting are examined, using an extensive dataset from the mountain range of the Sudetes, Poland. The role of local conditions in influencing the geomorphic efficacy of tree uprooting is examined, as well as issues of upscaling individual observations from experimental sites. This problem is approached at a range of spatial and observational scales, from monitoring of root plate degradation over time through to examination of wind effects at a slope scale and region‐wide analysis. In our study area the mean root plate volume is between 0.4 and 4.2 m³ for spruce and 2.4 m³ for beech, and their degradation may last tens of years. The density of relict pit‐and‐mound microtopography varies from 2.7 up to 40 pairs per hectare and the maximum coverage of terrain is 4.7%. The volume of treethrow mounds varies from 0.5 to 3.1 m³ and mounds seem to outlive the pits formed in the same episode of disturbance. However, in specific lithological and topographic conditions, pit‐and‐mound topography does not form. The maximum biogenic transport attributable to a single windstorm event is c. 80 m³ ha^?1, while soil turnover times are calculated in the order of 1000–10 000 years. Rock fragment ‘mining’ is an important biogeomorphic process, both in terms of impact on hillslope surfaces and on soil properties. Gravel armours and small‐scale stepped topography may form instead of typical pit–mound associations in specific circumstances. Managed forests appear more prone to wind damage and associated geomorphic consequences. In the Sudetes Mountains, the variable role of tree uprooting in local and regional hillslope denudation is governed by forest stand structure, topography and regolith properties, with the former significantly influenced by human activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Observations of coastal cliff base waves,sand levels,and cliff top shaking

Concurrent observations of waves at the base of a southern California coastal cliff and seismic cliff motion were used to explore wave–cliff interaction and test proxies for wave forcing on coastal cliffs. Time series of waves and sand levels at the cliff base were extracted from pressure sensor observations programmatically and used to compute various wave impact metrics (e.g. significant cliff base wave height). Wave–cliff interaction was controlled by tide, incident waves, and beach sand levels, and varied from low tides with no wave–cliff impacts, to high tides with continuous wave–cliff interaction. Observed cliff base wave heights differed from standard Normal and Rayleigh distributions. Cliff base wave spectra levels were elevated at sea swell and infragravity frequencies. Coastal cliff top response to wave impacts was characterized using microseismic shaking in a frequency band (20–45 Hz) sensitive to wave breaking and cliff impacts. Response in the 20–45 Hz band was well correlated with wave–cliff impact metrics including cliff base significant wave height and hourly maximum water depth at the cliff base (r² = 0.75). With site‐specific calibration relating wave impacts and shaking, and acceptable anthropogenic (traffic) noise levels, cliff top seismic observations are a viable proxy for cliff base wave conditions. The methods presented here are applicable to other coastal settings and can provide coastal managers with real time coastal conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

Characterizing Heterogeneity in Infiltration Rates During Managed Aquifer Recharge

Infiltration rate is the key parameter that describes how water moves from the surface into a groundwater aquifer during managed aquifer recharge (MAR). Characterization of infiltration rate heterogeneity in space and time is valuable information for MAR system operation. In this study, we utilized fiber optic distributed temperature sensing (FO‐DTS) observations and the phase shift of the diurnal temperature signal between two vertically co‐located fiber optic cables to characterize infiltration rate spatially and temporally in a MAR basin. The FO‐DTS measurements revealed spatial heterogeneity of infiltration rate: approximately 78% of the recharge water infiltrated through 50% of the pond bottom on average. We also introduced a metric for quantifying how the infiltration rate in a recharge pond changes over time, which enables FO‐DTS to be used as a method for monitoring MAR and informing maintenance decisions. By monitoring this metric, we found high‐spatial variability in how rapidly infiltration rate changed during the test period. We attributed this variability to biological pore clogging and found a relationship between high initial infiltration rate and the most rapid pore clogging. We found a strong relationship (R² = 0.8) between observed maximum infiltration rates and electrical resistivity measurements from electrical resistivity tomography data taken in the same basin when dry. This result shows that the combined acquisition of DTS and ERT data can improve the design and operation of a MAR pond significantly by providing the critical information needed about spatial variability in parameters controlling infiltration rates.     

Geochronology of Mount Morning, Antarctica: two-phase evolution of a long-lived trachyte-basanite-phonolite eruptive center

Mount Morning is a Cenozoic, alkaline eruptive center in the south-west Ross Sea, Antarctica. New ages on 17 Mount Morning volcanic rocks (combined with 34 existing ages) allows division of Mount Morning volcanism into two phases, erupted between at least 18.7 Ma and 11.4 Ma, and 6.13 and 0.02 Ma. The position of Mount Morning on the active West Antarctic Rift System within the stationary Antarctic plate is a key factor in the eruptive center’s longevity. The earliest, mildly alkaline, Phase I volcanism comprises predominantly trachytic rocks produced by combined assimilation and fractional crystallization processes over 7.3 m.y. Strongly alkaline Phase II volcanism is dominated by a basanite – phonolite lineage, with the youngest (post last glacial maximum) activity dominated by small volume primitive basanite eruptions. The evolution from mildly to strongly alkaline chemistry between phases reflects magma residence time in the crust, the degree of mantle melting, or the degree of magma—country-rock interaction. Phase I magmatism occurred over a comparable area to the present-day, Phase II shield. The 5.2 m.y. volcanic hiatus separating Phase I and II coincides with a cycle of eruption and glacial erosion at the nearby Minna Bluff eruptive center. Mount Morning is the likely source of volcanic detritus in Cape Roberts drill-core (about 24.1 to 18.4 Ma) and in ANDRILL drill-hole 1B (about 13.6 Ma), located 170 km north and 105 km north-east respectively, of Mount Morning. Based upon the timing of eruptions and high heat-flow, Mount Morning should be considered a dormant volcano.     

Characterizing hyporheic transport processes — Interpretation of electrical geophysical data in coupled stream–hyporheic zone systems during solute tracer studies

Quantifying hyporheic solute dynamics has been limited by our ability to assess the magnitude and extent of stream interactions with multiple domains: mobile subsurface storage (MSS, e.g., freely flowing pore water) and immobile subsurface storage (ISS, e.g., poorly connected pore water). Stream-tracer experiments coupled with solute transport modeling are frequently used to characterize lumped MSS and ISS dynamics, but are limited by the ability to sample only “mobile” water and by window of detection issues. Here, we couple simulations of near-surface electrical resistivity (ER) methods with conservative solute transport to directly compare solute transport with ER interpretations, and to determine the ability of ER to predict spatial and temporal trends of solute distribution and transport in stream–hyporheic systems. Results show that temporal moments from both ER and solute transport data are well correlated for locations where advection is not the dominant solute transport process. Mean arrival time and variance are especially well-predicted by ER interpretation, providing the potential to estimate rate-limited mass transport (i.e. diffusive) parameters from these data in a distributed domain, substantially increasing our knowledge of the fate and transport of subsurface solutes.     

Detection and mapping of maize streak virus using RapidEye satellite imagery

The aim of this study was to detect and map MSV using RapidEye multispectral sensor in Ofcolaco farm. To achieve this objective, the acquired RapidEye sensor was classified using the robust Random Forest algorithm. Furthermore, the variable importance technique was used to determine the influence of each spectral band and indices on the mapping accuracy. For better performance of image data, the value of the commonly used vegetation indices in improving the classification accuracy was tested. The results revealed that the use of RapidEye spectral bands in detection and mapping of MSV yielded good classification results with an overall accuracy of 82.75%. The inclusion of vegetation indices computed from RapidEye sensor improved the classification accuracies by 3.4%. The most important RapidEye spectral bands in classifying MSV were near infrared, blue and red-edge. On the other hand, the most important vegetation indices were the Soil adjusted vegetation index, Enhanced vegetation index, Red index and Normalized Vegetation Index. The current study recommends future studies to assess the importance of multi-temporal remote sensing applications in detecting and monitoring the spread of MSV.     

Remote sensing of spider mite damage in California peach orchards

Remote sensing techniques can decrease pest monitoring costs in orchards. To evaluate the feasibility of detecting spider mite damage in orchards, we measured visible and near infrared reflectance of 1153 leaves and 392 canopies in 11 peach orchards in California. Pairs of significant wavelengths, identified by Partial Least Squares regression, were combined into normalized difference indices. These and 9 previously published indices were evaluated for correlation with mite damage.     

Diel vertical migration of medusae in the open Southern Adriatic Sea over a short time period (July 2003)

Diel vertical migration (DVM) of medusae was investigated at a fixed station in the oligotrophic Southern Adriatic Sea at several depths during summer (July) 2003. We hypothesized that medusan DVM is considerably influenced by environmental variables such as hydrographic features, light intensities, and potential prey densities. We used short-term repetitive sampling as an approach to detail these relationships. Of the 26 species collected, the highest abundance was in the layer between the thermocline (15 m) and 100 m depth, where Rhopalonema velatum predominated, reaching the maximum count of 93 individuals per 10 m³. Seven species were observed over a wide depth range: Solmissus albescens (15–1200 m), R. velatum (0–800 m), Persa incolorata (50–1200 m), Octophialucium funerarium (200–1200 m), Arctapodema australis (200–1200 m), Amphinema rubra (100–800 m), and Rhabdoon singulare (15–600). According to the medusan weighted mean depth (WMD) calculations, the longest DVMs were noted for the deep-sea species S. albescens , O. funerarium , and A. australis . The shallowest species, Aglaura hemistoma , was primarily non-migratory. Certain medusan assemblages were associated consistently with a particular depth layer characterized by a particular light intensity. The interplay of environmental factors and trophic relationships explains some of the features of medusan migratory patterns. These findings thus contribute to understanding the variables that determine patterns of medusan vertical migratory behavior.     

Field expressions of the transformation of debris flows into turbidity currents, with examples from the Polish Carpathians and the French Maritime Alps

Various transformation mechanisms can generate turbidity currents from subaqueous debris flows. Different transformation mechanisms have been described and interpreted in the past from laboratory experiments and from deposits, but the two approaches have not generally been linked. This has made the genetic interpretation and comparison of deposits difficult. In this paper a generic classification scheme of debrite–turbidite couplets is proposed based on transformation mechanisms inferred from laboratory experiments. Five different flow types (called A–E herein) and their resulting deposits are detailed, but they are all part of a continuous spectrum, and a mixture of types is likely to be found in the field. Type A flows are strong, dense debris flows that undergo little transformation. Their deposit will be a debrite overlain by a thin turbidite, which is separated from it by a clear grain size break. Type B flows are weaker and can develop waves at the debris flow-turbidity current interface. The deposit will be a debrite with a wavy top overlain by a turbidite that is thicker than for type A flows. For type C flows, the interfacial waves will grow so much that the debris flow disintegrates into separate parts. The deposit will consist of debrite lenses encased in a turbidite. Type D flows will undergo even more mixing than type C flows so that the debrite parts will be mixed. Their deposit will be a turbidite with laterally varying areas of debrite characteristics near the bed. Type E flows will be so transformed that the debris flow character has disappeared and the flow is a turbidity current with high sediment concentration. The deposit will be largely turbiditic. The flow types and deposits will be illustrated with some examples from two field areas: the Polish Carpathians and the French Maritime Alps.