- Geosciences, Vol. 8, Pages 308: Evidence for Basement Reactivation during the Opening of the Labrador Sea from the Makkovik Province, Labrador, Canada: Insights from Field Data and Numerical Models
The onshore exposures adjacent to modern, offshore passive continental margins may preserve evidence of deformation from the pre-, syn-, and post-rift phases of continental breakup that allow us to investigate the processes associated with and controlling rifting and breakup. Here, we characterize onshore brittle deformation and pre-rift basement metamorphic mineral fabric from onshore Labrador in Eastern Canada in the Palaeoproterozoic Aillik Domain of the Makkovik Province. Stress inversion (1) was applied to these data and then compared to (2) numerical models of hybrid slip and dilation tendency, (3) independent calculations of the regional geopotential stress field, and (4) analyses of palaeo-stress in proximal regions from previous work. The stress inversion shows well-constrained extensional deformation perpendicular to the passive margin, likely related to pre-breakup rifting in the proto-Labrador Sea. Hybrid slip and dilatation analysis indicates that inherited basement structures were likely oriented in a favorable orientation to be reactivated during rifting. Reconstructed geopotential stresses illuminate changes of the ambient stress field over time and confirm the present paleo-stress estimates. The new results and numerical models provide a consistent picture of the late Mesozoic-Cenozoic lithospheric stress field evolution in the Labrador Sea region. The proto-Labrador Sea region was characterized by a persistent E–W (coast-perpendicular) extensional stress regime, which we interpret as the pre-breakup continental rifting that finally led to continental breakup. Later, the ridge push of the Labrador Sea spreading ridge maintained this general direction of extension. We see indications for anti-clockwise rotation of the direction of extension along some of the passive margins. However, extreme persistent N–S-oriented extension as indicated by studies further north in West Greenland cannot be confirmed.
- Geosciences, Vol. 8, Pages 307: Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes
This work investigates the timing, paleoclimatic framework and inter-hemispheric teleconnections inferred from the glaciers last maximum extension and the deglaciation onset in the Arid Tropical Andes. A study area was selected to the northeastward of the Nevado Coropuna, the volcano currently covered by the largest tropical glacier on Earth. The current glacier extent, the moraines deposited in the past and paleoglaciers at their maximum extension have been mapped. The present and past Equilibrium Line Altitudes (ELA and paleoELA) have been reconstructed and the chlorine-36 ages have been calculated, for preliminary absolute dating of glacial and volcanic processes. The paleoELA depression, the thermometers installed in the study area and the accumulation data previously published allowed development of paleotemperature and paleoprecipitation models. The Coropuna glaciers were in maximum extension (or glacial standstill) ~20–12 ka ago (and maybe earlier). This last maximum extension was contemporary to the Heinrich 2–1 and Younger Dryas events and the Tauca and Coipasa paleolake transgressions on Bolivian Altiplano. The maximum paleoELA depression (991 m) shows a colder (−6.4 °C) and moister climate with precipitation ×1.2–×2.8 higher than the present. The deglaciation onset in the Arid Tropical Andes was 15–11 ka ago, earlier in the most southern, arid, and low mountains and later in the northernmost, less arid, and higher mountains.
- Geosciences, Vol. 8, Pages 306: Monitoring Thermal Activity of the Beppu Geothermal Area in Japan Using Multisource Satellite Thermal Infrared Data
The Beppu geothermal area, one of the largest spa resorts on the northeast Kyushu Island of Japan, is fed by hydrothermal fluids beneath the volcanic center of Mt. Garan and Mt. Tsurumi in the west. We explored the thermal status of the Beppu geothermal area using nighttime multisource satellite thermal infrared data (TIR) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Landsat 8 thermal infrared scanner (TIRS) to monitor heat loss from 2009 to 2017. We also assessed heat loss from Mt. Garan fumaroles to investigate a relationship between them. The normalized differential vegetation index (NDVI) threshold method of spectral emissivity, the split-window algorithm for land surface temperature (LST), and the Stefan–Boltzmann equation for radiative heat flux (RHF) were used to estimate heat loss in this study. Total heat loss increased by about a 35% trend overall from 2009 to 2015 and then declined about 33–42% in 2017 in both the Beppu geothermal area and Mt. Garan fumaroles overall. The higher thermal anomalies were found in 2015 mostly in the southeastern coastal area of the Beppu geothermal region. The highest thermal anomaly was obtained in 2011 and the lowest in 2017 within the Mt. Garan fumaroles. The areas with a higher range of RHF values were recorded in 2015 in both study areas. Finally, the results show similar patterns of heat loss and thermal anomalies in both the Beppu geothermal area and Mt. Garan fumaroles, indicating a closely connected geothermal system overall. This suggests that nighttime TIR data are effective for monitoring the thermal status of the Beppu geothermal area.
- Geosciences, Vol. 8, Pages 305: Adapting Cultural Heritage to Climate Change Risks: Perspectives of Cultural Heritage Experts in Europe
Changes in rainfall patterns, humidity, and temperature, as well as greater exposure to severe weather events, has led to the need for adapting cultural heritage to climate change. However, there is limited research accomplished to date on the process of adaptation of cultural heritage to climate change. This paper examines the perceptions of experts involved in the management and preservation of cultural heritage on adaptation to climate change risks. For this purpose, semi-structured interviews were conducted with experts from the UK, Italy, and Norway as well as a participatory workshop with stakeholders. The results indicate that the majority of interviewees believe that adaptation of cultural heritage to climate change is possible. Opportunities for, barriers to, and requirements for adapting cultural heritage to climate change, as perceived by the interviewees, provided a better understanding of what needs to be provided and prioritized for adaptation to take place and in its strategic planning. Knowledge of management methodologies incorporating climate change impacts by the interviewees together with best practice examples in adapting cultural heritage to climate change are also reported. Finally, the interviewees identified the determinant factors for the implementation of climate change adaptation. This paper highlights the need for more research on this topic and the identification and dissemination of practical solutions and tools for the incorporation of climate change adaptation in the preservation and management of cultural heritage.
- Geosciences, Vol. 8, Pages 304: Fluvial Geomorphology, Root Distribution, and Tensile Strength of the Invasive Giant Reed, Arundo Donax and Its Role on Stream Bank Stability in the Santa Clara River, Southern California
Arundo donax (giant reed) is a large, perennial grass that invades semi-arid riparian systems where it competes with native vegetation and modifies channel geomorphology. For the Santa Clara River, CA, changes in channel width and intensity of braiding over several decades are linked in part to high flow events that remove A. donax. Nevertheless, the area of A. donax at the two study sites increased fivefold over a period of 28 years at one site and fourfold over 15 years at the second site. Effects of A. donax on bank stability are compared to those of a common native riparian tree—Salix laevigata (red willow)—at two sites on the banks and floodplain of the Santa Clara River. There is a significant difference of root density of A. donax compared to S. laevigata and the latter has a higher number of roots per unit area at nearly all depths of the soil profile. Tensile root strength for S. laevigata (for roots of 1–6 mm in diameter) is about five times stronger than for A. donax and adds twice the apparent cohesion to weakly cohesive bank materials than does A. donax (8.6 kPa compared to 3.3 kPa, respectively). Modeling of bank stability for banks of variable height suggests that S. laevigata, as compared to A. donax, increases the factor of safety (FS) by ~60% for banks 1 m high, ~55% for banks 2 m high and ~40% for banks 3 m high. For 3 m high banks, the FS for banks with A. donax is <1. This has geomorphic significance because, in the case of A. donax growing near the water line of alluvial banks, the upper 10–20 cm has a hard, resistant near-surface layer overlying more erodible banks just below the near-surface rhizomal layer. Such banks may be easily undercut during high flow events, resulting in overhanging blocks of soil and A. donax that slump and collapse into the active channel, facilitating lateral bank erosion. Therefore, there is a decrease in the lateral stability of channels if the mixed riparian forest is converted to dominance by A. donax.
- Dynamic modelling of weathering rates – Is there any benefit over steady-state modelling?
Dynamic modelling of weathering rates – Is there any benefit over steady-state modelling? Veronika Kronnäs, Cecilia Akselsson, and Salim Belyazid SOIL Discuss., https//doi.org/10.5194/soil-2018-25,2018 Manuscript under review for SOIL (discussion: open, 1 comment) Weathering rates in forest soils are important for sustainable forestry, but can't be measured. In this paper, we have modelled weathering with the often used PROFILE model, as well as with the dynamic model ForSAFE, better suited in a changing climate, with changing human activities, but never before tested for weathering calculations. We show that ForSAFE gives comparable weathering rates as PROFILE, but that it shows the variation in weathering with time and is good for scenario modelling.
- Global meta-analysis of the relationship between soil organic matter and crop yields
Global meta-analysis of the relationship between soil organic matter and crop yields Emily E. Oldfield, Mark A. Bradford, and Stephen A. Wood SOIL Discuss., https//doi.org/10.5194/soil-2018-21,2018 Manuscript under review for SOIL (discussion: open, 0 comments) In this manuscript, we quantify the global-level relationship between soil organic matter and crop yield. We find that greater concentrations of soil organic matter are associated with greater yields, and that increases in yields saturate around 2 %. Using the relationship that we generate, we then provide an estimate of the potential for soil organic matter management to reduce global yield gaps for two of the most important staple crops (maize and wheat) grown worldwide.
- Evaluating the carbon sequestration potential of volcanic soils in South Iceland after birch afforestation
Evaluating the carbon sequestration potential of volcanic soils in South Iceland after birch afforestation Matthias Hunziker, Olafur Arnalds, and Nikolaus J. Kuhn SOIL Discuss., https//doi.org/10.5194/soil-2018-26,2018 Manuscript under review for SOIL (discussion: open, 1 comment) Afforestation on severely degraded volcanic soils/landscapes is an important process concerning ecological restoration in Iceland. These landscapes have a high potential to act as carbon sink. We tested the soil (0–30 cm) of different stages of afforested (mountain birch) landscapes and analyzed the quantity and quality of the soil organic carbon. There is an increase of the total SOC stock during the encroachment. The increase is mostly because of POM SOC. Such soils demand SOC quality tests.
- Soil nutrient content in relation to women's agricultural knowledge in the urban gardens of Kisumu, Kenya
Soil nutrient content in relation to women's agricultural knowledge in the urban gardens of Kisumu, Kenya Nicolette Tamara R. J. M. Jonkman, Esmee D. Kooijman, Boris Jansen, Nicky R. M. Pouw, and Karsten Kalbitz SOIL Discuss., https//doi.org/10.5194/soil-2018-24,2018 Manuscript under review for SOIL (discussion: open, 0 comments) In the urban gardens of Kisumu we interviewed women farmers to determine the sources and scope of their agricultural knowledge. We assessed the impact of their knowledge by comparing the influence of 2 types of management on soil nutrients. While one type of management was more effective in terms of preserving soil nutrients, the other management type had socio-economic benefits. Both environmental and socio-economic impact has to be considered in agricultural training to increase their impact.
- No silver bullet for digital soil mapping: country-specific soil organic carbon estimates across Latin America
No silver bullet for digital soil mapping: country-specific soil organic carbon estimates across Latin America Mario Guevara, Guillermo Federico Olmedo, Emma Stell, Yusuf Yigini, Yameli Aguilar Duarte, Carlos Arellano Hernández, Gloria E. Arévalo, Carlos Eduardo Arroyo-Cruz, Adriana Bolivar, Sally Bunning, Nelson Bustamante Cañas, Carlos Omar Cruz-Gaistardo, Fabian Davila, Martin Dell Acqua, Arnulfo Encina, Hernán Figueredo Tacona, Fernando Fontes, José Antonio Hernández Herrera, Alejandro Roberto Ibelles Navarro, Veronica Loayza, Alexandra M. Manueles, Fernando Mendoza Jara, Carolina Olivera, Rodrigo Osorio Hermosilla, Gonzalo Pereira, Pablo Prieto, Iván Alexis Ramos, Juan Carlos Rey Brina, Rafael Rivera, Javier Rodríguez-Rodríguez, Ronald Roopnarine, Albán Rosales Ibarra, Kenset Amaury Rosales Riveiro, Guillermo Andrés Schulz, Adrian Spence, Gustavo M. Vasques, Ronald R. Vargas, and Rodrigo Vargas SOIL, 4, 173-193, https://doi.org/10.5194/soil-4-173-2018, 2018 We provide a reproducible multi-modeling approach for SOC mapping across Latin America on a country-specific basis as required by the Global Soil Partnership of the United Nations. We identify key prediction factors for SOC across each country. We compare and test different methods to generate spatially explicit predictions of SOC and conclude that there is no best method on a quantifiable basis.