The described dataset was the result of a field effort consisting of several campaigns to assess the influence of carbon increase as a result of agroforestry treatments on soil hydrological characteristics and water fluxes at two sites in Malawi. At the sites, two experimental trials have been established which differ in age and soil characteristics, while climatic conditions are roughly comparable. At both sites we focused on control plots of maize and agroforestry treatments including Gliricidia sepium (Jacq.) Walp. as the tree component. The dataset contains soil characteristics such as texture, porosity, carbon and nitrogen concentrations, carbon density fractions, dispersible clay proportions, soil hydraulic conductivity and water retention curves. To assess the differences in water fluxes between treatments and sites, we installed soil moisture and matric potential sensors and a small weather station at the sites and monitored the fluxes over the course of about three months. The resulting time series are also part of the dataset, as well as some measurements of maize heights. The file structure of the dataset as well as details on the sites, sampling procedures, measurements and methodology are included in the data description.
The Quaternary Drilling at the Rehhag under the supervision of members of the Institut für Geologie (QDR-RE-IfG) was interested in the unconsolidated sediment infill of a bedrock trough in the Northern Alpine Foreland (NAF). Such bedrock troughs, now hidden beneath their sediment infill and/or in lakes, occur in formerly and currently glaciated areas, and are linked to increased glacial erosion. The base of these bedrock troughs is located beneath today's base level, which puts them beyond fluvial erosion, and this is why they are referred to as over-deepenings. Such overdeepenings can be found in the vicinity of the Alps which includes the NAF. After the formation or re-occupation of such overdeepenings by glacier ice these troughs provide accommodation space for the deposition of sediments. Hence, overdeepenings are likely to preserve sediments through glacial-interglacial cycles. As erosive agents, glaciers re-shape landscapes, and excavate and re-use sediments of previous glaciations which makes the preservation of intact sedimentary sequences through multiple glacial cycles unlikely. These repeated cut-and-fill cycles limit the Quaternary sedimentary record and make the investigation of the number and chronology of Quaternary glacial-interglacial cycles difficult. Overdeepenings, however, can preserve fractionated and probably intact sedimentary sequences throughout multiple glaciations. Hence, accessing the sediment infill of overdeepened bedrock troughs through core drillings provides insight into phases of the Quaternary at locations where formerly little information was available.
To gain new insight into the Mid- to Late-Pleistocene sedimentary record in the Bern area (Switzerland) the drilling QDR-RE-IfG was conducted in Bern-Bümpliz, where a minor branch of the Aare Valley overdeepening is located in which Quaternary sediments at least 150 ka in age were expected. In Bern-Bümpliz, at the Rehhag, the uppermost 30 m of the sedimentary succession are accessible in an abandoned clay pit. The drilling reached 211.5 m driller's depth, recovering 208.5 m of unconsolidated sediment and, below a sharp contact, 3 m of Miocene Molasse bedrock. The recovery of intact core from unconsolidated sediment is challenging. Nevertheless, 92.3% of the core material was recovered in 1 m-long plastic liners in pristine condition. As the drilling reached the bedrock it is the first scientific drilling that recovered the full sedimentary suite in a part of the Aare Valley overdeepening. Within the sedimentary succession two sequences (A = lower, B = upper) were identified. Each of the sequences is initiated by the deposition of glacial till that is overlain by lacustrine or glacio-lacustrine sediments. First luminescence ages indicate a depositional age between 250 and 340 ka for sequence B.
The drill core was transported from the drill site to the Institute of Geological Sciences, University of Bern, where it was analyzed and sampled. The first step in the analysis was scanning the whole core contained in the liners on a Multi Sensor Core Logger (MSCL; Geotek Ltd.) which provided measurements of the core (γ-)density, p-wave velocity and magnetic susceptibility. The liners were then opened under light sensitive conditions, the cores split in half to allow their macroscopic description, and one half was sealed from light and other alterating influences. After the description, the core was documented with a digital line scanner on the MSCL. After the documentation, a vane meter was used to determine the shear strength of the material and samples for pollen analysis, analysis of the carbon content, provenance analysis, and the measurement of cosmogenic nuclides 10Be and 26Al were extracted.
This report provides limited information about the drilling operation, describes the available datasets form scanning and sample analysis, and the results of the first data processing as well as the tools used in the data analysis.
The data set ": Soil physical and hydraulic properties along two chronosequences of proglacial moraines" consists of several individual files in tabstop delimeted text format. The data set contains soil physical data from two chronosequences of moraines in glacier forefields in the central Alps, Switzerland. Aim of the study was to investigate the impact of age and parent material on soil physical characteristics. At the forefield of the Stone Glacier the moraines developed from silicate parent material (S) and at the forefield of the Griessfirn from calcareous parent material (C). At each forefield disturbed and undisturbed soil samples were collected from four moraines of different ages and porosity, bulk density, particle size distribution, gravel content, ignition loss, retention curves and unsaturated hydraulic conductivity curves were determined. Per moraine, three sampling sites were identified based on the level of vegetation complexity [low, medium, high] (for details on this vegetation classification see Maier et al., 2019).
Two sampling locations spaced 3 to 4 m apart were selected per vegetation complexity at each moraine. These different sampling locations are identified in the files as location 1 and 2. Data sets from the moraines developed from silicate parent material are marked with S and data from the moraines with calcareous parent material are marked with C. For the C forefield bulk density, porosity and ignition loss are listed in a single file. For the S location the ignition loss data is listed in a separate file from the bulk density and porosity data. In each file the sample type, the sample volume, the sample number, the moraine age, the sampling depth, and the level of vegetation complexity are provided. The particle size distributions of the fine earth and the gravel content are also listed in individual files. Again, the sample number, moraine age, vegetation complexity, sampling depth and sampling location are noted in the files.
For the retention curves and the unsaturated hydraulic conductivity curves, two files exist for each curve and glacier forefield, which are named accordingly with the glacier forefield identification and type of curve. An overview file for each glacier forefield contains a list with the sample number, moraine age, sampling depth, vegetation complexity and sampling location. The other two files per curve contain the lab measurements. For the retention curve data, the sample numbers link the pressure head [cm] values provided in one file to the corresponding volumetric water content [-] values provided in the other file. The same applies to the hydraulic conductivity curve where the sample number now links the unsaturated hydraulic conductivity [cm/h] to the corresponding pressure head [cm].
The effects of climate and topography on soil physico-chemical and microbial parameters were studied along an extensive latitudinal climate gradient in the Coastal Cordillera of Chile (26° - 38°S). The study sites encompass arid (Pan de Azúcar), semiarid (Santa Gracia), mediterranean (La Campana) and humid (Nahuelbuta) climates and vegetation, ranging from arid desert, dominated by biological soil crusts (biocrusts), semiarid shrubland and mediterranean sclerophyllous forest, where biocrusts are present but do have a seasonal pattern to temperate-mixed forest, where biocrusts only occur as an early pioneering development stage after disturbance. All soils originate from granitic parent materials and show very strong differences in pedogenesis intensity and soil depth.
Most of the investigated physical, chemical and microbiological soil properties showed distinct trends along the climate gradient. Further, abrupt changes between the arid northernmost study site and the other semi-arid to humid sites can be shown, which indicate non-linearity and thresholds along the climate gradient. Clay and total organic carbon contents (TOC) as well as Ah horizons and solum depths increased from arid to humid climates, whereas bulk density (BD), pH values and base saturation (BS) decreased. These properties demonstrate the accumulation of organic matter, clay formation and element leaching as key-pedogenic processes with increasing humidity. However, the soils in the northern arid climate do not follow this overall latitudinal trend, because texture and BD are largely controlled by aeolian input of dust and sea salts spray followed by the formation of secondary evaporate minerals. Total soil DNA concentrations and TOC increased from arid to humid sites, while areal coverage by biocrusts exhibited an opposite trend. Relative bacterial and archaeal abundances were lower in the arid site, but for the other sites the local variability exceeds the variability along the climate gradient. Differences in soil properties between topographic positions were most pronounced at the study sites with the mediterranean and humid climate, whereas microbial abundances were independent on topography across all study sites.
In general, the regional climate is the strongest controlling factor for pedogenesis and microbial parameters in soils developed from the same parent material. Topographic position along individual slopes of limited length augmented this effect only under humid conditions, where water erosion likely relocated particles and elements downward. The change from alkaline to neutral soil pH between the arid and the semi-arid site coincided with qualitative differences in soil formation as well as microbial habitats. This also reflects non-linear relationships of pedogenic and microbial processes in soils depending on climate with a sharp threshold between arid and semi-arid conditions. Therefore, the soils on the transition between arid and semi-arid conditions are especially sensitive and may be well used as indicators of long and medium-term climate changes. Concluding, the unique latitudinal precipitation gradient in the Coastal Cordillera of Chile is predestined to investigate the effects of the main soil forming factor – climate – on pedogenic processes.
The data presented here is part of the German-Chilean Priority Program “EarthShape” (Earth Surface Shaping by Biota), funded by the German Research Foundation (DFG). We provide the basic background data, which includes investigations into the influence of climate, vegetation and topography on pedogenesis and microbial abundances. The data are supplementary material to Bernhard et al. (2018).
All tables are available as one Excel file, as individual tables in .csv format in a zipped archive and as PDF file. The samples are assigned with International Geo Sample Numbers (IGSN) and linked to a comprehensive sample description in the internet.
The content of the five data tables is:
Table S1: Soil profile field description for the EarthShape study sites
Table S2: Soil physico-chemical properties for the depth increment samples in the four study sites
Table S3: Soil physico-chemical properties for the horizon samples in the four study sites
Table S4: Relative microbial abundances in the four study sites
Table S5: Plant species and abundance (% cover) in the four study sites