Holocene landscape evolution, palaeoclimate and human impact in the Fotsch Valley, Stubai Alps, Austria: Interrogating biomarkers, stable isotopes, macrofossils and palynological indicators from a subalpine mire archive

Peatlands are receiving increasing attention in palaeoenvironmental research and represent very useful terrestrial archives for reconstructing vegetation, climate and human history. Previous palaeoenvironmental studies in the Fotsch Valley, Stubai Alps, Austria, focused on geoarchaeological investigations on the Ullafelsen representing a very important prehistorical encampment site used by Mesolithic hunter-gatherers (10.9–9.5 cal. kyr BP). In order to contribute to a better understanding of the landscape evolution of the Fotsch Valley, we here studied the close-by subalpine ‘Potsdamer Hütte Mire’ by applying radiocarbon dating as well as elemental, biomarker, compound-specific stable isotope, palynological and macrofossil analyses on bulk peat samples. The calculated age-depth model using R Bacon indicates the beginning of peat formation during the Early Holocene and shows a strongly reduced peat accumulation rate (PAR) from 170 to 121 cm depth (8.5–2.1 cal. kyr BP) and/or a striking hiatus. Results of leaf wax-derived n-alkane biomarkers as well as macrofossils and palynological indicators reflect the local presence of coniferous trees and the synchronous expansion of deciduous trees during the Early Holocene. The above-mentioned strongly reduced PAR and/or hiatus coincides with the Neolithic, the Bronze and the Iron Age, and goes hand in hand with strong changes in vegetation and an increase of micro-charcoal and black carbon. Despite age uncertainties, these changes can be explained with strongly increasing human and livestock activities in form of deforestation, domestic fires and the beginning of Alpine pastoralism. The latter is confirmed by the finding of pasture and cultural indicator pollen (Cerealia-type, Rumex, Plantago lanceolata, Poaceae) occurring since the Middle to Late Bronze Age. The oxygen isotope composition of sugar biomarkers (δ18Osugars) likely reflects the dry versus humid climatic variability associated with the Holocene climatic optimum during the Mesolithic, the Roman Age, the Late Antique Little Ice Age, the Middle Ages and the Little Ice Age

Die Böden der Alpen: Spiegel der Landschaftsentwicklung und menschlicher Nutzung

Böden erfüllen zahlreiche Funktionen und bieten wichtige Umweltdienstleistungen für den Menschen. Neben sehr konkreten Leistungen, etwa für den Wasser- und Nährstoffhaushalt, stellen Böden auch Archive dar, in denen die vergangene Entwicklung von Landschaften eingeschrieben ist. Diese Informationen zu entschlüsseln, ist gerade in so kleinräumig diversen und dynamischen Landschaften wie den Alpen von besonderem Interesse

Automated Extraction of Shallow Erosion Areas Based on Multi-Temporal Ortho-Imagery

Abstract: In several areas of the Alps, steep grassland is characterized by shallow erosions. These erosions represent a hazard through the increased availability of unconsolidated material in steep locations, loss of soil and impaired landscape aesthetics. Generally, the erosions concern only small areas but sometimes occur in large numbers. Remote sensing technologies have emerged as suitable tools to study the spatio-temporal changes of these eroded areas. The detection of such eroded areas is often done by manual digitalization of aerial photographs, which is labour-intensive and includes a certain risk of subjectivity. In this study we present a methodological tool that allows the automatic classification of shallow erosions on the basis of orthophoto series. The approach was carried out within a test site in the inner Schmirn Valley, Austria. The study covers both the detection of erosion areas and a multi-temporal analysis of the geomorphological changes. The presented approach is an appropriate tool for detecting shallow erosions and for analysing them in multi-temporal terms. The multi-temporal analysis revealed one period of higher increases in eroded areas compared to shrinking during the other periods. However, the analysis of the change of all single erosions indicates that in each stud

How and to What Extent Does Topography Control the Results of Soil Function Assessment: A Case Study From the Alps in South Tyrol (Italy)

Soil function assessments (SFA) are becoming increasingly important as a tool to integrate soil-related issues in decision-making processes in order to maintain soil quality. We present the SEPP (Soil Evaluation for Planning Procedures) tool, which calculates a level of fulfillment for 14 soil functions based on the information generally collected in soil pit descriptions. By using a statistical modeling approach based on support vector machine classification, we investigate how and to what extent topography, as representated by local terrain parameters and landform classes computed with the GRASS GIS tool r.geomorphon algorithm, controls soil parameters and hence the output of the SEPP tool. A feature selection procedure is applied which highlights those topographic attributes best suited for modeling the various soil function fulfillment levels. By evaluating the model for each soil function using cross-validation we show that the prediction accuracy varies from function to function. While some terrain attributes are directly implemented in the SFA algorithms of SEPP, others are implemented indirectly due to the link between topography and land use. Minimal curvature and slope were found to be first indicators of function fulfillment level for a number of soil functions

Rapid decrease of soil erosion rates with soil formation and vegetation development in periglacial areas

High mountainous areas are geomorphologically active environments which are strongly shaped by redistribution of sediments and soils. With the projected climate warming in the twenty‐first century and the continued retreat of glaciers, the area of newly exposed, highly erodible sediments and soils will increase. This presents a need to better understand and quantify erosion processes in young mountainous soils, as an increase in erodibility could threaten human infrastructure (i.e. hydroelectric power, tourist installations and settlements). While soil development is increasingly well understood and quantified, a coupling to soil erosion rates is still missing. The aim of this study was, therefore, to assess how soil erosion rates change with surface age. We investigated two moraine chronosequences in the Swiss Alps: one in the siliceous periglacial area of Steingletscher (Sustenpass), with soils ranging from 30 a to 10 ka, and the other in the calcareous periglacial area of Griessgletscher (Klausenpass) with surfaces ranging from age of 110 a to 13.5 ka. We quantified the erosion rates using the 239+240Pu fallout radionuclides and compared them to physical and chemical soil properties and the vegetation coverage. We found no significant differences between the two parent materials. At both chronosequences, the erosion rates were highest in the young soils (on average 5−10 t ha‐1 a‐1 soil loss). Erosion rates decreased markedly after 3−5 ka of soil development (on average 1−2.5 t ha‐1 a‐1 soil loss) to reach a more or less stable situation after 10−14 ka (on average 0.3–2 t ha‐1 a‐1). Climate change not only causes glacier retreat, but also increased sediment dynamics. Depending on the relief and vegetational development, it takes up to at least 10 ka to reach soil stability. The establishment of a closed vegetation cover with dense root networks seems to be the controlling factor in the reduction of soil erodibility