Reconstructing Environmental Changes in the Swiss Alps

Objective

We aim to establish an interdisciplinary research group and develop a project proposal focused on utilizing caves and cave-based palaeoenvironmental records to investigate landscape and environmental changes of the Swiss Alps during the late Quaternary. The Saegistal region in Switzerland provides a unique opportunity to reconstruct glaciation dynamics and geomorphological evolution using a range of techniques, including the use of caves for dating glacier advances and studying topographic and geomorphological development, speleothem-based clumped isotopes for palaeothermometry, trace elements for assessing water availability, and cryogenic carbonates as permafrost time markers. Preliminary studies conducted in the region demonstrate the high potential for environmental reconstructions through cave documentation and speleothem analysis.

Participants

Agenda

Presentation of research groups should include skills and available facilities (15 min + 5 min discussion). A second presentation contains an illustrative example of own research related to the topic (15 min + 5 min discussion).

Each group should also prepare a "state of the art" of their potential contribution to the project.

Wednesday, November 8th

Thursday, November 9th

Friday, November 10th

Materials

Paper

carbon cycle

• E. B. Larson, J. E. Mylroie: Quaternary glacial cycles:, Acta Carsologica, 42(2–3), 197–202 (2013). DOI:10.3986/ac.v42i2-3.661 » Abstract
  Extensive research has been conducted investigating the re- lationship between karst processes, carbonate deposition and the global carbon cycle. However, little work has been done looking into the relationship between glaciations, subsequent sea level changes, and aerially exposed land masses in relation to karstic processes and the global carbon budget. During glaciations sea-level exposed the world’s carbonate platforms. with the sub-aerial exposure of the platforms, karst processes can occur, and the dissolution of carbonate material can commence, resulting in the drawdown of CO2 from the atmosphere as HCO3−. Furthermore, the material on the platform surfaces is primarily aragonite which is more readily soluble than calcite allowing karst processes to occur more quickly. During glaciations arctic carbonates and some of the temperate carbonates are blanketed in ice, effectively removing those areas from karst processes. Given the higher solubility of aragonite, and the extent of carbonate platforms exposed during glaciations, this dissolution balances the CO2 no longer taken up by karst processes at higher latitudes that were covered during the last glacial maximum The balance is within 0.001 GtC / yr, using soil pCO2 (0.005 GtC / yr assuming atmospheric pCO2) which is a difference of <1% of the total amount of atmospheric CO2 removed in a year by karst processes. Denudation was calculated using the maximum potential dissolution formulas of Gombert (2002). On a year to year basis the net amount of atmospheric carbon removed through karstic processes is equivalent between the last glacial maximum and the present day, however, the earth has spent more time in a glacial configuration during the quaternary, which suggests that there is a net drawdown of atmospheric carbon during glaciations from karst processes, which may serve as a feedback to prolong glacial episodes. This research has significance for understanding the global carbon budget during the quaternary.
• M. R. V. Ross, F. Nippgen, B. A. Hassett, B. L. McGlynn, E. S. Bernhardt: Pyrite Oxidation Drives Exceptionally High Weathering Rates and Geologic CO 2 Release in Mountaintop‐Mined Landscapes, Global Biogeochemical Cycles, 32(8), 1182–1194 (2018). DOI:10.1029/2017GB005798 » Abstract
  Weathering is the ultimate source of solutes for ecosystems, controls chemical denudation of landscapes, and drives the geologic carbon cycle. Mining and other land‐moving operations enhance physical weathering by bringing large volumes of shattered bedrock to the surface. Yet, the relative influence of these activities on chemical weathering remains poorly constrained. Here we show that catchments impacted by mountaintop removal coal mining have among the highest rates of chemical weathering ever reported. Mined catchments deliver more than 7,600 kgtextperiodcenteredha −1 textperiodcenteredyear −1 of dissolved solids downstream. The chemical signatures of these exceptionally high weathering rates reflect the product of sulfuric acid weathering of carbonate‐bearing rock, driven by the oxidation of pyritic materials. As this strong acid rapidly weathers surrounding carbonate materials, H + ions are consumed and Ca 2+ , Mg 2+ , and HCO 3 − ions are exported to balance the elevated SO 4 2− exports, generating alkaline mine drainage. The sulfate exports from pyrite oxidation in mountaintop‐mined catchments account for ~5–7% of global sulfate derived from pyrite, despite occupying less than 0.006% of total land area. Further, the suite of weathering reactions liberate 100–450 kg of rock‐derived Ctextperiodcenteredha −1 textperiodcenteredyear −1 as CO 2 , with an additional 90–150 kg Ctextperiodcenteredha −1 textperiodcenteredyear −1 of C released when HCO 3 − reaches the ocean. This rock C release contributes to the high carbon costs of coal combustion.
• S. Zeng, Z. Liu, G. Kaufmann: Sensitivity of the global carbonate weathering carbon-sink flux to climate and land-use changes, Nature Communications, 10(1), 5749 (2019). DOI:10.1038/s41467-019-13772-4 » Abstract
  The response of carbonate weathering carbon-sink flux (CCSF) to its environmental drivers is still not well understood on the global scale. This hinders understanding of the terrestrial carbon cycle. Here, we show that there is likely to be a widespread and consistent increase in the global CCSF (ranging from + 9.8% (RCP4.5) to + 17.1% (RCP8.5)) over the period 1950–2100. In the coming years the increasing temperature might be expected to have a negative impact on carbonate weathering. However, the increasing rainfall and anticipated land-use changes will counteract this, leading to a greater CCSF. This finding has been obtained by using long-term historical (1950–2005) and modeled future (2006–2100) data for two scenarios (RCP4.5 and RCP8.5) for climate and land-use change in our CCSF equilibrium model. This study stresses the potential role that carbonate weathering may play in the evolution of the global carbon cycle over this century.
• G. Zhou, B. Jia, X. Tao, H. Yan: Estimation of karst carbon sink and its contribution to CO2 emissions over a decade using remote sensing imagery, Applied Geochemistry, 121, 104689 (2020). DOI:10.1016/j.apgeochem.2020.104689 » Abstract
  Research on the carbon source and sink imbalance in global carbon cycle has demonstrated that the mass of CO2 consumed by rock weathering is a portion of the “missing carbon sink.” To further understand the karst carbon sink contributions to atmospheric CO2 emissions, the present study establishes the relationship between the karst carbon sinks and the atmospheric CO2 emissions. We first estimated the mass of CO2 consumed by rock weathering using the Global Erosion Model for CO2 fluxes (GEM-CO2), based on the distribution of different types of rock in Guangxi, China. The rocks were classified using remote sensing imagery, and we estimated the relationship between the mass of CO2 consumed by rock weathering and the CO2 emitted into atmosphere from 2003 to 2012. The analyses reveal that (1) the mass of CO2 consumed by rock weathering could be rapidly estimated using remote sensing imagery, as it not only considers different types of rocks but also simultaneously considers the geological structure and meteorological data, such as rainfall, temperature, and vegetation coverage; (2) the mass of CO2 consumed by rock weathering from 2003 to 2012 displays a “wavy pattern”, which might have been primarily caused by the annual variations in rainfall, whose tendency could be fitted by a straight line at an average annual increasing rate of approximately 8.7%; (3) the mass of emitted CO2 from 2003 to 2012 in Guangxi display a “straight line” at an average annual increasing rate of approximately 12.7%; (4) the mass of CO2 consumed by rock weathering is positively correlated with the mass of emitted CO2 with a correlation coefficient of R2

geology

• H. Günzler-Seiffert: Der geologische Bau der östlichen Faulhorngruppe im Berner Oberland, Eclogae Geologicae Helvetiae, 19(1), 1–87 (1925). DOI:10.5169/seals-158409

• K. Goldschmid: Geologie der Morgenberghorn- Schwalmerngruppe bei Interlaken Geologie der Morgenberghorn-Schwalmerngruppe Zur topographischen Karte : Schiffli, In: Mitteilungen der Naturforschenden Gesellschaft Bern, 194–272 (1926). DOI:10.5169/seals-319335

• H. Seeber: Beiträge zur Geologie der Faulhorngruppe (westlicher Teil) und der Männlichengruppe, (2011).

geomorphology

• P. Audra, A. Bini, F. Gabrovšek, P. Häuselmann , F. Hoblea, P.-Y. Jeannin, J. Kunaver, M. Monbaron, F. Šušteršič, P. Tognini, H. Trimmel, A. Wildberger: Cave genesis in the Alps between the Miocene and today: A review, Zeitschrift für Geomorphologie, 50(2), 153–176 (2006). DOI:10.1127/zfg/50/2006/153

• P. Beck: Grundzüge der Talbildung im Berner Oberland, Eclogae Geologicae Helvetiae, 16(2), 139–176 (1920). DOI:10.5169/seals-157919

• C. Gnägi, C. Schlüchter: High-altitude erratics in the Bernese Alps (Switzerland), Swiss Journal of Geosciences, 105(3), 401–415 (2012). DOI:10.1007/s00015-012-0111-7 » Abstract
  Little is known about the Early Pleistocene landscape and glacial history of the Swiss Alps, largely because of the scarcity of sediments dating from that period. Here we investigate high-altitude, presumably Early Pleistocene relics of unconsolidated, near-surface sediments that occur at the Stockeseen site (close to the Stockhorn) and at Wagenmoos (close to Sibe Hängste) in the Bernese Alps. We complemented our study by analysing cave gravels from 13 sites. Whereas the underlying bedrocks are part of the purely sedimentary Penninic Prealps and the Helvetic zone, the investigated sediments and cave gravels contain characteristic erratic crystalline clasts (HP-LT-metagabbro, medium-grade metamorphic quartzite, jadeitite, glaucophane-schist, low-grade metamorphic gabbro and peridotite). The erratics originate from Penninic and Austroalpine nappes which are exposed only south of the Bernese High Alps, today's water divide. In combination with partly distinct glacial features of the indicator erratics, this suggests that transfluences existed from the Valais (Rhône valley) to the Bernese Alps. Our findings suggest two transfluence routes, one over a precursor of the Gemmipass to the palaeo-Kander valley, providing crystalline erratics towards Sibe Hängste, and one over precursors of the Sanetschpass and Saanenmöserpass into the palaeo-Simmen valley and towards the Stockhorn. The Wagenmoos erratics must have been deposited before the re-routing of the palaeo-Aare river (from northward to westward) and its subsequent deepening, which indicates an Early Pleistocene timing of the respective transfluence. This is in agreement with published burial ages of ~1. 87 Ma ± 0. 21 for cave gravels with crystalline components in the cave system Reseau Siebenhengste-Hohgant (beneath the Wagenmoos site).
• P. Haeuselmann, D. E. Granger, P.-Y. Jeannin, S.-E. Lauritzen: Abrupt glacial valley incision at 0.8 Ma dated from cave deposits in Switzerland, Geology, 35(2), 143–146 (2007). DOI:10.1130/G23094A » Abstract
  Glacial erosion dramatically alters mountain landscapes, but the pace at which glaciers carve a previously fluvial landscape remains poorly defined because long-term valley incision rates are difficult to measure. Here we reconstruct the lowering history of the Aare Valley, Switzerland, over the past 4 m.y. by dating cave sediments with cosmogenic ²⁶Al and ¹⁰Be. Incision accelerated from ∼120 m/m.y. to ∼1200 m/m.y. at 0.8–1.0 Ma, at least 1 m.y. after the onset of local glaciation. Rapid incision may have been triggered by lowering of the equilibrium line altitude at the mid-Pleistocene climate transition.
• None: Appendix, In: Schweizerische Zeitschrift für Vermessungswesen und Kulturtechnik (1933).

glacialcycles

• S. Ivy‐Ochs, H. Kerschner, A. Reuther, F. Preusser, K. Heine, M. Maisch, P. W. Kubik, C. Schlüchter: Chronology of the last glacial cycle in the European Alps, Journal of Quaternary Science, 23(6-7), 559–573 (2008). DOI:10.1002/jqs.1202 » Abstract
  Chronological data for glacier advances in the European Alps between the Last Interglacial (Eemian) and the Holocene are summarised (115 to 11 ka). During this time glaciers were most extensive, extending tens of kilometres out onto the forelands, between 30 and 18 ka, that is, synchronous with the global ice volume maximum of Marine Isotope Stage (MIS) 2. Evidence for ice expanding to just past the mountain front for an earlier major glacier advance comes from Swiss sites, where advances have been luminescence dated to MIS 5d (100 ka) and MIS 4 (70 ka). Up to now no such evidence has been found in the Eastern Alps. By 18 ka, more than 80% of the Late Würmian ice volume had gone. Subsequently glaciers readvanced, reaching into the upper reaches of the main valleys during the Lateglacial Gschnitz stadial, which likely occurred around 17 ka, with final moraine stabilisation no later than 15.4 ka. The link of the Egesen stadial with the Younger Dryas climate deterioration is supported by exposure ages from four sites as well as minimum‐limiting radiocarbon dates from bogs within former glacier tongue areas. Key questions on the spatial and temporal variability of ice extents throughout the last glacial cycle have yet to be answered.

hydrology

• H. Furrer: Geologischer Bericht über die Staumöglichkeit des Sägistalsees, Technical Report, Interlaken, 1–6 (1944).

• P. Pfister: Chessiloch, Stalactite, 35(1), 31–34 (1985).

• D. Spengler: Die Auslotung der drei Gebirgsseen Bachalpsee, Sägistalsee und Hinterburgsee, In: Jahrbuch vom Thuner- und Brienzersee, Uferschutzverband Thuner- und Brienzersee, Interlaken, 30–40 (1973). » Abstract
  Meist spricht man nur von den beiden Zwillingsseen Thuner- und Brienzersee; diese Seen wurden durch verschiedene Wissenschafter erforscht (Hofer, Nydegger, Matter usw.). Dabei werden meist die kleinen Schwesterseen im benachbarten Faulhorngebiet durch die beiden «Großen» in den Schatten gestellt und von den Wissenschaftern wegen ihrer Kleinheit vergessen. Die Schönheit, Unberührtheit und Romantik dieser Bergseelein haben mich bewogen, sie etwas näher unter die Lupe zu nehmen, und so wählte ich den Bachalpsee (2265 Meter über Meer, zwischen Faulhorn und First), Sägistalsee (1937 Meter über Meer, südlich Iseltwald) und den Hinterburgsee (1514 Meter über Meer, östlich Axalp) zu meinen Studienobjekten. Neben vielen andern Untersuchungen (Färbungen, Wärmebilanzen, Wasserbilanzen, Verdunstungsmessungen, sedimentologische Untersuchungen, morphologische Untersuchungen unter anderem) befaßte ich mich auch mit der Morphometrie (Messung der Oberflächenformen) dieser Gebirgsseen.
• D. Spengler: Limnologische, hydrologische und morphologische Untersuchungen im Faulhorngebiet (Berner Oberland), (1974).

mineralogy

• N. Marwan: Cave Blisters in der Oberländerhöhle (M3)/ Découverte de blisters dans la Oberländerhöhle (M3), Stalactite, 50(2), 103–105 (2000). » Abstract
  In der Oberländerhöhle im Sägistal (Berner Oberland, Schweiz) wurden blasenartige Gebilde gefunden, sogenannte Cave Blisters. Eine Analyse mittels Röntgendiffraktometrie ergab eine Zusammensetzung der Kruste der Blasen aus Gips und Calcit. In den Blasen wurde eine lockere Mischung aus Calcit und Gips festgestellt. Der Gips entsteht durch die Verwitterung des Pyrits im Kalkstein. Die Auskristallisation des Gipses zerstört die den Kalkstein bedeckende Sinterschicht und verursacht Krusten aus einem Gemisch von Gips und Verwitterungsresten aus Kalzit. Die Blasen könnten durch die ringförmigen Ausblühungen des Gipses entstehen.

palaeoclimate

• W. Tinner, A. F. Lotter: Central European vegetation response to abrupt climate change at 8.2 ka, Geology, 29(6), 551 (2001). DOI:10.1130/0091-7613(2001)029<0551:CEVRTA>2.0.CO;2 » Abstract
  Oxygen isotope records show, a major climatic reversal at 8.2 ka in Greenland and Europe. Annually laminated sediments from two lakes in Switzerland and Germany were sampled contiguously to assess the response of European vegetation to climate change ca. 8.2 ka with time resolution and precision comparable to those of the Greenland ice cores. The pollen assemblages show pronounced and immediate responses (0-20 yr) of terrestrial vegetation to the climatic change at 8.2 ka. A sudden collapse of Corylus avellana (hazel) was accompanied by the rapid expansion of Pinus (pine), Betula (birch), and Tilia (linden), and by the invasion of Fagus silvatica (beech) and Abies alba (fir). Vegetational changes suggest that climatic cooling reduced drought stress, allowing more drought-sensitive and taller growing species to out-compete Corylus avellana by forming denser forest canopies. Climate cooling at 8.2 ka and the immediate reorganization of terrestrial ecosystems has gone unrecognized by previous pollen studies. On the basis of our data we conclude that the early Holocene high abundance of C. avellana in Europe was climatically caused, and we question the conventional opinion that postglacial expansions of F. silvatica and A. alba were controlled by low migration rates rather than by climate. The close connection between climatic change and vegetational response at a subcontinental scale implies that forecasted global warming may trigger rapid collapses, expansions, and invasions of tree species.

palaeoenvironment

• J. Catalan, M. Ventura, A. Brancelj, I. Granados, H. Thies, U. Nickus, A. Korhola, A. F. Lotter, A. Barbieri, L. Lien, T. Buchaca, L. Camarero, G. H. Goudsmit, G. Lemcke, D. M. Livingstone, M. Rautio, S. Sorvari, M. Toro: Seasonal ecosystem variability in remote mountain lakes: implications for detecting climatic signals in sediment records, Journal of Paleolimnology, 28, 25–46 (2002). DOI:10.1023/A:1020315817235 » Abstract
  Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes. Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the lakes showed a number of common features. They were ice-covered between 5–9 months, and all but one were dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was greater in the most productive lakes. Two types of lakes were distinguished according to the number of production peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: one at the onset of stratification, and the other during the autumn overturn. Lakes with shorter stratification had a single peak during the ice-free period. All lakes presented deep chlorophyll maxima during summer stratification, and subsurface chlorophyll maxima beneath the ice. Phosphorus limitation was common to all lakes, since nitrogen compounds were significantly more abundant than the requirements for the primary production observed. The major chemical components present in the lakes showed a short but extreme dilution during thawing. Certain lake features may favour the recording of particular climatic fluctuations, for instance: lakes with two distinct productive periods, climatic fluctuations in spring or autumn (e.g., through chrysophycean cysts); lakes with higher oxygen consumption, climatic factors affecting the duration of the ice-cover (e.g., through low-oxygen tolerant chironomids); lakes with higher water retention time; changes in atmospheric deposition (e.g., through carbon or pigment burial); lakes with longer stratification, air temperature changes during summer and autumn (e.g., through all epilimnetic species).
• O. Heiri, A. F. Lotter: 9000 Years of chironomid assemblage dynamics in an Alpine lake: Long-term trends, sensitivity to disturbance, and resilience of the fauna, Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 273–289 (2003). DOI:10.1023/A:1026036930059 » Abstract
  Subfossil chironomid analysis was applied to a sediment core from Sagistalsee, a small lake at present-day treeline elevation in the Swiss Alps. During the whole 9000-year stratigraphy the chironomid fauna was dominated by taxa typical of alpine lakes. Major faunistic trends were caused by changes in accumulation rates of three taxa, namely Procladius, Stictochironomus, and Tanytarsus lugens-type. In the early Holocene Procladius was the dominant taxon. In younger samples, Stictochironomus tended to have as high or higher abundances and both taxa showed an increase in accumulation rates. A possible cause of this succession is the decrease of lake-water depth due to infilling of the lake basin and changes in associated limnological parameters. The immigration of Picea ( spruce) at ca. 6500 cal. C-14 yrs BP and the resulting denser woodlands in the lake's catchment may have promoted this trend. During three phases, from ca. 70 - 1450, 1900 - 2350, and 3500 - 3950 cal. BP, remains of Procladius, Stictochironomus, and Tanytarsus lugens-type are absent from the lake sediment, whereas other typical lake taxa and stream chironomids show no change in accumulation rate. Together with sediment chemistry data, this suggests that increased oxygen deficits in the lake's bottom water during these intervals caused the elimination of chironomids living in the deepest part of the lake. All three periods coincide with increased human activity in the catchment, as deduced from palaeobotanical evidence. Therefore, enhanced nutrient loading of the lake due to the presence of humans and their livestock in the catchment is the most likely cause of the increased anoxia. The chironomid fauna reacted the same way to intensive pasturing during the last ca. 1500 years as to Bronze Age clear-cutting and more moderate pasturing during the Bronze, Iron, and Roman Ages, suggesting that alpine lake ecosystems can be extremely sensitive to human activity in the catchment. On the other hand, the chironomid assemblages show a considerable amount of resilience to human disturbance, as the chironomid fauna reverted to the pre-impact stage after the first two periods of human activity. In recent years, even though pasturing decreased again, the chironomid fauna has only partly recovered. This is possibly due to other human-induced changes in the lake ecosystem, e. g., the stocking of the lake with fish. The chironomid stratigraphy is difficult to interpret climatologically as the strongest changes in chironomid-inferred temperatures coincide with periods of intensive human activity in the catchment
• O. Heiri, L. Wick, J. F. N. van Leeuwen, W. O. van der Knaap, A. F. Lotter: Holocene tree immigration and the chironomid fauna of a small Swiss subalpine lake (Hinterburgsee, 1515 m asl), Palaeogeography, Palaeoclimatology, Palaeoecology, 189(1-2), 35–53 (2003). DOI:10.1016/S0031-0182(02)00592-8 » Abstract
  Early Holocene reforestation by stone pine (Pinus cembra) and tree birch (Betula pubescens) took place ca. 500 years after the end of the Younger Dryas at Hinterburgsee, a small subalpine lake in the northern Swiss Alps. During the next ca. 3000 years the local vegetation consisted of open woodlands with many pioneer dwarf shrubs and herbs. The expansion of silver fir (Abies alba) at ca. 7400 calibrated radiocarbon years before present (cal. BP) and Norway spruce (Picea abies) at ca. 6000 cal. BP in Hinterburgsee's catchment led to a closing of the local forests with a successive decrease in erosion and a distinct change in Hinterburgsee's sediment composition. First signs of probably human-induced openings of the catchment forest are apparent at ca. 2500 cal. BP, but it is not until the past ca. 800 years that pollen analysis suggests strong local and regional anthropogenic activity. The strongest and most abrupt changes in the Holocene development of Hinterburgsee's chironomid fauna took place at ca. 11 500 cal. BP and at ca. 10 000 cal. BP, when parts of the alpine taxa that were dominant during the Younger Dryas disappeared from the lake. The first change is most likely related to the increasing temperatures after the end of the Younger Dryas, the second possibly to decreasing lake depth and increasing summer insolation in the early Holocene that may have led to warmer bottom water temperatures in the lake. No clear relationship between the changes in catchment vegetation and the development of the chironomid fauna was found. Possibly the increase in sediment organic matter associated with the denser catchment forests was responsible for a succession in the chironomid stratigraphy between 7000 and 4500 cal. BP. However, due to the high sedimentation rates in Hinterburgsee this trend could also be a consequence of, or be promoted by, the sediment infilling of the lake basin. This conjecture is supported by the increasing importance of Tanytarsus lugens-type, a chironomid taxon dominant in the extant chironomid assemblages of shallow mountain lakes in Switzerland. The only shift in the chironomid fauna that clearly parallels a change in catchment vegetation is found during the past ca. 800 years. We discuss possible reasons for the comparatively weak influence of catchment vegetation on the chironomid fauna of Hinterburgsee and the implications of our results for multi-proxy studies on past climate involving both palaeobotanical and chironomid-based reconstructions.
• A. M. Hirt, L. Lanci, K. Koinig: Mineral magnetic record of Holocene environmental changes in Sagistalsee, Switzerland, Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 321–331 (2003). DOI:10.1023/a:1026028728241 » Abstract
  The Holocene magnetic signature due to environmental change has been investigated in sediments from Sagistalsee, a small alpine lake in the Bernese Alps, Switzerland. The environmental signal in the mineral magnetic parameters of the sediments was compared with palynological and geochemical data. The types of magnetic minerals and their grain size reflect changes in the lake catchment, vegetation, and degree of erosional input. The concentration of the magnetic minerals, as expressed by isothermal and anhysteretic remanent magnetizations also reflect changes in vegetation, but may also be related to redox conditions during sedimentation. Climate influence on the mineral magnetic record has been recognized and interpreted as a consequence of the production of an authigenic mineral with particularly uniform magnetic properties during warmer stages and the influx of heterogeneous detrital magnetic mineral during cooler stages and under increased human activity.
• W. Hofmann: The long-term succession of high-altitude cladoceran assemblages: A 9000-year record from Sägistalsee (Swiss Alps), Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 291–296 (2003). DOI:10.1023/A:1026084813220 » Abstract
  Cladoceran remains were analysed in a 1344 cm long sediment core from Sagistalsee ( Swiss Alps, 1935 m asl) which covered the last 9000 years. Planktonic Cladocera were almost exclusively represented by Daphnia species, which occurred throughout the core. The chydorid fauna consisted of four species: Alona quadrangularis, Alona affinis, Acroperus harpae and Chydorus sphaericus of which the former was by far the most frequent species. The chydorid succession was characterised by disappearance and re-appearance of Acroperus harpae and Chydorus sphaericus at about 8400 and 3340 cal. BP, respectively. As a result, there was a long period of about 5000 years in which only two chydorid species were present with strong predominance (88.9%) of Alona quadrangularis. There was also a long-term trend of an increase of Alona affinis at the expense of Alona quadrangularis throughout the core.
• K. Koinig, W. Shotyk, A. F. Lotter, C. Ohlendorf: 9000 Years of Geochemical Evolution of Lithogenic Major and Trace Elements in the Sediment of an alpine lake – the role of climate, vegetation, and land- use history, Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 307–320 (2003). DOI:10.1023/a:1026080712312 » Abstract
  A 9000cal. year record of geochemistry was analysed in a sediment core obtained from a Swiss alpine hard-water lake (1937 ma.s.l.) that is located at the present-day tree-line. Geochemical stratigraphies are compared to changes in mineralogy, grain-size, pollen, and macrofossil records. This allows the reconstruction of the effects of changes in vegetation and of 3500 years of land-use in the catchment area on sediment geochemistry. Using principal component analysis, two major geochemical groups are distinguished: (i) Changes in concentrations of Rb, Ti, Zr, Fe, As, and Pb are closely related to corresponding changes in the concentrations of quartz and clay. They are thus considered to represent the silicate fraction which shows an increase from the oldest to the youngest core section. (ii) In contrast, Ca and Sr concentrations are positively correlated with changes in silt, sand, and calcite. They are therefore considered to represent the carbonate fraction which gradually decreased. Based on constrained cluster analysis, the core is divided into two major zones. The oldest zone (A; 9000–6400 cal.BP) is characterised by high concentrations of detrital carbonates. The more open catchment vegetation at that time promoted the physical weathering of these carbonates. The second major zone (B, 6400 cal.BP–1996 AD) is divided into four subsections with boundaries at ca. 3500, 2400, and 160cal. BP. The lower part of this zone, B1, is characterized by a gradual decrease in the carbonate-silt fraction and a pronounced increase in the silicate-clay fraction. This is concurrent with the expansion of Picea in the catchment area, which probably stabilized the soil. The middle part, B2 and B3 (3500–160cal. BP), comprises pronounced fluctuations in all elements, especially Ca, Sr, Mn, and Rb, but also in clay and silt. These changes are related to varying intensities of alpine farming. In the same section, Mn/Fe ratios are highly variable, suggesting changes in the mixing regime of the lake with phases of anoxic bottom water. The uppermost section, B4 (since 160cal. BP), is characterized by a steep decline in the silicate fraction and an increase in Ca and Sr. Despite the decrease in the silicate fraction, Pb increases, due to elevated atmospheric input resulting from early metal pollution, are masked by the high natural variability. Generally, changes in vegetation, which correspond to climate changes in the early Holocene and to human activities since ca. 3700cal. BP, are the controlling factor for variations in the geochemical composition of the sediment of Sägistalsee.
• L. Lanci, A. M. Hirt, W. Lowrie, A. F. Lotter, G. Lemcke, M. Sturm: Mineral-magnetic record of Late Quaternary climatic changes in a high Alpine lake, Earth and Planetary Science Letters, 170(1-2), 49–59 (1999). DOI:10.1016/S0012-821X(99)00098-9 » Abstract
  The magnetic properties of a sediment core from a high altitude lake in the Swiss Alps were compared with palynological and geochemical data to link climatic and mineral magnetic variations. According to pollen data, the sediments extend from the present to the Younger Dryas, i.e., they cover more than 10,000 years of environmental change in the Alps. The major change in magnetic properties corresponds to the climatic warming of the early Holocene. High-coercivity magnetic minerals that characterize the late-glacial period almost disappeared during the Holocene and the concentration of ferrimagnetic minerals increased sharply. The contribution of superparamagnetic grains also decreased in the Holocene sediments. Similar variations in SP content and coercivity, of smaller magnitude, are found in the Holocene and are interpreted to represent minor climatic variations. Comparison with the historical record of the last 1000 years confirms this interpretation. The magnetic mineralogy, the superparamagnetic contents, and the IRM intensity in the coarse-grained, late-glacial sediments are similar to those measured in the catchment bedrock. This indicates a detrital origin. The different properties and the higher concentration of magnetic minerals in the Holocene sediments are due to authigenic phases. Magnetic properties provide a high resolution record of climatic change. They are sensitive even to small variations that are not recorded in the pollen or LOI data. Magnetic parameters show fine-scale variation and constitute a valuable supplement to conventional climatic indicators.
• L. Lanci, A. M. Hirt, A. F. Lotter, M. Sturm: A record of Holocene climate in the mineral magnetic record of Alpine lakes: Sägistalsee and Hinterburgsee, Earth and Planetary Science Letters, 188(1-2), 29–44 (2001). DOI:10.1016/S0012-821X(01)00301-6 » Abstract
  The effect of climate variations on the magnetic properties of sediments from two small Alpine lakes in the Bernese Alps, Switzerland was investigated. Although relatively similar in water volume and general environment, Sägistalsee and Hinterburgsee have different catchment vegetation and lithology due to their different elevation and geographic locations. The climatic signal in the mineral magnetic parameters of the sediments was validated and interpreted with the aid of palynological and geochemical data. The sediment age was determined with several accelerated mass spectrometry 14C dates. The results from the different lakes compare well on a common time scale and show that the influence of local conditions on the magnetic record is rather small. A climatic influence on the mineral magnetism has been recognized at both studied sites. This is interpreted as a consequence of the production of an authigenic mineral with particularly uniform magnetic properties during the warmer stages and the influx of heterogeneous detrital magnetic minerals during the colder stages. The clearest climate record is found in sediments with no organic matter whereas the anoxic conditions found in highly organic sediment can completely obliterate the climate signal recorded in the sediment magnetic properties.
• D. M. Livingstone, A. F. Lotter: The relationship between air and water temperatures in lakes of the Swiss Plateau: A case study with palæolimnological implications, Journal of Paleolimnology, 19, 181–198 (1998). DOI:10.1023/A:1007904817619 » Abstract
  In palaeolimnological studies, inference models based on aquatic organisms are frequently used to estimate summer lake surface water temperatures. However, the calibration of such models is often unsatisfactory because of the sparseness of measured water temperature data. This study investigates the feasibility of using air temperature data, usually available at much higher resolution, to calibrate such models by comparing regional air temperatures with surface water temperatures in 17 lakes on the Swiss Plateau. Results show that altitude-corrected air temperatures are sufficiently uniform over the entire Swiss Plateau to allow local air temperatures at any particular lake site to be adequately estimated from standard composite air temperature series. In early summer, day-to-day variability in air temperature is reflected extremely well in the temperature of the uppermost metre of the water column, while monthly mean air temperatures correspond well, with respect to both absolute value and interannual variations, with water temperatures in most of the epilimnion. Standardised altitude-corrected air temperature series may therefore be a useful alternative to surface water temperatures for the purposes of calibrating lake temperature inference models. In Northern Hemisphere temperate regions, mean air and water temperatures are likely to correspond most closely in July, suggesting that calibration and reconstruction efforts be concentrated on this month.
• A. F. Lotter, B. Ammann, H. J. B. Birks, O. Heiri, A. Hirt, L. Lanci, G. Lemcke, M. Sturm, J. van Leeuwen, I. R. Walker L. Wick: AQUAREAL: A multi-proxy study of Holocene sediment archives in alpine lakes, Würzburger Geographische Manuskripte, 41, 127–128 (1997). » Abstract
  Abstract on the 7th International Symposium on Palaeolimnology
• A. F. Lotter: Late-glacial and Holocene vegetation history and dynamics as shown by pollen and plant macrofossil analyses in annually laminated sediments from Soppensee, central Switzerland, Vegetation History and Archaeobotany, 8(3), 165–184 (1999). DOI:10.1007/BF02342718 » Abstract
  The palynostratigraphy of two sediment cores from Soppensee, Central Switzerland (596 m asl) was correlated with nine regional pollen assemblage zones defined for the Swiss Plateau. This biostratigraphy shows that the sedimentary record of Soppensee includes the last 15 000 years, i.e. the entire Late-glacial and Holocene environmental history. The vegetation history of the Soppensee catchment was inferred by pollen and plant-macrofossil analyses on three different cores taken in the deepest part of the lake basin (27 m). On the basis of a high-resolution varve and calibrated radiocarbonchronology it was possible to estimate pollen accumulation rates, which together with the pollen percentage data, formed the basis for the interpretation of the past vegetation dynamics. The basal sediment dates back to the last glacial. After reforestation with juniper and birch at ca. 12 700 B.P., the vegetation changed at around 12 000 B.P. to a pine-birch woodland and at the onset of the Holocene to a mixed deciduous forest. At ca. 7000 B.P., fir expanded and dominated the vegetation with beech becoming predominant at ca. 50014C-years later until sometime during the Iron Age. Large-scale deforestation, especially during the Middle Ages, altered the vegetation cover drastically. During the Late-glacial period two distinct regressive phases in vegetation development are demonstrated, namely, the Aegelsee oscillation (equivalent to the Older Dryas biozone) and the Younger Dryas biozone. No unambiguous evidence for Holocene climatic change was detected at Soppensee. Human presence is indicated by early cereal pollen and distinct pulses of forest clearance as a result of human activity can be observed from the Neolithic period onwards.
• A. F. Lotter, C. Bigler: Do diatoms in the Swiss Alps reflect the length of ice-cover?, Aquatic Sciences, 62(2), 125 (2000). DOI:10.1007/s000270050002 » Abstract
  Diatom analyses in the water column, sediment traps, surficial sediments as well as in a short sediment core from Hagelseewli (2339 m asl, Swiss Alps) give information about the present-day seasonal cycle of diatom blooms, taphonomic processes in the lake basin and the lake's history. Analyses of surficial sediments show that water depth and thus light and nutrient availability is the most important factor influencing the production and distribution of diatom assemblages in Hagelseewli, and that periphytic diatom valves deposited in the deeper part of the basin originate from the shallow, littoral parts and are transported to the central part by processes such as lateral currents or sediment focussing. The lake is characterised by a very short period (2-3 months) of open water. Water-column and sediment-trap data revealed that planktonic diatoms bloom during and after the ice break-up, whereas mainly periphytic Fragilaria species entered the traps during the ice-covered period. These results suggest that plankton development is strongly inhibited by the ice-cover, with longer periods of ice-cover favouring Fragilaria species in Hagelseewli. The diatom analysis of a short sediment core that includes the last five centuries revealed several changes in the proportion of planktonic diatoms to Fragilaria species. The colder phases of the Little Ice-Age correspond to phases of lower concentration of planktonic diatoms. The highest, statistically significant amount of variance in the downcore diatom data is explained by winter precipitation, which directly influences the length of the ice-cover but inversely influences the light regime.
• A. F. Lotter, W. Hofmann, C. Kamenik, A. Lami, C. Ohlendorf, M. Sturm, W. O. van der Knaap, J. F. N. van Leeuwen: Sedimentological and biostratigraphical analyses of short sediment cores from Hagelseewli (2339 m a.s.l.) in the Swiss Alps, Journal of Limnology, 59(1s), 53–64 (2000). DOI:10.4081/jlimnol.2000.s1.53 » Abstract
  Several short sediment cores of between 35 and 40 cm from Hagelseewli, a small, remote lake in the Swiss Alps at an elevation of 2339 m a.s.l. were correlated according to their organic matter content. The sediments are characterized by organic silts and show in their uppermost part a surprisingly high amount of organic matter (30-35%). Synchronous changes, occurring in pollen from snow-bed vegetation, the alga Pediastrum, chironomids. and grain-size composition, point to a climatic change interpreted as cooler or shorter summers that led to prolonged ice-cover on the lake. According to palynological results the sediments date back to at least the early 15th century A.D., with the cooling phase encompassing the period behveen late I6th and the mid-19th century thus coinciding with the Little Ice Age. Low concentrations of both chironomid head capsules and cladoceran remains in combination with results from fossil pigment analyses point to longer periods of bottom-water anoxia as a result of long-lasting ice-cover that prevented mixing of the water column. According to our results aquatic biota in flagelseewli are mainly indirectly influenced by climate change. The duration of ice-cover on the lake controls the mixing of the water column as well as light-availability for phytoplankton blooms.
• A. F. Lotter, H. J. B. Birks, U. Eicher, W. Hofmann, J. Schwander, L. Wick: Younger Dryas and Allerod summer temperatures at Gerzensee (Switzerland) inferred from fossil pollen and cladoceran assemblages, Palaeogeography, Palaeoclimatology, Palaeoecology, 159(3-4), ISBN: 4131332205, 349–361 (2000). DOI:10.1016/S0031-0182(00)00093-6 » Abstract
  Linear- and unimodal-based inference models for mean summer temperatures (partial least squares, weighted averaging, and weighted averaging partial least squares models) were applied to a high-resolution pollen and cladoceran stratigraphy from Gerzensee, Switzerland. The time-window of investigation included the Allerod, the Younger Dryas, and the Preboreal Characteristic major and minor oscillations in the oxygen-isotope stratigraphy, such as the Gerzensee oscillation, the onset and end of the Younger Dryas stadial, and the Preboreal oscillation, were identified by isotope analysis of bulk-sediment carbonates of the same core and were used as independent indicators for hemispheric or global scale climatic change. In general, the pollen-inferred mean summer temperature reconstruction using all three inference models follows the oxygen-isotope curve more closely than the cladoceran curve. The cladoceran-inferred reconstruction suggests generally warmer summers than the pollen-based reconstructions, which may be an effect of terrestrial vegetation not being in equilibrium with climate due to migrational lags during the Late Glacial and early Holocene. Allerod summer temperatures range between 11 and 12°C based on pollen, whereas the cladoceran-inferred temperatures lie between 11 and 13°C. Pollen and cladocera-inferred reconstructions both suggest a drop to 9-10°C at the beginning of the Younger Dryas. Although the Allerod-Younger Dryas transition lasted 150-160 years in the oxygen-isotope stratigraphy, the pollen-inferred cooling took 180-190 years and the cladoceran-inferred cooling lasted 250-260 years. The pollen-inferred summer temperature rise to 11.5-12°C at the transition from the Younger Dryas to the Preboreal preceded the oxygen-isotope signal by several decades, whereas the cladoceran-inferred warming lagged. Major discrepancies between the pollen- and cladoceran-inference models are observed for the Preboreal, where the cladoceran-inference model suggests mean summer temperatures of up to 14-15°C. Both pollen- and cladoceran-inferred reconstructions suggest a cooling that may be related to the Gerzensee oscillation, but there is no evidence for a cooling synchronous with the Preboreal oscillation as recorded in the oxygen-isotope record. For the Gerzensee oscillation the inferred cooling was ca. 1 and 0.5°C based on pollen and cladocera, respectively, which lies well within the inherent prediction errors of the inference models. (C) 2000 Elsevier Science B.V.
• A. F. Lotter, P. G. Appleby, R. Bindler, J. A. Dearing, W. Hofmann, C. Kamenik, A. Lami, D. M. Livingstone, C. Ohlendorf, N. Rose, M. Sturm: The sediment record of the past 200 years in a Swiss high-alpine lake: Hagelseewli (2339 m a.s.l.), Journal of Paleolimnology, 28, 111–127 (2002). DOI:10.1023/A:1020328119961 » Abstract
  Sediment cores spanning the last two centuries were taken in Hagelseewli, a high-elevation lake in the Swiss Alps. Contiguous 0.5 cm samples were analysed for biological remains, including diatoms, chironomids, cladocera, chrysophyte cysts, and fossil pigments. In addition, sedimentological and geochemical variables such as loss-on-ignition, total carbon, nitrogen, sulphur, grain-size and magnetic mineralogy were determined. The results of these analyses were compared to a long instrumental air temperature record that was adapted to the elevation of Hagelseewli by applying mean monthly lapse rates. During much of the time, the lake is in the shadow of a high cliff to the south, so that the lake is ice-covered during much of the year and thus decoupled from climatic forcing. Lake biology is therefore influenced more by the duration of ice-cover than by direct temperature effects during the short open-water season. Long periods of ice-cover result in anoxic water conditions and dissolution of authigenic calcites, leading to carbonate-free sediments. The diversity of chironomid and cladoceran assemblages is extremely low, whereas that of diatom and chrysophyte cyst assemblages is much higher. Weak correlations were observed between the diatom and chrysophyte cyst assemblages on the one hand and summer or autumn air temperatures on the other, but the proportion of variance explained is low, so that air temperature alone cannot account for the degree of variation observed in the paleolimnological record. Analyses of mineral magnetic parameters, spheroidal carbonaceous particles and lead suggest that atmospheric pollution has had a significant effect on the sediments of Hagelseewli, but little effect on the water quality as reflected in the lake biota.
• A. F. Lotter, H. J. B. Birks: Holocene sediments of Sagistalsee, a small lake at the present-day tree-line in the Swiss Alps, Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 253–260 (2003). DOI:10.1023/a:1026041030967 » Abstract
  Sagistalsee is a small lake located at the modern tree-line in the Swiss Alps. A 13.5 m long core taken in the central part of the 9.5 m deep basin consists of clayey silts and sands and dates back to about 9000 cal. BP. These sediments have a low organic content that steadily increases from 4 - 8% loss-on-ignition at 550 degreesC towards the top of the core, whereas the carbonate content decreases from 20 to about 10% loss-on-ignition at 950 degreesC. We outline the aims of an interdisciplinary research project centred on the Holocene sediments of Sagistalsee. We also present information about the lake, its sediments, and its catchment that forms the basis for different biotic and abiotic multiproxy studies carried out on the sediments of Sagistalsee.
• A. F. Lotter, H. J. B. Birks: The Holocene palaeolimnology of Sägistalsee and its environmental history – A synthesis, Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 333–342 (2003). DOI:10.1023/A:1026091511403 » Abstract
  Multi-proxy palaeoecological and palaeolimnological studies of the sedimentary record of Sägistalsee, a small lake at the present-day timberline in the Swiss Alps, reveal distinct changes in its catchment vegetation in relation to Holocene climate change and human impact. Four phases of catchment vegetation type were defined based on plant macrofossil analyses: open Betula-Pinus cembra woodland, Abies alba-Pinus cembra woodland, Picea abies forest, and cultural pasture. The expansion of spruce ∽ 6300 cal. BP had a major impact on all abiotic proxies, whereas the reaction of the biotic proxies to this catchment change was lagged by several centuries. During the Bronze Age (ca. 4000 cal. BP) the spruce forest was cleared and the catchment began to be used as grazing pastures. Changes in sedimentology, geochemistry, and magnetic parameters closely reflect the changes in catchment vegetation. The catchment vegetation types explain a statistically significant amount of the variance in the chironomid, cladoceran, sedimentological, and magnetic data but not in the geochemical data. The strong catchment-lake interaction masks any biotic responses to millennium-scale climatic oscillations.
• E. Messikommer: Alte und neuere Untersuchungen über die Algenflora des östlichen Berner Oberlandes, Mitteilungen der Naturforschenden Gesellschaft in Bern, 13, 81–152 (1956). DOI:10.5169/seals-319467

• C. Ohlendorf, C. Bigler, G.-H. Goudsmit, G. Lemcke, D. M. Livingstone, F. F. Lotter, B. Müller, M. Sturm: Causes and effects of long periods of ice cover on a remote high Alpine lake, Journal of Limnology, 59(1s), 65–80 (2000). DOI:10.4081/jlimnol.2000.s1.65 » Abstract
  The response of the physical and chemical limnology of Hagelseewli (2339 m a.s.l.) to local meteorological forcing was investigated from 1996 to 1998 using an automatic weather station, thermistor chains, water samples and sediment traps. On-site meteorological measurements revealed the paramount importance of local topographic shading for the limnology of the lake. A high cliff to the south diminishes incident radiation by 15% to 90%, resulting in a long period of ice cover. Hence, the spring and summer seasons are extremely condensed, allowing only about 2 months per year for mixing, oxygen uptake, nutrient inflow, water exchange and phytoplankton growth. Regular measurements of water temperature, chemistry and diatom composition show that Hagelseewli responds very rapidly to changes in nutrient concentrations and light conditions. This response is restricted mainly to an extremely short productivity pulse, which takes place as soon as the lake is completely free of ice. Ice-free conditions are indicated by the occurrence of planktonic diatoms. In contrast to most low-altitude lakes, maximum productivity occurs in the middle of the water column (6-9 m), where first light, and then soluble reactive phosphorus (SRP), are the limiting factors. During the period of thawing, large amounts of ammonium enter the lake. Nevertheless, allochthonous nutrient input is not important because SRP, the limiting nutrient for algal growth, originates from the sediments. Water chemistry data and data from sediment traps show that, although autochthonous calcite precipitation does occur, the calcite crystals are redissolved completely in the bottom waters during the extended period of ice cover. Thus, the most important factor for changes in the nutrient budget, primary production and preservation of calcite is the bottom water oxygen status, which is governed by the occurrence of an ice-free period. We hypothesise that the duration of the ice-free period is of minor importance for the generation of particles that might be archived in the sedimentary record as proxy climate indicators. Such particles are produced mainly during times of peak primary production, which last only for a few days before production decreases again to very low levels. Therefore, with respect to the type of climatic signal that might be recorded in Hagelseewli, we presume that what is most likely to be archived in the sedimentary record is the mere occurrence, rather than the duration of the ice-free period.
• C. Ohlendorf, M. Sturm, S. Hausmann: Natural environmental changes and human impact reflected in sediments of a high alpine lake in Switzerland, Journal of Paleolimnology, 30, 297–306 (2003). DOI:10.1023/A:1026032829150 » Abstract
  From the high alpine Sägistalsee (1935 m a.s.l.), 13.50 m of continuously laminated sediments comprising the last 9050 years, were analyzed. Even though Sägistalsee is a high elevation site, human-induced environmental changes start as early as 4300 cal. BP and leave a clearly detectable signal in the mineralogy of the sediments, which is much stronger than the signal from natural environmental changes that occurred before this time. Variations in the physical and mineralogical sediment properties of this clastic sequence reflect erosional changes in the catchment, where almost pure limestone contrasts with carbonaceous, quartz-bearing marl, and shist. The calcite/quartz (Cc/Qz) ratio was found to be most indicative of these changes, which occurred around AD 1850 and at 650, 2000, 3700, and 6400 cal. BP. The first four are interpreted as erosion events, which are related to human-induced changes in the vegetation cover and land use. We associate them to the recent development of tourism and grazing, the medieval intensification of pasturing, Roman forest clearance, and Bronze Age forest clearance, respectively. The Cc/Qz-ratio increases significantly within less than 100 years during these events, reflecting the erosion of unweathered or poorly weathered soils. The time intervals in between are characterized by a gradually decreasing Cc/Qz-ratio and reflect the stabilization or formation of new soils. Only the change at 6400 cal. BP, which represents the initial gradual stabilization of the catchment, is related to the immigration of Picea abies.
• J. L. Teranes, J. A. McKenzie, S. M. Bernasconi, A. F. Lotter, M. Sturm: A study of oxygen isotopic fractionation during bio-induced calcite precipitation in eutrophic Baldeggersee, Switzerland, Geochimica et Cosmochimica Acta, 63(13-14), 1981–1989 (1999). DOI:10.1016/S0016-7037(99)00049-6 » Abstract
  In order to better understand environmental factors controlling oxygen isotope shifts in authochthonous lacustrine carbonate sequences, we undertook an extensive one-year study (March, 1995 to February, 1996) of water-column chemistry and daily sediment trap material from a small lake in Central Switzerland. Comparisons between calculated equilibrium isotope values, using the fractionation equation of Friedman and O'Neil (1977) and measured oxygen isotope ratios of calcite in the sediment-traps reveal that oxygen isotopic values of autochthonous calcite (delta18O) are in isotopic equilibrium with ambient water during most of the spring and summer, when the majority of the calcite precipitates. In contrast, small amounts of calcite precipitated in early-spring and again in late-autumn are isotopically depleted in 18O relative to the calculated equilibrium values, by as much as 0.8‰. This seasonally occurring apparent isotopic nonequilibrium is associated with times of high phosphorous concentrations, elevated pH (~8.6) and increased [CO32-] (~50 μmol/l) in the surface waters. The resulting weighted average delta18O value for the studied period is -9.6‰, compared with a calculated equilibrium delta18O value of -9.4‰. These data convincingly demonstrate that delta18O of calcite are, for the most part, a very reliable proxy for temperature and delta18O of the water.
• W. O. van der Knaap, J. F. N. van Leeuwen, A. Fankhauser, B. Ammann: Palynostratigraphy of the last centuries in Switzerland based on 23 lake and mire deposits: chronostratigraphic pollen markers, regional patterns, and local histories, Review of Palaeobotany and Palynology, 108(1-2), ISBN: 4131332205, 85–142 (2000). DOI:10.1016/S0034-6667(99)00035-4

• W. O. van der Knaap, J. F. N. van Leeuwen, A. Fankhauser, B. Ammann: Erratum to “Palynostratigraphy of the last centuries in Switzerland based on 23 lake and mire deposits: chronostratigraphic pollen markers, regional patterns, and local histories” [Rev. Palaeobot. Palynol. 108 (2000) 85–142], Review of Palaeobotany and Palynology, 114(3-4), 269–270 (2001). DOI:10.1016/S0034-6667(01)00049-5

• W. O. van der Knaap, J. F. N. van Leeuwen, B. Ammann: Seven years of annual pollen influx at the forest limit in the Swiss Alps studied by pollen traps: relations to vegetation and climate, Review of Palaeobotany and Palynology, 117(1-3), 31–52 (2001). DOI:10.1016/S0034-6667(01)00075-6 » Abstract
  Annual pollen influx has been monitored in short transects across the altitudinal tree limit in four areas of the Swiss Alps with the use of modified Tauber traps placed at the ground surface. The study areas are Grindelwald (8 traps), Aletsch (8 traps), Simplon (5 traps), and Zermatt (5 traps). The vegetation around the traps is described. The results obtained are: (1) Peak years of pollen influx (one or two in seven years) follow years of high average air temperatures during June-November of the previous year for Larix and Picea, and less clearly for Pinus non-cembra, but not at all for Pinus cembra and Alnus viridis. (2) At the upper forest limit, the regional pollen influx of trees (trees absent within 100 m of the pollen trap) relates well to the average basal area of the same taxon within 10-15 km of the study areas for Pinus cembra, Larix, and Betula, but not for Picea, Pinus non-cembra, and Alnus viridis. (3) The example of Zermatt shows that pollen influx characterises the upper forest limit, if the latter is more or less intact. (4) Presence/absence of Picea, Pinus cembra, Larix, Pinus non-cembra, and Alnus viridis trees within 50- 100 m of the traps is apparent in the pollen influx in peak years of pollen influx but not in other years, suggesting that forest-limit trees produce significant amounts of pollen only in some years. (5) Pollen influx averaged over the study period correlates well with the abundance of plants around the pollen traps for conifer trees (but not deciduous trees), Calluna, Gramineae, and Cyperaceae, and less clearly so Compositae Subfam. Cichorioideae and Potentilla-type. (6) Influx of extra-regional pollen derived from south of the Alps is highest in Simplon, which is open to southerly winds, slightly lower in Aletsch lying just north of Simplon, and lowest in Zermatt sheltered from the south by high mountains and Grindelwald lying north of the central Alps.
• L. Wick: Vegetational response to climatic changes recorded in Swiss Late Glacial lake sediments, Palaeogeography, Palaeoclimatology, Palaeoecology, 159(3-4), 231–250 (2000). DOI:10.1016/S0031-0182(00)00087-0 » Abstract
  High-resolution pollen analysis at five lakes on an altitudinal transect in Switzerland (Gerzensee, 603 m; Leysin, 1230 m; Regenmoos, 1260 m; Zeneggen, 1510 m; Heremence, 2290 m) focused on the vegetational response to the rapid climatic changes at the end and beginning of the Younger Dryas and to the minor Gerzensee and Preboreal climatic oscillations. An absolute time scale transferred from the Greenland GRIP ice core to the Gerzensee and Leysin records by wiggle-matching the oxygen-isotope stratigraphies facilitates the estimation of pollen influx and rates of change. The climatic warming at the end of the Younger Dryas, indicated by increases in oxygen-isotope values and/or the beginning of organic sedimentation in the lakes, was immediately reflected in the vegetation at all the sites investigated. The time lags at sites situated above the timberline during the Younger Dryas are considered to be migrational lags. At the onset of the Younger Dryas a time lag of several decades occurred between the oxygen-isotope record of climatic cooling and the major response of the vegetation, whereas minor vegetation changes occurred with or without short time lags. Betula reacted earlier to the new environmental conditions (within about 40–50 yr at Gerzensee and within less than 36 yr at Leysin) than Pinus and Artemisia (about 170 yr), suggesting that time lags are due to the ecological requirements of the different taxa. For the Gerzensee and Preboreal oscillations little or no change can be observed in the pollen record from Gerzensee, whereas at Leysin both climatic oscillations produced a statistically significant vegetational response to both climatic oscillations. Generally the vegetation responses to climatic changes are more pronounced near vegetation ecotones at medium and higher altitudes than in the lowlands.
• L. Wick, J. F. N. van Leeuwen, W. O. van der Knaap, A. F. Lotter: Holocene vegetation development in the catchment of Sagistalsee (1935 m asl), a small lake in the Swiss Alps, Journal of Paleolimnology, 30(3), ISBN: 0921-2728, 261–272 (2003). DOI:10.1023/a:1026088914129 » Abstract
  Pollen and plant macrofossils were analysed at Sagistalsee ( 1935 m asl), a small lake near timber-line in the Swiss Northern Alps. Open forests with Pinus cembra and Abies alba covered the catchment during the early Holocene (9000 - 6300 cal. BP), suggesting subcontinental climate conditions. After the expansion of Picea abies between 6300 and 6000 cal. BP the subalpine forest became denser and the tree-line reached its maximum elevation at around 2260 m asl. Charcoal fragments in the macrofossil record indicate the beginning of Late-Neolithic human impact at ca. 4400 cal. BP, followed by a extensive deforestation and lowering of the forest-limit in the catchment of Sagistalsee at 3700 cal. BP ( Bronze Age). Continuous human activity, combined with a more oceanic climate during the later Holocene, led to the local extinction of Pinus cembra and Abies alba and favoured the mass expansion of Picea and Alnus viridis in the subalpine area of the Northern Alps. The periods before 6300 and after 3700 cal. BP are characterised by high erosion activity in the lake's catchment, whereas during the phase of dense Picea-Pinus cembra-Abies forests ( 6300 - 3700 cal. BP) soils were stable and sediment-accumulation rates in the lake were low. Due to decreasing land-use at higher altitudes during the Roman occupation and the Migration period, forests spread beween ca. 2000 and 1500 cal. BP, before human impact increased again in the early Middle Ages. Recent reforestation due to land-use changes in the 20th century is recorded in the top sediments. Pollen-inferred July temperature and annual precipitation suggest a trend to cooler and more oceanic climate starting at about 5500 cal. BP.

regionalclimate

• C. Frei, C. Schär: A precipitation climatology of the Alps from high-resolution rain-gauge observations, International Journal of Climatology, 18(8), 873–900 (1998). DOI:10.1002/(SICI)1097-0088(19980630)18:8<873::AID-JOC255>3.0.CO;2-9 » Abstract
  A new precipitation climatology covering the European Alsp is presented. The analysis covers the entire mountain range including adjacent foreland areas and exhibits a resolution of about 25 km. It is based on observations at one of the densest rain-gauge networks over complex topography world-wide, embracing more than 6600 stations from the high-resolution networks of the Alpine countries. The climatology is determined from daily analyses of bias-uncorrected, quality controlled data for the 20 year period 1971-1990. The daily precipitation fields were produced with an advanced distance-weighting scheme commonly adopted for the analysis of precipitation on a global scale. The paper describes the baseline seasonal measns derived from the daily analysis fields. The results depict the mesoscale distribution of the Alpine precipitation climate, its relation to the topography, and its seasonal cycle. Gridded analysis results are also provided in digital form. The most prominent Alpine effects include the enhancement of precipitation along the Alpine foothills, and the shielding of the inner-Alpine valleys. A detailed analysis along a section across the Alps also demonstrates that a simple precipitation-height relationship does not exist on the Alpine scale, because much of the topographic signal is associated with slope and shielding rather than height effects. Although systematic biases associated wtih the rain-gauge measurement and the topographic clustering of the stations are not corrected for, a qualitative validation of the results, using existing national climatologies shows good agreement on the mesoscale. Furthermore a comparison is made between the present climatology and the Alpine sections of the global climatology of Legates and Willmott and the Greater European climatology from the Climate Research Unit (University of East Anglia). Results indicate that the pattern and magnitude of analysed. Alpine precipitation critically depend upon the density of available observations and the analysis procedure adopted.
• C. Frei, E. Häller: Mesoscale precipitation analysis from MAP SOP Rain-gauge data, In: MAP newsletter, 15(06), 257–260 (2001).

speleo

• N. Marwan: Das Höhlengebiet Sägistal – 20 Jahre ISAAK-Forschung, Stalactite, 60(1), 12–17 (2010). » Abstract
  Die Internationale Speläologische Arbeitsgruppe Alpiner Karst (ISAAK) hat ihre Ursprünge in der Erforschung des Sägistales. 1988 trafen sich Vertreter des Vereins Höhlenforschung im Berner Oberland (VHBO) und der Höhlenforschergruppen Lethmate und Karlsruhe erstmals, um das gerade erst wiederentdeckte Sägistal zu bearbeiten.
• N. Marwan: Karstgebiet Sägistal, Proceedings 14. Nationaler Höhlenforscher-Kongress, Sinterlaken19, 69–74 (2019). » Abstract
  Das Sägistal ist ein abgelegenes Hochtal der Berner Voralpen mit typischen Karsterscheinungen. Die Erforschung der Höhlen begann in den 1970er Jahren durch die SGH Interlaken und wird seit 1988 durch die Internationale Speläologische Arbeitsgruppe Alpiner Karst (ISAAK) unter Beteiligung zahlreicher Höhlenforschergruppen aus verschiedenen Ländern organisiert. Mittlerweile wurden über 400 Höhlen gefunden mit dem "Oberländer-Chessiloch"-System als größtem Objekt (2346 m Länge, -488 m Tiefe).
• N. Marwan: Der digitale Sägistal-Kataster, Stalactite, 73(1), 24–33 (2023). » Abstract
  Der Höhlenkataster zum Gebiet Sägistal (Berner Oberland, Schweiz) beinhaltet fast 460 Höhlen. Er entpricht einer einfachen, skriptbasierten Lösung, die dynamisch aus den einzelnen Katasterblättern (die in Form von HTML-Seiten vorliegen) erzeugt wird. Dies erlaubt schnelle Änderungen am Inhalt mit einem beliebigen Texteditor und somit einen langjährigen und nachhaltigen Betrieb.

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