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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).
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
