PEOPLERoland Psenner

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Roland Psenner

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roland.psenner@eurac.edu

https://orcid.org/0000-0002-9209-0298

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About

Roland Psenner was born in Bozen-Bolzano, Italy, in 1950. After his PhD in microbiology, limnology and biochemistry at the University of Innsbruck, Austria, he worked at the University of Innsbruck for international programmes focussed on environmental problems of lakes, as public officer for settlement planning in Italy, and with the Austrian Academy of Sciences. Since 1997, he is Professor of Limnology at the University of Innsbruck.

He is an expert in eutrophication and phosphorus cycling, biogeochemistry of acidification, global change effects on lakes, aquatic microbial food webs, and ice ecosystems. He worked on different aspects of UV radiation effects on aquatic microorganisms, with image analysis and flow cytometry methods and as paleo-ecologist with a focus on alpine ecosystems. He participated in several Framework Programs of the EU and has published 500 articles, more of 150 of them in peer-reviewed journals. His papers have been cited more than 13,000 times (Google Scholar, h=63), he belongs to the top two percent scientists worldwide (https://doi.org/10.1371/journal. pbio.3000918), has written more than 30 book chapters and edited a book series on mountain issues with 15 volumes up to now.

As president of the International Scientific Committee of Alpine Research (ISCAR, Berne, CH) in 2000-2002 and speaker of the Research Focus "Alpine Space – Man & Environment" of the University of Innsbruck he has become interested also in social and cultural problems of mountain regions. From 2013 to 2021 he was the president of the national committee “Global Change” of the Austrian Academy of Sciences. From 2008 to 2012 he served as Dean of the Faculty of Biology, from 2012 to 2015 he was Vice Rector of the University of Innsbruck and since July 2015 he is the president of Eurac Research in Bolzano/Bozen (Italy). Since 2018, when he became professor emeritus, he is vice president of the university council of BOKU, the University of Natural Resources and Life Sciences, Vienna.

He is married to Barbara Golderer and has two sons.

Scientific Publications

Journal article2023

Changes in air temperature, but not in precipitation, determine long-term trends in water chemistry of high mountain lakes of the Alps with and without rock glacier influence

Schreder S, Sommaruga R, Psenner R, Chimani B, Ganekind M, Koinig KA

Roland Psenner

Climate change has strongly affected lakes around the world, but the relative effects of warmer air temperatures and changing precipitation on the water chemistry of alpine systems are not well understood. Here we tested the effect of monthly and seasonal climate on the water chemistry of six high mountain lakes located in the Alps. From 1982 to 2020, water samples were collected annually from different depths during the autumn mixing. We observed a simultaneous increase in electrical conductivity, ionic content, and pH with air temperature. In lakes with rock glacier influence, the increase in conductivity, ionic content, and especially in sulfate was even more pronounced, but accompanied by a strong decrease in pH. These differences are attributed to the direct influence of acidic meltwater from active rock glaciers in catchments with acidic bedrock. We then analyzed changes in lake chemistry, taking into account seasonal trends in air temperature and precipitation, using redundancy analysis. Temperature increase significantly affected water chemistry in five of the six lakes, especially at times of ice breakup. Increasing warming explained 17% to 32% of the changes in electrical conductivity, alkalinity, pH, major ions, and nitrogen. In contrast, precipitation had little effect on the changes of those parameters. Nevertheless, late spring snowfall and high snowfall in early fall, which result in prolonged ice cover, had a dampening effect on the impact of climate warming on lake chemistry. Our results confirm that climate warming remains a major driver of chemical changes in alpine lakes, but provide new evidence that late spring temperatures are the most important triggers.

DOI

DOI: 10.1016/j.scitotenv.2023.167750

Journal article2019

The Little Ice Age signature in a 700-year high-resolution chironomid record of summer temperatures in the Central Eastern Alps

Ilyashuk EA, Heiri O, Ilyashuk BP, Koinig KA, Psenner R

Roland Psenner

Despite the fact that the Little Ice Age (LIA) is well documented for the European Alps, substantial uncertainties concerning the regional spatio-temporal patterns of temperature changes associated with the LIA still exist, especially for their eastern sector. Here we present a high-resolution (4–10 years) 700-year long mean July air temperature reconstruction based on subfossil chironomid assemblages from a remote lake in the Austrian Eastern Alps to gain further insights into the LIA climatic deterioration in the region. The record provides evidence for a prolonged period of predominantly cooler conditions during AD 1530–1920, broadly equivalent to the climatically defined LIA in Europe. The main LIA phase appears to have consisted of two cold time intervals divided by slightly warmer episodes in the second half of the 1600s. The most severe cooling occurred during the eighteenth century. The LIA temperature minimum about 1.5 °C below the long-term mean recorded in the mid-1780 s coincides with the strongest volcanic signal found in the Greenland ice cores over the past 700 years and may be, at least in part, a manifestation of cooling that followed the long-lasting AD 1783–1784 Laki eruption. A continuous warming trend is evident since ca AD 1890 (1.1 °C in 120 years). The chironomid-inferred temperatures show a clear correlation with the instrumental data and reveal a close agreement with paleotemperature evidence from regional high-elevation tree-ring chronologies. A considerable amount of the variability in the temperature record may be linked to changes in the North Atlantic Oscillation.

DOI Fonte

DOI: 10.1007/s00382-018-4555-y

Journal article2018

Assessment of climate change effects on mountain ecosystems through a cross-site analysis in the Alps and Apennines

Rogora M, Frate L, Carranza ML, Freppaz M, Stanisci A, Bertani I, Bottarin R, Brambilla A,

Roland Psenner, Ulrike Tappeiner, Roberta Bottarin

Mountain ecosystems are sensitive and reliable indicators of climate change. Long-term studies may be extremely useful in assessing the responses of high-elevation ecosystems to climate change and other anthropogenic drivers from a broad ecological perspective. Mountain research sites within the LTER (Long-Term Ecological Research) network are representative of various types of ecosystems and span a wide bioclimatic and elevational range.

Here, we present a synthesis and a review of the main results from ecological studies in mountain ecosystems at 20 LTER sites in Italy, Switzerland and Austria covering in most cases more than two decades of observations. We analyzed a set of key climate parameters, such as temperature and snow cover duration, in relation to vascular plant species composition, plant traits, abundance patterns, pedoclimate, nutrient dynamics in soils and water, phenology and composition of freshwater biota.

The overall results highlight the rapid response of mountain ecosystems to climate change, with site-specific characteristics and rates. As temperatures increased, vegetation cover in alpine and subalpine summits increased as well. Years with limited snow cover duration caused an increase in soil temperature and microbial biomass during the growing season. Effects on freshwater ecosystems were also observed, in terms of increases in solutes, decreases in nitrates and changes in plankton phenology and benthos communities. This work highlights the importance of comparing and integrating long-term ecological data collected in different ecosystems for a more comprehensive overview of the ecological effects of climate change. Nevertheless, there is a need for (i) adopting co-located monitoring site networks to improve our ability to obtain sound results from cross-site analysis, (ii) carrying out further studies, in particular short-term analyses with fine spatial and temporal resolutions to improve our understanding of responses to extreme events, and (iii) increasing comparability and standardizing protocols across networks to distinguish local patterns from global patterns.

DOI

DOI: 10.1016/j.scitotenv.2017.12.155

Journal article2018

Climate warming increases vertical and seasonal water temperature differences and inter-annual variability in a mountain lake

Niedrist GH, Psenner R, Sommaruga R

Roland Psenner

Lakes around the world are warming, but not all water layers are warming at the same rate, and some are even cooling. Most studies have focused on summer lake water surface temperatures or analyzed short-time series. Here, we analyze a 44-year time series of water temperature from nine depths in a small mountain lake using dynamic linear models and temporal trend decomposition. We observe a significant long-term warming trend, but this occurred only from August to December in all water layers. The lake warmed ca. twice as fast (0.23 °C decade−1) as the air, but warming of the epilimnion slowed down remarkably (from 0.65 to 0.10 °C per decade) after 1993, a consequence of changing stratification timing. Deeper water layers even cooled thereafter, pointing to a stronger isolation from surface layers, which were still warming over the whole study period. This differential warming of the lake was accompanied by significant shifts of lake freezing and thawing dates leading to shorter ice-cover periods (~ 5 days decade−1). As a result, the thermal Schmidt stability of the water column strengthened, but also temperature variance in the epilimnion increased significantly, together with increasing variance and extremes of local air temperature. Our results show a significant autumn/winter warming effect of lake water together with an increasing intensity of temperature fluctuations in this seasonally ice-covered mountain lake, suggesting that current broad scale estimates of climate change impacts on lakes, based on summer temperature measurements and surface layers, do not fully reflect the effect of climate change.

DOI

DOI: 10.1007/s10584-018-2328-6

Journal article2018

Rock glaciers in crystalline catchments: Hidden permafrost-related threats to alpine headwater lakes

Ilyashuk B, Ilyashuk E, Psenner R, Tessadri R, Koinig KA

Roland Psenner

A global warming-induced transition from glacial to periglacial processes has been identified in mountainous regions around the world. Degrading permafrost in pristine periglacial environments can produce acid rock drainage (ARD) and cause severe ecological damage in areas underlain by sulfide-bearing bedrock. Limnological and paleolimnological approaches were used to assess and compare ARDs generated by rock glaciers, a typical landform of the mountain permafrost domain, and their effects on alpine headwater lakes with similar morphometric features and underlying bedrock geology, but characterized by different intensities of frost action in their catchments during the year. We argue that ARD and its effects on lakes are more severe in the alpine periglacial belt with mean annual air temperatures (MAAT) between −2°C and +3°C, where groundwater persists in the liquid phase for most of the year, in contrast to ARD in the periglacial belt where frost action dominates (MAAT < −2°C). The findings clearly suggest that the ambient air temperature is an important factor affecting the ARD production in alpine periglacial environments. Applying the paleoecological analysis of morphological abnormalities in chironomids through the past millennium, we tested and rejected the hypothesis that unfavorable conditions for aquatic life in the ARD-stressed lakes are largely related to the temperature increase over recent decades, responsible for the enhanced release of ARD contaminants. Our results indicate that the ARDs generated in the catchments are of a long-lasting nature and the frequency of chironomid morphological deformities was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods, suggesting that lower water temperatures may increase the adverse impacts of ARD on aquatic invertebrates. This highlights that temperature-mediated modulations of the metabolism and life cycle of aquatic organisms should be considered when reconstructing long-term trends in the ecotoxicological state of lakes.

DOI

DOI: 10.1111/gcb.13985

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Journal article2018

Assessment of climate change effects on mountain ecosystems through a cross-site analysis in the Alps and Apennines

Rogora M, Frate L, Carranza ML, Freppaz M, Stanisci A, Bertani I, Bottarin R, Brambilla A,

Roland Psenner, Ulrike Tappeiner, Roberta Bottarin

DOI

DOI: 10.1016/j.scitotenv.2017.12.155

Roland Psenner

About

Scientific Publications

Changes in air temperature, but not in precipitation, determine long-term trends in water chemistry of high mountain lakes of the Alps with and without rock glacier influence

The Little Ice Age signature in a 700-year high-resolution chironomid record of summer temperatures in the Central Eastern Alps

Assessment of climate change effects on mountain ecosystems through a cross-site analysis in the Alps and Apennines

Climate warming increases vertical and seasonal water temperature differences and inter-annual variability in a mountain lake

Rock glaciers in crystalline catchments: Hidden permafrost-related threats to alpine headwater lakes

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Scientific Publications

Changes in air temperature, but not in precipitation, determine long-term trends in water chemistry of high mountain lakes of the Alps with and without rock glacier influence

The Little Ice Age signature in a 700-year high-resolution chironomid record of summer temperatures in the Central Eastern Alps

Assessment of climate change effects on mountain ecosystems through a cross-site analysis in the Alps and Apennines

Climate warming increases vertical and seasonal water temperature differences and inter-annual variability in a mountain lake

Rock glaciers in crystalline catchments: Hidden permafrost-related threats to alpine headwater lakes