The Mediterranean and coastal site of Port-Miou is a wide regional carbonate aquifer, with a catchment area around 400 km², in south of France (Provence, France). It extends mainly over natural land, in the vicinity of one of the main city of France (Marseille), facing recent urban expansion and future groundwater resources management issues. Top of the recharge area culminates at 1100 m asl, and the main outlets are submarine springs. Karst features are observed in surface (polje, intermittent rivers, sinkholes, karren, caves) and underground. Many karst networks have been explored in the unsaturated zone of the aquifer, but also in the saturated zone below the sea level. Karst features and conduits drive the groundwater flows to the main outlets. The Port-Miou submarine springs outflow from huge flooded karst conduits, explored by cave diving over several kilometers inland, and to -235 m deep. Groundwater is brackish, polluted by seawater intrusion. The Port-Miou observation site includes flow rate, salinity and temperature monitoring at the main brackish spring, in an in-situ underground laboratory located 500 m inland from the seashore, directly in the main karst conduit. Rainfall is also recording in the catchment area, and rain water samples are collected for water isotopes observation.

The LTER site is a COMPLEX site, with observation sites focusing (a) on the three glaciers in the Kaunertal Valley, (b) 10 ecological and erosion sites along a succession gradient in the pro glacial, and (c) one climate station. The station (a) is run by Andrea Fischer (AAS), stations (b) and (c) within the PHUSICOS project coordinated by Sabine Kraushaar (University of Vienna). In the proglacial area of the Gepatschferner glacier ten mechanical erosion sites with each three plots (each 2x3m, see picture) are installed monitoring biotic and abiotic interrelations in 5 different succession classes. Small scale erosion processes such as splash, rill and interill erosion processes are quantified as a function of the present species composition. A climate station on 2350m run by solar power complement the set up.

This study site is in the south of the city of Moulins, including the National Nature Reserve of the Val d'Allier which protects 1,450 hectares over approximately 28 km along the lower course of the Allier River. The Allier river is considered as the last wild river of Europe because of its strong fluvial dynamics and remaining free meandering river segments. The studied sector within the nature reserve is still very mobile, with a strong lateral dynamic, where the width of the divagation can be of the order of one kilometer. At this scale, it is unique in Europe.

The LTER site Kaunertal reaches from the glaciated peak of the Weißseespitze (3600 m) to the Gepatschferner, the second-biggest Austrian glacier, down to the community of Kaunertal. The Gepatschferner is one of the most thoroughly studied glaciers in Austria, with a chronology of advances and retreats that covers the Holocene. Comprehensive data also exist on changes in the tree line and the distribution of permafrost and rock glaciers. Run-off and mass balance data on the glacier and detailed studies on the geomorphology of the glacier forefield and the role of biota for sediment mobilization complement the studies in the glaciated catchment area. In 2023 we started a project on butterfly monitoring. In 2021 the community of Kaunertal created a museum dedicated to research.

The "Istituto Scientifico Angelo Mosso" research site is located on the watershed between Piedmont and Valle d'Aosta (NW-Italy), in the Municipality of Alagna Valsesia (Monte Rosa massif). The Scientific Laboratories of the "Angelo Mosso Institute" at Col d’Olen (2901 m a.s.l.), the heart of this research site, were built between 1905 and 1907, when it became clear that the Capanna Regina Margherita on Monte Rosa (4554 m a.s.l.), as a high-elevation research centre, had become insufficient to the increasing number of requests for use by the international scientific community. From here the idea promoted by Angelo Mosso (1846-1910), professor of human physiology at the University of Turin, to add an additional structure to the Observatory of the Capanna Regina Margherita for make larger laboratories available to researchers and allow study stays at high elevation. This project soon became a reality thanks to the intervention of Queen Regina Margherita, Ministries of Education and Agriculture, the Italian Alpine Club and various personalities of the time. The research conducted at the Institute did not concern only human physiology, but also other disciplines, including alpine meteorology and glaciology, thanks also to the presence of the Meteorological Observatory that flanked the Institute, directed in the years 1925-40 by Umberto Monterin. It is now home to an automatic snow and weather station, managed by the Alpine Troops-Meteomont service. In addition to the University of Turin, the research groups that operate at the site and contribute to data collection and implementation are currently CNR-IRSA, Alpine Troops Command-Service Meteomont, Monterosa 2000 SpA and Monterosa SpA (Monterosa Ski), Protected areas of Valsesia, ARPA Piemonte, ARPA Valle d'Aosta and Sesia Val Grande Geopark. In addition to the valuable historical series of climate data, a series of research activities are devoted to the study of snow-soil-vegetation interactions, with particular reference to carbon dynamics e soil nitrogen (Magnani et al. 2017a,b; Freppaz et al. 2019). In addition, investigations are performed focusing on the chemical characteristics of high-elevation surface waters, fed by different cryospheric features such as rock glaciers, glaciers, and permafrost (Colombo et al. 2018a,b; 2019a,b; 2020; Vione et al., 2021). New research lines, aimed at investigating the most recent environmental challenges, have been added to the previous ones. For instance, investigations on sources and routes of atmospheric carbon and nitrogen species are ongoing. References: Colombo N. et al. (2018a), https://doi.org/10.1002/esp.4257. Colombo N. et al. (2018b), https://doi.org/10.1016/j.scitotenv.2018.05.098. Colombo N. et al. (2019a), https://doi.org/10.1016/j.scitotenv.2019.06.233. Colombo N. et al. (2019b), https://doi.org/10.1007/s00027-019-0670-z. Colombo N. et al. (2020), https://doi.org/10.1016/j.catena.2020.104700. Freppaz M. et al. (2019), https://doi.org/10.3897/natureconservation.34.30737. Magnani A. et al. (2017a), https://doi.org/10.1657/AAAR0016-037. Magnani A. et al. (2017b), https://doi.org/10.1016/j.catena.2017.03.007. Vione D. et al. (2021), https://doi.org/10.1016/j.scitotenv.2020.143464.

The Bessanese high-elevation experimental site is located in the Western European Alps (Graian Alps, municipality of Balme, Italy). This site is representative of the glacial and periglacial environments of the Alps. In this site, glaciers have been the main morphogenetic agent: the head of the basin hosts a well-developed glacial cirque, while the LIA has left an imposing moraine on the left side of the glacier as an indelible mark in the landscape. Additional cryogenic and atmospheric processes, running waters and gravity have contributed to shape the study area. These latter processes are becoming more and more important, compared to glacier shaping, in the present context of climate change, which led to an impressive-areal and volume reduction of the glacier. Most of the area once occupied by the glacier is now covered with debris which, in many cases, is ice-cored, or contains ice lenses. Downstream of the main lake of the basin, located at an elevation of about 2580 m, the debris forms a large and characteristic rock glacier. Among gravitative processes, rockfalls are particularly common and relevant from the hazard point of view in the study area. dataset available on Pangaea repository: 1. Nigrelli, Guido; Chiarle, Marta; Merlone, Andrea; Coppa, Graziano; Musacchio, Chiara (2022) – Rock temperature variability in the alpine cryosphere. Pangaea Data Publisher for Earth & Environmental Science, https://doi.pangaea.de/10.1594/PANGAEA.950246 2. Nigrelli, Guido; Barbero, Secondo; Chiarle, Marta (2021) – Solar radiation at the Bessanese high-elevation experimental site (Italy). Pangaea Data Publisher for Earth & Environmental Science, https://doi.org/10.1594/PANGAEA.930679 3. Nigrelli, Guido; Chiarle, Marta; Merlone, Andrea; Coppa, Graziano; Musacchio, Chiara (2018) – Rock and debris temperature in the alpine cryosphere. Pangaea Data Publisher for Earth & Environmental Science, https://doi.org/10.1594/PANGAEA.894317

Obergurgl lies about 1930 m a.s.l., very much at the head of the Ötz-valley (municipality of Sölden) in the central Alps. The research areas of the LTER site Obergurgl are located at the slopes, glacier valleys and glaciers south and south-west of Obergurgl. A variety of logger stations (mostly wheather stations) are installed at different locations at the site, some of them measuring since 1953. Various research project, most of them performed by researchers of the University of Innsbruck, are carried out in this area. Habitat types are alpine grassland, alpine forests, pasture and dwarf shrub heath, glacier forelands and glaciers. The LTER site Obergurgl is managed by the Alpine Research Centre Obergurgl (http://www.uibk.ac.at/afo/), a branch office of the University of Innsbruck (http://www.uibk.ac.at/). The Alpine Research Centre Obergurgl is located at the edge of the village Obergurgl. It is consolidated with the University Centre Obergurgl (http://www.uz-obergurgl.at/), a congress centre and hotel with up to 100 beds. Indoor infrastructure are a lecture hall, a seminar room, a small laboratory and small libraries.

The Gesäuse Nationalpark and the Johnsbach valley belong to the Ennstal Alps, a part of the Northern Limestone Alps. They are situated in the province of Styria in the center of Austria. Together, they form the joint test site named Gesäuse-Johnsbachtal. This region is characterized by a mountainous landscape which is cut by the river “Enns”. In the north, it borders Eisenwurzen Nature Park and is only 6 km away from the Kalkalpen, a National Park in Upper Austria. In the south, the borders are the Eisenerzer Alps. The total area of the site is about 155 km². The terrain shows a great elevation range from 600-700 m in the Johnsbach valley to over 2300 m in the summit region of the Gesäuse, with Hochtor (2369 m) being the highest mountain. Due to the great range of altitude differences within small areas the Gesäuse-Johnsbachtal shows extremely diverse habitats and, consequently, species of animals and plants. In general, the landscape is dominated by mountain forests along with high Alpine rock formations and meadows. These complex topographic, hydrological, geological, geomorphological and meteorological conditions pose a scientific challenge for all kinds of environmental monitoring and modeling.

In the Rofental (Ötztal Alps) a consortium of the three institutions, and open to research partners worldwide, concentrates on studying and monitoring cryospheric, atmospheric and hydrological processes and changes with particular attention to the complex topography and climate settings of the Alpine terrain. First documents from glaciers in the Rofental, Ötztal Alps, date back as far as 1601 and regular observations and systematic studies had begun more than 150 years ago. First geodetic maps where generated in the late 19th century, first rain gauges were mounted in 1929 and glacier mass balance time series of Hintereis-, Vernagt- and Kesselwandferner are among the longest uninterrupted world-wide, building a basis for regional hydrological studies, for glacier-climate and ice dynamic research, and for estimating the world wide glacier’s contribution to sea level rise. By 2014, networks of stakes and pits for mass balance monitoring are maintained at Hochjoch-, Hintereis-, Kesselwand- and Vernagtferner by the consortium members. Runoff gauges at Vernagtferner and in Vent (operated by the Hydrological Office of Tyrol) and a network of rain gauges in the Rofental basin are the basis for high mountain hydrological studies. A varying number of automatic weather stations on and in the surroundings of the glaciers are operated by the Rofental consortium. The glaciers in the Rofental are frequently used as a test site for process studies, model development and evaluations and for new remote sensing or ground based methods in glaciological research. A series of airborne LIDAR derived high resolution DTMs of Hintereisferner and its surroundings are available since 2001. They are subject of ongoing evaluations and method comparison studies as well as for monitoring and studying periglacial morphodynamics. The generated data are available from the consortium partners, glaciological key results are annually reported to the World Glacier Monitoring Service (WGMS). A research station on Hintereisferner (with observer status in the Horizon 2020 INTERACT network) and one at Vernagtbach serve as logistic bases for fieldwork. In recent studies, socio-ecological research aspects – e.g. in relation with the use of water for energy production and tourism – comprise the natural scientific investigations.

Socio-ecological interactions in ecosystems of mid-altitude mountains The LTSER Zone Atelier Arc Jurassien belongs to LTER-France network and is located in eastern France.The LTSER site Jurassian Arc (ZAAJ stands for Zone atelier Arc jurassien, in French) is designed to promote long-term interdisciplinary research into the environment and ecosystems in relation to society issues. It federates a network of research partnerships around interactions between the environment, society and the dynamics of moutain socio-ecological systems.ZAAJ helps to capitalise on field data and to analyze and promote the results from long-term observation schemes at the interface between ecology, the environment and society. Benefiting of more than 25 years of experience on the issue, accredited by the CNRS Ecology and Environment Institute (INEE) in 2013, ZAAJ is a cluster of five research units totalling 40 researchers.