The Sonnblick Observatory is located in the Austrian Central Alps at an elevation of 3100 m a.s.l. It is situated at the alpine main divide, which is a clear climatological border. It also lies in the “Nationalpark Hohe Tauern” which covers 1856 km2 of the Austrian Alps. Research of the Sonnblick Observatory is currently formulated in the research programme ENVISON. It covers three main topics (the atmosphere, the cryosphere, and the biosphere) in an extensive monitoring programme and with many research projects.The Sonnblick Observatory is outstanding with respect to its long-term climate observations and studies on glacier changes. Thus, the impact of Climate Change on the cryosphere is a major research topic at the Sonnblick Observatory. Since 1886, the observatory is also involved in many international projects on atmospheric chemistry and atmospheric physics. The research is described on www.sonnblick.net. The Sonnblick Observatory cooperates with several Austrian and international universities/research institutions. Within the frame of the GAW-DACH cooperation, Sonnblick has a special partnership with the observatories Jungfraujoch (in Switzerland), Zugspitze and Hohenpeissenberg (both Germany) for common research on atmospheric processes and Climate Change. The Sonnblick observatory ist part of the BSRN-Network, LTER Austria, ACTRIS, etc. Data are available via the SBO Data Portal. In the frame of eLTER the SBO will be part of the eLTSER Cluster NPHT.

The HOBE experimental catchment is located in the western part of Denmark. The topography of the catchment is relatively flat. The surface elevations in the eastern part of the catchment are about 125 m above sea level at the Jutland ridge and gently decreasing to sea level elevations towards the coast. Alluvial outwash deposits in the form of sand and gravel dominate the central part of the catchment. Towards east, glacial deposits of moraine till are present with a higher content of clay. Also the remnants from the Saale glaciation have higher clay content and the dominant sediment type at these locations is clayey sand. Overall the top sediments are highly permeable with little water retention capability and the stream flow is therefore dominated by groundwater inflow. Based on a classification of the topsoil four soil classes can be identified in the catchment. The by far most dominating soil type is fine/coarse sandy soil. The Quaternary deposits have a thickness less than 50 m in the eastern and central part of the area increasing up to 250 m towards west. The Quaternary deposits are underlain by Miocene sediments in the form of alternating layers of marine, lacustrine and fluvial deposits forming layers of clay, silt, sand and gravel. Further below thick layers of Paleogene clay are found with little permeability and thus acting as a lower impermeable boundary for the aquifer systems. The sand and gravel layers from the Quaternary and Miocene periods form interconnected aquifer systems. The land surface of the catchment is predominantly agriculture and due to the sandy soil characteristics extensive irrigation of the agricultural crops takes place. Based on satellite data the land-use distribution is estimated as follows: grain and corn (55%), grass (30%), forest (7%), heath (5%), urban (2%) and other (1%). The climate of the observatory is of maritime origin and influenced by weather systems coming from the Atlantic Ocean. The weather conditions are variable with frequent precipitation. The prevailing winds from west lead to relatively mild winters and cool summers. The mean annual precipitation is about 1050 mm/year. It varies over the season with highest amounts in the months of October-December and lowest in the months of April-May. The mean annual temperature is 8.20C. The highest mean monthly temperature is in August (16.50C) and the lowest in January (1.40C). Precipitation in the form of snow is highly variable from year to year; in some years, no snowfall occurs and in others, it may stay on the ground for months.

The site Klausen-Leopoldsdorf is part of the European Level II Forest Monitoring System in the frame of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). The site was established in 1995 and is, since 2006, part of the LTER Austria network. It is situated in a homogenous 80 years-old managed beech stand about 20km west of Vienna. The LTER-CWN research area in Klausenleopoldsdorf is divided into 3 subplots: a measuring weir, a dendrometer/sapflow measuring facility and GHG-chambers for measuring the fluxes of CO2 and other relevant GHG´s. All 3 subplots were installed in 2019 to collect high-resolution data. The measuring weir is located at about 475m a.s.l and the other subplots (denrometer/sapflow, GHG measuring chambers) are located at about 510m a.s.l. The observed catchment of the measuring weir has an area of 46 hectares. The dominating soil types in the catchment are Planosoils and Stagnosols. The subplots are situated in the near vicinity of the ICP-forest plot.

The LTER-site of Brasschaat is a 2 ha scientific zone in a first generation plantation (1929) of Scots pine (Pinus sylvestris L.) on former heathland located in a mixed coniferous/deciduous forest in the Campine plain of Flanders. The landscape is flat, with a gentle (0.3%) slope at a mean elevation of 16 m. To the South and East, the forest extends over 2 km before turning into rural, partially forested terrain. The site is equipped with a measuring tower and an intensive forest monitoring plot (ICP Forests level II). The site is also part of an ICOS monitoring site which is operated by the University of Antwerp in collaboration with the Research Institute for Nature and Forest. The air pollution characteristics at this site are typical for a suburban forest exposed to vehicle emission (NOx), which is strongly affecting the NO-NO2-O3 chemistry. The site is, additionally, located in the waste plume derived from stack emissions (SO2, NOx, black carbon) generated by the petrochemical refinery in Antwerp port. Although no important agricultural emission sources are present in close proximity to the site, ammonia levels are elevated when winds blow from the eastern wind sector (due to remote agricultural activities > 5 km). The monitoring of air pollutants will be continued with special focus on chemical and biological recovery of the forest ecosystem from historical elevated sulphur and nitrogen depositions. Also the research on the combined effects of ozone, nitrogen and climate change on forest ecosystem functioning (gross primary production) will be emphasized.

The ZA PYGAR covers the whole Garonne river basin up to the upper part of the Gironde estuary (La Reole station). Within this territory, research is structured around 4 main sites: the Pyrénées mountains, covering the upstream part of the Garonne river basin (PYRénées site), the farmland of the foothills of the Pyrénées (Vallées et Coteaux de Gascogne site), the Garonne river (Axe Fluvial Garonne site) and the basin of two tributaries of the Garonne river in the Massif Central moutains (Aveyron-Viaur site).

The Cairngorms National Park is one of 15 National Parks in the UK (one of two in Scotland) and is Britain's largest National Park (4,528 km2). It is the location for some of the most spectacular landscapes in Britain and is home to an incredible diversity of wildlife and plants. http://cairngorms.co.uk/the-park/facts-figures/ The aims of the National Park are: • To conserve and enhance the natural and cultural heritage of the area; • To promote sustainable use of the natural resources of the area; • To promote understanding and enjoyment (including enjoyment in the form of recreation) of the special qualities of the area by the public; • To promote sustainable economic and social development of the area’s communities. Cairngorms National Park, seven broad habitats can be identified: • Enclosed farmlands • Woodlands • Open waters (rivers, lochs, wetlands and floodplains) • Mountains • Moorland • Semi-natural grasslands • Urban • Population of c17,500 • 25.8% of population over 60 (higher than Scottish average) • Average health index in top 25% of Scotland (based on deprivation indices) • Extensive core paths network • 55 Munros including 5 summits over 4000 feet • 3 ski centres • National Cycle Network Route 7 • 1 Long Distance Route (Speyside Way) • Relatively low atmospheric pollution • Annual precipitation over 2250mm on summits and under 900mm in straths • Average annual snow cover 200 days on summits and 50 days on low-ground • Prevailing winds from south-west

Monitoring stations in Aukštaitija NP started functioning in 1993. Aukstaitija station (LT01) was founded in strict reserve zone of Aukstaitija national park in Ažvinčių old forest, Versminis river closed basin. The area of the basin is 101.5 ha. The lowest place is at 159.5 m, the highest - 188.6 m above sea level. Geographical co-ordinates of the basin are: longitude - 26*03*20* - 26*04*50*, latitude - 55*26*00* - 55*26*53*. The climate is characterised as average cold with high humidity and abundant precipitation. The average air temperature is 5.8 C, average precipitation - 682 mm. Length of vegetation period - 189 days. Side glavioacvalic accumulation forms with sand, gravel and stones are typical for river basin and in the western part of the basin, with the decrease of surface altitude transfers into fliuvioglacial terrace delta plain with fine sand, and at the source- into marsh accumulation forms with organic sediments. At the eastern side of the basin, which has higher altitudes, the typical for this basin glavioacvalic accumulation forms transfer into gravel sand. Carbonates start foaming at 45 cm depth (Gulbinas et al., 1996). The saturation of the river water with the oxygen is very weak. The average yearly oxygen concentration equals to 2.9 mg/l (minimal allowable concentration – 6 mg/l). The pH value of the water fluctuates from 7.10-7.75 mg/l, which indicates the alkalisation of the water. Concentration of hydro-carbonate ions varies in the intervals of 148-224 mg/l. Concentrations of sulphates and chlorides are very small. Calcium and magnesium ions are dominating in the media of cations. Concentration of natrium ions is insignificant – 2 mg/l 9DLK=120 mg/l), concentration of kalium ions reaches only tenths of mg/l (DLK=50 mg/l). According to the size of mineralisation the river water could be described as having average mineralisation levels. Concentrations of nitrogen materials (ammonium nitrogen, nitrates) are small, compared to maximum allowable concentrations (DLK) set for surface waters. Concentrations of phosphates are small. Silicium concentrations fluctuate from 2 mg/l to 9 mg/l (Čeponienė, 1997). Main ecosystems Coniferous multi-layered forest stands are prevailing in the basin, which are mainly pine trees with a mixture of spruce. Those stands usually have a second and third tree layer with abundant under layer vegetation. Spruce stands are also of complicated structure. The second and third spruce layer with abundant under layer vegetation are common. Remarkable amounts of territory are occupied by mixed conifer-deciduous or mixed conifer forests. Pure birch stands in more wet habitats in the vicinity of Versminis river source can also be found. According to the forest stand age they are old pure overmature or with accompanying forest stands of several age classes. It is mainly multi-aged and multi-layered over mature pine and spruce stands. In addition The study was based on monitoring data on crown defoliation of more than 3000 Scots pine (Pinus sylvestris L.) trees from 20 permanent observation stands (POS) annually obtained between 1994 and 2009 in Aukstaitija national park (ANP), located in the eastern part of Lithuania (Fig. 1). Over 16yr period mean values of crown defoliation of every sample pine stand were computed annually. Therefore the total number of treatments made N=320. These stands were classified according to stand maturity: 4 sapling stands (45 to 50 years – Table 1, section “Stand maturity”, group 1), 5 middle aged stands (61 – 80 years – group 2), 4 premature stands (81-100 years – group 3), 3 mature stands (101-120 years – group 4) and 4 over mature stands (> 121 years – group 5). Main characteristics of the considered stands are compiled in table 1. All stands represent the prevailing in Lithuania Pinetum vaccinio-myrtilosum forest type.

Small agricultural catchment (320 ha) with 30 years of data to study impact of climate change and agricultural practices on soil erosion, weathering rate and river fluxes. Continuous measurements with sensor: river discharge, Temperature, pH, conductivity, turbidity, dissolved oxygen, nitrate Weekly samples and high resolution sampling during storm runoff: major cations and anions, alkalinity, pH, dissolved silica, conductivity, total suspended solids, stable isotopes (13C of DIC, 2H and 18O of H2O, 15N of nitrates), heavy metals, some pesticide molecules Climatological station, rain collector for precipitation chemistry, soil solution station with lysimetric plate at different depths. Continuous measurement since 2004 of CO2, N2O, water vapor, energy exchange in the soil-vegetation-atmosphere continuum thanks to Eddycovariance and closed chamber methodologies (see OZCAR-RI Regional Spatial Observatory in the South West France contribution) Collaboration with the Aurade farmer association for fertilizer and pesticide inputs, cultivation, agricultural practices... Aurade experimental catchment and flux site are an international field site of the Critical Zone Exploration Network CZEN and of ICOS network, a field site of the French Research Infrastructure OZCAR and it is also a site of the French LTSER ZA PYGAR "Zone Atelier Pyrénées-Garonne". and a regional Platform of Research and Innovation-Midi Pyrénées.

The Hyytiälä SMEAR II site (Station for Measuring Ecosystem-Atmosphere Relations) is situated in the Hyytiälä Forestry Field Station of the University of Helsinki. The site consists is a managed, 60-yr old Scots pine forest stand. The main idea of SMEAR type infrastructures is continuous, comprehensive measurements of fluxes, storages and concentrations in the land ecosystem–atmosphere continuum. The forest measurements are operated continuously since 1996, and include e.g. leaf, stand and ecosystem scale measurements of greenhouse gases, volatile organic compounds, pollutants (e.g. O3, SO2, NOx) and aerosols, in addition to full suite of meteorological measurements. The biogeochemical cycles and vegetation–soil–atmosphere interactions are studied both experimentally and with long-term observations. The site has full carbon, water and nitrogen budgets made over 10 years, and it is a full ICOS ecosystem and atmospheric station. Ecosystem and atmosphere measurements also exist nearby in two open oligotrophic fen sites and a humic lake with forested catchment. Most of the measured data can be retrieved from: https://smear.avaa.csc.fi/