Central Europe maintains a considerable diversity of dry-mesic oak forests as the main representatives of zonal forest vegetation types in Hungary, covering the major part of foothills of the middle-range mountain, Inner Western Carpathians. The 669 m high, Triassic limestone hill called ‘Vár-hegy’ belongs to the Bükk Mountains. The annual mean temperature is about 8◦C and the annual precipitation is about 650 mm. The core area of the reserve (94 ha) is covered mainly by close-to-nature. long untouched oak dominated forests stands: Pannonic woods with Quercus petraea and Carpinus betulus; Pannonian-Balkanic Turkey oak-sessile oak forests; Pannonian woods with Quercus pubescens. It has been set aside for preservation in 1991, though several previous conservation acts had already secured almost spontaneous natural development of the stands. Most of the area was cut around 1880, however, several over-mature trees were retained. The intensive use in the previous centuries and during the world wars left a sessile oak dominated, 120-130-year-old, mostly coppice forest. The abandonment and the precedent severe oak decline contributed to generate a more diverse forest composition and structure developing towards a mixed forest with pronounced ‘old-growth’ characteristics.

In Britz we study the water consumption (evapotranspiration) of important commercial tree species since 1974. The main feature are the nine large-scale lysimeters, installed at a depth of over 5 m with a surface area of 100 m² (10x10 m) each. They are planted with 0.3 ha experimental stands of Scots pine (Pinus sylvestris) (3 lysimeters), European beech (Fagus sylvatica) (2), European larch (Larix decidua) (2), and Douglas fir (Pseudotsuga menziesii) (2) spaced corresponding to the forestry practice at that time. About 15 years ago one Larch lysimeter was clear-cut and replanted with sessile oak (Quercus petraea). On two Scots Pine lysimeters, European beech was planted building now the understory. The areas surrounding the lysimeters were planted in a similar fashion. Seepage water collecting at the bottom of the lysimeter flows down a shaft and is measured mechanically by a tipping counter and registered electronically. Soil moisture is measured with probes to a total depth of 5 m. Precipitation in the open field and the stand is recorded with Hellmann rain gauges. In addition, the station is equipped with devices assessing individual tree water transport and growth (sap-flow sensors, dendrometers), an Eddy-Fluy-Tower and much more. The studies are aimed at revealing the effects of different tree species and mixtures on the ground and landscape water balance. Moreover, the effects of drought on tree performance and tree-internal water budgets are of interest. However, recently we added acoustic monitoring, a pollen collector, regular UAV flights to our assessments and are always open to more co-operations.

The Hölstein site is located in in the eastern part of the Swiss Jura mountains (47°26’16.4’’, 7°46’31.1’’; 540 m a.s.l.), in a mixed, temperate forest with an exceptionally high biodiversity and a vigorous tree regeneration. The research plot has a size of 1.6 ha and comprises 540 mature trees. The main tree species are Fagus sylvatica and Picea abies with an admixture of Abies alba, Quercus petraea, Pinus sylvestris, Acer pseudoplatanus, Carpinus betulus, Fraxinus excelsior and Sorbus torminalis. A canopy crane is installed in the center of the research area to access the tree canopies for in situ measurements and for sampling of leaf material. Rainout shelters will be installed in 2019 for conducting a long-term throughfall exclusion experiment.

The site is located next to Wettingen in the canton of Aargau, within a natural, mixed forest stand which mainly consists of 150 year-old beech (Fagus sylvatica) and 120-170 year-old spruce (Picea abies) trees. Among others, the site is equipped with two meteorological measurement stations; one is located within the forest stand, the second is co-located in the nearby open-field, allowing to measure the forest stand effect on micro-climate. The following parameters are being measured since 2013: Soil solution chemistry (lysimeters), TREENET, atmospheric deposition (throughfall and bulk deposition), circular vegetation plots, crown condition assessment, diameter and height measurements, foliar analyses, leaf area index (LAI), litterfall, manual circumference band measurements, Ozone visible injury assessment, permanent vegetation quadrats, phenological observations, sapflow measurements, soil matrix chemistry, tree core sampling, automated point dendrometer measurements, automatic circumference band measurements.

As the largest contiguous pine forest in Switzerland, the Pfyn forest in Canton Valais (46° 18' N, 7° 36' E, 615 m ASL) offers the best conditions for such measurements. In light of this, a WSL research team installed a long-term experiment of 20 years duration in the Pfyn forest. The average temperature here is 9.2°C, the yearly accumulated precipitation is 657 mm (average 1961-1990). The pines in the middle of the forest are about 100 years old and 10.8 m high. The test area has 876 trees covering 1.2 ha divided into 8 plots of 1'000 m2 each (Image 4). Between the months of April and October four of these plots are irrigated by a sprinkler system providing an additional 700 mm of water, annually. In the other four plots, the trees grow under natural, hence relatively dry conditions.

Berchtesgaden National Park was established in 1978 and is the only German national park located at the Alps. It comprises three major valleys and covers an elevantional range from 600 to 2700 m. Ecosystems include montane mixed forest and subalpine coniferous forest, alpine grasslands, pastures and rocky habitats. The Department for Research and Monitoring is linked to the Techincal University of Munich. It conducts monitoring on climate, hydrology, ecosystem dynamics and biodiversity. Main research topics include drivers of natural ecosystem dynamics, human impacts on ecosystems and climate change effects on ecosystems.

Suserup Skov (19.2 ha) is an old growth temperate forest dominated by beech Fagus sylvatica, pedunculate oak Quercus robur, ash Fraxinus excelsior, wych elm Ulmus glabra, and black alder Alnus glutinosa, admixed with lime Tilia platyphyllos and sycamore maple Acer pseudoplatanus. KU/IGN-SNB, is a 19,2 ha old-growth beech-dominated mixed deciduous forests on western Zealand owned by Sorø Academy. The forest use dates back to 4200 BC. A conservation act was placed on the forest in 1925 for biological and recreational purposes but allowing a minimum odd felling until the act was updated in 1961 to a non-intervention forest. The forest is unique at European level in terms of nonintervention, and the long-term status as non-intervention forest has led to a unique steady state in biomass and accumulation of dead wood, thus serving as an important reference site for unmanaged temperate deciduous forest development. There are long-term data records of e.g. biomass, dead organic matter, soil, forest structure, flora and fungi starting from 1992. The platform is included in a series of paired managed and non-intervention forests for studies of forest structure, biodiversity and biogeochemistry in mature and old beech-dominated forests. Suserup Forest includes an ICP Forests level II plot (2001-). Upgrades: eLTER master sites: soil moisture content (TDR), remote sensing of growth and forest structure, LAI, NDVI (Lidar, camera), continuous plant phenology (web cam),and insect monitoring (optical sensors) as biodiversity measures, ambient air quality and air pollution.

Vestskoven is a 15 km2 ongoing afforestation area located 15 km west of central Copenhagen. Since 1967 arable land has successively been bought up for afforestation in order to establish a large forest area for outdoor activities and wood production. In 1998, afforestation chronosequences in oak (Quercus robur) and Norway spruce (Picea abies) were established as a research platform to quantify soil carbon dynamics, water recharge, nitrogen budgets and ground vegetation species diversity. The soil and grund vegetation species composition were resampled in the chronosequences after 13 years in 2011. Since 2003, an ICP-Forests Level II/Core plot with integrated monitoring under the UN Convention on Long-Range Transboundary Air Pollution (CLRTAP) is placed in an oak stand. Monitoring has developed over time. There is no time limit on the monitoring financed by the Ministry of Environment and Food in Denmark.

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/

Beech forest in the Central italian Apennines