Measurements and surveys

As part of the study programme, various measurements and samples are taken to record data on soil, plants, and water compartments. The Thünen Institute and its partners collect this data and transmit it to the UBA. The UBA then compiles the data and submits it to the ICP IM Programme Centre.

Soil Chemistry:

Sampling is carried out according to depth levels. Sulfur (S) and nitrogen (N) deposition are important for assessing the acidification and eutrophication of the site. All laboratory analyses are conducted according to the guidelines of the ICP IM manual.

Analysis of Needles and Leaves:

Analysis of needles and leaves are conducted to assess the current nutritional status of the trees. Sampling is performed annually, separately for conifers and deciduous trees. Conifer samples are taken during winter months, while deciduous trees are sampled in late summer. Eight conifer and eight deciduous trees are selected for sampling.

Assessment of ground vegetation:

In 2024, a vegetation survey will be conducted on a 400 m² area to provide basic characterization and classification of other forest ecosystems. This survey will comprehensively record all species (herbaceous, moss, shrub, and tree layers), contributing essential data on overall biodiversity within the sample area.

Mikrobial decomposition:

This is a new measurement method which, if successful, will be permanently included in the monitoring programme. Fresh leaf litter in meshed bags is brought out on the soil surface; after 1 to 3 years the difference in mass compared to the intial values is determined. The bags do not prevent the exposition to water and microorganisms.

Tree bioelements:

Methods from the National Forest Soil Survey (BZE) are employed here for a survey at stand level, including natural regeneration and deadwood. If practicable the measurement method will also be permanently integrated into the monitoring programme.

Analysis of trace gas emissions:

Six semi-automatic chamber systems, installed by ZALF e.V. in Müncheberg, are used to analyze CO₂ trace gas emissions. These chambers measure net ecosystem exchange and ecosystem respiration on site. The systems are battery-operated and can automatically record CO₂ flux rates for around 24 hours in automatic mode. This is a new measurement method for this location, so the data is not 100% comparable with previous years

Open field precipitation:

Precipitation is collected in the open field to determine ion concentrations, pH value and conductivity. Measurements of the amount of precipitation are important for the water balance and are evaluated in combination with throughfall and stem flow. The chemical analyses mentioned allow conclusions to be drawn about the nutrient budget.

Throughfall and stem flow:

In a forest stand, precipitation comprises throughfall and stemflow. Exchange processes in the canopy lead to a decrease in the concentrations of substances that are taken up by the tree and a simultaneous accumulation of substances washed out of the leaves and needles. The term throughfall refers to the precipitation that falls through the canopy. Analysis of canopy flow, just like bulk deposition collected on the open field, includes precipitation quantity, ion concentrations, pH value, and conductivity. For smooth-barked tree species such as beech, stemflow accounts for a significant proportion of the precipitation in the stand. The measurement data for throughfall and stemflow undergo various quality control steps and are then used, among other things, for the canopy balance. For the canopy balance, the atmospheric deposition of substances is determined according to Ulrich's (1983) approach using the Na factor.

Soil solution chemistry:

Soil is crucial for investigating substance balances, regulatory mechanisms, and adaptation processes. Monthly soil solution chemistry samples are collected from six different depths to measure pH value, electrical conductivity, and ion concentrations.

Litterfall:

Needle and leaf analyses provide information about the nutritional status of forest trees as well as the uptake and accumulation of pollutants and heavy metals. At the Neuglobsow ICP IM site, twelve collectors are used to collect monthly litterfall samples. These samples are dried at 40°C until a constant weight is achieved and then sorted. The chemical composition of each subsample is analyzed, distinguishing between:

• Pine needles
• Beech leaves
• Pine fruits
• Beech fruits
• Wood and bark
• Needles/leaves from other tree species (if present)
• Other biomass

In addition to measuring the total mass of each fraction, the specific mass of 100 leaves or 1000 needles, along with their corresponding surface area, is documented.

Groundwater chemistry:

Groundwater samples are taken at least six times a year from various deep wells. Regular sampling is particularly important during snowmelt. Groundwater data includes ion concentrations, pH value, conductivity, and groundwater level from different depths (levels) and different points. The definition of the catchment area is crucial for evaluating groundwater chemistry.

Xylem flow:

Xylem flow measurements are used to derive water movement through the trunk on a daily and seasonal basis, and to calculate the transpired water volume of the entire tree crown. By using high-resolution dendrometers, it is possible to determine the degree of water saturation of the tree trunk. This allows a high degree of accuracy in determining a stable zero point with regard to the xylem flow, so that it is also possible to record a nocturnal xylem flow. Data readings are conducted every ten minutes.