4. Gewinnung und Analyse von Nadelproben

Wien

2016

S. 23-24

Artikel aus einer ZeitschriftUnselbständiges Werk

200201348

Die Nährstoffgehalte in Nadeln und Blättern können Störungen der Nährstoffversorgung und Aufnahme erkennen lassen, der Schwefelgehalt kann als Indikator für die Luftqualität dienen. Da sich die Elementgehalte während der Vegetationsperiode stark verändern, wird die Probenahme zu einem fixen Zeitpunkt im Frühherbst während der Vegetationsruhe durchgeführt. Aufgrund der Erfahrungen des Österreichischen Bioindikatornetzes BIN (www.bioindikatornetz.at), bei dem große Schwankungen der Gehalte in Einzeljahren festgestellt wurden, werden in Ausweitung der international verpflichtend vorgeschriebenen zweijährigen Probenahme die Erhebungen alljährlich durchgeführt. Auf der Fläche Unterpullendorf (02) werden Weißkiefern und auf allen übrigen Flächen Fichten beprobt. The sample trees are located in the buffer zone of the monitoring plot and are permanently marked. The sampling is done carefully to prevent damages to the trees by tree climbers from the local forest authorities. The twigs are collected in the upper part of the crown (7th whorl). Twigs from the needle sets 1 (new shoot) and 2 (shoot of the previous year) are collected, separately packed in plastic bags and submitted to the unit for Air Pollution Monitoring and Plant Analysis at the BFW. After checking the samples they are deep frozen down to -15 °C to preserve them. Sample preparation starts with drying at 80 °C and after removing all wooden parts the needles are milled. The elements sulphur, carbon and nitrogen are analysed with element analyzers. All other elements (P, K, Ca, Mg, Fe, Mn, Zn) are analysed after a microwave digestion (HNO3/H2O2) with ICP-AES (Inductively coupled plasma atomic emission spectroscopy). In addition weight per 100 needles is determined.
Nutrient contents in foliage can indicate disturbances in the nutrient supply and in the nutrient uptake. The sulphur content is an indicator for air quality. The element concentrations are varying during the vegetation period, due to this fact sampling must be done during the dormancy period (early autumn). The samples are taken annually as the results from the Austrian Bioindikatorgrid (www.bioindikatornetz.at), revealed huge variations between individual years. In Unterpullendorf (02) samples from Scots pine and on all other plots samples of spruce are collected. The sample trees are located in the buffer zone of the monitoring plot and are permanently marked. The sampling is done carefully to prevent damages to the trees by tree climbers from the local forest authorities. The twigs are collected in the upper part of the crown (7th whorl). Twigs from the needle sets 1 (new shoot) and 2 (shoot of the previous year) are collected, separately packed in plastic bags and submitted to the unit for Air Pollution Monitoring and Plant Analysis at the BFW. After checking the samples they are deep frozen down to -15 °C to preserve them. Sample preparation starts with drying at 80 °C and after removing all wooden parts the needles are milled. The elements sulphur, carbon and nitrogen are analysed with element analyzers. All other elements (P, K, Ca, Mg, Fe, Mn, Zn) are analysed after a microwave digestion (HNO3/H2O2) with ICP-AES (Inductively coupled plasma atomic emission spectroscopy). In addition weight per 100 needles is determined.