LTER Zöbelboden, Austria, Soil water chemistry, 1993-2012

Soil solution was collected at plots with condensed field measurement equipment (so called intensive monitoring plots IP1, IP2 and IP3) at the LTER Zöbelboden site (LTER_EU_AT_003), Austria. IP1 and IP3 are situated on a plateau (850–956 m a.s.l.) and IP2 on a steep north facing slope (30–60°) extending from 850 m down to 550 m a.s.l. Triassic dolomite is the predominant bedrock material, partly interspersed with limestone plate layers. Soils are mainly chromic cambisols or hydromorphic stagnosols on the plateau and lithic or rendzic leptosols with patches of chromic cambisols on the slope.

Soil water (abbreviation in column SUBPROG = SW) was collected at the subsoil – bedrock interface (B/C horizon) using tension plate lysimeters (r = 3 cm) with a double 0.2 µm nylon filter membrane. At IP1 (SCODE=300), four clusters of each two to six plate lysimeters (n = 16) were installed to account for the variety of soil types and soil depths, i.e. (i) shallow Rendzic Leptosols (SCODE = 265) (ii) Hydromorphic Stagnosols (SCODE =256) and (iii) deep Chromic Cambisols (261, 264). Soil solution measurements at IP1 started in the year 1993 and ceased in September 2009 due to small-scale wind throw events and bark beetle infestations on the plot. At IP2, three clusters with each five to six lysimeters (n = 16) cover the heterogeneity of microtopography on soils characterized by Rendzic Leptosols, i.e. pit (SCODE=756), mound (SCODE=757) and an intermediary between pit and mound (SCODE=755). Soil solution measurements at IP2 started in the year 1998. Similarly to IP1, three clusters with each 3x5 lysimeters (n=45) account for the variety of soil types and soil depths at IP3, i.e. (i) Rendzic Leptosols (SCODE= 2957), (ii) Hydromorphic Stagnosols (SCODE= 2955) and (iii) deep Chromic Cambisols (SCODE = 2956). Measurements at IP3 started in 2008 after the disturbance events on IP1. Soil solution was sampled weekly, filtered and kept cool (4°C) until final sample preparation. From the years 1993 to 1998, weekly samples were analysed in the laboratory. Thereafter, soil water samples from two consecutive weeks were mixed (volume-weighted) and analysed. From March 2009 onwards, weekly soil water samples from four consecutive weeks were pooled (volume-weighted) and analysed. Soil water samples were filtered in the laboratory. From 2010 onwards, samples were solely filtered by the double nylon membrane (0.2 µm) of the lysimeters in the field, except for DOC, which was filtered until 2018.