DOI: 10.17897/rb61-wy47
title: GeoBasis Zackenberg - Soil properties - Fen_SoilCore_CN

description: In 2019 a new soil core initiative focusing on carbon and nitrogen pools was implemented in the GeoBasis Zackenberg program.
Two plots of 10 by 10 meters were allocated for the sampling of 20cm soil cores + aboveground biomass, one on the heath and one in the fen. From each plot five soil cores were taken and labelled according to the system: location (Fen/Heath) + number of core (1-10, were 1-5 were sampled in the Fen and 6-10 on the heath). The aboveground biomass samples, where 10 by 10cm. In the fen the diameter of the soil cores was 5.2cm and on the heath 2.7cm. The diameter of the cores were a compromise between what was practically possible and a wish for minimum impact, as these arctic ecosystems have a relatively slow recovery. The cores were kept intact and immediately frozen. The cores were brought to the lab at Department of Geosciences and Natural Management, where they were defrosted and separated into 8 different pools: Leaf, Litter, Stem, Moss, Roots from 0-5cm (0 being the surface), Soil from 0-5cm, Roots from 5-20cm and Soil from 5-20cm. The pools were dried for 48 hours at 70°C, where after subsamples were crushed using Retsch mixer mill MM200. The representativeness of the subsamples was assessed visually. From each sub sample, three replicates were analyzed for fraction of C%, N%, Delta-D-13‰ and Delta-N-15‰ isotope values. The total carbon and nitrogen contents are measured in solid samples on an elemental analyser (Flash 2000, Thermo Scientific, Bremen, Germany). For analysis of organic material, a 2mg sample of homogenized and dried soil is weighed out into tin combustion cups. For soils either 10 or 20mg was weighed, depending on organic content. Acetanilide (Merck, Darmstadt, Germany) and soil standards (Elemental Microanalysis, Okehampton, UK) are used for elemental analyser mass calibration.
Leaf area index (LAI) was determined in ImageJ from photos of the green aboveground biomass taken in the lab, following the procedure in Schneider, C. A., Rasband, W. S., Eliceiri, K. W. (2012). NIH Image to ImageJ: 25 years of Image Analysis. Nature Methods, 9(7), 671–675. Soil core sampling in the fen and on the heath is planned to be repeated every fifth year, next sampling year being 2024. Soil properties:Soil properties GeoBasis Zackenberg:The GeoBasis monitoring programme focuses on selected abiotic characteristics in order to describe the state of Greenlandic terrestrial environments and their potential feedback effects in a changing climate. Monitored plot data is up-scaled to a landscape level and is used to improve ecosystem models to be able to quantify these feedback mechanisms. The GeoBasis programme provides an active response to recommendations in international assessments such as ACIA and SWIPA; and is continuously being adapted based on AMAP and other international founded recommendations. Furthermore, the GeoBasis programme is directly involved in several international networks and research projects (e.g. the Circumpolar Active Layer Monitoring (CALM) programme, the Nordic Centre of Excellence DEFROST, the Danish Centre of Excellence CENPERM, the EU-projects PAGE21 and INTERACT, and the Arctic Research Centre at Aarhus University). The GeoBasis programme is divided into a number of sub-groups, including: