https://datadoi.ee/handle/33/405 2026-04-08T00:01:12Z https://datadoi.ee/handle/33/735 Global organic soils - organic matter quality, carbon and nitrogen stocks and fluxes Pärn, Jaan; Mander, Ülo We conducted a global survey of soil organic matter formation and transformation processes in organic soils, during the dry season (i.e. the annual water table minimum time of year including temperate and boreal summers) at each site between 2011 and 2022. We used 156 organic soil samples from the top 10 cm in 61 sites in our global organic soil database throughout the rainy tropical, temperate, and boreal climate zones. The main purpose of the dataset is to investigate water-extractable organic matter (WEOM) of soil to determine which ecosystem properties (e.g. temperature, water content, land use, plant carbon inputs, nutrients, respiration or methanogenesis rates) control the persistence of organic matter. We applied ultrahigh-resolution mass spectrometry to analyse molecular species and nominal oxidation state of carbon (NOSC) of WEOM. 2026-01-01T00:00:00Z Pärn, Jaan Mander, Ülo https://datadoi.ee/handle/33/726 Global peatlands - microbiological data Espenberg, Mikk; Pärn, Jaan; Mander, Ülo Nitrous oxide fluxes, microbiological (sequencing, qPCR) and soil physicochemical parameters data of peatlands globally; We sampled gas and soil in 29 regions throughout the A (rainy tropical), C (temperate), and D (boreal) climate types of the Köppen classification from six continents during the vegetation period between August 2011 and June 2018, following a standard protocol. Within the sites, we established 1–4 stations 15–500 m apart to maximize the captured environmental variation. Each of the 196 stations were equipped with 3–5 opaque PVC 65 L truncated conical chambers 1.5–5 m apart and an observation well (perforated, 50 mm diameter PP-HT pipe wrapped in geotextile; 1 m in length). From each of the 645 chambers, N2O fluxes were measured following the static chamber method using PVC collars (0.5 m diameter, installed to 0.1 m depth in soil). Soil samples of 150–200 g were collected from the chambers at 0–10 cm depth after the final gas sampling, and transported to laboratories in Tartu, Estonia. The homogenized samples were divided into subsamples for physical–chemical analyses and DNA extraction. The samples for chemical analyses were stored at 4 °C and microbiological samples were stored at –20 °C. DNA extraction was provided at the Tartu University environmental microbiology laboratory (see details below). Soil physico-chemical analysis, DNA extraction, DNA library preparation, and sequencing, Quantitative PCR were performed. 2022-01-01T00:00:00Z Espenberg, Mikk Pärn, Jaan Mander, Ülo https://datadoi.ee/handle/33/725 Global peatlands N2O Mander, Ülo; Pärn, Jaan; Espenberg, Mikk Locations, dates, measurements of soil chemistry and physics, and N2O fluxes used in the analyses for the paper 'Nitrogen-rich organic soils under warm, well-drained conditions are global nitrous oxide emission hotspots' submitted to Nature Communications . A'air_t_max', air temperature at the nearest weather station in the warmest month of the year (KNMI Climate Explorer http://climexp.knmi.nl). Nitrogen-rich organic soils under warm, well-drained conditions are global nitrous oxide emission hotspots. N2O is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N2O, predicting soil response to changes in climate or land use is central to understanding and managing N2O. In a global field survey of N2O emissions and potential driving factors across a wide range of organic soils, we find that N2O flux can be predicted by models incorporating soil nitrate concentration (NO3-), water content and temperature. N2O emissions increases asymptotically with NO3-and follows a bell-shaped distribution with water content. Combining the two functions explains 72% of N2O emission from all organic soils. Above 5 mg NO3--N kg-1, either draining wet soils or irrigating well-drained soils increases N2O emission by orders of magnitude. As soil temperature together with NO3- explains 69% of N2O emission, tropical wetlands should be a priority for N2O management. 2018-01-01T00:00:00Z Mander, Ülo Pärn, Jaan Espenberg, Mikk https://datadoi.ee/handle/33/620 Estonian wetland forest Mander, Ülo Nitrous oxide observations from the soil, stems and ecosystem (eddy covariance), meteorological and soil chemical measurements in the Agali experimental forest, Estonia, 2017-2019 2021-01-01T00:00:00Z Mander, Ülo