Riparian forests are assumed to play a crucial role in the global carbon cycle. However, little data are available on C stocks of floodplains in comparison to other terrestrial ecosystems. In this study, we quantified the C stocks of aboveground biomass and soils of riparian vegetation types at 76 sampling sites in the Donau‐Auen National Park in Austria. Based on our results and a remotely sensed vegetation map, we estimated total C stocks. Carbon stocks in soils (up to 354 t ha–1 within 1 m below surface) were huge compared to other terrestrial ecosystems. As expected, soils of different vegetation types showed different texture with a higher percentage of sandy soils at the softwood sites, while loamy soils prevailed at hardwood sites. Total C stocks of vegetation types were significantly different, but reflect differences in woody plant biomass rather than in soil C stocks. Mature hardwood and cottonwood forests proved to have significantly higher total C stocks (474 and 403 t ha–1, respectively) than young reforestations (217 t ha–1) and meadows (212 t ha–1). The C pools of softwood forests (356 t ha–1) ranged between those of hardwood/cottonwood forests and of reforestations/meadows. Our study proves the relevance of floodplains as possible C sinks, which should be increasingly taken into account for river management. Furthermore, we conclude that plant‐species distribution does not indicate the conditions of sedimentation and soil C sequestration over the time span of interest for the development of soil C stocks.

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Core Ideas The work describes the estimation of soil thermal conductivity (λ) from easily available soil data. Measured high‐resolution λ(θ) data were used to improve the accuracy of the model of Lu et al. (2014). Reliable pedotransfer functions estimated soil thermal conductivity of classes Sand, Silt and Loam. Good quality λ data need precise, quantitative measurements and accurate, model‐based estimations. Data of soil thermal conductivity (λ) covering the whole range of soil water content (θ) are needed in many environmental disciplines. However, laboratory measurements of λ(θ) are time consuming and costly. Therefore the use of pedotransfer functions is promising. In this study, we describe the procedure of deriving such λ(θ) pedotransfer functions for the FAO texture groups (TG) of Sand, Silt and Loam. First, high‐resolution λ(θ) measurements from saturation to dryness of 43 soils were conducted by two laboratory methods: the evaporation approach and single‐point measurements of λ at distinct water contents. Measurements were obtained for a set of sandy, silty, loamy, and clayey soils, and for two urban soils and two peat soils. The slope and magnitude of the λ(θ) curves show typical dependencies on bulk density (ρb) and soil texture. In a second step, the λ(θ) data were used to evaluate the λ(θ) model as suggested by Lu et al. (2014). Fitting this model to the complete data set yielded a poor agreement with RMSE = 0.53 W m‐1 K‐1. However, satisfying results were obtained by dividing the data into TGs Sand, Silt and Loam resulting in RMSEs of 0.18, 0.11 and 0.24 W m‐1 K‐1, respectively. Estimated λ values at low soil moisture (wilting point) were hardly different among texture classes, but λ differences become highly relevant when soil moisture increased to field capacity. The derived pedotransfer functions are an easy‐to‐use approach providing reliable λ(θ) curves for sandy, silty and loamy soils, when only basic soil information (texture and bulk density) are available.

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Im Rahmen des Förderprogrammes „Ressourceneffiziente Abwasserbeseitigung NRW“ des Ministeriums für Klimaschutz, Umwelt, Landwirtschaft, Natur- und Verbraucherschutz (MKULNV) wurde das Forschungs- und Entwicklungsvorhaben „LEIREV“ durchgeführt. Die Abkürzung steht für „Leistungsfähigkeit und Zustand langjährig betriebener dezentraler Regenwasserversickerungsanlagen“. LEIREV beinhaltete eine umfassende betriebliche, hydraulische und stoffliche Überprüfung von dezentralen Versickerungsmulden mit einer Laufzeit von mehr als zehn Jahren. Die Ergebnisse zeigen Defizite, deren Ursache oftmals in einer nicht ausreichend differenzierten Planung liegen. Die hydraulische Leistungsfähigkeit entspricht nach wie vor den Anforderungen nach DWA-A 138. Die stoffliche Belastung fällt dagegen differenziert aus, erhöhte Schadstoffgehalte treten häufig bei punktuellen Einläufen auf; in einigen Fällen sind diese aber auch auf unsachgemäßen Einbau oder fehlenden Abraum vorbelasteter Substrate oder Böden zurückzuführen.