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Seedeiche stellen nicht nur ein wichtiges Küstenschutzelement, sondern gleichzeitig auch ein Ökosystem dar, das wertvolle Ökosystemleistungen mit sich bringen kann. Ziel des EcoDike-Projektes war es, Ansätze und Methoden zur ökologischen Aufwertung von See-deichen unter Bewahrung der Deichsicherheit zu erarbeiten und wissenschaftlich zu unter-suchen, um schlussendlich Empfehlungen für ökologisch aufgewertete und ökosystemfördernde Seedeiche zusammenzustellen. Dabei haben die Deichsicherheit und somit die Küstenschutzfunktion des Deiches weiterhin oberste Priorität. Möglichkeiten zur ökologischen Aufwertung von Seedeichsystemen stellen (i) die Förderung von natürlichen oder naturbasierten Lösungen im Vorland, z. B. Vorlandvegetation, und (ii) eine angepasste Gestaltung des Deichbauwerks selbst, z. B. durch Begrünung mit ökologisch wertvollerer Deichvegetation, dar. Bei der Untersuchung der Interaktion von hydrodynamischen Prozessen und Vorlandökosystemen wurden neue Methoden zur Parametrisierung von Vorlandvegetation entwickelt und neue Erkenntnisse zur Reduktion von Wellenbelastungen an Seedeichen durch Vegetation gewonnen. Der ökologische Wert der Deichdeckschicht kann durch Verwendung ökologisch wertvollerer Vegetation, insbesondere Kräutern und Leguminosen, erhöht werden. Hierbei ist der Erosionsschutz der Deckschicht weiterhin zu gewährleisten. Anhand von physikalischen Modellversuchen, in-situ Tests und Laboranalysen konnte neues Wissen zur Etablierung, dem ökologischen Wert und dem Erosionswiderstand verschiedener Vegetationen unter Küstenbedingungen erlangt werden. Bestehende Deichmonitoring- und Deichunterhaltungsstrategien wurden analysiert und neue in-situ-Tests und Bewertungsschemata entwickelt und erprobt., Grüne Seedeiche, Ökologische Aufwertung, Naturbasierte Methoden, Deichvegetation, Wellen-Vegetations-Interaktion, Deichunterhaltung, Ökotoxikologie, Ökosystemleistungen, green sea dikes, ecological enhancement, nature-based solutions, dike vegetation, wave-vegetation-interaction, dike maintenance, ecotoxicology, ecosystem services, Sea dikes are not only an important coastal protection element, but also represent an ecosystem that can supply valuable ecosystem services. The objective of the project EcoDike was to develop and investigate methods and approaches for ecological enhancements of sea dikes and finally compile recommendations for ecologically enhanced and ecosystem-supporting sea dikes. The dike safety, however, and with this the coastal protection function still have highest priority. Options for ecological enhancement of sea dikes were found by (i) supporting natural or nature-based solutions in the foreshore, e.g. foreshore vegetation, and (ii) enhancing the dike structure itself, e.g. with ecologically more valuable sea dike vegetation. Investigating the interaction of hydrodynamic processes and foreshore vegetation, new methods for vegetation parameterization were developed and new insights into reduction of wave loads on sea dikes due to foreshore vegetation were gained. The ecological value of dike covers can be enhanced by applying ecologically more valuable vegetation, especially herbs and legumes. In doing so, the erosion protection of the dike cover has to be maintained. With physical model tests, in-situ tests and laboratory analyses, new knowledge on vegetation establishment, ecological value and erosion resistance of different vegetations under coastal conditions was acquired. Monitoring and maintenance strategies were analyzed and in-situ tests and evaluation schemes were developed and tested.

Increasing sward phytodiversity has been suggested as having potential to increase primary production of grasslands, but whether any such gains are converted into secondary production, through improved performance of grazing livestock, remains uncertain. Animal production by cattle and sheep can also be enhanced by mixed-grazing. To our knowledge, this effect has never been studied in relation to differences in sward phytodiversity. Therefore, a rotational grazing experiment was conducted over 5 years (2007–2011) on permanent grassland in Germany using sheep and cattle in mono- (single-species) or mixed-grazing of swards differing in plant species richness. Herbicides against dicotyledonous plant species were used to create different sward types: species-poor, grass-dominated swards in contrast to untreated “diverse” control swards. We found no differences in herbage production between the sward types. However, compared to the grass-dominated sward, the diverse sward showed greater concentrations of crude protein and lower contents of acid detergent fiber in the herbage dry-matter. Lamb live weight gains were slightly greater on the diverse-swards (P < 0.05), but calf performance was unaffected by sward type. Mixed-grazing increased daily average live weight gains of suckler cows (g cow⁻¹ d⁻¹) (P < 0.05) as well as area-related daily live weight gains (kg ha⁻¹ d⁻¹) and total live weight gains (kg ha⁻¹) during the complete grazing season (P < 0.001). This indicates advantages of combining livestock species, attributed to complementary pasture use. We suggest that mixed-grazing of cattle and sheep on phytodiverse swards is an effective and sustainable means to enhance ecological and agronomic traits such as livestock production and plant species conservation. Lamb production especially showed benefits under mixed-grazing, with a 17% increase in live weight gain. Compared to the grass-dominated sward, diverse swards resulted in an average 12% increase of live weight gains (across grazing systems and livestock species). Open-Access-Publikationsfonds 2020 peerReviewed

Biogas digestate (BD) is increasingly used as organic fertilizer, but has a high potential for NH3 losses. Its proposed injection into soils as a countermeasure has been suggested to promote the generation of N2O, leading to a potential trade-off. Furthermore, the effect of high nutrient concentrations on N2 losses as they may appear after injection of BD into soil has not yet been evaluated. Hence, we performed an incubation experiment with soil cores in a helium–oxygen atmosphere to examine the influence of soil substrate (loamy sand, clayey silt), water-filled pore space (WFPS; 35, 55, 75 %) and application rate (0, 17.6 and 35.2 mL BD per soil core, 250 cm3) on the emission of N2O, N2 and CO2 after the usage of high loads of BD. To determine the potential capacity for gaseous losses, we applied anaerobic conditions by purging with helium for the last 24 h of incubation. Immediate N2O and N2 emissions as well as the N2 ∕ (N2O+N2) product ratio depended on soil type and increased with WFPS, indicating a crucial role of soil gas diffusivity for the formation and emission of nitrogenous gases in agricultural soils. However, emissions did not increase with the application rate of BD. This is probably due to an inhibitory effect of the high NH4+ content of BD on nitrification. Our results suggest a larger potential for N2O formation immediately following BD injection in the fine-textured clayey silt compared to the coarse loamy sand. By contrast, the loamy sand showed a higher potential for N2 production under anaerobic conditions. Our results suggest that short-term N losses of N2O and N2 after injection may be higher than probable losses of NH3 following surface application of BD.