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The restoration of degraded arable land to species-rich and functional grasslands by sowing native species has been tested successfully, while studies on restoration considering land use interest and climate change challenges are underrepresented. In this five-year study, we focused on the process of restoring grassland biodiversity and biomass production under different fertilizer levels in the face of several years of under-averaged precipitation. In 2017, we sowed a species and forb-rich native seed mixture to establish a submontane Arrhenatherion grassland. We applied fertilizer treatments (0, 60, 120 kg N ha-1 y-1, combined with and without P and K fertilizing) in order to meet local farmers' demands on biomass for hay production with nature conservation goals that aim to promote a highly species-rich and functional grassland community. Our results show that sowing a high-diverse and forbs-rich mixture not only leads to a high species richness, but also to usable aboveground biomass production for animal feeding, even with below-average precipitation. However, the slight decline in species number and cover of sown forbs following the dry period in the first year after sowing indicates the sensitivity of less drought-resistant forbs. Due to the priority effects of sown species, no undesirable species have invaded the sward. The nitrogen treatments shifted the grass-forb ratio, with grasses dominating in the nitrogen enrichment treatments due to their increased competition ability, while forbs dominating in the non-nitrogen enrichment treatments. Biomass production was higher at the first cut than at the second, and non-nitrogen fertilized treatments had a lower biomass production compared to nitrogen fertilized treatments. Both grasses and forbs contributed to drought resilience related to biomass production, but forbs contributed relatively more in the first cut under moderate or no nitrogen fertilization and in the second cut only without nitrogen application. Biomass production was strongly determined by year, and thus precipitation. Under drought conditions, species-rich stands produced sufficient biomass even without nitrogen fertilization. In order to establish and maintain species and forb-rich grasslands on ex-arable land, nitrogen fertilization should be moderate at most. Six of the 44 sown species, namely Arrhenatherum elatius, Alopecurus pratensis, Dactylis glomerata, Poa pratensis, Centaurea jacea, and Trifolium pratense, contributed significantly to the biomass and could act as matrix species in climate-adapted high-diverse native seed mixtures for our study region.

Photovoltaics is one of the key technologies for reducing greenhouse gas emissions and achieving climate neutrality for Europe by 2050, which has led to the promotion of solar parks. These parks can span up to several hundred hectares, and grassland vegetation is usually created between and under the panels. Establishing species-rich grasslands using native seed mixtures can enhance a variety of ecosystem services, including pollination. We present an overall concept for designing native seed mixtures to promote pollinators, especially wild bees, in solar parks. It takes into account the specific site conditions, the small-scale modified conditions caused by the solar panels, and the requirement to avoid panel shading. We highlight the challenges and constraints resulting from the availability of species on the seed market. Furthermore, we provide an easy-to-use index for determining the value of native seed mixtures for wild bee enhancement and apply it as an example to several mixtures specifically designed for solar parks. The increased availability of regional seed would allow a more thorough consideration of pollinator-relevant traits when composing native seed mixtures, thereby enhancing ecosystem services associated with pollinators such as wild bees.

Renewable energy production will require large areas of land; production sites should be designed to include biodiversity conservation. Guidance for decision-makers on reasonable coexistence is needed. We use time-series data alongside a meta-study on birds in solar parks, utilizing succession theory to indicate which bird groups can thrive in solar parks. Using an evidence-based and interdisciplinary approach, we documented biodiversity and conditions at a 6 ha site in the newly created post-mining landscape of Lusatia, Germany, for 16 years, grouping avian species depending on the ecosystem state in which they were observed. In a key mid-period of early succession lasting eight years, the avifauna was characterized by successional groups 2, herbaceous plant-preferring, ground-breeding species; and 3, open shrub-preferring species. The preceding and following groups were: (1) pioneer bird species that prefer open ground; and (4), pre-forest species. Comparison of these data with available bird monitoring in solar parks showed that bird species of groups 2 and 3 can also successfully settle in open-space solar parks that have some natural habitat attributes, whereas this is hardly possible for the preceding and following groups. Using this information, opportunities for habitat improvement are facilitated, and potential conflicts can be addressed more purposefully.

Since alluvial meadows of river valleys of the Cnidion dubii are protected by the EU Habitats Directive, reconciling farmers’ demands for forage quality with the objective of maintaining them in good conservation status is an important issue in grassland research. In a long-term experiment from 2010 to 2018, we investigated the impact of fertilizing on forage quality and species assembly on a species-rich and twice-mown alluvial grassland in the Dessau Elbe floodplain (Germany). The experiment was composed of an unfertilized control, PK, N60, N60PK and N120PK applications. A significant improvement in forage quality was achieved by nitrogen fertilization only for crude protein, with higher feeding requirements for sheep met only in individual years. The legume cycle was inhibited by the application of nitrogen and high grass cover was maintained, but not increased, at the highest nitrogen application after an exceptional summer flood. The target forbs persisted in numbers over the study period in all treatments. For cover, the low-competitive target forbs responded neutrally to nitrogen fertilization, whereas detrimental effects were demonstrated for the competitive ones. Thus, we recommend not applying more than 60 kg year−1 of nitrogen and only in combination with phosphorus and potassium.