Flower reflectance and floral traits data from Ökologisch-Botanischer Garten (OBG), Germany.

Not all colours are perceived and interpreted equally. The electromagnetic spectrum is perceived differently by the distinct visual systems of animal species, resulting in differences in each species' colour perception. Given the diverse colours found in flowering plants, it is interesting to consider the colour perception of insects and the co-evolution of flowering plants to attract pollinators. Here, we considered the differences between human visual systems and that of bees and flies-the two largest insect pollinator groups. We collected flower reflectance spectral data of 73 species across seven human-perceived colours using a spectrophotometer. Minimum of 3 different flowers were used to measure the reflectance properties of flower colours. The raw data can be used to visualize the different animals' visual systems i.e. it can be processed and translated into known photoreceptors of human, bee, and fly visual systems. Overall, our data will help to compare how different animals see flower colours in the natural world and will also highlight the importance of understanding the interspecific communication in plant-pollinator communities. Thus, our data will assist scientists in the future to recognize the floral colour evolution in angiosperms.

Stable plant community biomass production despite species richness collapse under simulated extreme climate in the European Alps.

Direct observation of biodiversity loss in response to abrupt climate change can resolve fundamental questions about temporal community dynamics and clarify the controversial debate of biodiversity loss impacts on ecosystem functioning. We tracked local plant species loss and the corresponding change of aboveground biomass of native and non-native species by actively pushing mountain grassland ecosystems beyond their ecological thresholds in a five-year, multisite translocation experiment across the European Alps. Our results show that species loss (ranging from a 73 % to 94 % reduction in species richness) caused by simulated climate extremes (strong warming interacting with drought) did not decrease community biomass. Even without non-native species colonization, the community biomass of native species remained stable during native species richness collapse. Switching our research focus from local extinction in the face of climate change towards the beneficial impacts of persisting native species (in addition to novel plant-plant interactions) might yield insights on transformative opportunities for boosting climate resilience.

Linking changes in species composition and biomass in a globally distributed grassland experiment.

Global change drivers, such as anthropogenic nutrient inputs, are increasing globally. Nutrient deposition simultaneously alters plant biodiversity, species composition and ecosystem processes like aboveground biomass production. These changes are underpinned by species extinction, colonisation and shifting relative abundance. Here, we use the Price equation to quantify and link the contributions of species that are lost, gained or that persist to change in aboveground biomass in 59 experimental grassland sites. Under ambient (control) conditions, compositional and biomass turnover was high, and losses (i.e. local extinctions) were balanced by gains (i.e. colonisation). Under fertilisation, the decline in species richness resulted from increased species loss and decreases in species gained. Biomass increase under fertilisation resulted mostly from species that persist and to a lesser extent from species gained. Drivers of ecological change can interact relatively independently with diversity, composition and ecosystem processes and functions such as aboveground biomass due to the individual contributions of species lost, gained or persisting.

Fertilized graminoids intensify negative drought effects on grassland productivity.

Droughts can strongly affect grassland productivity and biodiversity, but responses differ widely. Nutrient availability may be a critical factor explaining this variation, but is often ignored in analyses of drought responses. Here, we used a standardized nutrient addition experiment covering 10 European grasslands to test if full-factorial nitrogen, phosphorus, and potassium addition affected plant community responses to inter-annual variation in drought stress and to the extreme summer drought of 2018 in Europe. We found that nutrient addition amplified detrimental drought effects on community aboveground biomass production. Drought effects also differed between functional groups, with a negative effect on graminoid but not forb biomass production. Our results imply that eutrophication in grasslands, which promotes dominance of drought-sensitive graminoids over forbs, amplifies detrimental drought effects. In terms of climate change adaptation, agricultural management would benefit from taking into account differential drought impacts on fertilized versus unfertilized grasslands, which differ in ecosystem services they provide to society.

Vegetation traits of pre-Alpine grasslands in southern Germany.

The data set contains information on aboveground vegetation traits of > 100 georeferenced locations within ten temperate pre-Alpine grassland plots in southern Germany. The grasslands were sampled in April 2018 for the following traits: bulk canopy height; weight of fresh and dry biomass; dry weight percentage of the plant functional types (PFT) non-green vegetation, legumes, non-leguminous forbs, and graminoids; total green area index (GAI) and PFT-specific GAI; plant water content; plant carbon and nitrogen content (community values and PFT-specific values); as well as leaf mass per area (LMA) of PFT. In addition, a species specific inventory of the plots was conducted in June 2020 and provides plot-level information on grassland type and plant species composition. The data set was obtained within the framework of the SUSALPS project ("Sustainable use of alpine and pre-alpine grassland soils in a changing climate"; https://www.susalps.de/ ) to provide in-situ data for the calibration and validation of remote sensing based models to estimate grassland traits.

Invader presence disrupts the stabilizing effect of species richness in plant community recovery after drought.

Higher biodiversity can stabilize the productivity and functioning of grassland communities when subjected to extreme climatic events. The positive biodiversity-stability relationship emerges via increased resistance and/or recovery to these events. However, invader presence might disrupt this diversity-stability relationship by altering biotic interactions. Investigating such disruptions is important given that invasion by non-native species and extreme climatic events are expected to increase in the future due to anthropogenic pressure. Here we present one of the first multisite invader × biodiversity × drought manipulation experiment to examine combined effects of biodiversity and invasion on drought resistance and recovery at three semi-natural grassland sites across Europe. The stability of biomass production to an extreme drought manipulation (100% rainfall reduction; BE: 88 days, BG: 85 days, DE: 76 days) was quantified in field mesocosms with a richness gradient of 1, 3, and 6 species and three invasion treatments (no invader, Lupinus polyphyllus, Senecio inaequidens). Our results suggest that biodiversity stabilized community productivity by increasing the ability of native species to recover from extreme drought events. However, invader presence turned the positive and stabilizing effects of diversity on native species recovery into a neutral relationship. This effect was independent of the two invader's own capacity to recover from an extreme drought event. In summary, we found that invader presence may disrupt how native community interactions lead to stability of ecosystems in response to extreme climatic events. Consequently, the interaction of three global change drivers, climate extremes, diversity decline, and invasive species, may exacerbate their effects on ecosystem functioning.